Servicing a SONY DAT machine (Pictorial)

I have has sony's myself. But my Tascam DA-30 seems to go on forever.
Still, I like some of the Sony mechanisms. I think in general that prolonged non-use isn't good for any mechanical deck. Have to exercise the mechs from time to time to keep lubricants where they belong. I have had a few sony DAT's recently that just needed to be run a bit before they settled back in. On these, the brake bands were fine. The deck's just getting a little sticky. I suspect, though, that this is just the prelude to having to re-lube it.
 
SaSi said:
Sometimes things break just because they aren't used. I know it sounds funny, but my Aiwa AD-F880 cassette decks developed a slack on the main belt just because I didn't use it much for a few years. It was 5 years old. I replaced the belt and used it regularly since then - 2001. It's working fine until now.
Click to expand...

Yes, this is indeed true - that's why it also is a bad idea to put a car for years on end in storage without ever starting up the engine. Even classic cars which could be worth millions need to be fired up and driving a bit at least a few times each year.

Anyway: I was hoping that you could indicate if my problem, which is probably as you indicated, caused by the pad being stuck to the take up spool plate, is something seriously or something that can be taken care of relatively easily?

Thanks!

Btw. Some basic small repairs on audio gear is something I sometimes do, but fiddling around with the delicate mechanism of a DAT deck is not my piece of cake - I'd much rather leave that to a professional.
 
Tinman said:
I think in general that prolonged non-use isn't good for any mechanical deck. Have to exercise the mechs from time to time to keep lubricants where they belong.
Click to expand...

Tinman,

I think you're right - I should have used my Sony DTC-690 DAT deck a bit more intensively instead of keeping it as a mint backup unit to my JVC DAT deck. The JVC has been used more intensely and on a more regular basis and is an active part of my system.

Regarding 'exercising the mechs': do you think the same applies for cassette decks and VCRs? I have so many of these that only two of each are used regularly whilst the other ones remain vitually unused. If so, I'd have to set up 'exercise programs' for all of these.
 
There is a rather easy and safe way to check the problem on your DAT transport. It might also do the trick and fix it, although the chances are low.

If you can remove the top cover and then remove the transport mechanism as a whole (unplug the unit, slide and remove the outer cassette compartment cover, undo the 3 or 4 screws securing the plastic mounting of the transport to the base of the unit).

You don't even need to remove the wires from the main board.

Lift the transport out of the unit so that you can see the front edge of the mechanism, where the manufacture date is stamped (BTW what does it read there?).

To the left edge of the transport you can see a lever mounted on a rod driven by a solenoid. To the right edge you can see the reduction gears.

Use a clip, pen, screwdriver to gently push the left side rod inwards. This should release the reel plate brakes. Once this is done, you should be able to freely rotate the reel plates with your fingers. You should be able to rotate them even with the breaks engaged, but in that case you should feel a slight drag from the brakes.

If releasing the brakes makes no difference on the drag while rotating the RHS reel manualy, then the problem is a sticky tension pad.

Another test you might be able to to easily is to test the reel plate motor.

It is located underneath and it drives a toothed plastic band. You can rotate it to either direction. In one direction it should engage the supply reel and rotate that, in the other direction it should engage the take up reel and rotate that in the correct direction. It takes a firm spin with the pointer finger to make the inner "fly-gear" engage the proper reel. It might not be able to reproduce it manualy so the result of this test is not conclusive.

BTW, the sony transport mechanisms on these decks must not be lubed. They should run dry. the cleaner the better. Don't be tempted to spray WD40 or anything similar inside, it will only ruin the pads.
 
After reading this thread again, I made sure to power up my mechanical transport components and use them for a bit to get the "Juices" flowing! ;)
 
I have to admit that my basement storage room has some magical abilities. Two units, one cassette deck and a DAT deck were briefly tested and stored with faults to be fixed. I left them be there for a couple of months. I brought up one of them to work on it, but it works. I gave it some time to fail but it doesn't. I am listening to some cassettes right now played on that.

I then thought, what the heck, it might as well be a DAT day today. So I brought that to the bench. It was supposed to have sluggish FF/REW and I was supposed to bring up some additional info to this thread. It works fine.

What's happening?
 
SaSi said:
I have to admit that my basement storage room has some magical abilities. Two units, one cassette deck and a DAT deck were briefly tested and stored with faults to be fixed. I left them be there for a couple of months. I brought up one of them to work on it, but it works. I gave it some time to fail but it doesn't. I am listening to some cassettes right now played on that.

I then thought, what the heck, it might as well be a DAT day today. So I brought that to the bench. It was supposed to have sluggish FF/REW and I was supposed to bring up some additional info to this thread. It works fine.

What's happening?
Click to expand...

Huh.... maybe it'll restore old tapes as well. :scratch2:
 
SaSi said:
I have to admit that my basement storage room has some magical abilities. Two units, one cassette deck and a DAT deck were briefly tested and stored with faults to be fixed. I left them be there for a couple of months. I brought up one of them to work on it, but it works. I gave it some time to fail but it doesn't. I am listening to some cassettes right now played on that.

I then thought, what the heck, it might as well be a DAT day today. So I brought that to the bench. It was supposed to have sluggish FF/REW and I was supposed to bring up some additional info to this thread. It works fine.

What's happening?
Click to expand...

After reading that I think I'll let my DTC690 'rot' for a few months in a basement as well... if only I had a basement. Perhaps an outside somewhat moist shed would do the trick, that's where I keep my bicycles as well.
 
Help need with diagnosing DAT problem

I've read through this thread with great interest as I try to fix a problem with my Sony DTC-690 DAT machine. I'm a novice at this having not taken such a machine apart before - but I've got as far as taking out (but not disassembling) the transport and am getting a bit nervous about going further and not being able to work out how to go back. I thought I would stop for the moment and explain what I have noticed so far, in the hope that someone might be able to help pinpoint whether further disassembly is needed or whether I should stop and make some adjustment at this stage and retest.

What the machine did before I started:

It would wind tapes forwards and backwards (most of the time) OK.
Tapes would sometimes not eject properly and I could only eject them after power off and on and ejecting immediately.
Playback of already recorded tapes mostly resulted in nothing, digital noise, or short bursts of coherent sound. During playback the machine made a series of loud double-clicks and the sampling frequency would change or be flashing. It sounded like it was unable to detect the right signal to start decoding.
Tapes were sometimes getting mangled along one edge after trying (unsuccessfully) to play them.
I recorded some fresh material but this also failed to play back properly. However, the playback failed at different points during repeated plays making me think that the recording was there but just not being read correctly.

What I noticed during disassembly:

After removing the case I placed a tape in the machine and observed the loading, playback and ejection of a tape. I noticed that sometimes the tape did not load or eject properly because the S1 guide arm was not 'hooking' the tape correctly at the start. It seemed that the tape was catching the top of the arm and sometimes failing to go over the guide roller. Then, when the guides retracted to pull the tape around the drum, only the T1 guide would be engaged with the tape, meaning that the tape was coming away from the drum directly to the left-hand spool of the cassette. If the tape was played this seemed to be causing the tape mangling that I'd seen (I guess from snagging on the cassette housing). When this happened, the tape would not eject properly either - not quite sure why, but it seemed that the tape did not end up fully tensioned in the cassette and this seemed to make the problem more likely the next time it was inserted.

I separated the transport from the plastic cassette loading mechanism to see the transport more clearly as SaSi described in this thread. I noticed that the S1 guide did not seem to come forward fully into place when the tape was in the disengaged state. Moving the guides using the cog visible at the front, the S1 guide seems to stop in a different position to the T1 guide. The T1 guide stops about 2mm from the long circuit board (I think it is) that runs across the width of the unit. The S1 guide stops about 6mm away and the last part of the track is still visible on the front edge beneath the guide. It's as if it has stopped short of the end of the track. The S1 guide also feels very loose to the touch compared to the T1 guide and rattles around when touched lightly - but I cannot make it move further forward. I can't tell from the pictures in the thread if this different positioning of the guides is as intended or not.

I also tried the test of the brake mechanism mentioned in this thread (pushing in the bar on the front-left of the transport and testing how easy it is to turn the two spool hubs (not sure what the right name is). I found that the right-hand hub turned easily when the bar was pushed in but stopped when the bar was out. The left hand hub would turn easily in either position.

I can see nothing else obviously wrong at this stage - everything looks clean and dirt-free.

So now I wonder what to do next. Is there any point disassembling further (a daunting prospect) or is there something I could try at this stage? Or maybe the fault (or faults) aren't connected with the mechanics.

Any advice or pointers would be very much appreciated.

Thanks.
 
Last edited:
Sounds like one of the clips came off the underside of the loading arm.

You have to get underneath the mechanism to see it.

Marc
 
Getting better

Thanks for the pointer. I disassembled the transport and found two missing clips: one on the underside of the S1 guide and one in the front under the spool hubs mechanism. One of the clips was in the mechanism and had split - I could not find the other. I replaced the one on the guide with a good one from under the spool hubs and replaced that one with the split one glued back together as best I could. That seems to have fixed the problem with load/unload of cassettes and improved the tracking quite a bit. It's still relatively poor though - it lasts a few minutes sometimes before dropping out, but is still not consistent.

Is there any adjustment that might improve the tracking as I can't see any other mechanical issues other than the missing clip (which I can't see how I can replace without another machine to strip down for spares)?

Thanks.
 
Fixing a Sony DAT DTC-690

I have a couple of follow-up questions which I hope someone might be able to answer:

Reading the service manual for the DTC-690 it seems that tracking issues can be addressed by adjustment of the two guides S1 and T1. I see screws at the top of the guides which I guess are the points to be adjusted - but they have a odd types of broken-slot screw head that I can't find anything to fit. Does anyone know what type of tool is needed to adjust this type of screw?

When I play back tapes through the DTC-690 I hear (when its working OK) good sound from the analogue outputs but sound mixed with a constant background crackling noise through the optical output. The noise is only there when sound is playing - it disappears during gaps between tracks. It sounds like a sort of digital jitter that might result from sample rate mismatches but I've checked that the sample rates on my computer sound card match that of the incoming data. Is there something else I could check or could the sound just another indication that the tape is not being read correctly but the problem is being masked by the digital to analogue conversion inside the DAT machine?
 
I filed a notch into a screwdriver to make a guide alignment tool.

Works great. Do not adjust the guides unless you are SURE that they are seating fully at their end stops when playing tape.

Marc
 
Best left alone?

OK - thanks for the advice. Sounds like I could do more damage than good since I have no test equipment. Since the deck was working fine some time ago and has not been adjusted since, it sounds like my problem is more likely to be the result of some mechanical failure and adjustment of the tracking is unlikely to fix it. I will continue the search for a fault.
 
Yes, make SURE the 2 guides actually seat fully in their slots when the tape engages.
You can also gently try to turn the guides with one finger. If they DO, they are loose to begin with. This was a Sony disease with 8mm decks. The guides unscrewed themselves. If the guides are tight, something is mechanically not "quite" right.

Marc
 
You must log in or register to reply here.

Similar threads

C
DAT Sony DTC-59ES : rescue
2
Replies
25
Views
3K
chercheur
C
A
Tips on fixing a Sony DAT
Replies
1
Views
404
hdrobien
H
SaSi
DAT Audio vs DAT Data transports
Replies
5
Views
726
matt_s78mn
matt_s78mn
uxwbill
A Sort of DAT Disaster - Sony DTC-790
Replies
8
Views
2K
alfista
A
H
Issue with a Sony DTC-59es DAT
Replies
3
Views
3K
hdrobien
H
Back
Top Bottom