Tascam 488 MKII problem

bearhead

New member
Hi, I recently bought a 488 MKII from a friend of mine, and I'm having some issues recording on channels 4 and 5. I'm assuming it could be an erase head issue... I say that because I can record audio onto those channels on a clean tape. But if there is audio on its channel(s) and I attempt to record, the old audio is still there, and the new audio barely comes through. I can route those channels to record audio onto other channels just fine, so I'm positive the strips are okay.

Is there a way to go about fixing this? Also, where is the erase head in the 488? I see the record head and the split play head(s), alongside this black plastic piece which I'm assuming guides the tape.

I really would love to get this thing working properly. Thanks in advance for any help and advice you guys might have to give me.
 
Almost...

The "split play head" is a record/play head, and it's indeed split.
The head to the left of it is the erase head.

You should start by cleaning the heads thoroughly.

:spank::eek:;)
 
The "split play head" is a record/play head, and it's indeed split.
The head to the left of it is the erase head.

You should start by cleaning the heads thoroughly.

:spank::eek:;)

Thanks for the quick response!

I cleaned the heads a week ago when I got it. I used 91% alcohol and q tips. I should mention that there seemed to be (although I'm not sure if it actually was) corrosion on the right head of the split heads. I'm guessing that's the play head, so that'd have no influence on this issue? A friend of mine told me to get a demagnetizer. Could that fix this issue?
 
...

The split head was the technology TASCAM used to squeeze 8 tracks onto cassette. The magnetic elements in the heads are incredibly small. One half of the split head is for tracks 1-4 and the other half is for tracks 5-8. Each half of the split head arrangement records and plays. The less fancy looking head to the left is the erase head.

Cleaning is more important when the tracks are so small. Demagnetizing might help, but couldn't hurt.

:spank::eek:;)
 

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The split head was the technology TASCAM used to squeeze 8 tracks onto cassette. The magnetic elements in the heads are incredibly small. One half of the split head is for tracks 1-4 and the other half is for tracks 5-8. Each half of the split head arrangement records and plays. The less fancy looking head to the left is the erase head.

Cleaning is more important when the tracks are so small. Demagnetizing might help, but couldn't hurt.

:spank::eek:;)

I cleaned the heads for about 5 minutes, both the record play heads and the erase head, but nothing came up on the q tip. No black debris. Does this mean the heads are clean, or does it mean I'm improperly cleaning the recorder?
 
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In general that means they are clean, but a small amount of oxide wouldn't necessarily be visible on the swab.

You may also notice that Track 4 and Track 5 are not adjacent to each other.

Likewise, Tracks 4 & 5 are not serviced by the same Group # on the mixer.

By simple logic you'd assume Tracks 4 & 5 would not be malfunctioning from any single cause, which doesn't mean they couldn't fail simultaneously for other reasons as yet unknown.

Maybe you should consult with your friend for ideas or any clues you can find.

TRY recording one signal onto all 8 tracks by routing one mic or guitar to all 4 Groups and recording 1-4 and 5-8 in two passes to a blank tape. Play back and see what you get. Then immediately follow this by recording "blank" (no-signal) to all 8 tracks in 2 passes. See if all 8 tracks erase properly.

You have to start with the most basic troubleshooting. If it records on the first pass on a blank tape, but not on subsequent passes, lends you to suspect the erase head, but it's inconclusive. Some of this testing should help narrow it down.

:spank::eek:;)

I had to edit that test procedure because if you flip the tape over Track 4 and 5 physically match to each other and is therefore inconclusive.
 
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In general that means they are clean, but a small amount of oxide wouldn't necessarily be visible on the swab.

You may also notice that Track 4 and Track 5 are not adjacent to each other.

Likewise, Tracks 4 & 5 are not serviced by the same Group # on the mixer.

By simple logic you'd assume Tracks 4 & 5 would not be malfunctioning from any single cause, which doesn't mean they couldn't fail simultaneously for other reasons as yet unknown.

Maybe you should consult with your friend for ideas or any clues you can find.

TRY recording one signal onto all 8 tracks by routing one mic or guitar to all 4 Groups and recording 1-4 and 5-8 in two passes to a blank tape. Play back and see what you get. Then immediately follow this by recording "blank" (no-signal) to all 8 tracks in 2 passes. See if all 8 tracks erase properly.

You have to start with the most basic troubleshooting. If it records on the first pass on a blank tape, but not on subsequent passes, lends you to suspect the erase head, but it's inconclusive. Some of this testing should help narrow it down.

:spank::eek:;)

I had to edit that test procedure because if you flip the tape over Track 4 and 5 physically match to each other and is therefore inconclusive.

I tried recording a test signal (a single note from a synth lead in my daw) and recorded it at the same level across the recorder, and I noticed that channels 4 and 5 were much weaker than the rest of the channels. Channel 3 was just slightly weaker than the others, but not by much. There was audio already on this tape though, so I think that's partly the reason why it was so weak, but the signal still came through.

When first recorded, channel 4 was the weakest sounding channel. I flipped the tape, and channel 5 became the weakest channel.

The same thing happens when the tape is blank.

I notice looking at the meters, the tracks 1-5 seem to have a staircase effect in levels. Tracks 6, 7, and 8 seem to staircase back up, but much less dramatic than the first 5.

When recording silence, tracks 4 and 5 seem to still have a bit of the test signal on the tape.

What could this mean?
 
...

The heads should be cleaned again as well as possible. A little scrubbing motion in the direction of tape travel would be reasonable. Given the nature of the problem a head cleaning issue could cause this. Remember to clean the erase head as well as the R/P head.

After that, it could just need a calibration. It definitely appears to be marginally recording and not erasing on those tracks.

However, if this recorder has sat around a long time, I think there's a slight possibility that reseating all the internal connectors might solidify any signal paths that are intermittent. Sometimes connectors tarnish or go intermittent from environmental factors. I can't say for sure, but I'm just tossing that out.

Is there any information your friend can give about the working condition of this unit?
 
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Like I said, when I cleaned the heads earlier, nothing appeared on the q tip. I can try cleaning them again for a little longer, but I don't see that fixing anything.

I feel like the issue could be more pointed in the direction of the last two in your list of speculation as I've tried cleaning the heads twice. I suppose once more wouldn't hurt.

I think my friend said he bought it used from a pawn shop 3 years ago, and I'm not sure if he used it much or not. When I got it, it was really dirty on the outside... you know, dusty clumps in the creases that takes a bit of elbow grease to get out. I cleaned it all up from the outside of the recorder, to the knobs and in between the faders.

I don't have enough knowledge to open this thing up and look inside at the electronics (I'm not even sure what the connectors are or where they're located). I know only basic stuff unfortunately.
 
...

Here is a thread that details opening up a 424mkII, which is very similar to the 488mkii, but as I recall there's an additional screw to remove from inside the cassette compartment...
https://homerecording.com/bbs/gener...ly/tascam-424-mkii-how-expose-innards-289340/

Given how dirty it was it's possible any issue you're having now is dirt relating to the connectors. Reseating the internal connectors is something a non-technical person could do with some effort. Calibration is a more complicated thing that can be done by hardcore DIYers or may be best to refer it to a qualified tech.

:spank::eek:;)
 
Here is a thread that details opening up a 424mkII, which is very similar to the 488mkii, but as I recall there's an additional screw to remove from inside the cassette compartment...
https://homerecording.com/bbs/gener...ly/tascam-424-mkii-how-expose-innards-289340/

Given how dirty it was it's possible any issue you're having now is dirt relating to the connectors. Reseating the internal connectors is something a non-technical person could do with some effort. Calibration is a more complicated thing that can be done by hardcore DIYers or may be best to refer it to a qualified tech.

:spank::eek:;)

I saw this thread a while back when my 414 started eating tapes. Still never fixed it...

I really appreciate the help you've given me so far, but I really don't want to risk opening up the recorder. I could easily damage it due to my lack of knowledge as far as electronics go.

Any other thoughts?
 
...

You clean it. You cover the basics. You do what you can. You find a tech if necessary.

The electronics in these machines will need a tune up after so many years, as things drift out of spec. That seems to me what you're dealing with, but the way you described it as dirty and not well kept would lead me to believe some of the connectors are dirty or intermittent. That's just a hunch. Unless you go into the guts of the unit, you may not be able to fully address this issue.
 
You clean it. You cover the basics. You do what you can. You find a tech if necessary.

The electronics in these machines will need a tune up after so many years, as things drift out of spec. That seems to me what you're dealing with, but the way you described it as dirty and not well kept would lead me to believe some of the connectors are dirty or intermittent. That's just a hunch. Unless you go into the guts of the unit, you may not be able to fully address this issue.

I do know a few people who are more handy with this type of stuff, electronics wise. I could have them look into that a bit more. You've helped me get a clearer idea of what could be wrong with it. I'd like to think it's not permanent damage, nor expensive to fix if I do have someone else get into it. I'd use what you've said here as a reference.

Anyway, thanks a lot for your input. It's much appreciated. :listeningmusic:
 
Did this issue ever get resolved?
I am similar issues with recording tracks 5 and 7 on my 488 mkii.

Did it end up being bad internal connections or were there some burnt out components?
 
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