Tascam 388 Total Beater, looking for initial advice

N

nateflanigan

New member
Hello,

In the past I've always posted at group DIY or tapeop for recording related questions, however it seems like this is the place to be for the Tascam 388. A total beater 388 has landed in my lap, I won't bore you with the entire back story but it was free and it is not in good shape. For starters the bias cards and power supply card have been pulled out. I'm having a heck of a time getting the power supply card to seat properly, is there a trick to it?

I'm thinking the first thing to do is just get it to a state where I can turn it on and check basic signal flow and transport functions in order to asses the scope of the project.

I have a nice copy of the manual.

As a side note, I won't actually have the 388 in my hands for another two weeks. It's being given to me by a friend, the unit is at his house and he'll be away (for two weeks). We checked it out together last night and tried to get the PSU card back in, but kept bending some of the pins. I know it might be a bit early to start asking questions since theres nothing I can do at the moment, but I'm excited to get the ball rolling.

Thanks friends.
 
I shouldn't be hard to get the power card seated properly, you kind of just move them around until you feel them slot in and then you gently press down. Not hard to do and you don't need to force anything that's for sure. Maybe if the pins are bent you might have to check them out. Failing that you can take the bottom cover off and remove the mother PCM relatively easily, then you can work out why the power cards aren't connecting to the mother pcb so easily.

I'm sure others more experienced will have better advise than mine however.

I wouldn't worry about it being a beater. These machines can take a beating in my experience :) If there is no logic problems then you can probably get it running nicely yourself. I hear logic problems are a nightmare best left for the technicians would know what they're doing (and have the extender cards).
 
That's very helpful, thanks. I wasn't sure if sliding in the cards was just normally difficult or if there is possibly something wrong.


mr.blisset said:
I wouldn't worry about it being a beater. These machines can take a beating in my experience :) If there is no logic problems then you can probably get it running nicely yourself. I hear logic problems are a nightmare best left for the technicians would know what they're doing (and have the extender cards).
Click to expand...

That's encouraging, I have a lot of experience repairing and building tube amps and pedals however not much with servicing reel to reels. Again, I can't wait to dig in. :listeningmusic:
 
I always use a flashlight when re-seating cards. You gotta make sure everything is lined up correctly.
 
Good points above on the card re-seating, and I would add if you are having trouble and you keep bending pins, then check the card itself and make sure the connectors are properly anchored. The plastic housings for the connector sockets have a tab on each end of the housing that are sometimes broken off, so when you try to plug the card in one or more of those housings just flexes and the pins and sockets can never line up. I'd check that first. If everything is in order, as was said above, once you feel things lined up it should be a pretty gentle push to get that power supply card plugged in.

If you find one or more connector housings loose on the card what I've done is run a bead of super-glue between the housing and the card and hold it until its set.

Let us know how you are getting along once it's in your hands.
 
The female molex connectors on the card were definitely wiggling around. Thanks for the super glue tip, I wouldn't have know that was a problem.
 
Hey everyone, just a quick update...

The 388 is now in my hands. Today I, glued down the molex connectors on the power supply pcb and resoldered all of their connections. I also noticed that one of the mating connectors on motherboard 2 was loose so I removed the bottom cover and resoldered those connections. After that it was pretty easy to slot in the power supply card. The unit powered up, to start with I just wanted to check out the mixer section, I just used a mic so I haven't tested the line inputs yet. There's a few issues already...

Ch4: The signal only appears on the odd tracks and the left side of the master regardless of pan pot position.

Ch5: To get signal to pass I have to flip the input selector switch back and forth, it never stays ON but flicking the switch gets me a second of signal. This channel also only appears on the odd tracks and the left side of the master regardless of pan pot position.

Ch6: No signal, no activity on the overload LED

Ch7: Also odds only

Ch8: works but TRIM pot is touchy, only passes signal when all the way up, cuts out if I tap it

Thats as far as I got tonight, I checked the EQs on the good channels but didn't check the AUXs yet. Also I haven't gotten into the transport yet since those cards aren't installed and have some loose pins on the molex connectors as well.

Also, there's a few bulbs out and a few missing knobs and switch caps but those are low priority.
 
I should have the replacement knob and switch cap parts. PM me if interested.

Your other itemized issues we'd need to tackle one at a time, but it will likely involve removing the bottom cover. Suspecting connections that are oxidized and need re-seating or cold solder joints.

Does this 388 look like it was in a humid environment at all? Look at the screw heads on the jack panel...are they rusty at all?
 
Ok, now I'm up against some real issues. Tonight I installed the Bias and Servo boards, I'm getting some strange behavior from the tape transport. When I press play, the capstan engages for a second and the reels spinout in opposite directions, then the tape goes slack and the capstan drops back down. I also tried pulling the tape out of it's normal path and just manually holding the tension roller up in place. When doing this the play indicator light will stay on but neither the reel motor or capstan spin. Fast Forward and Rewind behave the same way. Here are two quick videos I shot to better show what I'm describing...

388 1 - YouTube

388 2 - YouTube

So... Where should I start trouble shooting this? Right now I haven't got a clue.

Thanks!
 
Hi Sweetbeats,
I just saw your post after I posted about transport functions. Thank you very much for the parts offer, I will definitely hit you up once I've resolved bigger issues.

I do believe this has seen some humidity, it's generally pretty clean but banged up, but there is some oxidation on some of PCBs. At the moment I'm not too worried about the malfunctions in the mixer section. Those sorts of repairs are things I have some experience with and at least know how to begin trouble shooting. It's the tape transport stuff that is uncharted territory for me.

Seeing as how I have 3 mixer channels that at least pass audio and can be routed to all the various tape tracks my plan is to focus on the tape transport problems first. If I can't get my head around that then the mixer is sort of meaningless. I'll start studying the manual and eagerly await any insights you might have.

Thanks!
 
Nope, I suppose I could have talked in the videos, that may have been helpful :facepalm:

If you playback video 1 very slowly you can see that after pressing play the reel on the right spins counter clockwise and the reel on the left spins clockwise. Thus resulting in the instantly slack tape.

Do you think step 1 is testing the capstan motor? Wonder how one does that?
 
Just checked the capstan belt before I head in to work. It seems OK, it's on, not broken, and not goo, maybe a little loose. If I manually spin the capstan motor the flywheel spins as well. It would seem perhaps that either the motor is not functioning or not receiving voltage. Is there an easy way to test for that?
 
Not sure. However, the capstan motor's often on a separate fuse. Did you check that? It might also be worth checking the microswitch or photointerrupter on the right tension arm, whichever it uses to trigger the capstan motor.
 
I'll dig in to those leads, thanks. I checked all four fuses on the PCB near the power transformer, I think I noticed either in the manual or some pictures online that there is another fuse board deeper in bowels of the unit.
 
nateflanigan said:
I'll dig in to those leads, thanks. I checked all four fuses on the PCB near the power transformer, I think I noticed either in the manual or some pictures online that there is another fuse board deeper in bowels of the unit.
Click to expand...

Not sure what that would be - I'd expect the capstan fuse to be one of the four by the PSU, though... that seems to be the norm for TASCAM decks. I'd investigate the switch on the tension arm next if it were me.

EDIT: I can't get a clear picture of the deck internals, but it looks like it might be using a vane and photointerrupter rather than a microswitch. If so, that makes things a little more complex. A microswitch could switch the whole 24v for the capstan motor directly, whereas a logic-based switch will need some kind of a relay or power transistor to do it. I don't have the schematics to hand, unfortunately...

EDIT EDIT: Found the schematics. It looks to me like it might actually have two photointerruptors, one for each tension arm. Is it possible you have to hold both of them up to get the capstan motor to spin?
 
Last edited:
I removed the Tape Transport Panel tonight and reconnected the control board in order to get a better look at the goings on.

If I hold up the right tension arm and press play:
1) the brake solenoid activates and releases the brakes
2) the the pinch roller solenoid activates and pulls the pinch roller into position

No motors spin. If i also hold up the left tension lever the results are the same. I can't seem to do anything to activate the lifter solenoid, if I manually push it in the little guard pins pull up into the tape heads, the same thing can be accomplished by pushing the tape lifter switch on the control board.

I checked some voltages from the bottom of the unit on the Mecha Joint PCB. On J2 (the connector that goes to the cap servo pcb and also has connections to the capstan motor itself, I measured 32VDC at both pins 3 and 4 (motor+ and motor-) *note this was while the tape machine was inert, I'll have to rig up some rubber bands or something to test voltage while in PLAY mode.

I think part of my confusion is I don't really know what normal is on this machine, or what specifically should happen when PLAY is pressed.



Found the schematics. It looks to me like it might actually have two photointerruptors, one for each tension arm. Is it possible you have to hold both of them up to get the capstan motor to spin?
Click to expand...

Which schematic are you looking at is it the one for Mecha Joint PCB?
 
nateflanigan said:
Which schematic are you looking at is it the one for Mecha Joint PCB?
Click to expand...

No, it was something else - my bad. Might actually have been the tach readers, actually. Looking at the mecha joint schematic, there's one photointerruptor for the capstan motor shutoff, and two more associated with the reel motors, might be some kind of tension sensor. So yeah, on this deck it is just the right tension arm to activate the capstan motor.

It might be interesting to know what pin 5 is doing, with the tension arm in the on and off positions.
 
jpmorris said:
No, it was something else - my bad. Might actually have been the tach readers, actually. Looking at the mecha joint schematic, there's one photointerruptor for the capstan motor shutoff, and two more associated with the reel motors, might be some kind of tension sensor. So yeah, on this deck it is just the right tension arm to activate the capstan motor.

It might be interesting to know what pin 5 is doing, with the tension arm in the on and off positions.
Click to expand...

Yes that's correct...photo-interrupts (not microswitch) on each tension arm, only takeup tension arm needs raised to activate the capstan motor.

I'll have to look at the schematics to find the joint PCB scheme...it's bundled in with another schematic iirc. Busy week. I'll look when I can. The fact the brakes release and pinch roller engages when the takeup tension arm is raised tells me the 24V transport supply is working.
 
You must log in or register to reply here.
Back
Top