Grundig GV-250 Repair problem. (Video inside post)

[hugocarmo]

Hi everyone.
I have the following problem.
I have a Grundig GV-250 VCR which has not been used for over 10 years. When I turned it on, the fuse of the PSU burned out, after being replaced it burned again, I ended up verifying that I had the bridge rectifier and the mosfet in short, I ended up replacing it, and I replaced all the electrolytics of the PSU. However, it started to behave strangely, as I will show you in the video that I will attach as a link.
In short, I ended up replacing all the ICs on the power supply CNY17G, TDA4605, TL431, TDA8137, TL082CP, AN3824K, L2720, this on the upper part of the power supply board. On the soldering part, I replaced the bas20 switching diode.
Always with the same result. I ended up disassembling the video head and removing the plate that is soldered to the motor, then I replaced all the electrolytics, and IC AN3814K. Same result.
I don't know what to do anymore, can someone help me?
I also enclose the Service Manual for this model.
P.S.- At the end of the video, as you can see, the video recorder is working normally.

Video Link:

https://vimeo.com/790579424

Service Manual Link:

https://drive.google.com/file/d/17es...usp=share_link


Thanks in advance,

Compliments,

Hugo do Carmo.

[nomoresonys]

Re: Grundig GV-250 Repair problem. (Video inside post)

video not working for me, can you explain the issue or is it fixed?

[hugocarmo]

Re: Grundig GV-250 Repair problem. (Video inside post)

Hi nomoresonys.
Thank You for your reply.
I can try to upload the video to another platform but anyway, the issue is not fixed.
When I connect the mains the vcr does nothing for a minute or so, then it starts to spin the head drum full speed for 2, 3 minutes and after that it starts to slow down until it stops, and after that the VFD turns on, it blinks and then the vcr starts to operate as normal.

Thank You,

Hugo.

[hugocarmo]

Re: Grundig GV-250 Repair problem. (Video inside post)

Here´s the Youtube video link.

https://www.youtube.com/watch?v=UkrY4mZ1nJ4

video not working for me, can you explain the issue or is it fixed?

[R_J]

Re: Grundig GV-250 Repair problem. (Video inside post)

Post the voltages on both plugs of the power supply. Also post pictures of both sides of the power supply so we can see what we are dealing with.
The voltage of interest is the +12VF and the Reset

[nomoresonys]

Re: Grundig GV-250 Repair problem. (Video inside post)

vcr's are complicated, guess sometimes they can act funny if the sensors see too much light coming in, maybe try it while shielding the top with a big piece of cardboard or when the room is darker, may need to clean the mode switch, it seems like it isn't anything major, since you say it works ok after the 3+ minute spin of the head: This youtuber is very good with vcr's etc: https://www.youtube.com/watch?v=X2HXUaLe2vI

[nomoresonys]

Re: Grundig GV-250 Repair problem. (Video inside post)

wondering what the 23 means on display, could it be some kind of error code.

[hugocarmo]

Re: Grundig GV-250 Repair problem. (Video inside post)

Hi!!
Just fixed the problem!
It was a bad TDA4605, the one I replaced was new but not good, don´t know why.
Replaced it and now everything working as expected.
I want to thank You all for your answers.

Best regards,

Hugo.

[nomoresonys]

Re: Grundig GV-250 Repair problem. (Video inside post)

Glad to hear it. was wondering if maybe one of the components you switched out was bad, you switched out quite a few, how did you determine which one was bad?

[hugocarmo]

Re: Grundig GV-250 Repair problem. (Video inside post)

Glad to hear it. was wondering if maybe one of the components you switched out was bad, you switched out quite a few, how did you determine which one was bad?

Hi nomoreonys.
I figured out measuring voltages on tda output pins, and they were lower than expected as mencioned on the service manual.

Regards.

[nomoresonys]

Re: Grundig GV-250 Repair problem. (Video inside post)

thanks, nice puzzle solving.