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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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19th Jan 2023, 11:19 am | #1 |
Triode
Join Date: Jan 2021
Location: Beja, Portugal.
Posts: 19
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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. |
19th Jan 2023, 8:21 pm | #2 |
Heptode
Join Date: Jan 2007
Location: Luton, Bedfordshire, UK.
Posts: 891
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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!
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Regards, John |
20th Jan 2023, 3:14 pm | #3 |
Triode
Join Date: Jan 2021
Location: Beja, Portugal.
Posts: 19
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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. |
20th Jan 2023, 7:11 pm | #4 |
Heptode
Join Date: Jan 2007
Location: Luton, Bedfordshire, UK.
Posts: 891
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Re: Grundig GV-250 Repair problem.
Well done!
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Regards, John |
21st Jan 2023, 1:06 pm | #5 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,203
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Re: Grundig GV-250 Repair problem.
TDA4605 come in multiple flavours, it might have been just the wrong brand or suffix.
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