Tascam 488 Mark 1 | Tear Down lower section

[@bunnyw8170]

thank you for making these videos! This is helping me repair my 488 that I bought broken.

[@bucksmoonlightrevival]

Thanks for making all your videos! Our 488mki broke recently after years of flawless recording. We did our whole first album on it, but it was making a bit of a humming sound for a while and eventually the capstan stopped spinning. Gonna take it apart and figure it out!

[@Tetrakan]

Belt or motor. Good luck!

[@vangelis.gavalakis]

Hello. Thank you for your videos. I recently received a 488 mki but have some problems. Do you have any insights as of where/what to look for? 1) Tracks 1 & 5 (group 1) does not record at all. (input sound does come through though and show up in meters fine) 2) Paning from all channels assigned to 1L&2R bus does not work (it is always center both for mixing and for odd/even track selection when recording). Pan from all channels assigned to bus 3-4 works fine though. 3) If I record on a track of a group and then try to record on the other track of that same group, the previous track is erased or not played back for the duration of that recording only. As if tracks in the same group are mutually exclusive O.o. Group 3 (tracks 3 & 7) work fine though. Maybe I will have to through it away 😞 Thank you!

[@Tetrakan]

1) check the corresponding erase heads are plugged in, or record will not work. Assuming the erase heads are present and have approx 13 ohm resistance on the coils, signal trace group one record amplifier to find where the signal cuts out, or just replace all electrolytic capacitors for that record amp - chances ate high that will fix the issue. 2) deep clean 1/2 master fader and recap pre and post opamp stages 3) someone swapped the erase plugs for those two channels, swap them back. If this is beyond your skill, do NOT throw it away: Sell it as a spares donor on eBay please.

[@vangelis.gavalakis]

@@Tetrakan Thank you very much for your detailed reply! I wasn't going to through it away, it was just a metaphor on how bad my unit is :) Thanks again!

[@johansjolin6495]

Hey! Not related to this video, but I wanna thank you for your Tascam 244 playlist! Managed to pick one up for 100 euros (not sure if that's good or not, but the guy initially listed it for 500 euros, so I'm happy), and have been working on fixing the issues with the transport. That part is all good now, replaced the idler tires and tested the function with rubber bands while waiting for the real belts to arrive. One issue still remains though, mixer channel 4 is completely dead. When sending an input and increasing the gain I can see the input overload LED lighting up, so it seems to be getting that far. Looked over the signal schematics (it included mint manuals, which was very handy) and my theory right now is that the signal never actually enters the mixer channel, but maybe the input selector switch is a dud? Or maybe just oxidized to hell. Tried monitoring track 4 from tape, and it results in the same thing, but I can listen to it via the cue knobs. Do you have any experience with similar issues? Just cleaning the input selector might help?

[@Tetrakan]

100 euros used to be the going rate for faulty 244s a few years ago but they've shot up in price in the last 18 months, so you got a good deal. Your logic seems sound, you could verify that the issue is contained within the mixer channel PCB by swapping its position with a working one, i.e. if ch3 mixer works, swap it with ch4, if your hypothesis is correct, you will now have a working ch 4 and a faulty ch3, does thta makle sense? .f it is a problem with the mixer channel you would begin by deep cleaning the switches knobs and faders (see my video on the subject). Failing that, you could use signal tracing to figure out how far through the PCB the signal is getting - you would;d do this by introducing a signal from a function generator or even a synth with one key taped down and testing for the presence of the audio at major landmarks between the input and the output, in this sort of circuit the location of opamps and potentiometers give you a good idea of how the signal istravelling from the input to the output. Once you find a a component where there should be a signal present but isn't, you can move on to looking for damaged solder contacts, reflowing the solder, replacing components (nearby capacitors too if an opamp seems dead) as necessary. I do have videos on these processes, check my channel, and thanks for watching!

[@johansjolin6495]

@@Tetrakan Thanks! That makes sense! Was considering it when I had all the mixer channels out last night, but I forgot haha. Just did some light cleaning for now until I can get some decent cleaner for it. I did however bring out a multimeter to measure the differences in the input switch signal paths from a working channel, and found none, so my initial theory is probably wrong. Will try your other suggestions :) Put it all back together again, at least my intense knob twisting and light dust removal has resulted in som of the crackly pots being almost not crackly at all. Guess I should tear out 3 and 4 again at least and test. I really appreciate your channel. I wouldn't even have taken the risk of buying the machine if I didn't find this . Thanks again!

[@bloubear2557]

odd, the control board on mine doesn't have any fuse slots and any fuse

[@Tetrakan]

Could be a regional legal thing. With 244s for instance, EU/UK models included a fuse board, whereas models for the US market did not.