Tascam 388 Track 1 / 3 Crosstalk / Bleed

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Jazzzyyy

Far East Man
I have an issue with my Tascam 388 : (

I cannot record an isolated track on Track 1 and 3.
There's a crosstalk between these two channels. Both channels reproduce very clear at a correct volume.

Example:
If I record a "Guitar" on Track 1 - Play back will have "Guitar" on Track 1 and 3.
If I record a "Bass" on Track 3 - Play back will have "Bass" on Track 3 and 1.
It's like it would be assigned to record on both of these channels.

Remaining channels 2, 4, 5, 6, 7 and 8 work perfectly.
The sad part is that swapping the Rec / Rep cards does not solve this. Issue remains.

Heads are very clean and demagnetised...

Any ideas where should I look next?
 
Hi. The first step is to find out if this is a recorder section issue, or a mixer section issue. Let’s find out if it’s happening on the way to the recorder section…

Assign an input to PGM 1, make sure no sources are assigned to any other PGM groups (especially PGM 3), raise the PGM ODD master fader to the shaded area, and now check at the PGM 1 OUT jack on the back. Is your signal present there? Now check the PGM 3 OUT jack. Is your signal also present there?

Report back.
 
Hi!

Thank You!
Reporting back : )

***
PGM 1
Assigned Input to PGM1 ONLY (No other sources are assigned to any other PGM groups)

PGM OUT Readings:

PGM OUT 1 - 100% VOLUME
PGM OUT 3 - 5% VOLUME
PGM OUT 5 - 1% VOLUME
PGM OUT 7 - 1% VOLUME

PGM OUT 2 - 5% VOLUME
PGM OUT 4 - 0% VOLUME
PGM OUT 6 - 0% VOLUME
PGM OUT 8 - 0% VOLUME

***
PGM 3
Assigned Input to PGM3 ONLY (No other sources are assigned to any other PGM groups)

PGM OUT Readings:

PGM OUT 1 - 5% VOLUME
PGM OUT 3 - 100% VOLUME
PGM OUT 5 - 1% VOLUME
PGM OUT 7 - 1% VOLUME

PGM OUT 2 - 5% VOLUME
PGM OUT 4 - 0% VOLUME
PGM OUT 6 - 0% VOLUME
PGM OUT 8 - 0% VOLUME

**************

Signals are present in their designated locations.
Its barely audible on other PGM OUTs

What would be the next step?
 
How are you getting your percentage measurements?
 
I did not know how to describe how audible the sound was.

*Because it wasn’t that nothing was coming out from other PGM OUTs.

Apologies for confusion.
 
Okay. I just wanted to verify that was all subjective. I’ll go with “Signals are present in their designated locations. Its barely audible on other PGM OUTs”

Swap the dbx cards.
 
Swapped the DBX cards.

Signals are present in their designated locations on PGM OUTs.

I have tried to record Track 1 once again with everything set up and assigned accordingly but it is still fully audible on Track 3.
It is audible to an extent that it feels like Rec Function Buttons 1 and 3 have been pressed during recording.

***
Just a guess : )
One time the Rec Function (3) LED was not present when it was pressed.
After touching the LED it light up again, but that just happened once.
Could this be an indication that the problem is most likely within the Monitor PCB???
 
Let’s not conjecture about what it might be. The only worthwhile focus with this sort of thing is objective testing and resultant conclusions…assumptions and chasing ghosts leads to more assumptions and more ghosts.

Let’s backup. Remember that I know nothing about the machine or its history. So fill me in. Is this a new machine to you? If so were you aware of this issue before you acquired it and did you get any background on the history of the issue or work that was done prior to the issue arising or work done to resolve the issue? If it is not a new machine to you, is this a new issue that arose suddenly or did it manifest over time? Is there *anything* you can share with me about trauma the machine may have encountered or errors in judgment on the part of you or others operating the machine? There is no shame here and I’m not making any assumptions or accusations either. I’m just asking because I know I’ve done some regrettable things in my years, and didn’t want to share, only to realize I wasted an inordinate amount of time for those trying to help me by not just giving them the basic history and/or the skinny on what the hell went down when the thing stopped working right. Again, no judgment, these have just become my SOP line of questions because I value my time, and have little to spare.
 
Thank You for Your reply.

This is a new machine to me that I have acquired a couple of months ago. Unfortunately it came without any history and it was in a really terrible state.
Let's list a few... There was no consistent sound from the Inputs, scratchy pots, heavily damaged EQ pots, stiff faders, burned out VU Meter bulbs, extremely dirty transport section, broken belt and damaged Reel Servo PCB. The list can go on and on : )

Full disassembly, deep cleaning, recap (Nichicon KA Series), exchanging of all of the EQ pots, restoring faders, NOS bulbs, new belt, new Reel Servo PCB and head demagnetisation has been done to bring it back to life. After all of this, everything works and looks flawless except the issue I'm asking for help.
I have tested every function and I'm very happy with it and how it sounds but I cannot understand what is happening with the Track 1 and 3...

I respect Your time and would like to book a consultation if that would be possible.
 
So when you are attempting to record to track 1 only via PGM 1, do you see high-level bleed to track 3 on the PGM 3/track 3 meter, or do you only see signal on the PGM 1/track 1 meter? Similarly, while attempting to record to only track 1 via PGM1, when you monitor PGM 1 via the monitor mixer can you hear the high-level bleed to track 3 via monitor mixer channel 3?

Hopefully that makes sense what I’m asking.

Also, and I apologize if you shared this already, but when you attempt to record only to to track 1 via PGM 1, and you hear high-level bleed to track 3 upon playback, how are you monitoring that? Via the input mixer with sources set to RMX, or via the monitor mixer? And have you verified there is actually high-level signal erroneously printed to tape on track 3 in addition to track 1 by checking playback at the TAPE OUT jacks 1 & 3?

Just trying to narrow in on where the fault may reside.

By the way your comment about the LED not working and then working when you touched it is more likely nothing more than bad continuity between the LED contacts and the socket; oxidation, etc. The power to the LED is independent of the control signal itself represented by the LED (i.e. it is possible for the control signal to be active but the LED to not light if the power to the LED is interrupted or the LED itself is non-functional).

And also by the way, thanks for the background. That sounds like a horrific project and one, after my years of horrific projects, I would take a pass. Good job getting this far.
 
I only see the VU Meters move at their designated channels. There is no crosstalk / High-Level bleed during monitoring before attempting to record on any PGM channel. I have tested them all : )

I cannot hear any High-Level bleed on Track 3 via Monitor mixer via Monitor mixer Channel 3.

I strictly follow all the steps by reading the User Manual to set everything up for recording. I have no issues with Track 2 / 4 / 5 / 6 / 7 / 8 by following these steps.

I’m monitoring the playback via Input mixer set to RMX. Yes, I just verified that there is indeed a High-Level signal erroneously printed to tape on Track 3 by checking playback at the TAPE OUT jacks 1 & 3.

This makes me guess that there is a serious error within the Recording side of the 388. It is not a big task to swap out the full recording tray to another one to see if the issue remains. What do You think?

Thank You for Your encouragement!
 
Flip the tape over. Does your signal play back now on tracks 6 & 8, or just 8?
 
Wow! Mystery continues!
After flipping the tape over, my signal was only present on Track 8.
I have checked the Track 6 & 8 TAPE OUT jacks as well and it was only present on TAPE OUT 8.

So it is not printed erroneously on tape after-all...
 
And that’s why I had you do that. I’ll take all the clues and develop a theory to test as soon as I can.
 
Thank You so much!
I really feel clueless here right now... I will be waiting patiently.
 
Just to be redundantly sure, would you do me a favor and record something track 3 and verify when you flip the tape it reproduces only on channel 6, even though when it is not flipped the signal reproduces on both channels 1 & 3?
 
Of course! I just did exactly what You asked me to do.

Yes, it was reproducing only on Channel 6 once the tape was flipped over.
I have recorder a signal on Track 3 and during playback I was hearing it on channels 1 & 3.
But once the tape was flipped over I could only hear it on Channel 6.

I have checked all the designated TAPE OUT jacks as well just to be 100% sure.
 
So tell me if this is true…just to verify:

When you record signal to track 1 on a blank section of tape, and then reproduce that recording from track 1, the signal recorded to track 1 can be heard via input channel 1 set to RMX and input channel 3 set to RMX, and also via TAPE OUT 1 & 3 jacks, correct? But what is also true is the meter bridge reflects signal reproducing from track 1 only (no activity on the track 3 meter), and furthermore you can only hear signal reproducing from track 1 on channel 1 of the monitor mixer, correct? There is no signal on channel 3 of the monitor mixer?
 
Close : )
Just did one more test!

When I record a signal to Track 1 on a blank section of the tape and then reproduce that recording from Track 1, the signal recorded on Track 1 can be heard via Input Channel 1 set to RMX and Input Channel 3 set to RMX as well.

I can also hear it via TAPE OUT 1 & 3 jacks.

On the Monitor Mixer section I'm actually able to hear the signal on Channels 1 & 3.

I'm not sure how I have missed this before but this time the VU Meters 1 & 3 were reflecting the signal.

If a Rec Function button 1 is pressed, the Channel 1 VU Meter stops. If a Rec Function button 3 is pressed, the Channel 3 VU Meter stops as well.

I'm sorry but it is slightly confusing...
 
No, not confusing. If you latch a record function switch, depending on the position of the PGM/CUE switch, the meter is then monitoring the PGM group signal, not the tape track.

And confirm again you did swap the tracks 1 & 3 R/P amp card with another card and the problem did not follow the card, correct? The card swap resulted in no change to the symptoms?
 
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