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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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13th May 2021, 1:55 pm | #1 |
Tetrode
Join Date: May 2019
Location: Northumberland, UK.
Posts: 52
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JVC VCR PSU problems
Hi,
I’m having problems with JVC 8700ek S-VHS player I recently got. When plugging in from a cold start up ie being unplugged for 24 hours then plugging it back in all that seems to happen is the fluorescent display flickers and there is a very slight clicking coming from the PSU. Then after about 30 seconds to a minute it’ll power up and work completely fine. Something is obviously not working correctly until it’s been heated up. Do you think this could be PSU capacitors on their way out or some other component? Thought I’d ask on here first for some suggestions as these late VCR’s aren’t very service friendly And isn’t easy to test any components in circuit with having to remove the whole board and loading mechanism |
13th May 2021, 4:38 pm | #2 |
Heptode
Join Date: Mar 2015
Location: Lefkada, Greece
Posts: 969
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Re: JVC VCR PSU problems
I would start by checking all the electrolytics in the primary and secondary side of the power supply with an ESR meter. Also look for dry or cracked solder joints. A wise man once said, the reliability of any electronic device is inversely proportional to the number of electrolytic capacitors it contains.
Fivos |
13th May 2021, 5:06 pm | #3 |
Octode
Join Date: Sep 2020
Location: Thetford, Norfolk, UK.
Posts: 1,731
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Re: JVC VCR PSU problems
Agreed. In fact I personally would just change all the electrolytics in the power supply.
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13th May 2021, 6:17 pm | #4 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
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Re: JVC VCR PSU problems
Certainly suspect secondary side caps on power supply.
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13th May 2021, 6:27 pm | #5 |
Tetrode
Join Date: May 2019
Location: Northumberland, UK.
Posts: 52
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Re: JVC VCR PSU problems
I’ve currently just been leaving it plugged in on standby.
Not sure how hard it’ll be trying to get the whole thing removed from the chassis. I’ll check them with my ESR meter Capacitors look to be made by Samsung. |
13th May 2021, 6:55 pm | #6 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,185
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Re: JVC VCR PSU problems
Probably Sam but not Sung. Maybe Young or Wha. Those do tend to fail over time.
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14th May 2021, 7:20 am | #7 |
Octode
Join Date: Feb 2007
Location: Ely, Cambridgeshire, UK.
Posts: 1,967
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Re: JVC VCR PSU problems
C1502 27u 35v in psu primary was always the main one to go use a 33uf its next to the chopper transformer
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14th May 2021, 2:43 pm | #8 | |
Tetrode
Join Date: May 2019
Location: Northumberland, UK.
Posts: 52
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Re: JVC VCR PSU problems
Quote:
It’s annoying that there doesn’t seem to be any sort of service manuals for these last of the line JVC’s I’m guessing JVC obviously thought they would be scrapped in favour of a DVD player long before they ever started to need maintenance. Does feel quite cheap compared to earlier players, however it plays most tapes very well. Although I do find TBC can make some tapes look worse which I found quite disappointing |
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14th May 2021, 6:24 pm | #9 | |
Tetrode
Join Date: Apr 2021
Location: Wimbledon, London, UK.
Posts: 56
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Re: JVC VCR PSU problems
Quote:
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14th May 2021, 7:27 pm | #10 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,549
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Re: JVC VCR PSU problems
When you replace the electrolytics, make sure you use Low ESR types 105 degree. Using cheaper 85 degree types will end in tears or at very least a power supply that won't work at all. Switch mode supplies such as this are very critical of capacitor types. Fitting the wrong type can cause damage to semiconductor devices....
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15th May 2021, 11:53 am | #11 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,884
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Re: JVC VCR PSU problems
To add to this, I'd suggest Panasonic 105 degree or similar by, for example, Vishay or Rubycon. Steer clear of anything with an X in the name or something that sounds vaguely Chinese. Also I have had bad experiences with Multicomp, also marketed as RS Pro.
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15th May 2021, 1:32 pm | #12 |
Tetrode
Join Date: May 2019
Location: Northumberland, UK.
Posts: 52
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Re: JVC VCR PSU problems
I usually use 105c Panasonic capacitors or Chemicon.
I’ve noticed a lot of Nichicon’s tend to be undervalued when it comes to the UF capacitance whereas the Panasonic’s always tend to be a few UF’s over on my meter. |