UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Television and Video

Notices

Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

Closed Thread
 
Thread Tools
Old 19th Jan 2023, 11:19 am   #1
hugocarmo
Triode
 
Join Date: Jan 2021
Location: Beja, Portugal.
Posts: 19
Unhappy Grundig GV-250 Repair problem.

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:

vimeo.com/790579424

Service Manual Link:

drive.google.com/file/d/17est7qRDt1T8Wtz-iBWRr_WgWDnXXumv/view?usp=share_link


Thanks in advance,

Compliments,

Hugo do Carmo.
hugocarmo is offline  
Old 19th Jan 2023, 8:21 pm   #2
John123
Heptode
 
Join Date: Jan 2007
Location: Luton, Bedfordshire, UK.
Posts: 891
Default Re: Grundig GV-250 Repair problem.

Hello Hugo,

Provided all of your power supply rails are nominal, check for some more obvious things like a dirty mode switch, and also remove the backup battery for the clock and timer, especially if it is showing signs of leakage (check for corroded PCB traces).

If it hasn't leaked already, I highly recommend you remove the battery (or batteries) anyway, as a partially-charged or non-charging battery can lock-up the micro with erroneous data that gets held in RAM, and then the machine will exhibit strange logic faults.

Hope that helps!
__________________
Regards,
John
John123 is offline  
Old 20th Jan 2023, 3:14 pm   #3
hugocarmo
Triode
 
Join Date: Jan 2021
Location: Beja, Portugal.
Posts: 19
Default Re: Grundig GV-250 Repair problem.

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 John123 for your answer.

Best regards,

Hugo.
hugocarmo is offline  
Old 20th Jan 2023, 7:11 pm   #4
John123
Heptode
 
Join Date: Jan 2007
Location: Luton, Bedfordshire, UK.
Posts: 891
Default Re: Grundig GV-250 Repair problem.

Well done!
__________________
Regards,
John
John123 is offline  
Old 21st Jan 2023, 1:06 pm   #5
Maarten
Dekatron
 
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,184
Default Re: Grundig GV-250 Repair problem.

TDA4605 come in multiple flavours, it might have been just the wrong brand or suffix.
Maarten is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 3:06 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.