Teac vrds 10 service help needed - diyAudio
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Old 11th March 2005, 11:31 PM   #1
m127 is offline m127  Hungary
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Default Teac vrds 10 service help needed

Hi all,
I have recently won a faulty Teac vrds 10 on ebay (cheap enough, so it made sense). The seller said some caps were missing but it was not just that. It seems like someone tried to tweak the player but didn't manage. The clock (the quartz) was disconnected, but no new clock was installed. Lots of caps were removed, but the seller sent a copy with a small part of the schematics and with the missing parts marked, so I managed to get some good quality caps of the correct values and soldered them in nicely. The player is still not working. If I switch it on, nothing happens, just the power switch lamp is lit, that's all. No operation, no door opening, no display. I've tested all the voltage regulators, everything is alive. All the cable connections OK. Then I noticed that a 7805 is very warm, and also a 7404, which has correct supply voltage. After some seconds of switching the unit on these ICs both start to run really hot. The 7404 is in position U11. Only two of its gates are used.
My questions are:
- What do you think can make an simple inverter IC run hot? All the voltages are normal. (On its inputs also.)
- Does anyone have service manual and/or schematics for this player to help me out?
- What else would you test? What next?
It's a really nice player and this piece is in very good shape so I don't want to waste it.
Thank you all in advance!
M.
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Old 12th March 2005, 07:30 AM   #2
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I have the Service Manual. I'll send you later today the Servo board schematics.

Regular VRDS10 or SE version ?
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Old 12th March 2005, 09:12 AM   #3
m127 is offline m127  Hungary
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Hi,

A Big Thank You first! I guess the schemas will help a lot. If you have any problems with the size of the files email me and I'll give you a different email address I use.

I have an idea that maybe the player has a corrupted clock signal or no clock at all. It has a CXD2500AQ chip which controlles the clock (and many more of course), just as in my other player, the Denon DCD-755 AR. I think I'll take a look at my Denon with an oscilloscope today to find out what signals I have to see. I guess what could have happened to the TEAC is that someone tried to use an external clock module and connected that to the XTAI pin (53) of the CXD2500 chip, and maybe screwed up something in there with an incorrect signal. The funny thing is, I can't see anything on the CLK (74) pin, I'll take a look how that looks in my Denon. If the chips don't have clock signal, then that's it, it's a good reason why nothing is working.
Any other ideas are welcome!!

M.
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Old 12th March 2005, 09:17 AM   #4
m127 is offline m127  Hungary
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Oh, forgotten to say, this is a VRDS-10 SE.
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Old 12th March 2005, 03:43 PM   #5
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ok, I need to ask a friend. I don't have the SE schematics on hand.

On the servo board, I replaced all chimical caps with Rubycon ZA and ZL, and some Panasonic FC.

If you use the analog part, you can do the same, and replace the opamps with 627 (first stage) and 2604 (second stage).


If no clock, nothing works.
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Old 12th March 2005, 04:33 PM   #6
m127 is offline m127  Hungary
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First, I do not want to tweak it, but to repair it. In my other player (Denon) I did some cap and opamp replacements as well as you.

A big change today. I have managed to find out that the 7404 (which runs hot) is a so-called 'Reset' circuit. It gives a specified voltage level (High for some circuits and low for others) if the supply is OK. There is a small transistor circuit before the IC, doing the work of checking voltages, what the IC does is only sending out the preferred level signals.

Now, I have found that both inverter stages of the ic which were used were faulty! Fortunately this ic has six inverters, so I managed to change stages and have the function OK now. This means, the player swithces on, starts up, the pickup focuses, it manages to read the TOC, and -with difficulties in tracking though- slowly it finds the tracks and manages to play them. Good news!

Two problems still. One of them is that the cd tray cannot open or close. The only way I could try the player was to steal in a cd by disassembling the drive partly. I had a look at the mechanism, all the belts are OK and the motors seem to be OK also. I fear that the digital drive circuits of the door open motor are faulty.

The other problem which still exists is that the same inverter IC (7404) which I had problems with is still hot. Very hot. After 1 minute of operation you cannot even touch it. Maybe I'll have to replace that part, which comes next week (until then I cannot get replacements).

That's the status so far. I still need the drawings of course, and any other ideas or help is appreciated. Should I manage to fix ev'rything I'll let you know.
M.
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Old 12th March 2005, 04:47 PM   #7
m127 is offline m127  Hungary
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Anyway, as far as I know the servo pcb is the same on the SE and the non-SE version. I my information is correct, the only differences are on the analogue board.
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Old 12th March 2005, 05:09 PM   #8
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jpg files are ready for you.

Need your email with a good disk quota.
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Old 18th March 2005, 12:04 AM   #9
Hans L is offline Hans L  Netherlands
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Quote:
Originally posted by stef1777
I have the Service Manual. I'll send you later today the Servo board schematics.

Regular VRDS10 or SE version ?
Hi Stef,

can you send me a copy of the service manual and schematics as well? I also happen to have a broken down VRDS10 which is presently collecting dust

Please mail me via diyaudio.com for the correct emailaddress.

Thank you!

Hans.
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Old 22nd March 2005, 01:50 PM   #10
m127 is offline m127  Hungary
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Hello guys,
My VRDS-10SE is ready! It had a faulty reset circuit which I replaced (different type but works perfect), it had a lot of caps missing, I installed them, and it had a faulty motor driver (for the motor opening the tray), I have replaced that also. Ev'rything is perfect now! Though the sound is not as good as my modified Denon DCD-755AR (with PCM1702 DACs), and it seems to me that my Onkyo DX-6870 also outperforms it. Of course the VRDS mechanic is perfect, much better than any other one of my players. I also have a Teac CD-5, I cannot make any difference between the two Teacs. Now my idea is to use the VRDS as a transport and build a DAC for it (external). Or, try to mount a digital input onto my Onkyo DX-6870, so as I will be able to use it with the Teac VRDS. On the other hand I have read somewhere that the VRDS-10 has its digital output somewhat limited, though I don't know what that means. Mine is an SE, but I think the only difference is in the analogue section. Any info on that? (I mean the dig. out?)
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