Tascam 388 - Please help me fix it!!

F

Floti

New member
Hi guys!

I bought a Tascam 388 some months ago and haven't been able to make it work right. It was in good condition before I bought it, but I guess the shipping didn't make it any good. It was also serviced not long ago, so I guess all components should be fine (in theory).

The thing is that it doesn't play, rewind or ff. I've been reading every single post in this forum regarding those problems. I've changed the belt, fuses, taken pcb's away and reseating them just in case. I've cleaned the machine inside, the springs under the reels and all this stuff. I also had the chance and switched the power supply pcb and reel servo pcb for ones that were inside a working machine. I re-tensioned the arms too. Nothing worked. I read somewhere something that areelperson wrote about some transistor located on the TR pcb¿?, I asked a tech to check those transistors for me and he said they were fine.

So, I recorded a video showing what my machine does right now and I would like you guys to help me fix it. I will do whatever you suggest me to do and document it with pictures or videos if needed. I'm not a tech and I don't know much about electronics, but I can try and I'm sure that with your help I'll get this fixed! I ask you guys please to be detailed in your instructions so I can understand things and get them done.

They don't let me post the video, since I haven't made 10 posts, but it is on vimeo and the url goes like this: vimeo.write-three-Ws-here/40473799

Thank you so much!!
 
This might seem stupid, but when you hit rewind it's trying to pull the tape and struggling.

Is it sticky?

Take the tape off, hold the tension arms up and hit play/rw/ff with your third hand. :p

At least that way you can figure out exactly what's working and what's not.
 
I guess that's not the problem. I just changed the tape for a new one and the machine kept doing the same thing. Also tried without tape and it plays normally, but when FF it starts doing it and gets locked, you can't stop it any way and you have to switch off the machine to maki it stop. I can make a video of that too if you prefer too see it.

Thank you so much! Any other idea?
 
When you're fast-forwarding without tape it goes crazy and won't stop until you release the tension roller, right? That's normal, the more modern machines tend to panic if the tach roller isn't turning, which it won't when there's no tape.
 
jpmorris said:
When you're fast-forwarding without tape it goes crazy and won't stop until you release the tension roller, right? That's normal, the more modern machines tend to panic if the tach roller isn't turning, which it won't when there's no tape.
Click to expand...

But the stop button should still stop it, right?

If you were using sticky tape, I guess you'd know about it.
The tape path would obviously need cleaned in order to run smoothly.
 
jpmorris said:
When you're fast-forwarding without tape it goes crazy and won't stop until you release the tension roller, right? That's normal, the more modern machines tend to panic if the tach roller isn't turning, which it won't when there's no tape.
Click to expand...

I don't believe that applies to the 388 though...IIRC on the 388 you only need to have the right tension arm raised and you should be able to step through the transport functions.
 
Just watched the video.

I hate to say it but it looks like your servo logic is hosed somehow. This is wayyyyyy over my head, but I'm seeing that in FFWD the counter readout goes blank, is that correct?

When you put it into REW what happens if you lift the left tension arm up?
 
Hi sweetbeats! I read you full Tascam 388 story! Thanks for coming and helping!

Well, I did a second video with and without tape, so you guys can see how random this is. It's true that the counter goes blank when FF, but the other function seem to work with some help when there's no tape. That servo logic thing sounds bad, though I don't really undestand what you mean...

Here's the new video:



Thanks again!!!
 
Hmmmmmm...

It does look intermittent, though less so when unloaded.

Does STOP ever work?

What's the history on this machine?

Any damage?

The only thing I can suggest at this point is to reseat the reel servo PCB (the card next to the power supply PCB in the cardbay) and look for anything toasted on the card, and ALSO to pull the bottom cover off and reseat the connections going to the control panel assembly...look for damaged wiring and such.

It LOOKS like, as I said, it is more normal with the reels unloaded and when you have the reel tables loaded and do something like pressing REW, the left side should start going right away but its not, and because the right reel starts unwinding right away the tension arms drop and put it back into STOP condition. With the reels unloaded and you holding the tension arms that same scenario doesn't play out.

But it definitely looks like something is wrong with the servo electronics which facilitiates reel motors and tension arms all talking together to maintain proper tape tesnion in all the different transport conditions.

When did it last work and did anything happen that might give clues as to where the problem or problems exist?
 
Just re-read your first post.

Please describe in detail how it was packaged and who the carrier was.
 
Well, I live in the Canary Islands, so yeah, transport is probably guilty for this situation. I can't blame the company or the guy that packed it, I wanted the machine so bad and asumed the risks. The things is that as is shown in the videos, it doesn't seem to be a mechanic problem, which would be expected. To me it seems too some electronic failure, but I've tried (as little as I know) to follow the schemes and if it's not something in the Reel Servo, Power Supply or TR PCBs I guess it could still be on the cap servo pcb. elsewhere I would be lost.

The machine does STOP when I have no tape loaded. In the second video I manage to STOP while playing and RWing.

I will check connections on the control panel when I get back home.

I has never seen the machine working, but it was in perfect condition before I bought it, and I am sure of that.

Thank you so much again! Hope we can find a cure!
 
It's very likely a transport logic control issue. These sorts of problems aren't usually the IC itself, but rather supporting components around the IC, like resistors and capacitors... usually bad capacitors. Or even more simple like the previous owner spilling beer or pop on the unit and it creates new connections with residue and dust, which confuses the logic chip.

I can't possibly diagnose the problem from afar, but my gut says that if you opened the unit up and cleaned the pins on the top side of the transport control IC with a toothbrush, isopropyl alcohol and compressed air, the problem might just go away. As I said, it might be a bit more involved like a bad capacitor or two. In that case you have to track down the bad component, desolder and replace it. It could be any number of more serious issues, but that's where I'd start. Best of luck.
 
You might want to take a look for any cracks on the transport logic circuit boards. Shipping damage might do stuff like that if it was banged around or dropped too hard while in transit. And especially considering the unit was said to be working properly when it left the seller's hands, this would be the number one suspect in my books.

Luck!

Cheers! :)
 
Hi again! I was able to soend some time todays with it. Opened it and couldn't find any cracks or any visibly damaged components. Also capacitors and resistors seemed to be in shape, with no visible problems. I checked connections and cleaned dust on the control pcb too.

Things are just the same. Most functions are still working without tape but when iI load some tape there's no way to make it work. Any other ideas?

Thanks again!!
 
I don't mean to be a rain cloud here but this won't be as simple as tracing out a problem in the audio path. The transport logic relies on so many factors. You can't always tell a component is bad by looking, and you typically can't see bad solder joints or traces. I believe, unless there is something obvious that I'm missing, that it will be time to pull out your diagnostic equipment and start troubleshooting at the circuit level. The first step is always to make sure the power supply is producing clean power of the appropriate levels on all rails and then to make sure that that power is reaching the appropriate places. If this is beyond your comfort level then its time you find a tech locally.

You also never described how it was packed. It could help lend a clue as to areas that may have been stressed. If there wasn't sufficient torsional support it would be easy for multiple pcb's to be torsionally stressed and for solder lands or traces to be damaged.

Have you re-seated the reel servo PCB and the power supply PCB cards on the right-hand side of the cardbay? Have you checked the connections on the cap servo PCB (under the fuse PCB at the right-hand side of the cardbay)?
 
You must log in or register to reply here.
Back
Top