Servicing a SONY DAT machine (Pictorial)

[uzvarb]

In the last month I have serviced 4 DTC-77ES. Only one had a problem with the left guide, my DAT. But all 4 had bad capacitors on the front panel, and RF amplifiers. It seemed to be ok, machine work, but the removal will discover that they leaked. On the pictures you can see how to set up the new capacitors that can be assembly with no problems.

 

[jascha]

In the last month I have serviced 4 DTC-77ES. Only one had a problem with the left guide, my DAT. But all 4 had bad capacitors on the front panel, and RF amplifiers. It seemed to be ok, machine work, but the removal will discover that they leaked. On the pictures you can see how to set up the new capacitors that can be assembly with no problems.

I wasn't so lucky to reach the troublesome caps in time on the control board. It's not my machine and was not in my possession and has been sitting dormant for around 10 years I believe. I tried to repair the etched tracks as much as I could and got it back to working however I still have an issue with some buttons in that they only work on switch on after the machine has not been switched on for some days and they only work for a couple of times and then they become unresponsive. The buttons in question are the Display Mode button and the tow of small buttons starting from Auto (Start ID) all the way to Erase (End ID). I understand that these are secondary buttons and not so important but it would be great to restore their function as well. Everything else works on that board. Nothing was till I repaired it. I am guessing it's an issue with some grounding perhaps to do with discharging of the caps? A wild guess. Such corrosion can be hell and hope at least the buttons that are not responding are all linked to the same circuitry on that board and someone might identify the issue please. Hope it's not an IC. Maybe I try different caps? These were NOS. cheers

 

[uzvarb]

I have problems only with one button on 1 of them. Start ID , it's first to bad capacitor.

 

[hdrobien]

Why don't you try to replace the defective switches ?

 

[jascha]

The switches are fine, I tested them with a continuity meter. Due to corrosion caused by leaking capacitors I will need to triple check that I have repaired the board correctly. If I don't switch on the machine for say 2 days the fault still appears but if I leave it for longer the buttons will work for say 2 times and then again non responsive. I am suspecting some issue either with the caps or some tracks in connection with grounding. I tried a different board (from a PCM 2700) and the buttons worked so that eliminated any fault from any other board.

 

[uzvarb]

Hdrobien talking about this part of mechanic.

 

[uzvarb]

Hi, I need help. I have dtc-55es, I serviced mechanics, all brake pads, rotary encoder, degrease...clean heads and change capacitors in RF amp. After that dat is working perfectly for 3-4 hours and start to mute audio. Rew, ff, ABS time shows perfectly, no bad sounds like bad tracking (digital mistakes). Perfect sound and no sound for sec or two. Like blank parts on tape, no relay click...abs time is correctly shown...sampling freq correct.
Try to clean head again byt no effect.I try to let them to coll down. And again the same on cold machine. .I think it's a new problem, beside what I already wrote. Do anybody have some idea or hint for problem?

 

[jascha]

Hi, I need help. I have dtc-55es, I serviced mechanics, all brake pads, rotary encoder, degrease...clean heads and change capacitors in RF amp. After that dat is working perfectly for 3-4 hours and start to mute audio. Rew, ff, ABS time shows perfectly, no bad sounds like bad tracking (digital mistakes). Perfect sound and no sound for sec or two. Like blank parts on tape, no relay click...abs time is correctly shown...sampling freq correct.
Try to clean head again byt no effect.I try to let them to coll down. And again the same on cold machine. .I think it's a new problem, beside what I already wrote. Do anybody have some idea or hint for problem?

Just a thought...does it do it both using the audio out jacks and headphone output? Do the meters still show a signal when the sound mutes itself? How about inputing a signal and monitoring the output, does it cut off the sound?
Just trying to use a process of elimination which might help.

 

[hdrobien]

Did you check the rf signal with a scope ?

What about the meters during mute ?

Could you try the digital output to narrow the problem ?

 

[uzvarb]

Hi, I do not own an oscilloscope. Peakmeters go off when it comes to drop out. But there's no clicking of the relay, the electronics not "see" the problem and not mute output.
Also, there is not a characteristic of bad sound on the loudspeaker.
Today I washed the RF amplifier in 96% alcohol, and then DAT is again worked perfectly for several hours. On the PCB of the RF Amp is visible traces of repairs, a soldering of most elements and the chip. I suspect that the problem is only in the RF amp board.
I've had some time ago dtc-55es for parts but I gave it as a gift.
Do any of You have to sell me a RF amplifier for DTC-55(75)es..dtc-700?
It also will record how the problem looks and put video on youtube and link it here.

Thanks !!!

P.S.
Without cassette in the DAT, DA conversion works well and there is no problem, but when recording on tape issues are heard, regardless of which input is in use.
The tape being recorded until the problem starts to happen is well recorded and played back on 55es and other machines

 

[jascha]

The switches are fine, I tested them with a continuity meter. Due to corrosion caused by leaking capacitors I will need to triple check that I have repaired the board correctly. If I don't switch on the machine for say 2 days the fault still appears but if I leave it for longer the buttons will work for say 2 times and then again non responsive. I am suspecting some issue either with the caps or some tracks in connection with grounding. I tried a different board (from a PCM 2700) and the buttons worked so that eliminated any fault from any other board.

Hi, I decided to revisit the control board this morning and sorted the issue with some buttons not functioning always. Although they are secondary functions it still bothered me the fact that I did not get to the bottom of the problem. I analysed my work on the board and wasn't pleased with the way I patched up tracks around the cap that sits right below the middle of the LCD. After some thought I removed the cap, cleaned the board and decided to mount the cap at the back of the board. A neater job, less clutter and it all works beautifully (functions wise!). Due to the damage the corrosive liquid from the leaky cap caused, I could only get back continuity of the tracks by taking advantage and make use of points on the tracks that had no components connected to them but their contacts appeared on both sides of the board. I therefore pierced through 3 such contacts with thin leads from capacitors in my spares and connect the 100uf cap to the new connections I made. I used however a 16v cap rather than a 10v one. All functions are working. No way Sony would do such a repair!
Now still have to sort out the issue with drop outs during playback & sounds to me like oscilloscope time again and checking the rf pattern.

 

[hdrobien]

Do any of You have to sell me a RF amplifier for DTC-55(75)es..dtc-700?

Send me a pm with your address and I will send you one that is supposed to be ok (although I did not test it myself).

 

[jascha]

Hi, I do not own an oscilloscope. Peakmeters go off when it comes to drop out. But there's no clicking of the relay, the electronics not "see" the problem and not mute output.
Also, there is not a characteristic of bad sound on the loudspeaker.
Today I washed the RF amplifier in 96% alcohol, and then DAT is again worked perfectly for several hours. On the PCB of the RF Amp is visible traces of repairs, a soldering of most elements and the chip. I suspect that the problem is only in the RF amp board.
I've had some time ago dtc-55es for parts but I gave it as a gift.
Do any of You have to sell me a RF amplifier for DTC-55(75)es..dtc-700?
It also will record how the problem looks and put video on youtube and link it here.

Thanks !!!

P.S.
Without cassette in the DAT, DA conversion works well and there is no problem, but when recording on tape issues are heard, regardless of which input is in use.
The tape being recorded until the problem starts to happen is well recorded and played back on 55es and other machines

What you need is a very powerful magnification lens that watchmakers use and investigate every solder joint. It sounds to me that you have a dry joint somewhere on that RF board. Inspect every solder joint where work was done. Without a mag.lens I would not have managed to inspect my faulty control board and fix it. Try also operating the machine with the rf board out of its shell if you can or at least without the top cover and move the components with a non conductive screwdriver and see if you can get the sound back while playing back the machine. You might find the culprit component not being soldered properly. I had this issue on a pc monitor recently even though everything looked soldered well. Careful not to short out anything! I don't have a spare rf board unfortunately.

 

[uzvarb]

What you need is a very powerful magnification lens that watchmakers use and investigate every solder joint. It sounds to me that you have a dry joint somewhere on that RF board. Inspect every solder joint where work was done. Without a mag.lens I would not have managed to inspect my faulty control board and fix it. Try also operating the machine with the rf board out of its shell if you can or at least without the top cover and move the components with a non conductive screwdriver and see if you can get the sound back while playing back the machine. You might find the culprit component not being soldered properly. I had this issue on a pc monitor recently even though everything looked soldered well. Careful not to short out anything! I don't have a spare rf board unfortunately.

I believe that the problem is just in poor solder joints. But the two capacitors have made extensive damage, checked their close surroundings and closer elements with ohm meter. All pcb tracks were ok. But I can not know how much leaked electrolyte damaged parts and PCB itself. PCB washing is reduced the problem, even now I can not record video, as long as I'm sitting in front of it with a camera, he acts like a frog from cartoon that sings only when is with the owner.
Drop outs is now far shorter and less frequent, and more like the crunch of gramophone records.

 

[madcity]

I have a DAT 2000 ES mint rarely used but a couple hours with open box manuals and unused remote. Came out of collectors edition. Is there much interest for these around the Midwest or? Shawn

 

[uzvarb]

I have a DAT 2000 ES mint rarely used but a couple hours with open box manuals and unused remote. Came out of collectors edition. Is there much interest for these around the Midwest or? Shawn

You're a lucky man, if I owned a DTC 2000es only where I'd go out of the box is a hi-fi rack in the room.
I made a video in which we see that my problematic DTC 55es when she wants to play the tape to the end of 4 hours dds, rewound without problems.

 

[jascha]

Tonight I worked more on the 77es which had another fault of not tracking properly and before I touched the 2 guides, after doing so much work on the control board due to those awful sm caps, I decided to check out the RF boards and thank God I did. All caps were gone and two of them just literally came in my hand. There was corrosion and one of the caps I could not simply replace with another and solder the new cap onto the 2 solder pads were the old one was! Had to solder it to adjacent connections. Never trust those caps. Just change them straight away. The machine is now working however I still have to work on the left guide as it's turning very loosely when trying to adjust it. The left hand side of the scope image is not right. Both guides were misaligned but adjusted the right one so far and although the left one is not right yet it still plays well. Next step will be to take the transport out again and check the guide, sort it out, align it and gladly return it to my friend abroad. It also needs a brake lining as it perished.

 

[uzvarb]

Nice job. I successfully repeired my 77es, but 55es make me crazy. Yesterday perfectly played two dds3 tapes, with almost no problems. When I try third, drop outs come immediately. And after that drops all tape including previously good played.
I'll try to adjust right guide, byt no response.

 

[jascha]

Nice job. I successfully repeired my 77es, but 55es make me crazy. Yesterday perfectly played two dds3 tapes, with almost no problems. When I try third, drop outs come immediately. And after that drops all tape including previously good played.
I'll try to adjust right guide, byt no response.

Thank you . Make sure you use an oscilloscope to adjust guides not only by using ears as it's very critical. DDS3 tapes might not be compatible so much. Best use normal DAT when setting up the machine. Make sure you check the rf board solder contacts with a magnifying glass used by watchmakers! You'll be amazed at the detail or horrified. Change all caps on rf board. They are terrible. On mine they corroded the board at one place and couldn't solder a replacement cap so easily. Good luck

 

[vinylgenie]

I have a lot of DAT tapes to transfer so a friend gave me his old Sony DTC-1000ES machine. He told me it wasn't working. When I switch it on the display shows the L&R volume bar (I have attached a picture) but nothing else. If I press any of the functions, no change to the screen and the open/close button has no affect on the door opening. I have never owned one of these before and I'm not very technically minded in this way so just wanted to ask if anyone could advise what might be the issue? Any information would be really appreciated. Mark.