Tascam 388 insanely hot resistor help

I'll have to look at the schematics regarding W4. "W" would indicate a "wire" jumper. The schematics should be referenced. The complicating factor is that changes to product specs and design could and did occur, and the reference documents were not always updated. When I get a chance I'll refer to the schematics but ultimately it may be helpful to see if we can get other 388 owners to chime in and say what is mounted on their 388s.

Please be mindful about the power supply extender cables...not all the connectors remain connected in order to isolate the power supply and I don't recall which ones do and which ones don't get connected. You need to look at the schematics. Some of the connectors bring inputs to the power supply, and some are outputs, but at least one of this connectors carrying outputs needs to remain connected because it is outputting to the power transistors on the heatsink, which are an extension of the power supply. This is all advance level stuff as far as I'm concerned. Great care needs to be taken in order to avoid compounding your already complex issues.
 
Hi Cory,

Thanks for that, I think I solved the regulator on the heatsink getting hot issue. I replaced it, and also desoldered the motherboard 2 to replace the original resistor that was getting hot, plus the W4 one. The regulator on the heatsink is fine now, no excessive heat at all. Also found a couple of posts that I think might solve my problem. This (https://homerecording.com/bbs/general-discussions/analog-recording-and-mixing-tape-and-gear/tascam-388-please-help-me-fix-341314/4/), describes the exact problems I was having before, I'm going to test the transistors etc on the cap servo board when I get a chance this week. Also this (Replacing old diodes.), again describes the problem I was having with the right tension arm bouncing and general transport issues, again the fix was a transistor. Wouldn't be surprised if I find it's a bad transistor on the control pcb thats stopped the transport functioning. I'm going to test it all thoroughly at some point this week, I'll let you know how I get on.

Thanks again for your help with this.
 
So, bit of an update. I tested all the transistors on the control, cap servo and servo board, found two that needed replacing. Turned it on, motor turned fine, no excessive heat on anything, but the transport was still dead. Thought it might be to do with the cracked M5L8243p that I replaced, so swapped it with the same chip that's in u404 on the control board, turned it on and the motor didn't start. swapped them again and the motor started fine. So it's something to do with this chip i think. I had another spare that I bought, tried that one, same scenario. Any idea why this is? Ics are a bit beyond me, so not sure where to go from here.
 
So just realised I need to program it. Any know how I need to program it? Or know anyone in the UK that can help? Really don't want to let my 388 die.
 
What's wrong with the original part? And are you sure it actually needs to have a program burned into it? I was under the impression the multiplexer chip was given instructions from the CPU during boot, rather than having an internal EPROM area... but I could be wrong. I'll have to fire up my EPROM programmer and see if it can program these.
 
Hey mate, the original one had a crack right across the top, has done since I got it. Since it's been playing up black goo has been seeping out of it, which can't be good? And then the transport display went completely dead. This is all way beyond me, I've had problems with it since I got it, but they've been intermittent. I've literally tested everything now. When I swap the replacement with u404 which is working, the motor stops and makes a pretty awful noise when I turn it on. Tested it twice now, same thing. I could be completely wrong and it's something else, (which I apologise if so!) but I'm pretty sure. Only other parts I haven't tested are the ics on the control pcb, but with the change in behaviour when I swap the two bigger M5Ls make me think it's got to be that?
 
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