Tascam 388 issue...part 2

[jjones1700]

Ok, this is more or less a continuation of

https://homerecording.com/bbs/showthread.php?t=310516

After doing some more tinkering with the 388, I've noticed that nothing will pan to the right, it just mutes everything. I've got both of the master buss faders up and the channels assigned accordingly, but still nada. The only way I get anything out of the right channel is if I use "mono".

I connected my SM7b up to channel 1 and messed with it a little bit. I noticed that if I peaked the meter and tripped the OL, I would get a crackling noise with the audio, otherwise, silence. I'll have to run through this again to record it and post it up for further diagnosis. I just find it really odd that one side totally is toast.

Any suggestions in the meantime until I can get under the hood of this beast??

Oh yeah, it doesn't matter what the source is either: mic/line/tape all has the same outcome.

 

[sweetbeats]

Can you get any positive effect if you (gently) apply pressure to the master fader knob and/or rock it to the right? Just wondering of the possibility of a wiper in the fader not making good contact.

Outside of that it sounds like it could be a bad cap. Caps block DC voltage but allow AC voltage to pass (audio signal is AC, most of what we attribute to unwanted hum/RF noise in the audio path is DC). If a cap is blown or dried up then nothing passes unless you blast it but then it is only momentary. This is the same kind of symptom I had in my MX-80 summing amp on one of the channels. Turnout out to be 1 or two bad caps and a bad opamp.

Check that fader thingy out, I'll re-read your posts and then, if you're interested, we'll start honing in on the troublemaker.

 

[jjones1700]

I'm betting on bad caps...

If I remember correctly, the guy I bought it from said it hasn't been used that much. It was moved around more than anything. I'd be willing to bet that the caps probably went bad from lack of use.

I'll do more in depth diagnostic over the latter part of the weekend. The faders aren't noisy on it though.

Now my 32 on the other hand, is pretty noisy only through the headphones.

 

[sweetbeats]

The fader test I'm talking about doesn't have anything to do with noisy faders...it has to do with the wiper not touching the element...I had that happen on my 388 on the buss master faders. Granted I'd been cleaning/tinkering, buthey...its a quick think you can test from the control surface.

Noisy headphone amp? Hey...any Tascam headphone amp I've had on any unit that is based around the 386 opamp is noisy...I've just accepted it because the 386 pinout is somewhat unique so there isn't a drop-in upgrade. Most of the models we talk about here have that same headphone amp circuit and they are indeed noisy.