Radio Repair - bad vacuum fluorescent display (VFD)
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- čas přidán 21. 09. 2012
- Write up summary at my blog site: www.toddfun.com/2012/09/22/rad...
This is an epic video on all my efforts to fix my radio out of my 1994 Jeep Grand Cherokee. It is a limited edition Jeep with a very nice CD/Radio sound system but for about 10 years now the vacuum fluorescent display (VFD) has been dead although the radio and CD work fine. This meant my only headache was I never knew what station I was on. But after setting the stations who cares, right? Well it drove my daughter nuts because she likes to channel surf and after having the battery disconnected it was a challenge to find and set the stations again. - Věda a technologie
I really thought you were going to just give up when that replacement chip didn't work.... Well done Todd. I really enjoy the fact you continually tell the viewer what your thought process is while you work. Thanks for sharing.
Any repair is preferable to most people's reflex of tossing it and buying another one, though I'm not usually able to fix surface mount stuff. Now that I've seen you do it, I'll give it a try next time. Very cool shop you have there too. I'd never even heard of a hot air rework station.
35:40 Legend has it that radio is still searching for a station to this day.
Excellent, I'm chuffed to hear that your son is having fun with the meter...it's certainly a great way of learning without even realising it. Cheers, Martin.
Hats off to you Todd. Great demonstration and video.
Brilliant project, so many people would have just gone out & bought a new radio. Thanks it is very interesting to watch you work.
Very much enjoyed it. Watched the whole thing. This video is the video that finally opened my eyes to the realities and limitations of working with electronics. It was a real blessing. Thanks from Texas!
Wow, you are both patient and persistent! This was a really great video to watch. Thanks for sharing your repair adventure :)
Thank you for making this excellent video. Great job on explaining your logic in troubleshooting. Hopefully, your daughter appreciates your effort to make her happy with the radio display.
Your troubleshooting is legend. You inspired me to work on mine, with great results, thanks!
Thanks for sharing. I like the way you troubleshoot and do your repairs.
Really enjoyed this video. 3000gt's have a climate control display that is a VFD that are always going out. Myself and others have replaced nearly every component on the display only to find out that the display will work for a few minutes until the 1 ohm 1 watt resistor/fuse burns up. I appreciated seeing power it up offline and demonstrate your techniques. Thank You
Awesome video. I loved watching the troubleshooting steps and the "hack" was nice. The overriding thing it taught me was that I cannot repair my radio display. I do not have those skills. So now I just have to figure out what I'm going to do about the display. So, thanks for saving me the time and trouble of taking the thing out and messing with it.
I'm having the same problem with the exact radio in my Jeep. Loved the video! Was entertained the whole time and enjoyed following your troubleshooting process.
Thanks! My fix worked for me for quite some time but now I have upgraded the radio to a Kenwood that works with my iPhone.
Nice work around and a great effort.
You can always add another resistor to dim it more for night operation and enable with a small switch on the face plate somewhere
I've had a semi dead display for 9 years. you could push on the bottom left corner of the display and it'd come on for a couple seconds. I watched your video and took it apart and discovered that 3 of the power pins had lifted out of the solder. resoldered and working on the first try. thanks.
futurefesty90 glad to have helped. Mine is still working 100%
Todd Harrison Say, what would be the easiest/cheapest way to run 12v power on my work bench? I don't really have the money for an expensive power supply
If you are working on circuits that are not noise sensitive this is a good option: www.circuitspecialists.com/multi-output-power-supply-ps-28.html
If you are working on video, audio or signal circuits you will want to avoid this cheap supply unless you can build a filter for it first.
thats a nice radio! my '94 grand cherokee laredo had every option but the factory infinity sound system. it had the am-fm-cassette with 4 speakers, but all that was replaced by a sony cd player and pioneer speakers. the cassette player and radio combo barely functioned when i took the radio and speakers out and replaced them.
@Laharl, We think alike. I had setup a LM317 first but found you can't dial them down that low. I didn't try a 7805 like that but it would have worked just as you say. A big old fat ceramic resistor worked just fine I guess.
Good on you, Todd. This reminds me that I have a Tektronics scope with a weird little VFD display integrated multimeter, and the VFD is so dim it's barely usable.
I thought this was awesome! I really like the step by step process of elimination, it really helps beginners like me.
it's amazing how the simplest repair are the best :)
Great video Todd, Your presentation is fine. thanks for sharing.
Really cool my radio stopped working altogether and I took it apart and metered some components but it's to advanced for my abilities. Thank you for making this video it was very interesting and informative.
Nice work. I enjoyed the video. Bummer on the parts swap not working. Great rework job.
Good video! I have noticed that VFDs that don't break and last for years eventually succumb to fade. The brightness decays, very slightly for a long time, then gets worse quickly. I have 2 VFDs in my 2004 Suburban, and noticed over time that I've had to turn the brightness dial up every so often. They're now (March 2019) reaching the point where the dial is maxing out and the displays are going fast, will be only a matter of months till they're like the radio. I'm presuming the Jeep radio faded out. Pre-1999, CRT TVs also could fail this way, as the picture tube cathode can also fade, making the TV picture darken and eventually no picture. I recall this TV repair guy installing a "booster" that gave us like 2-3 years. But ultimately the VFD itself has to be replaced.
this VFD's good for electrical and magnetic usage so this is very nice work
Отлично. Я то сначала подумал, что дисплей нерабочий. И удивился, когда увидел исполнение чипов на второй плате под индикатором. Я работаю с профессиональной электроникой, и данный вариант исполнения монтажа характерен для серьезных производителей электронных устройств. И еще скажу: данный вид индикаторов весьма распространен в промышленных аппаратах разного назначения, включая кофемашины :)
I have picked up 5 Pomona cable holders after knowing your reviews, and they have been very useful. I am using Hakko desoldering gun, it have been a workhorse. I think the elexp can be a good add-on for tougher joints. Thanks.
Иногда оловоотсосный прибор невозможно использовать- он рвет монтаж при распайке и я его практически не использую. Для этого у меня в мастерской стоит компрессор с большим ресивером для мягкости дуновения. Я просто дую в раскаленное олово и оно прекрасно потом убирается. Привет из Москвы!
Wow that is a nicely made radio! :D
Really nice informative video, I was looking into the history of car radio's and vacuum fluorescent display's . found out some where made in the 70's because I had a 76 mustang, but by the
1980's 100 of millions were built. And like you said they work simular to a triad tube filament (heater) the Grid and the phospher coated carbon Anode.
Nice dual power source I want one for christmas.
True. Keep me updated! Fun stuff.
Nice work! Also you could have fixed that with a PWM regulator, a small coil, couple resistors, and perhaps even hook the Light input into it to manage night power. But hey, who am I to say, all I did is watch. Great job...
Good ideas. Thanks for sharing.
Haven't worked on that many VFD's, but where did the filament supply go? When you supplied it external, the thing worked. Maybe an open resistor somewhere? Back on the main board maybe?
Thank you for the video. I think you should keep doing this kind of stuff, a lot of people like me enjoy watching it! By the way, maybe you could cut the board trace to avoid any back current, just in case. Anyway, nice solution Tod!
I am glad you got it working but that is a big resistor. you had 3.4 volts on the display panel. Just wounder if it might have been better to to the 3.4 volts down to 1 volt?
I learned what is electronic from you Todd, thanks
Glaiza Jake Glad to help a little.
Something to add. A cars operating voltage isn't 12 V, it is typically in the range of 13.8 / 14.4 . We just call it 12 V because a fully charged lead acid battery is 12.66 at rest, the higher voltage is needed to keep the battery at a 100% state of charge.
True, Thanks
That's a fair worry. I suppose if there was enough time, checking if it uses one of those ubiquitous LM7805 regulators and test how much current it was handling to see if you could suck a few more ma from it safely. I like the idea you had in the video about adding a LM317 for it.
Love those Fluke meters, especially the model 87 :)
really amazing job! respect!
Thanks for the reply, I'll probably just keep using it for awhile. I think we've got about 7 or 8 bottles left. :)
if you build in a µController that regulate the Voltage down to the 1Volt so you have a lot of disturbance inside the Radio. Use a Stepdownconverter this will have a low temperatur inside the Radio and a good regulation for your VLD.
Flames? As soon as you hooked up the supply and saw life, I thought, "meh, just drop the voltage of the ignition supply and be done with it". I guess I'm lazy, but this seems to be a solution that matches the value of the problem. I was actually surprised you tried for a 'proper' solution first.
Thanks, the video was informative and fun to watch.
I'm repairing a VFD on an older Jeep VIC display myself ('94) and have it down to a bad driver chip also. Can't find a source for the chips though. :( Very nice video and repair bench.
hey todd i was just thinking, wouldnt a lm7805 as a current regulator have worked better than the big chunky resistor? you would have the 7805 burning 7x0.1=0.7 wats and the corrent limiter resistor only half a watt. You could just wirewrap them together and then solder the wires just like the resistor. Not sure about the price, but i think it's almost the same, plus you get CC and the load is shared between the TO220 and the resistor, and also the 7805 has thermal protection.
Nice hack Todd. I have a question though, since there was a 5 volt rail, why not use that to drop down to your 1 volt required?
Good luck friend 👍👍👍👍👍 keep spirit
Thanks for great video.
Instead of a resistor, you can use the 5V on the front in series with six silicon diodes. The diodes will drop 4.2V, leaving 0.8V for the filament. 1N4001 diodes can handle 1A, more than enough for the 100ma the filament is using. The diode string will dissipate 420mw.
Any idea if that GC flux is any good? That's the same brand I've been using at work. Not sure if I'm using something that's relatively good or not for the price we've been getting it at. Thanks, Rob.
Your solution is "Crude, but efficient" as Seven Of Nine once said... ;-) Cheers
Couldn't you hook up the power to the ILLUM pin, which on my Plymouth minivan is a 0-12V source that changes with the dimmer switch on the dashboard? That way the screen would dim properly. Would still be hackneyed, but whatever.
the voltage is around 3 volts just till the heaters glow slightly in a dark room. running the heaters lower will destroy the display just like a vacuum tube heaters low will damage vacuum tubes. I have used a 3 terminal 3.3 volt regulator worked well.
just a quick question, does the radio still work to this day and is the display still working fine. or did you get a new radio?
ill be honest I think you did well with this.
chip swop failed but crap happens.
wow...would like to have a shop similar to yours with the latest and also old-school equipment, so i can know both. What would you suggest I have (and must-have), from the basics to the somewhat sophisticated, in my shop, how large a workspace, and on average how much does it cost to get a relatively modern, workshop? How much does yours cost, if you put a price tag on it, and if you dont mind my asking?
will your display handle 1.2A for 0.4 seconds? You can easily get 120V pulses in a 12V system car. It's called a "load dump" - you can google for it. So the resistor alone is not such a good idea, but well.. it's just a radio :)
It fought you at every turn, (as some things do), but you won :) Cool! I also valued the soldering lesson.
You welcome. And thanks. it was stubborn. I have since learned that a VFD with this problem can be fixed by just apply 9v DC across the cathode wires for a count of ten. This heats up the cathode filaments and cleans them. Then the display will come back to normal brightness. I never tried it but sounds like it would have worked too.
need your help buddy..i have a Pioneer DEH-P4000UB,radio in my car & its has 4 channels,2 of my channels stoped working..how can i fix this??thank you for your help pal.
Hi, I wonder how to determine the positive terminal of the display. I have the same problem but just newer model radio. Thanks
I would think you could just use a DMM.
Even though you didn't use the regulator as a solution for getting your 1V power supply, Check out Dave's EEVBlog videos on power supply design, he has some tricks to getting an LM317 down to under 1V.
@Tony, OK, I guess that counts as helping too. :)
Hi
Enjoy watching the video.
Anyway,How to increase the brightness of vfd?
And What is the reason for the negative voltage in this panel?
My panel works with -34 volts. ( pioneer mcs 737) How is it possible?
I have a question. There is a problem if this low 4 volt voltage is Always constant? Is there a problem with the screen burning?
Common VFD filament (anode) voltages are 1V, 3.3V, 5V, and 6.3V. Most car based and battery portable VFD displays are 1V. Every one I've seen uses a power resistor from the 5V to the filament. When the radio is off it turns off the 5V.
Todd why didn’t you measure the power from one of the other lights on the front of radio and tap into them? I’m sure they were running a lower voltage. But like you said it works.
good point. I'll have to do that next time.
Todd, I have an old TOTL JVC S-VHS player that has a dim display. It has -30V and 5vAC going into the display driver chip and I read that you can recover the brightness by increase the voltage to 'wake up' the display for a few seconds. What voltage am I increasing, the -30V or the 5VAC?
I have heard of this where you put a higher voltage load across the horizontal tungsten wires. Read "Fading" section here: en.wikipedia.org/wiki/Vacuum_fluorescent_display
I have seen this video too: czcams.com/video/-rrP4Prx1rc/video.html
Note there are many different types of VFD drive circuit. You have to know what are the input(s) for the horizontal tungsten wires and what are the output(s) of the horizontal tungsten wires in the display.
Ive got the opposite problem, although its not a car stereo, its a JVC shelf hifi, but the display being a Vacuum Flourescent Display is ALL lit up, every segment in the VFD is on, so im figuring that it must also be the driver chip thats gone. its a PT6324-HT. Now tryuing to locate the part is goign to be a challenge.......
ACC is not Auxiliary. It's ACCessory which is the part of the ignition cycle that turns on the electrical components.
Yes, ACC is the first click position you reach after inserting the key and begin turning. (The 2nd is "run" and the 3rd is "start").
that's a very helpful way to fix the radio, what's the year and model of Jeep?
Sonic Dash 1994 Grand Cherokee Limited Edition.
*****
cool
I have sony mhc p99x.125w small mini ...its fan does nt work and it gets hot around 60..70 C. can i use computer fan? will it burn if fan is not working?
What's the desoldering iron you are using?
that pin labelled park is supposed to be connected to ground when the hand brake is applied .... this normally enables some features that can other wise distract the driver from driving... my Sony head unit let's play dvds and videos though the video output when park is enabled!!....
It seems that the chip isn't providing enough voltage for the filaments. The filaments should be getting more like 4.5-5.2 volts. I would desolder the lead and connect +5v to it through a small resistor.
+douro20
I dunno, I've seen VFDs that only need like 2.5v for the filaments. I think it varies from display to display (different models of course).
nice video .. had lots of great info!
@azsitemaster, Thanks
Good job!! I have the same radio, but some components are burned, do you know what’s the value for L903?, the inductor next to the transformers.
I hope you can help me
Sorry I have recently replaced that radio with an after market model that works with my phone.
I used the 5 (1/4 Watt) resistors and it worked perfectly
Good to know. Thanks!
I wouldn't mind knowing where I could order one from, it'd be really handy.
Good luck sir....
Have you tried finding the chip online?
Nice video Todd. Real nice cheap answer to getting the display going. The repair has to be balanced against the cost of the radio.
I noticed you had a nice PSU there with large LCD displays, was that very expensive? What is its spec?
Anyhow I enjoyed the video, thanks for that... Mike
Michael Hawthorne It is ok, but I really don't like the over current protection. It works but it hard to set and you never really know if it is set right without checking it often, plus the setting goes away when you restart. It is this one: www.circuitspecialists.com/bench-power-supply-csi3005xiii.html
But I would get the one Dave Jones last review if I wanted something better at a price I might be able to afford someday: www.eevblog.com/2013/11/19/eevblog-549-rigol-dp832-lab-power-supply-followup/
You have a lab my friend so accurate job
Thanks
Good video, learned a lot, trying to learn electronics at home :). And nice t-shirt. Where did you get it?
T from EEVblog and if you want a ton of links for beginners checkout my menu item for beginners at ToddFun (dot) com. That will keep you busy until next year sometime.
I took principles of technology and electronics 1 and 2 in the mid 90's and really regret not having furthered my education
It fought you at every turn, (as some things do), but you won :) Cool!
yes. Thanks!
That really cool.
Nice repair
Thanks 👍
I was just looking at your theory at 33:45 about using X5 - 550ohm 1/4w resistors in parallel to get the 110ohms and 1.25W. Correct me if im wrong, but resistance does not drop if you put them in parallel, you will still have 550ohms of resistance but you will now have the 1.25W required. you would still need to have X5 - 110ohm X 1/4W resistors to get the 1.25W required.
BTW Great tutorial, very interesting.
Nope. Resistors in parallel will drop overall resistance. Resistors in series will increase overall resistance. Thanks for watching and glad to help.
I remember that now, it's been a few years since I have done component level troubleshooting, calibrations in the military. Is over of those user it or loose it, and I have lost it but trying to get it back
Sorry for the typo, " it's one of those use it or loose it"
***** So true.
Very good video thanks.
Thanks!
Never mind my stupid comment. Was thinking of home equipment - not car. You're right on about duty cycle probably...
Repair cd? 🤔
It's the challenge. My display in this same radio just went out too, and I had a spare radio which is now in the car. And these are cheap on eBay. But I'm a HAM (W3AFC), and I like to repair things. Plus, an eBay radio could fail within a couple months.
Oldradioguy2 you'll have to let me know how your repair turns out. I'm curious to know if you came up with a better solution and/or have the same problem. Others have told me that I needed to come up with an alternating voltage across the grid in order to prevent dimming at one end of the display. My DC solution did produce dimming across the display and further research shows that these elements do need to be driven with an AC source. At least I learned something, that's the good part.
This gives me a clue. I Google this. I have a theory to what might be wrong with the original circuit. I noticed on the pin outs for some Vacuum Florescent Display driver chips, there are lines marked "clock" and "strobe". I wonder if one of these lines is missing its the input, leading to the chip not outputting its AC voltage for the anodes because it needs that signal from somewhere else. I would try looking to see if that signal is being generated elsewhere and where that is coming from (perhaps a transistor, another IC, crystal oscillator, the clock chip of its CPU, the radio oscillator, etc) and perhaps there is a cap or resistor bad in what is driving the signal for that pin. You might also see if there is any short or disconnect that is somehow falsely enabling the blanking pin on one of those chips (yes, they usually have a pin that turns the display off). It is pretty obvious that most of the data circuit is working correctly. I also wonder if the dimmer "lamp" pin is connected to another circuit that drives the blanking, strobe, or clock inputs somehow as part of its dimming method and that is causing the display to go black.
Doc Brown: "Unbelievable that this little piece of junk could be such a big problem......no wonder this circuit failed, it says made in Japan."
Marty: "What do you mean doc, all the best stuff is made in Japan."
Doc Brown: "Unbelievable."
Funny. Thanks.
I am not familiar with the Term via. Do You mean path?👀
It is a term that means the circuit traces on the the top of the board are connected to the circuit traces on the back of the board using a through hole drill and metal insert. Once soldered the two sides of the circuit are connected at that point.
This hack fits perfectly the ol' adage "Jeeps are built, not bought." Leave fancy buck converters to the X5 guys. :-)
i haveo the same radio but it does not turn on when i push the power button any idea thanks for the vid
Robert Mccaffrey bad fuse. check radio fuse or all fuses.
if i push the volume button the clock comes on and if i put a cd in it it just ejects it out and that is it is there anything i can try thanks
Robert Mccaffrey Nope, I wouldn't know of anything simple. You would have to get it repaired or replaced at this point. You can try www (dot) car-part (dot) com
good job!
Thanks for the nice comment! :)
i love tubes
and that is the firsth weared down vfd i saw
(posted in 1 30 sec)
excellent
Power supply repaired and chip from china came in looking good. Installed and the display is up again. Sadly only top half of all the characters are showing. Was fun to try, but probably won't put much more in the attempt. These things are a pain.
Watched the whole video ! Great job but that's too much for me lol