Got my Tascam 388 Today. A few issues and questions.

  • Thread starter Thread starter fompsweeva
  • Start date Start date
F

fompsweeva

New member
Hello there,

Today I received my Tascam 388 in the post from a seller in Perth. It arrived in good condition in a very nice road case.

The 388 itself has some issues. The first one I've dealt with already as I had a day at my disposal and decided to get cracking and re-cap the power supply before attempting to power it up.

Before: (yuck)

IMG_1187.webp

After:

IMG_1189.webp

Power supply now works a treat.

I also found some caps on the Reel Servo Board, so I took care of those at the same time. They weren't displaying any critical signs of failure though. There is a transistor on the board that looks suspicious though, as mentioned in a thread which I was not allowed to link to.

I am going to get a transistor to replace it but cannot find one locally right now. I tested the transistor with my multimeter via some online guides and according to those checks it is functioning, however I will replace it anyway as there is a black area around the PCB so it has obviously been quite hot. I checked around the traces and surrounding components and everything seems to be okay.

The issue I'm having at this stage is that I don't have forward or play/record features. If I hold up the right hand tension arm, the pinch roller engages, the capstan shaft spins and the left reel spins. It doesn't do this with tape though?

I've done the fuse check and the fuses seem original and okay. They all pass a continuity test on my multimeter, but I'll receive a new set soon anyway.

I've opened up the bottom and found the belt was drooping off of the motor. I gave everything a good clean/vaccum and replaced the belt however I'm still not getting playback.

I might add that I'm a little new to reel to reel so I'm looking for some guidance on how to get this thing going well!

Any ideas where I might head from here, beyond replacing that suspect transistor?

Update:

1. The belt had slipped once again. Capstan motor still turns, waiting on a new belt.

2. I tried adjusting the tension rollers. The left roller adjust fine with R112. R212 does nothing, so no adjustment is possible. I'm yet to trace this on the PCB but it's one more thing. The caps should be good! Waiting on the spare transistor which should come next week.
 
Last edited:
Hey guys,

Good news.

1. Replaced the transistor. No fix.
2. bypassed the PCB traces to ensure good contact. No fix.
3. Replaced resistor near transistor. No Fix.
4. Opened up motors, inspected and spun them, put them back together.

Now, both reels spin. When I can get the old capstan belt (waiting on a new one) to stay on, I can get all the features except for one strange quirk. The take up reel (right reel) seems to be spinning in the wrong direction. Pressing "Load" causes both reels to jolt and the tape begins to spool onto the machine. I fast forwarded a tape like this and it seems okay, but just a little weird to me.

Here's a pic:

View attachment 72235

Anyway, I'm stoked that the motor is working. Just a little confused about the way the tape is spooling on to the take up reel.

Any ideas?
 
Last edited:
Yeah, the reels will try to spin in opposite directions, it's only usually obvious when there's no tape on the machine. This looks weird, but it's actually done to provide back-tension on the tape - when the machine's loaded the back-tension is weak enough that the spool turns the other way anyhow, it's just trying to provide enough resistance to keep the tape relatively taut against the heads.

If both reels are spinning the same way without tape being loaded, you've got a problem.
 
Hi JP,

Check this out. This illustrates it quite well. I'm not sure if I made a mistake here, but I'll do more tests tomorrow. The tape spools onto the wrong side as well, not just when the load button is pushed.

View attachment 72254

(Can you see the attachment?)
 
Last edited:
If you google "tape op 661434" I've also posted in the thread over there where you should be able to see my pic. Homerecording isn't allowing me to post links (including pictures) until I get ten posts. I'll see if a PM link will work.

I just confirmed that pressing 'fast forward' with the full reel on the left and the empty reel on the right results in the tape spooling on to the incorrect side of the right reel.
 
http://messageboard.tapeop.com/viewtopic.php?p=661434

Okay, that does not look right. The takeup spool is wired so that when it's got power it will always turn anti-clockwise in play or fast-forward. The left hand spool is wired to turn clockwise when it is powered on (i.e. in rewind).

It looks like the takeup spool is turning clockwise under its own power, which should never happen. I believe they're just basic DC motors.

Is it possible that the motor is plugged into the control board backwards? Is the power supply somehow providing -12v instead of +12v or whatever that motor normally uses?

Try loading the machine up with two empty spools (just in case it goes mental and ruins the tape). Raise the tension arm until the capstan starts turning, and then try pressing FF, play, and RW. Depending on how the 388 works, it may stop obeying commands while doing this - if so, release the tension arm and it should go back to normal.

Make a note of which way the reels are turning while this is happening. I would imagine Fast Forward and Play will behave the same. The real question is whether Rewind behaves normally - if the transport is working correctly, the left spool will turn clockwise and the right spool should turn anticlockwise.
 
Here's my update.

Testing with two empty reels:

[TABLE="class: grid, width: 500"]
[TR]
[TD][/TD]
[TD]LEFT REEL[/TD]
[TD]RIGHT REEL (Take Up)[/TD]
[/TR]
[TR]
[TD]PLAY[/TD]
[TD]CLOCKWISE ??[/TD]
[TD]CLOCKWISE ??[/TD]
[/TR]
[TR]
[TD]FAST FORWARD[/TD]
[TD]CLOCKWISE ??[/TD]
[TD]CLOCKWISE ??[/TD]
[/TR]
[TR]
[TD]REWIND[/TD]
[TD]CLOCKWISE ??[/TD]
[TD]NO SPIN (Could be calibration screw?)[/TD]
[/TR]
[/TABLE]

My next step is to figure out where the motors are told to spin anti-clockwise. There is one transistor near the dead transistor I'll replace just to make sure that's not the culprit.

A reel head scratcher... :P
 
The left motor seems to be working correctly. It should spin clockwise unless it's being dragged the other way by the tape. The right motor is turning the wrong direction and it should also be turning anticlockwise in rewind to provide back-tension.

I'll have to double-check this on my old '32, but that's what the TSR-8 does and I'm pretty sure it's what the Revox does too.
 
That's good news.

Currently I have some transistors/parts on order for the Reel Servo PCB. There are some transistors on there I am suspicious of so I thought I'd replace those before I go any further.

I have taken advantage of the waiting time to pull all of the circuit cards out to inspect them. Every single channel card has a leak at the largest capacitor on the board. I've made a decision to just re-cap everything now while I've got everything apart.

Another thing I'm doing is going through and replacing the globes with LED's. Although I found it odd that the Stereo meters seem to be getting AC power rather than DC power. The LED's still light up, but they flicker a bit.

I appreciate the time you've put in to helping JP. I'm remaining optimistic and it makes sense that the reel servo PCB is the cause of my troubles, however I have found a bad leaky cap on the control PCB under the transport controls, so that may also have something to do with my trouble.

It'll probably be a week or two before I get all the caps installed and the reel servo PCB fixed... here's hoping!
 
Hey guys,

Still having the reel reversal issue. Haven't had much luck tracing it. Still suspecting the reel servo PCB and I've tested all diodes and transistors and everything seems okay. I'm really confused as to why I'm having these direction issues.

I've also taken the control PCB out and given it new capacitors. I only have audio cards left to re-cap, but I'm wanting to get this reel issue sorted as it's really bothering me!

Anyone got any ideas?
 
I have traced down most parts for the Reel servo PCB. I've tested all resistors and transistors, except for the digital ones which are impossible to test. There are a few discrepancies between the service manual and the actual board I have - a few resistor values and I'm missing trim pots for R203 and 103. (Came with a fixed value 5.6k resistor)

I've ordered new everything, including the main logic chip which I was surprised is still available. The only thing I can't find locally is the large transistor array, so I'll need to order one of those from overseas.

Right now I have to put the reel issues aside and work on the mixer while I wait for parts to arrive.

I have successfully replaced all of the meter bridge lights with 'warm white' LED's and it looks great. I built a rectifier circuit to make use of the AC voltage that was already going to the meters, however I had to run it in an array of 4 + 4 +2. If anyone would like more details on how I did this I'd be happy to help out!
 
Reel Servo Documentation Gaff

Sorry if this is redundant, as I've not caught up on the body of this thread, but...

The 388 User/Service Manual has a misprint on the Reel/Servo reference page. The FF Tension and RW Tension pots are REVERSED in the docs. Not having the manual open in front of me, that's as specific as I can get. It took lots of T & E and frustration to determine that on the bench. When you adjust what the manual says is FF Tension, you're adjusting Rewind, and when you adjust what the manual says is RW Tension, it's actually Fast Forward. It's best to strike and rewrite those values into the manual correctly for future reference. If you've not discovered or determined this yourself already, it can cause you hours of frustration, as it did for me.

/DA

:spank::eek:;)
 
You must log in or register to reply here.
Back
Top