Diagnosing Portastudio Erase Problems | Tascam 488 Repair Report
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- čas přidán 30. 03. 2022
- I kept a video diary while repairing this Tascam 488.
Prior to filming, I'd already deep cleaned the unit, replaced the rubber parts and replaced the burned out control chip in the capstan motor - those steps brought the unit up to a point where I could thouroughly test it for more subtle electrical issues and think about calibrating the playback and record amplifiers.
I found the group faders were cuttign out and the play button was intermittently unresponsive - I was able to resolve these issues by introducing fresh solder to connections between the components and the circuit board.
Before coming to the conclusion that bad tape to head contact was causing an erase issue on one track, I went through a series of tests to establish the health of the erase head and the AC bias system, and I looked at the bias path on the schematic. I hope the footage is still useful for viewers wishing to understand how erase system on a portastudio works and how to troubleshoot it.
By the end of the video, I still haven't completely resolved the tape to head contact issue...I suspect this issue is due to a subtley warped plastic case? I say that becasue the variance in playback and recorded levels and erase performance is worse with the case shut than with it open; but for the sake of due dilligence I will be producing a follow-up video where I use the adjustment screws at the base of the magnetic heads to see whether that mitigates the issue.
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Beautiful stuff here, as per usual.
thank you for that repair report! i like your hand tattoo in form from a Diode. best wishes!
Tascam transport boards are soft and pressing tactile switches on the transport will eventually lift components and traces when you go to replace tactile switches with my experience mostly with the 2488 series harddrive recorders then things go wrong quickly.
It would be great if tascam got someone to copy the transport boards on every model they made and sent them to pcb way to manufacture fresh boards so we could just repopulate the components onto a better manufactured transport board
Just picked up a cheap 424 mk2, and the seller says track one erase isn't working.. This video give me some hope.. I've repaired and serviced some teac reel to reel, so feel confident I can resolve this, without losing it.
Great effort to make this video thank you
Thanks. So far as I can make out the r2r stuff is a lot harder to work with so you'll be fine!
@@Tetrakan R2R is alot easier to work on it's mostly mechanical and the steal components never crumble or bend or go out of shape cassette is a generation after R2R but there is way more working and fixable R2R's than cassettes i restored a Sony TC366 and there is no tape hiss on R2R vs cassette. If you never tried R2R repair you would be hooked on how easy it is
Is there a way to isolate the transport from the case and test? Massive PITA, using cable extensions for the audio/power cables from the transport etc. If that worked true to the calibration it's time to get physical with whatevers warped on the case and is touching parts it shouldn't. Pliers and wrath will be useful here. I do have one of these, but haven't used it very much, seems like a great machine so I might dig mine out and start squishing the case a bit!
Hi, thanks, yeah I've done that, though in a sense the plastic cassette cavity is part of the transport...the cassette tips in the naked transport which causes tape to head contact issues of its own. The adjustment screws on the 8 track tascams are more comprehensive and allow for improving tape to head contact, so eventually I'll try to make that adjustment, but doing so will mean the azimuth is out of whack, so I'll need to wait until I have a dual channel oscilloscope so I can rectify that. Like you say, massive PITA!
Hey, my 488 mkii has a problem with it’s pitch control knob. It doesn’t’t have the original plastic knob, instead it’s a silver-colored one without a line on it (I drew one with a sharpie). The bottom part of the knob is broken because it’s too small for the potentiometer. And it only works in the negative direction for a few seconds, then it speeds back up to normal. It also slows down briefly when I push down on it, which is weird. When I tried to adjust the speed on the potentiometer on the control pcb, it stayed the same speed. Also, where can I find a new door for it? Mine came without a door.
For the door you'll need a spares donor, unless someone 3D prints these unbeknownst to me...any tascam from the same generation and previous generation- 464, 424 mk ii etc - will have a compatible door and pitch knob. It could be one of the speed control wires to themotor is bad or the motor control chip is overheating.
Very informative video! What a pain, I’d never of guessed the casing alignment would be causing erase problems and it looks like it’ll be frustrating to sort out. I’m dropping off my two 488mkII’s (and 688) to get fixed tomorrow at a repair shop. I wonder if the misaligned casing is causing my issues too?
Looking at the service manual, it seems you can increase tape pressure using adjustment screws at the base of the head, provided you have a calibration tape to check azimuth afterwards, hopefully your tech can attend to this.
@@Tetrakan thanks, hopefully so. 👍
found it!
Hey! Thanks for the content.
I'm about to buy one but only thing that's not working is the pitch.
Is that an easy one to fix y think ?
Thank you 👍
Please can you clarify - do you mean the tape speed doesn’t respond to the user pitch control? Or something else?
@@Tetrakan is all ok. I bought a fostex x- 28 H. Trouble shoot o have now is the focusrite.( for my condenser mic and daw) Do you use a DI to get rid of the noise its producing? Thanx men! 👍
have the same issue with my tascam porta two thats in bits..... ur method is way more dilligent than mine.... i would just turn the bias up or down and see what it does lol
M8, my first three years trying to fix these was just me throwing shit at a wall to see what sticks, in lieu of better info just experimenting like that is good practice tbh
@@Tetrakan thats just me all over 😂😂am learning a fair wack from ur vids tho ! keep em comin- they are appreciated !
hey so my tascam 488 used to work great but since i moved to my new flat it just wont play any casettes anymroe. i can rewind and forward but when i press play the (i guess they are called tape heads) come out but then nothing happens :( if you could help me that would be so dope
Could be as simple as the capstan belt is loose or snapped, have you checked?
You seem to know everything about those machines. Have You tried to recalibrate one for type I tape? Is it even possible? Fresh type I tapes are more accessible than type II, and with proper calibration they sound excellent. At least from what i get on stereo deck.
Yeah, the bias frequency and amplitude can be adjusted. I’ve struggled to find the correct leavers for type one documented though….
Help, I couldn’t find a video covering 424 porta problems. When I record a clicking sound in the background is heard when I play back.
Upload a video or audio clip of the clicking sound and drop the link here, I'll have a look/listen
@@Tetrakan I’ll be able to get you a recording later this weekend. I’ll post here when I have it. Thanks a bunch!
My 488 won't play anymore... Gonna try and clean
do you fix these and resell them?
Used to. Almost full time at one point, now I'm back at a day job I'm concentrating on youtube.
Cheap plastic over too large a footprint?
Relying on plastic retaining its shape over such a large surface area, yeah maybe that's a factor, but also the unit in the video has had a hard life. Other 488s I've had didn't have this issue.