Hello and welcome back again!

1. Which restistors do you mean? Do you have a service manual? In the sm, all allign points (for service) are described, and those having no description MUST NOT get disadjusted! They are adjusted in GRUNDIG factory after production and can not get alligned by "normal" technicans.

2. It looks like a) the video heads are worn, so the DTF signals (recorded with the video signal) are read faulty. V-2000 works without a "normal" sync track, like VHS or Betamax. V-2000 has 5 different frequences recorded on the helical scan tracks. In play mode, these five signals get to the DTF-control, then the DTF module serves the DTF voltages to the piezo elements, on which the video heads are mounted.

This is, why V-2000 can offer perfect clear picture search FF and REW.
It is a really difficult "dynamic track following" system, and some troubles have not been removed entirely until the end of the system V-2000.

Now, after more than 25 years, the tapes have get older as well as the machines. It is nearly impossible today, to play a V-2000 tape in the same perfect quality as it was recorded. Even a new recording - the tape material is old!

I hope, you have checked all of the voltages coming from the power supply. This is a general presuppose for correct working of the VCR.

What about the DTF voltages (Oscilloscope on the pickup-shoes)? In normal mode (play), the voltages must not drift up or down very much. The oscilloscope should display a relative straight line.

If the drop-outs appear, is the picture still present? Or does it disappear in this time? Check the DTF-voltage, when the image interference appears.

3. The pin for the photo sensor (video headdisc speed indicator) is a little too wide! Original, this pin is only about 5 mm wide.
Perhaps, the servo control gets too long sync pulses because of the "big" pin on the head drum.

Best regards,
stego

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Hello, Stego! Again and again you help me to repair this VCR! Thank you for your help!

1. I don't have SM none in electronic or paper variants The resistors are R1194 and R1217. They are on the top of DTF/SERVO board (you can see broken one on the third photo).

2. If I understand correctly, DTF system works good, becsause there are no visible glitches on the picture, FF and REW works perfectly, PAUSE is perfect too. On TV the picture is very-very clean. But VirtualDub drops frames because of non-correct V-sync pulse. When drop occures, picture is good, but DScaler in that cases shows "2:1 Bad Pulldown", I'll post oscillograms of "good" (when there are no drops) and "bad" sync which goes from VCR. It looks like VCR is out of "sync-window" (like on floppydisk-controllers), and when it synchronises, there are no drops after that. On TV-set picture looks line about one line up or down, and fields are swapped (looks like "jerking picture"). RF-signal from head-amplifier is straight level, I'll make and oscillograms too at the evening...

3. Ok, I'll make this pin shorter, now it is about 7-8mm wide

Thank you for your Great help!!! I hope, thet together we will manage with this old V2000 VCR

Best reagrds,
Alexander

Now I see the two varaible resistors! As far as I know (without looking into my machine or into the sm), these are the two allign points for the correct DTF voltage (voltage output stage), one for each head. Every head has its own piezo element and its own output stage on the servo/DTF-board.

For calibrating this voltage correct, you must own the original Service cassette - and this is a problem now today, because this cassette is avilable NOWHERE !

I will take a look into the sm, how the adjustment is best without the service cassette. Wait until tomorrow!

Both variable resistors are of the same type (is there a print on it? Like "10k" or so?)

Perhaps the sync signal drops out because of the old recordings. But the machine itself has 25 years or more of age! Most of the electrolyt caps are out of tolerance, I guess. If such a V-2000 machine should work as new, most of the electrolyc caps must get changed and the whole circuit has to get alligned new.

Best regards,
stego

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Oh.... Service Cassette.... Noooo.... I'll tried to calibrate voltages in FF mode, just measured DTV voltages and set them at same levels. Rewinding and pause are good. Clean picture, without disturbs. Both resistors are 4,7KOhms.

About the sync: where I can read about all the sync methods of V2000 standard? I've found no literature on the web... Only some words about the lack of control track... What regulators are for sync tuning?

I'm sorry for bad photo quality, tomorrow will make better photos. The first corresponds to "good" sync (small "zero level" before V-pulse), second - for "bad" sync (no "zero level" before V-pulse).

The first photo is with good sync pulse, the second - with bad pulse.


[ Diese Nachricht wurde geändert von: Byteman am 23 Feb 2012 21:56 ]

I have forgotten:

Are all of the allignment screws still sealed with blue paint?
Or has someone turned around on this screws?

The FM packets look not very constant, especially when the picture is noisy...
It looks a bit, as if the tape does not drive correct at the run-out of the head drum.

Is the tape path ok after your work on the pinch roller?
There must be no crinkles in the whole tape path, and the tape has to turn around the white roller (tape guide) after the capstan/pinch roller very constant, even in Picture search forward and reverse!
If the tape gets up or down turning around this white roller when switching between forward and reverse, the tape path must get alligned.

This is what reminds me at the moment.

The service manual has a lot of description of the whole circuit - but only in german language!
Perhaps, somewhere in the internet, there is a service manual in english language. I don´t know, sorry!

Best regards,
stego

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Tomorrow I'll try to make photo of RF-packet directly from head-amplifier. All the tape path is aligned as "from factory". I've only tried to change pinch roller pressure (because roller became thinner).

Hello! Here is RF-packet looks like....I don't know, if it is good or bad. Here are some sample videos which I had digitized some months ago. You can notice drops on those videos. Some tapes have many drops, some are fewer, but picture quality on all records is the same... I can't beleive that V2000 standard was so critical to tape quality... Maybe this is misaligned tape path, or some troubles in sync-module. On TV the picture is almost perfect (sometimes picture goes some lines up and down, very fast, seems like sync errors).... I can't guess what to do the next step... I think that I'll have to buy another V2000 VCR, digitize all tapes on it, and sell it again

But if to be serious, I really want to know all details of V2000 standard, because it is more interesting thing, that usual VHS...

Best regards,
Alexander.

Hello, Stego!
I've tried another tape, RF-packets are more straight, like on VHS-machines. It only has a head-switching gap (if I understood correctly). On VHS this gap is abnormal and should be eliminated by tuning head-switching signals. And what about V2000? Is this gap normal?

Hello Byteman,

I don´t know off-hand, if the oscillogrammes are ok that way.
If I get time today, I will take a look into my service manuals. Some oscillogrammes are shown there.
When finding anything interesting for you, I will scan it and upload it here.

The head switch-over point is alligned with the optical sensor on top of the head drum. (Sliding the sensor unit). But for correct allignment, the service cassette is neccessary again...

Best regards,
stego

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Sorry, I didn´t have ONLY ONE minute time the last weekend!
These are days, where I have to work without any end!

Perhaps, next weekend I manage to take a look into my service manuals, but I can´t promise you anything at 100 %...

Sorry again and best regards,
stego

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Hi, Stego!

I'll wait for necessary time, because it doesn't matter for me, will I repair it today, or some months later Thanks again

Best regards,
Alexander

Hello Alexander,

now - I have found a Service manual in PDF!!
But: it´s about 100 Megabytes of data size!
I don´t know, where I can upload it for you...

You can try to download it yourself here:

http://freeservicemanuals.info/en/s.....280a/

After download, you get a file named "2x4" without .pdf, so you must rename it to "2x4.pdf", then you can open it with Adobe Reader.

Unfortunately, it is only in german language.
But I don´t really know, if the sm´s were also printed in other languages.

If your download is not successful, we must search for a alternative for uploading my PDF-file.

Best regards,
stego

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