388 - Tracks 2 & 7 recording distorted.

38869420

38869420

Member
I posted this on the Tascam forum but reckon it’s get more eyes here.

Anyway, Classic stuff, but it's been a while since i've been under the hood on the 388 and no other posts address the exact sitation.

So Channel 2 & 7 are recording kinda thin, distorted & quiet but playing back prerecorded stuff properly. Here's what i've done.
  • Cleaned the heads.
  • swapped the REC/PLAY pcbs with the working pairs.
  • Swapped the EQ cards and the problem remains.
  • tried bouncing from a good track to tracks 2 & 7 and they still recorded distorted with low level.
  • Also tested the recorded test tone from 2 & on the TAPE OUT and still the same distorted, thin and quiet.


So the REC / PLAY PCBs are fine, it monitors sound coming into those inputs (both line & mic) clean & nice, so what would be a logical next step?

I've attached a few photos (bit overkill but so hard to get a good photo of heads) of the heads, i'm not really too sure what i'm looking for with head wear, so if anyone can let me know how these look, I’d appreciate it
 

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Did you exercise the connections of the dbx cards? Any difference if you track with dbx out?

If it reproduces fine on all tracks with known good material then it’s not the head.

What happens if you try recording using the BUSS IN jacks?
 
sweetbeats said:
Did you exercise the connections of the dbx cards? Any difference if you track with dbx out?

If it reproduces fine on all tracks with known good material then it’s not the head.

What happens if you try recording using the BUSS IN jacks?
Click to expand...
EQ cards, the cards with the channel select & EQs on them you get at from the bottom, connected to the BUS PCB.

Haven’t touched the DBX cards, will try. And the BUSS IN jacks will try tonight.
 
Ok so I tried recording with DBX on and off. Off is as above, on the signal basically disappears. I’ve wiggled the DBX cards but will remove them and give them a clean. Do they pull out like the PLAY/REC PCBs? They’re pretty stiff if so, so I’m taking my time.
 
Removed the Right side DBX card & cleaned it up, put it back in and gave it a good wiggle and no change.

Recording direct on the BUSS IN for 2 & 7 is a slight level improvement, but still noisy & thin.

So it seems like it's related to the DBX card, which I would have never figured! I can have another go at cleaning it up and trying to follow what part of the circuit relates to channel 7 & 2 on the other card?
 
Last edited:
I’m having a little trouble following what you are saying…are you saying with dbx off signal is normal/consistent across all tracks, but with dbx on you have the issue with the weak signal to tape on tracks 2 & 7?

And what happens if you swap the dbx cards? Does the issue stay at tracks 2 & 7 or switch to tracks 3 & 6?

The left dbx card handles tracks 1, 2, 3 & 4, and the right dbx card handles tracks 5, 6, 7 & 8. So if this truly is some problem with the dbx PCB assembly it would be a problem with both of them since track 2 processing is on one card and track 7 is on the other. Swap them and see if the issue changes tracks. I’m betting it doesn’t.
 
Sorry, meaning that with DBX off it’s the same distorted sound, with it engaged the signal gets even quieter.

Didn’t get the left one out yet, but will swap them tonight!
 
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