I recently bought TWO 388s for $100 bucks.
Now that’s a disgustingly commendable deal…
…at first, the transport wasn't working on either. I did the reel servo adjustments (tension arm, winding speed, etc) and both came to life - Play, FF, RW, counter, etc. Everything was going well.
Maybe the slight manipulation of the plug-in card mitigated oxidized connections.
Have you reseated the cards in the cardbay and treated the connections with something appropriate like DeoxIT D5?
If the units were in storage and it was damp at all, that’s the problem with tin-plated connections…they don’t last and they oxidize. I’ve come to really appreciate gold-plated contacts in vintage equipment.
I tried my first recording and although I'm sending a strong signal (meters bouncing in channel and main, great sound in headphone/stereo/mon mix) however, the signal I get on playback is muffled and barely audible…I get exactly the same result on BOTH machines. My first thought was user error - if I'm seeing it on both, then I must be doing something wrong.
Well, that may be the case…sure…but you don’t know that, and the opposite could be equally true because the units are of similar vintage and we’re stored in the same location for a similar or identical amount of time.
Don’t get distracted by assumptions. Troubleshoot it using a methodical and reasonable process.
Is the recorded signal muffled off the TAPE OUT jacks as well?
I’m going to repeat my question/suggestion regarding reseating/treating the plug-in cards if you haven’t done that.
-It plays prerecorded tape just fine - so that would rule out the PLAY/RECORD head, no?
Correct. Good deduction. Since the same coils are used for recording and reproduction, if it can reproduce properly, your problem is not related to the head coils or head wiring.
I'm fairly certain that it's not a playback/RMX issue as I'm getting the same muffled garbage from headphones, mon, aux, stereo outs. It seems that it's just not getting recorded well.
Right, but take the unknown out of it and verify what’s coming straight off the reproduce amps and monitor straight off the TAPE OUT jacks. That bypasses the mixing section and monitor section. And on the other side of it, verify that what is going into the record amp is clean…route signal to the PGM groups and monitor off the BUSS OUT jacks. Is the signal clean and strong?
My suspicions are:
-Tape quality (although these are not ultra high quality, I should be getting something beyond a muffled rumble, no?)
I should think so. Though keep in mind it is likely the bias level is set too high for the tapes you are using…overbias conditions typically result in a diminished HF response and record level. Which to some can sound muffled. It might be worth uploading a sound clip of your issue somewhere and posting a link.
Also, and I’m pretty certain this has nothing to do with it, but you tried recording with dbx engaged and with it disengaged, yes? No significant difference except maybe a little less muffled with it disengaged.
-After sitting so long the bios pcb 1 crapped out…Maybe I pull this and check the capacitance on the components - might have a flat capacitor or three?
First, note that it is “bias” not “bios”. Maybe there is an issue with your bias system, sure. The bias system is what accomplishes erasure and applies bias signal to tape during recording to minimize distortion and improve HF response. That’s why I’m asking if it erases. If it won’t erase, the bias system is not working.
Did I mention it’s a good idea to reseat the plug-in cards and treat the connections?
Also, I don’t know where the idea comes from that capacitors are the possible culprit of such a wide variety of issues. Yes they can go bad like anything else, but in a system like this the typical symptoms of bad caps are complete signal loss for a completely roached cap, but most typically higher noise floor, possible hum if a primary filter cap is bad, increased “skritchies” when actuating switches and potentiometers (due to less effective DC blocking), and improper timing of certain processes since caps are also used that way, as signal timing delays, like control signals…I wouldn’t expect a bad cap or caps to cause the kind of symptom you are talking about…first time for everything I suppose. But if you’re having issues like described above, then it is likely time for a recap.
-Somehow i've wonked up the tape tension - I don't have (nor have I ever seen in real life) a tentelometer. However, this seems unlikely because prerecorded tapes work fine.
Let’s go with that last thing you said. Again, that’s a good reasonable deduction. The transport is operating the same way during record and reproduce. It’s only the status of the bias system and record/reproduce amplification systems that are different between those two modes. So if it reproduces a known good recording fine, it’s not the transport.