Thanks for the replies & guidance, I appreciate it.
I'm learning as I go with maintaining this stuff as there's no techs in Tasmania and I figure I should learn how to upkeep this stuff.
My first question is, as always, "why re cap?" Since the mixer is about 35yrs old, maybe academic in this case however I will venture my next point. MEASURE the fekker first! That is at least do a voltage table and a gain check and if at all possible check the LF turnover frequency. Doing that means you then have some numbers to ensure your work has not buggered anything.
Well, just off recommendations really, and because I have a spare machine I thought 'why not learn...' as it'll probably need to happen anyway. I've inspected the cards though and from looking, all the caps look fine so your advice of measuring it first is sound. It would need to be powered to measure everything, correct?
My spares machine has a host of problems, but now my main machine is rock solid again, I can worry about trying to make the second one operational but my first priority is trying to fix this 8200 / 16400Hz tone in the Monitor PCB I swapped out.
@sweetbeats Yeah, considering
Practical matters: Use a good quality temperature controlled iron of about 50W rating. Good quality 60/40 Lead solder because that is what is there. I would start by cleaning the PCB with meths and a stiff brush. Flood each capacitor joint with a little fresh solder then IMO use solder wick to remove solder. Some folks swear by the "click-clunk suckers" I swear at them, had them lift print. You will need a LOT of solder wick.
I've got a good soldering iron with temp control, was considering getting a desoldering gun. Would this be overkill? I've got an MPC 3000 i'm going to have to replace a bunch of Tact switches on soon and will always need to do little jobs here and there so figure it's a decent investment.
are you considering recapping your faulty monitor PCB? I really, really doubt your electrolytic caps have anything to do with your problem. I meant to comment on your other thread but I’ve been monumentally busy. If I was going to make a guess I’d bet the 4000 series logic chips are to blame. I don’t have the manual in front of me...U301 and U302? 4011 parts? Cheap and available. There have been other issues with the very limited selection of 4000 series parts on the 388, so I’d shotgun those if I was going to just shotgun something. Those logic chips accomplish analog switching and work in conjunction with transistors to auto-switch the signal path depending on modes. When they go bad weird stuff happens. If you’re bent on recapping just use the same voltage/value parts, and any modern low ESR parts are good here. You could replace all with Nichicon PW or the like.
Thanks for that, yeah trying to get rid of this high pitch tone and figured i'd start with the Caps. Was pretty noisy generally in hindsight now i've swapped to a good Monitor PCB.
Yeah there's a U301 & U302 in the parts list IC, MC14011BCP. Would this be a replacement?
https://tinyurl.com/5benyjbe there's no stock on Mouser or RS. Happy to just do that for now and see how I go. I'm happy with doing as little as possible really, then keep troubleshooting other problems, but would love to do as much as possible sooner or later to increase the working life of these machines.
can you tell me more about the link that’s broken? I’m not even sure I know what thread you’re talking about on tape op. I’d like to see if it’s something I can fix on my end.
Yeah, its in the big Tape Op 388 thread here -
https://messageboard.tapeop.com/viewtopic.php?t=76869 the link is for "
Tascam 388 refurb and recap thread:"Sweetbeats" numerous pictures of the process." http://homerecording.com/bbs/showthread.php?t=286434
there's a bunch of Home Recording threads of yours that go to dead links now. I've been meaning to collate a lot of this online info into some kind of extra manual.