Faulty Sony Walkman WM-FX43 REVISIT-Auto Reverse Not Working
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- čas přidán 26. 08. 2024
- Hi, this video is a revisit on the faulty Sony Walkman WM-FX43. The auto reverse is not working properly and it is just playing the same side backwards instead of playing the opposite side of the tape. With the help of the comments from the 1st video I try again to fix it.
Remember that this is just for entertainment and I am not an expert in these repairs. The processes in the video may not be the best way, the correct way or the safest way to fix these things.
I do love fault finding and trying to fix broken things so I hope that comes across in this 'Trying to FIX' series.
Many thanks, Vince.
Mate, you have firmly graduated from "trying to fix" and "don't know what I am doing" to Louis Rossman protege in a few videos. What with the schematics and whatnot. You're just a gem, sir!
Haha, it is shame that I don't understand them but I will still happily take the compliment. Thank you my friend :-)
@My Mate VINCE Nice Vince, if you continue this way you're going to convert yourself in an electronic technician :D
Checked again the schematics and the reverse mode works on the opposite way you think. When the cassette is playing on forward the pin 17 must be grounded. If you check the heads you can see that FWD ones are connected to pin 2 and 23, and if you check the datasheet of the LA4581 you can read "When connected to GND, PRE IN1R (pin 2) and IN2R (pin 23) turn on.", so the double transistor's base must be polarized positively when in fwd and tied to ground when in reverse, so pin17 will have 0v at forward and something over 0.2v when in reverse (REV condition: V17
Brilliant, I will have to go through your message a few times to take it all in but I will work through it and hopefully I will get there. Thanks for all the help in this :-)
@@Mymatevince Glad to help :D
Man You Should Start Your Own Tech Company Or Something
Sorry if I’m late but probably a broken leader on the circuit board as the transistor was ok. When you measured the transistor early on you’ve got some mega ohm. I think there the copper is broken. Try to fill with solder.
The day when i watched your 1st video was my best day of my ,,youtube,, life :D always when i am under pressure because of something, or when i am upset at something your videos always calm me and instantly i feel better
Excellent, well that is nice to hear :-)
Definitely a revisit is in order. I really enjoy you attempts and successes. It proves the old saying: nothing ventured, nothing gained. Please show you face on the video!
New series, trying to fix things with subscribers.
I love your videos and the help of the community of CZcams.
Fantastic progress Vince! Really pleased you revisited this! It could be that when the transistor switches you aren't getting a low enough level. In theory you might be able to get this working by adding a resistor between ground and pin 17. Are you sure the contacts on that switch are super super clean, it's the sort of thing that can effect the circuit - ie. whilst measuring as a short it could be say 10 ohms or something which would be too high.
Have you tried measuring the voltages on pin 17 to see what they are when switched either way? If the voltages there are OK, I would suspect that chip that handles the auto reverse - it's input isn't working as well as it should and needs pulling harder towards ground than the current circuit can do. Did you check R301? The resistor that leads from pin 17 to the double transistor? I wonder if its resistance has changed? The technique of pulling it nearer to ground to start with (or adjusting that resistor size there from 430K or whatever it is to say 330K) might get it working. I've seen the same sort of problem related to failing membranes (increased resistance) on the Atari 65XE keyboard (I did a video on that).
Wow, nice ideas Chris. This could be a perfect one for you as I feel I might have reached the limit of my ability on it. If GadgetUK164 feels like a challenge just let me know :-)
So.… from memory Pin 17 is measuring 0.44V no matter what position the auto reverse switch is in...….The Switch looks perfectly clean to me but I haven't put Deoxit on it so this could be a possibility...… I swapped R301 when I swapped the 3 components at the end so now R301 may be a different resistance than the original component. I haven't actually looked on the schematics to see the value of the one I changed it with so it may be lower or higher than the original value.
Really interesting ideas, thanks for sharing them :-)
No worries! If you do want to give up on this I can take a look! Drop me the schematics when you get a minute (or drop me a link) and I will take a look further - we can then theorise what could cause the behaviour.
Cheers Chris, I will email it over :-)
Re-re-visit means more walkman videos so that's a silver lining :D
Thank you for this video! I was able to fix my Sony Walkman WM-FX43 with the same problem! (for me the contact pins were bent, and when I moved them back together, I was able to get my auto-reverse working again)
Can't wait for the next revisit to hear your excitement after another successful repair! I was curious, would you be up to trying to repair a faulty inkjet printer? Those things are always failing for no apparent reason, with no useful technical support available.
Thanks, I never thought about a printer...I brought a typewriter to try and repair but a faulty inkjet printer could be interesting. Thanks for the tip :-)
With only a short look at what's on your screen in the video, I think this is how it works:
The left transistor in Q310 controls pin 17 voltage, the right transistor goes to the ribbon cable so presumably tells the door LCD to display the relevant direction.
When the Fwd/Rev witch is closed (reverse?) it connects battery voltage to the base of the left (and right) transistor in Q310. The Q310 package has internal resistors protecting the bases of the tranistors.
When battery voltage is on the base, the transistor turns on, effectively shorting the collector to the emitter, exactly like switching a switch on.
So base of the left transistor should have battery voltage (circa 3v?) and the other 2 pins should be ground (or near enough to it) when the Fwd/Rev switch is closed.
If no battery voltage at the base then the Fwd/Rev switch isn't delivering the battery voltage when closed and the switch is likely the problem. If battery voltage at the base and the collector isn't near (or at) ground then something is pulling the collector up, so try removing R301 (the 430K) and test left transistor collector again. If the collector is now at or near ground it might be the chip at fault. I saw when you ground pin 17 it worked so if after removing the 430k the transistor collector is at ground, you could try a smaller resistor in place of R301 until it works - but I'm not sure what other effects that might have. Wouldn't recommend shorting the pads of R301 as it might damage the chip but if it's a 'last chance' then it might be worth a try.
For the transistor on the right in Q310, when the Fwd/Rev switch is open, R316 and R317 are a voltage divider (10K and 100K), so the collector of the transistor should be around 2.7v, assuming the battery voltage is 3v. R319 looks like it pulls the base of the right side transistor to ground when the Fwd/Rev switch is open, so you should read 0v at the base.
When the switch is closed you'll have battery voltage (3v?) at the right transistor base and one side of resistor R316 should be battery voltage and the other side at ground (or near it). This voltage goes to what looks like the 4th pin from the left on the connector at the top centre of the on-screen schematic at 8:39. I'm presuming its the ribbon cable to the door.
Good luck. Very interesting pair of videos on this Walkman. Cheers.
Wow, this is exactly what I need. I will need to re read it quite a few times to fully understand it all :-) This is amazing...thank you :-)
Measuring the voltages at different points would help. Try the following table and see if the board meats the expected values:
Switch position Base T1/T2 Collector T2 Pin 17 LA4581 Collector T2
Expected Measured Expected Measured Expected Measured Expected Measured
FWD (switch closed) 2.4 V 0 V 0.1 V 0 V
RVS switch open) 0 V 0.4 V 0.4 V 2 V
Just noted the "Play" switch goes to the centre top connector and also Q308. If Battery voltage looks low at the switch/base of Q310 transistors then checking something in the door (assuming that connector is the door ribbon cable) isn't pulling down the voltage - i.e. does it work without the door connected? - but also the battery voltage seems to be supplied to the Play and Fwd/Rev switches through Q308, so that part of the circuit may be worth probing if "B+" at the switches looks low. Cheers.
Sorry for message after message but I'm interested :-) I just found the schematic and the Play and Fwd/Rev have connections to the door via the connector top centre marked K0 and K2. Both then go through diodes and into IC51 in the door. Is it coincidence that the "Play" switch line also connect to these lines (after the diode in the "Tuner board" door schematic) to button "PM1" and "PM6", which I presume are buttons 1 and 6?
So - if you've not already fixed it - do a quick check of the voltages as discussed before but I think a look around pins 46 and 48 of IC51 in the door (and the keypad) will probably be the issue. Water damage or dry/corroded connections?
Looking forward to the revisited revisit video. Cheers.
I agree with this, I think the issue is going to be on the other board, in the door, especially since it doesn't display PLAY properly without holding buttons one or six, and it's the play line which is being used to supply the voltage to switch the head input to the pre amp.
looks like the contacts supply power b+ to the base of transistor and shunts collector and emitter .Check. If you have voltage across the switch and. In the base
I have the same walkman with the same issue. I was able to fix it by spraying deoxit on the auto reverse mech and switching it back and forth a lot. now it plays tapes in both directions correctly.
The double transistor package is being used as two switches. Think of them as being closed switches when a voltage is applied to their bases and can operate individually. If the bases are connected together they will operate at the same time. So if you think of switches between the collector and emitter that operate when a base voltage is applied it makes it easier to understand. The collectors are at the top the emitters common at the bottom and each has a base into the sides. Yes they are NPN transistors. The leg with the arrow is the emitter and pointing out of the transistor is NPN pointing into the transistor would be PNP.
Thanks mate, just fixed my walkman based on this vid. ( Resoldered some capacitors and now works flawlessly)
I think Vince , you are a you tube genius , and have figured out the algorithm somehow ;-)
I am always so ecxited when there's a revisit video so fast! Didn't watch the video yet but felt like commenting. Fingers crossed!
That must have driven you mad Vince, but I'm sure you will fix it. Its normally the silliest of things too. Ive found that with electronics that I have worked on in the past. So when I get brain fog I leave it alone then go back to it at a later date and bingo that's when i normally find the problem. I'll go and do a bit of research and hopefully help you track it down. Kind regards. Paul.
Meggerohms and killerohms are my absolute favorites :D
Don't forget Big Clive's nanofarts!
At 10:40 where you were confused about the transistor pair, thinking it needs to "go up to the chip", it technically is.. The transistor pair are being used as a sink, to ground. When the transistor which pin 17 is connected to has voltage applied to its base, this will turn it on, and at that point pin 17 will get connected to ground through the transistor. When that transistor is not powered via the base, pin 17 will be disconnected, or "floating", as was referenced in the documentation
Love the channel, I love when you find the problem but you can't find the problem. it's fantastic I must say
Personally I'd prefer the ability to play tapes backwards over auto reverse.
It'd be pretty awesome if you did a live stream via twitch and use the live chat to get feedback, that way you can do investigations with instant commentary. The reason I suggest twitch is that youtube chat is absolutely terrible.
Alternatively you could create a discord server and we could all join and help you out, and just have general discussions.
@Jazzhandedly My comment was primarly regarding being able to talk directly with people - youtube chat is absolutely s**t.
Great video think your in the correct area you can measure Q310 with your meter on diode check. If you keep your red meter lead on the base on one side and the black on the emitter and then the collector it should read about the same either open or around 0.6 on your meter then if you swop your leads around Black on base you readings will swop around if any read short circuit or no reading both ways then you transistor is dead. You can then do the same with the other side of the transistor it should be the same. When the base gets a voltage around 0.6 volts it will conduct so when the switch is moved both those collectors will go to ground Zero volts. You could check that those two collectors change voltage when that switch is changed. You could do that with out the tape in possible but you might have to rock the take up reel so it things that a tape is present or it will stop.
Hope this helps at least it will tell you if the transistor is ok or not. I don't think your getting a voltage change on the base you would need to check that.
Thank you. I can try that later. I have never used diode mode before so thanks for explaining it. I think this will probably test ok because it would be unlikely to have the 2nd one that I swapped over faulty as well :-)
That's ok try it on a diode first to get the idea one way 0.6 ish and the other way very high reading but will varies because the part is in circuit. You can use this method to test any transistor PNP or NPN the results will just be opposite or diode.
Cool work Vince! I had discovered your channel just by now and I’m learning so much! It is so cool and calming to watch 🎀🎀🎀 I have an Walkman that is also a recorder too, I think is just like one you’ve showed in de 1st video, he is singing in his lowest voice 😭😭😭 I couldn’t find the video about the Walkman with volume problems, did you posted it?
Cheers 🌸🌸🌸
At 22:22 you effectively prove the transistor is working! by putting the +side of the capacitor onto to the base of the transistor and you hear the tape playing correctly!
So apparently there's no or not enough voltage at the base of the transisor when the switch is in reverse. There should be B+ (battery voltage) at the base in reverse you can measure that. And then trace back from the base through the play switch to Q308.
What are the voltages on base, collector and emmiter of Q308?
clicked off this so quick when he said there was a first video lol
Sub and press the bell to not miss any videos. :D
The head tape head isn't changing from bottom to the top when the reverse hits, If the tape is playing backwards which it looks like it is. You need to work out the line that's meant to swap the reading head to play reverse, So follow where ever you can from reading head back to components :)
That's exactly what he's been doing. It's the line from pin 17 on the pre amp chip, to the resistor and capacitor, and collector of the transistor, and from the fwd/rev switch to the base of the transistor he's been working on.
when you were shorting out the capacitors with the tape playing i noticed the ribbon cable looks like it's got a split on it near the right hand side. might be worth a relook
Thank you. Once I get all the messages in I will re open it again and I will double check the ribbon cable :-)
I'm going to toss in a thought from left field.. I think the way we have been looking at this is inverted, and it's not the heads/pre amp that are backwards.. According to the schematics, from both the walkman, and the pre amp chip, when the tape is playing forward, ie with the direction switch to the right, pin 17 should be grounded, which will pre amp the forward inputs. In your case it seems that pin 17 is not grounded, as when you manually grounded it, after switching the direction of the tape, it then switched the heads.
I am thinking that instead of the wrong heads being used when playing the tape in reverse (ie the direction switch to the left), that it's actually the opposite.. that the correct heads are being used when playing in reverse, but it's when you are putting the tape in normal/forward mode, that the wrong heads are being used (still using the reverse heads), and by you grounding pin 17, you are forcing it to use the forward heads instead of the reverse heads. This can probably be confirmed if you put in a tape where you know what content is on side A/B, I'll bet that when it's playing and sounding normal, it's playing the side of the tape that is on the bottom ie side B, rather than the top, side A, if you have side A facing you when you put it in.
Also, looking at the service manual, it shows that the display should show "FWD" or "REV" direction indicators, and the arrows are actually indicators for the fast forward/rewind, so that's another issue.
As a result of the LCD not showing PLAY, and having to push buttons 1 and/or 6, which I see join PC1 and/or PC2 from IC51, the system control/LCD driver chip, which connect to K0, which goes to the play button.. I think the fault is with the return of the 2.4v from the B+ line via K0, from the play button, which IC51 is trying to detect as a result of the play button being pressed, but when you are pressing 1 or 6, they supply 2.3v (from PC1/PC2) which is tricking the LCD into thinking it's detecting the play button via K0.
I would trace the B+ line, backwards from the play switch, to Q308. I'll bet there's something funny with Q308 not turning on, and there not being 2.4v being supplied to the play button. This would explain both why the play button is not being detected/displayed, and why the wrong heads are being used.
Thank you Simon for all the help on this. You were right with the 2.4v not being supplied to the play button. I am not sure if you have seen the Revisit Revisit video but there was a break in the trace under the Dolby Switch so voltage wasn't getting to that side of the board. I appreciate the help and suggestions you gave in this video as I learn a lot from the comments. Thanks mate :-)
I hadn't seen the rerevisit yet, which I just watched, and I'm really glad to see that you worked it out. That tiny break in the track, hiding under the switch.. Finding that was crazy. Really happy I could be of help too :-)
Had another thought for you Vince. Per the datasheet we know:
- When pin 17 is grounded, turn on pins 2 and 23, making the tape go in Forward
.
- When pin 17 is open, turn on pins 3 and 22, making the tape go in Reverse
.
What do you notice doesn't happen when you connect pin 17 to ground? The tape does not change direction but we hear audio correctly now.
We know that the motors haven't changed direction, despite the shorting of pin 17 but the way the tape is being read has.
Why is this? Hopefully someone knows.
Julian Biagi The tape doesn’t change direction because it’s already in reverse mode in that scenario.
@@AcornElectron Plus pin 17 is in reference to the tape heads and not the motor controls. My bad haha
@@thejudge34 when the switch is pressed, it closes the transistor, allowing power to be detected on #17, telling the IC to switch directions. I think it's a four-pot playback head, so two for each direction (left and right channel), so it doesn't need to change sides of the tape mechanically. when the tape changes direction it switches to side-B pair of read heads.
if the mechanism changes direction and the head doesn't switch to the side-B heads, it'll play side A in reverse.
I love your videos bro!
Thank you :-)
if i understood this correctly, the xn1215 transistor package turns on, as soon as a voltage of 0.25v is reached. B+ comes from base and goes to collector. Emitter should be ground. so its most likely R16 that doesn't let the transistors go into saturation, turning them on? Or R301 is open. Maybe.. *lol*
Or C302.. Yeah, I'm no help, heh.
No, not at all...It all helps. If gives me more options to look at :-) Thank you.
Vince tried replacing both R301 and C302, which made no difference. At that point I think it's something to do with the base of the transistor, and the B+ line/voltage.
The issue doesnt seem to be that the transistor isnt switching on, providing voltage to pin 17 of the fwd/reverse switch of the chip, it's more like when the transistor is off, theres no connection to ground. And the only connection to ground before pin 17 reaches the transistors is via C302.
Unless only one side of the double transitor is on when in forward or reverse play and one of them provides a connection to ground,
Which hot air station are you using bud. Keep the vids coming , really interesting
@Steven Hawkins Yeah Im kind of thinking/hoping its one of the cheaper ones as it seemed ok. Everyone talks about the Quick 861 but as a beginner and a hobbyist I dont really want to pay out £250 for general use
Correct Steven Hawkins :-) It is a 853D....I think it was approx. £80 from Amazon with next day delivery. It has served me OK so far. The times I struggle are with the soldering iron on thicker circuit boards. It doesn't seem to have the power behind it to keep the heat up when the thick board is sucking all the heat away. I was told you can change the inside of the soldering iron and it will fix the issue....But I haven't looked into it yet. I think for the beginner like me it is fine and it doesn't break the bank either :-)
@@Mymatevince Thanks Vince, I dont need the one with the iron on as I have a TS100 (really nice, small and firmare upgradeable ) So I can see just the hot Air stations 853D and 959D for about £40 so may buy one of those and give it a try as they all look similar . Thanks again
remember when trouble shooting always check voltages , you have the schematic and it shows voltages at the point you are working check to see if the voltage is present and correct is the voltage correct with the switch in either direction where does the voltage come from where does it go to
That tape needs a vacation!
The screws on mine are very tight. No way I can open it. Any suggestions? I don't want strip them
Just check that with the tape playing you have battery voltage on S301. If there isn't battery voltage on S301 then the transistor switch Q310 won't work. The battery voltage for both S301 and S302 is provided by Q308 that itself is switched by another of your dual transistors Q309 that detects whether its the tape or radio playing. Note the display is also being fed from S301, S302 and Q310 so without battery voltage being present the display will not properly display the functionality.
id say its a ground problem i noticed you didnt check continuity from the chip to the vea. i think there is either a broken trace for the ground i.e crack in the trace or maybe a bad soldier joint. but im 100% certain that the ground is broken so check continuity between the chip and ground. most likely throughout the years it has been dropped and cause the board to have a crack in its trace.
I agree that's also a possiblity! If the ground is floating somewhere that might account for the behaviour too.
OK, thanks for the suggestion, so I need to find a ground pin on the LA4581M chip and see if it shorts cleanly to ground. I like this idea :-)
@@MymatevinceThe ground pin on the Chip should have continuity to the ground where the vea is also should have ground to other parts on the board. I believe it doesn't also put your wire on the ground pin on the chip and send it to ground does it work? It could actually be grounding issue somewhere else also. So send ground to other parts of the board i noticed there some parts of the board that has horrible solder joints so reflow them and the chip.
Hey y’all, I got a question. So I bought the Sony WM-F2081 Walkman, and it plays just fine but if I play the tape in reverse. It plays for a few seconds then switches back to playing in the other direction. It’s auto reverse, I need your help, I was thinking that it was the main belt, but could it be more than that? Please help anyone!
The chip/s you exchanged are both perfectly fine Vince, Your diagnosis clearly confirms this via you sending the chip "That you thought was faulty" a signal to change states by "pulling it's input to low, thus Grounding a High voltage to a low or zero voltage, So when you grounded its input, the IC you swapped around behaved as it should.
Anyway if you follow it's input that you grounded, I would suspect the Logical Chip that is suppose to feed the swapped IC, is what is actually faulty, Mind you - It could also be any one of its supporting components that could be at fault if you replace it and it still misbehaves.
There has to be a faulty Chip that should feed a high signal and when you switch the direction a low signal to that swapped chip.
As usual I dropped a like Vince..
That makes sense, thank you :-)
In this case the chip has high or floating, vs low, and the design is using the floating state by default. It's Q310 which is being used to pull pin 17 low, but for some reason the left side of Q310 isn''t turning on, so pin 17 isn't being grounded to pull it low.
you can swap the xn1215 with two c945 tied at a common emitter and 100 ohmms at the base
My walkman does not fast forward with a cassette in it, any help?
Why Do I always have to think about a Disney Song when you say "Let it solder" 😂
Gosh, stubborn little raskal this walkman. I thought you had it there. Well, Lets wait for the revisit revisit then.
It is isn't it!!! Thanks for the great advice in the last video. I am hoping a viewer will have the magic answer :-)
Hello. Great videos as I found you about a week ago. I am not tech expert ok but I did notice the link for the inside workings etc for your machine was showing for a Sanyo unit? Are they the same running /circuit boards as the Sony Walkman? Just something I picked up on while watching your video but as I said I'm no expert when it comes to this sort of thing.
I love your videos
What kind of air gun are you using to unsolder the components?
Hi, it is a 853D solder rework station :-)
I need help with a wm-fx163 the motors wont spin but i can hear it trying to move
In general you have 2 networks. Audio and control. In this case you work yourself back from the audio out to the mixer/switch.
why not try bypassing the switch ?
Nice video
As it is making devil noises when you click the switch ...the only answer is to ask a priest to come and perform an exorcism.
lol
Got this one and just bought WMFX36 that i had in 1991and bought for $139 Australian
Is there any voltage on base of transistors? You can measure at switch contacts. If not than you focus on wrong side of circuit.
Also, component failure on low-voltage battery powered electronics? Maybe but my bet is stil on board crack or bad solder joint.
I am not sure but I can check this out. Thanks for the tips and suggestions:-)
Find a point on the board with a low voltage like half a volt and try touching that to the base of the transistor and see if that causes the head to switch tracks.
@@SimonQuigley using resistor of course, don't give him advice how to kill device's. All these poor Switches....RIP 😀😀
Well, I figured he'd be jumping it from an area on the board which already had a resistor
@@SimonQuigley yeah, you and I will do that but Vince stil didn't find time to take "basic electronics components and how not to kill them" class so you need to be specific with advices ;)
K0 and K2 go to the Micro-controller on the board with the tuner. K0 gets B+ or no B+ or 2.4 volts or no 2.4 volts. You could check to see if you are getting 2.4 volts on the B+ line. You could check if you are getting 2 volts at K2 when you are in reverse. I imagine a combination of K0 and K2 signal to the Micro-Controller fast forward, rewind, FWD or REV. Check the voltages around Q318 as per the schematic.
Excellent, thanks for the tips on the K0 and K2. I am having trouble finding Q318 on the schematic, could I have the grid reference or is it Q308 that I need to test for voltage? Thanks for the help :-)
Around F5 grid reference. The schematic indicates 2.4 or which I assume indicates the voltages around the transistor during different modes. The same goes for the base pin, it is either 2.5 Volts or 0 . The 2.5 on the emitter is always 2.5 volts so it doesn't have a set of brackets "". That is my best guess on how to interpret voltage on the schematic. If you are having trouble measuring parts you could solder a wire to a part and then measure the wire.
Oh, yes it's Q308
@@YUVYUV-fu5em Thank you :-)
I think this is the area to focus on. K0 comes from the front PCB, with either 2.4, or 0 volts on it, and goes directly to the play button. When the play button is closed/on, the 2.4v will go to the fwd/rev switch, and when this switch is on (presuming forward), it's going to supply 2.4v to the base of the transistor which pulls pin 17 low. When the fwd/rev switch is open (in rev?) then there's supposed to be 0 volts at the base of the transistor, turning it off, which should then allow pin 17 to float/go high, flipping the heads that the preamp is listening to, and the 2.4v from the play button (K0) will go via R316, where 2v goes to K2, and it looks like .4v must leak through the transistor pair to pin 17.
I would focus on measuring that there is 2.4v on K0, and then that there is 2.4v coming through the fwd/rev switch, when play is on, and that there is 2.4v on the base of Q310 or not, depending on the state of the fwd/rev switch. If there is screwy voltage on K0 or K2, this may explain why the front LCD doesn't display PLAY properly too.
Run wire from contact switch to ground try that
Try changing R317 (labeled 104) next to the double transistor. It's the only one you didn't change and the last component in that circuit you can try to change.
Julian Biagi the problem is all the other components around it. Vince should not melt any connectors again. Vince is already the Switch killer, I don’t want him to become the Walkman killer as well.
Always check for broken
Always check for. Broken trace on these older pcbs.
Time to go live Vince & get feed back at the time you get confused or need help 🤯
I'm still new electronics and at reading electrical schematics also but thought it would be good practice to look at this one. I think I was able to simplify to just the most important parts for pin 17 at halfdone.com/Offsite/MyMateVince-WM-FX43-auto-reverse.png and added some color coding. Also put in a redrawing of the circuit that would be easier to follow.
Assuming I'm reading it right, the Base of the NPN transistor is normally "pulled down" (via R319) to ground. This would make the transistor disconnect Collector from Emitter which makes pin 17 floating (not connected to anything).
When the auto-reverse switch is turned on, it will force the Base to be connected to Battery+. This would make the transistor connect Collector to Emitter which causes pin 17 to be "pulled down" to ground (via R301).
Fan of the channel! I'm still catching up on some of the older videos and looking forward to future repair challenges.
belt are on the wrong side of the wheel closest to the motor...
Use a small jumper wire to make the auto reverse work
Hi Vince,
at about 4:06 you said you are having constant 0.4 V at pin 17 of LA4581 even when swiching. After you swaped Q310 and some other components I presume this has not changed. You are expecting LA4581 to work fine but this does not need to be the case. You could short out R301 and check if this makes a difference. If so LA4581 might have an internal fault.
As 2001YUV 2001YUV already wrote IC51 (System Control etc.) gets a signal from the FRW/RVS area via K0 which is also connected to the button unit. So it might be worth having a closer look at the button unit and its connections to IC51 as well.
Jörg
After I saw the video a second time I realized that you swaped R301 with JR33 which if have seen this correctly means you might already have shortened R301. So you know IC301 works on pin 17 without R301 and Q310. You also know that Q310 is working because you swaped it and the tuner is working. This leads either to an open loop between IC301, R301 and Q310 or a fault within IC301.
BTW IC301 is always in revers condition while having 0.4 V on pin 17. So what really is going on is that FWD is not working.
Great info, so really I need to change back R301 and Q310 before I go any further as I didn't swap like for like!!!!!! This is really interesting as the top board did have evidence of a little bit of corrosion on it so maybe I am looking on the wrong board :-) Thanks for the help. I am looking forward to looking at this again as plenty of suggestions are coming in. Thank you.
Welcome!
You are looking at the correct board in terms of finding the fault for the FWD/RVS function. Try the table below to figure out what is going on in that part of the circuit.
Switch position Base T1/T2 Collector T2 Pin 17 LA4581 Collector T2
Expected Measured Expected Measured Expected Measured Expected Measured
FWD 2.4 V 0 V 0.1 V 0 V
RVS 0 V 0.4 V 0.4 V 2 V
(I hope the format will stay when I post this, but you will get the point)
K0 and K2 (as well as some buttons) are going to the µC on the tuner board and should indicate which state the device is in. If there is something faulty on these traces this would explain the wrong symbols/text on the display.
Sorry, one of the "Collector T2" in the table should be "Collector T1"...
@@Mymatevince I noted that also. The schematic says R301 should be 430k and JR33 should be a short. However as both have no markings I think you have a different board revision than as shown in the schematic (there is also only 1 capacitor on the schematic next to Q310 whereas your board has 2 capacitors) and in fact they will both be jumpers. Measure them with the ohm meter, either one will be 430k and the other a short or they will both be shorts. You don't need to change Q310 again, it's the same as the one you swapped.
Id throw in an itty bitty microswitch that the reverse bar hits, ground pin17 and pretend i fixed it
:)
Could it be anything to do with that capacitor that was 'swollen'?
Which one was that Emma, I didn't see it? Thanks:-)
My bad. In the 1st vid I thought you said 'one was swollen' but on looking again at 7 mins in 1st vid you actually say none are swollen.
If you look at the schematic, you will see that there is a capacitor, C302, connected to the line going to pin 17. C302 is connected to the emitter side of the transistor. You might want to find and test that capacitor.
Thanks, I did swap out C302 when I swapped out the 3 components at the end. But I just matched the colour and not the spec so it may be a different spec to what was originally there.
You say at 11.22 that you think the current should be going up to the chip. Let me explain the 3 types of current classifications.
The first most common which everyone uses is conventional current. Conventional current says that electrons flow from positive to the negative. This is wrong. Conventional current is how we used to think current flowed.
The second is electron current. An electron is a negatively charged particle on a atom. Since it is negatively charged like a negative pole on a magnet it is attracted to positive. This is the actual flow of electricity.
The last kind of current is hole current and doesn't really exist. When an electron jumps from one atom to the next.Before it gets to the next atom. There is a space or hole in the atom left by the electron jumping.When you look at a string of atoms it appears that the holes are moving from the positive to the negative. They aren't because nothing can't be moved and what we see is just an optical illusion.
At 23:36 you test the transistor on ohms. A transistor should be tested on diode test/continuity. A transistor is two diodes. One between the base and collector and one between base and emitter. In case you don't know how to test a diode. With the meter set to continuity a diode will only read one way out of circuit. In circuit you will find one way you get a low reading since it is going through the diode and the other way you will get a high reading since the electricity cant go through the diode so has to find a path back to the other probe through the rest of the circuit.
At 33.05 once you have swapped the transistors over and it still doesn't work. the problem is something connected to the base as when you short the collector and emitter together it works. So something isn't sending power to the base making the transistor switch. Looking at the schematic provided by geniwab one base is connected to R319 which is a 10KΩ resistor. My first thought are that this is more than likely not faulty. The other base is connected via the switch to Q308 and the base of this is controlled by Q309. One of these two transistors are more than likely faulty.
Thanks for the detailed replies. I have never used Diode mode on the multimeter before so I will have to learn it. Between your comment and another earlier one I should be able to understand it :-) The R319 was swapped with another one of the same value so I think that should have eliminated that component. I also swapped out Q309 with Q310 so again I think if it was faulty maybe a different issue would have showed up, but maybe not. Maybe testing them in Diode mode will show up something. On Q308 I have tested it for continuity and it appears to be OK. Once I get some more suggests in I will open it up again and do further testing with the suggestions given on here and hopefully it might be successful. Thanks for taking the time to comment :-)
@@Mymatevince on diode test it reads 0.000v for a short circuit and OL(or 1 depending on your meter) for open circuit. on a diode on a old motherboard that I have laying around. One way it reads 0.19v and the other way it reads OL(because there is no path the electricity from the meter probe can take to reach the other probe). On another diode it may read 0.2v one way and the other way 0.6v(because there is a path that the electricity from the meter probe can take to reach the other probe). Basically your just looking for a low reading one way and a high reading the other way. A transistor is just two diodes connected at the base. So from the base to the collector it reads low one way and high the other. The same when you test between base and emitter you get low reading one way and a high reading the other way. Just to make sure the transistor is fine you also test for a short between the collector and emitter.
There are two main kinds of transistors a PNP and a NPN the only difference is that the diodes are turned round. So on one type you get a low reading with the positive probe on the base and the negative probe on the collector/emitter and on the other type you get a low reading with the negative probe on the base and the positive probe on the collector/emitter.
Thanks PDS, that does makes sense to me. Thanks for explaining it in a simple way that myself and other people new to electronics will understand. Enjoy the weekend :-)
Just throwing it out there; and maybe I missed it, my kids kept coming in and asking questions; what would happen if you just attached a wire from the ground to the pin somewhere? could you just solider it and call it a day?
That is exactly what I thought but it won't work because then when I switch the auto reverse back it then plays it backwards again. So I have the same problem as I started with but with the switch in the down position instead of up :-)
That's a bummer... I'm more of an amateur than you and I love watching your channel! I'll keep thinking on this one! Great work!
Thanks mate :-)
Why can't they just use a simple mechanical switch to choose the the proper tracks. That's the way they used to do it.
The head has two sides, one for A side, the other for B side. A or B are not switching on. I think it is a cap or resistor.
Check the diodes, there are two of them. One of the heads is not turning on. The same side stays on, instead of switching.
I think I see them (D102 and D202) , either side of that double transistor (Q310). I can check them. Thanks for the help :-)
hi
First Super Fan Here
Hi everyone I hope you guys enjoy this vid and I hope you guys might enjoy my vids give it a try plz
Hi VINCE I have a faulty ps4 I no longer need if you are interested in it
Shoot, if he dont want it I'll make a video on it!!! lol
Thanks for the offer paulstarr15 but I have some much 'fixes' to get through at the moment so I will pass up on the kind offer :-) Cheers for asking though.
@@Mymatevince ok no problem
3rd great fan here
Change the Big capacitors there not feeding enough voltage to the ic 😳
Please get a decent tape.
Try this link for the part you are looking for www.cricklewoodelectronics.com/LA4581M.html
Thanks for the link, nice and cheap and a local company :-)
Maybe in the switch itself...
First
Can you fix rotten potatoes
It's the big chip you think is good