Tascam 34 - meters doing strange things

[sweetbeats]

Okay. You’re welcome. Good luck.

I still recommend, as a troubleshooting step, to pull the fuse for the +6V rail, and jumper the K-102 relay signal contacts on the r/p amp cards. This completely takes the mute timing circuit out of the picture and bypasses the muting relays. You’ll have thump on power up and power down so you have to be prepared for that.

And, yeah, when you posted you still had other equipment in the signal chain (your noise reduction unit), I was like (to myself) that would have been good to know. When you have a device that’s misbehaving, step one is to isolate the device as a measure of starting to sort out if the problem is related to the device itself, one or more other devices, or the interconnections between those devices. So keep that in mind when you are trying to resolve a problem or working with others in that effort.

 

[frnkfrkl]

Ok. I assume I DO NOT put the fuse back in after jumping the relays? Without that fuse-no VU meter lights. The Ghost in the Machine has decided for now that, ok, I can have VU meter lights but still no sound. The VU lights came back to life by magic so I'm thinking there's another batch of funky connections on the mother board. My choice is to dive into the Mother Board again (disassembly required) or jumping the relays (easier and proof-of-concept). I'm going to try the relays first just to be sure it's not a problem somewhere else and then decide if I really want to take it all apart again to check the mother board.

100% of the time I spent diagnosing and communicating with you the DX-4 WAS NOT CONNECTED. No remote control, either. Nothing extraneous. I only connected it when I believed (ha ha ha ) that the problem was fixed. It was then that I discovered that the DX-4 was not working and found the broken wire. I even tested the functionality at each stage of reassembly just to make sure I hadn't bumped or jiggled something as I wrestled this thing around on my bench. It's heavy and awkward to work on and each manoeuvre runs the risk of knocking something else out of whack.

My "day job" is saxophone repair. The skill set there comes down to being absurdly meticulous, proceeding by elimination when diagnosing a problem and NOT EVER hurrying or saying "that's probably good enough" when you have even the slightest doubt about something. My approach to this is the same, absent the concrete knowledge and experience required so I lean heavily on being meticulous and patient and striving to learn and understand as I go.

 

[frnkfrkl]

And just because the God of Electronic Zeitgeits wants to fuck with my head, the machine spontaneously started working again. I merely reseated the MON AMP card and, voila, music! Now, am I thrilled? No, not really. The machine is on my bench, on its back, panels off and it's butt-end chocked up with a piece of wood for easier access to the bottom. And now I'm afraid to touch it again. 40 year old connectors, wires, solder joints, PCBs and shotgunned components that prevent me from knowing what I actually fixed and what is just pure luck (or lack thereof). Absolutely confounding. I am going to leave it for 24 hours and try not to think about it and then come back and turn it on again to see what other surprises might be in store. This is just like a vintage car. You spend more time under the hood than behind the steering wheel. Crazy. I have thus far restrained myself from throwing this thing against a wall. Too heavy, anyway. Well, anyway, I'm holding off on jumping the relays for now...Having fun yet?