Servicing a SONY DAT machine (Pictorial)

[chercheur]

6) Free up access to the Capstan + motor assy



7) Remove the Capstan + motor assy



8) Access to the loading rings and guide arms
Round circle highlights the tape loading mechanism.
Two metal rings are moving the 2 guides.


Red arrows show the 2 arms fixed to their guides (on the other side of the mechanism) with plastic washers.
Remember their positions ! They are in the second whole.

IMPORTANT: (yellow arrow)
At this stage you are able to check the synchronization of the 2 rings (=both guides must move together).
When both arms/guides are in the lower position (red square) a whole is free that goes through both rings and the chassis. Use a small screw driver to confirm it.
You can modify the position by manually turning the wheel (red arrow)


This demonstrates the correct alignment of the rings.

9) Remove both rings and clean with isopropyl alcohol

Remove the plastic washer and then the white gear.
That gear must be repositionned when both rings are synchronized !


Remove both plastic washers from the guide arms


Finally, slightly unscrew the third holding "wheel". Just giving it room to move will enable the rings to move.

 

[chercheur]

Both rings are now free


Cleaning is required. Here are both rings still together. See the 2 springs. Don't remove them !


10) Time to mount back

First this one

 

[chercheur]

Start with the lower ring.
Place it correctly and fix it with the screw again.
It must freely turn around the 3 "wheels".

At this stage I already re-attach the guide arm and install his plastic washer


Mount the second ring.
Patience is required as both rings must be aligned in the 3 "wheels".
Once in place and freely rotating, fix the second arm guide + plastic washer.


The last step is to check rings synchronization as we did previously


Follow the revert order to re-mount the mechanism.

 

[hdrobien]

Thanks, this is a very nice tutorial.

I would add, when cleaning the 2 rings, that the "silver hook" must slide freely along its ring. This is the main key point of servicing a 2nd generation 4DD Sony DAT transport (note that the DTC-1000ES and its siblings, 1st generation of the 4DD transport, are slightly different and have a spring on the hook).

 

[Jim Smith Jr]

Please Delete

 

[alfista]

Hi guys, in another thread I posted about a 59ES I got, and now I have an oscilloscope (analog, 2 channels, 20 MHz). Before trying to recap the ref amp I exchanged it for a recapped one from other unit. The symptoms are the same, by ear I can adjust the guides so I got just slight distortion every few seconds in test mode. Ome problem is that I don’t have a test tape so I’m using a tape recorded in an Aiwa, but I think at least I should be able to calibrate the 59ES to work with the Aiwa?

I’m in no way an electronics professional, so I’m struggling with the oscilloscope. I connected the first probe to PBRF and ground, the second one to SWP as the service manual says, but I don’t see mention to which one if for triggering and the parameters for each channel.
Someone can help me?

 

[hdrobien]

The SWP signal is for triggering.

Set PBRF with 50mV caliber and set timebase so one frame is displayed (AC mode to remove the continous part of the signal). You don't need to visualize SWP.

 

[alfista]

The SWP signal is for triggering.

Set PBRF with 50mV caliber and set timebase so one frame is displayed (AC mode to remove the continous part of the signal). You don't need to visualize SWP.

Thanks! I got an image, but while I was adjusting, I noticed that the guide posts are stuck and don’t move and I cannot raise or lower them even if I rotate the adjustment screws. Is this common? Can this be fixed?

 

[hdrobien]

I'm afraid that the upper part of the guide where the screwdriver rests has come loose.

Try to remove it completely and clean the thread.

Then put a micro drop of oil in the shaft.

 

[alfista]

I'm afraid that the upper part of the guide where the screwdriver rests has come loose.

Try to remove it completely and clean the thread.

Then put a micro drop of oil in the shaft.

Thanks a lot hdrobien, I checked and the guides were in really bad shape, and now I know why they were sticky. I replaced them with the ones from a donor deck and they are very smooth. Now I have another problem. The tape is loaded but the guides don't move! By hand they seem fine, but somehow the deck doesn't try to move them. I noticed just a small movement on the left reel.

Maybe I misplaced or broke something while changing the guides? Any hints?

 

[hdrobien]

What do you mean by "By hand they seem fine" ? Do you suggest that the guides move when you rotate the black gear surfacing the front of the transport ?

 

[alfista]

What do you mean by "By hand they seem fine" ? Do you suggest that the guides move when you rotate the black gear surfacing the front of the transport ?

Yes, with the black gear they move freely. I checked that guides are correctly seated on the white plastic part underneath.

I think I moved or disconnected something inside the mech, but any hints about what I have to look for will be appreciated!

 

[hdrobien]

Check that you have not disconnected the loading motor from the board, under the transport, and not disconnected the twin switches located under the tape.

 

[alfista]

Check that you have not disconnected the loading motor from the board, under the transport, and not disconnected the twin switches located under the tape.

Thanks again! Just one doubt, where are those switches? I think there is the issue. I suppose the loading motor is the one that moves the black gear, and that is connected (I'll have to check under the PCB.

 

[hdrobien]

The switches are under the cassette shell, in the lower right corner. One switch detects the cassette and the other enables to record.

 

[alfista]

The switches are under the cassette shell, in the lower right corner. One switch detects the cassette and the other enables to record.

Thanks, the problem was one of the soldering points in the loading motor, exactly as mentioned. Now it's fixed and I will put the deck in test mode and then connect the oscilloscope to start again. Should I start with the right guide (S1)? Is there some best practice?

 

[hdrobien]

The right guide is T1 (T for Take-up), the left one is S1 (S for supply).

Start by adjusting S1 so the full left part of the frame can be observed ( small rectangle before the spikes).

 

[alfista]

The right guide is T1 (T for Take-up), the left one is S1 (S for supply).

Start by adjusting S1 so the full left part of the frame can be observed ( small rectangle before the spikes).

Thanks, I'm getting close, but the whole waveform slowly pulsates, that could be the RF Amp? Or it's just that I need to keep adjusting?

 

[hdrobien]

What do you mean by "slowly pulsates" ?

If you play a "trusted reference tape" (ie recorded on a well aligned deck), the waveform should be steady, symetrical (both from vertical and horizontal point of view).

Adjust both guides in test mode, cancelling the ATF, but in normal play speed.

To check the accuracy of the tracking: play a tape and press fast-forward: the sound should be chopped without digital artefact.

 

[alfista]

What do you mean by "slowly pulsates" ?

If you play a "trusted reference tape" (ie recorded on a well aligned deck), the waveform should be steady, symetrical (both from vertical and horizontal point of view).

Adjust both guides in test mode, cancelling the ATF, but in normal play speed.

To check the accuracy of the tracking: play a tape and press fast-forward: the sound should be chopped without digital artefact.

I started to think I'll not be able to align my deck. In fact it's getting worse, I cannot get the correct waveform and it's getting harder to get audible music. Can it be FWD torque?