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Old 6th Jul 2021, 11:34 pm   #1
willow5
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Default JVC HR-S8700 dead PSU

Hi, I have a JVC HR-S8700 VHS machine which is completely dead albeit for a repetitive clicking noise in the PSU. I suspect a bad cap somewhere but can anyone tell me where I should be looking in the PSU such as the primary or secondary part ?

Many thanks
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Old 6th Jul 2021, 11:50 pm   #2
toshiba tony
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Default Re: JVC HR-S8700 dead PSU

It's likely to be on the secondary. Check for s\c diodes. I'll look for psu diagram.
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Old 6th Jul 2021, 11:58 pm   #3
willow5
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Default Re: JVC HR-S8700 dead PSU

Quote:
Originally Posted by toshiba tony View Post
It's likely to be on the secondary. Check for s\c diodes. I'll look for psu diagram.
That's great advice thanks Tony
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Old 8th Jul 2021, 9:14 am   #4
steve c
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Default Re: JVC HR-S8700 dead PSU

From my notes
Change C1502 in PSU from 27m to 33m
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Old 9th Jul 2021, 6:41 pm   #5
willow5
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Default Re: JVC HR-S8700 dead PSU

Thank you Steve. The strange thing is that the machine eventually fires up after a few minutes like there is no fault. Could this be related to this faulty capacitor or could it be also be a diode?
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Old 9th Jul 2021, 7:46 pm   #6
gallowfields
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Default Re: JVC HR-S8700 dead PSU

is there a 1uf 50v in the primary [or similar ] like most of the panasonics ??.they do that come to life after a short while
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Old 9th Jul 2021, 8:41 pm   #7
willow5
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Default Re: JVC HR-S8700 dead PSU

Hi Steve, there is no C1502 anywhere I can see. Do you mean C5102 as this is a much smaller capacitor in the secondary part.

@Gallowfields, only 1 electrolytic cap in the primary circuit and that is 400v 68uF
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Old 10th Jul 2021, 9:01 am   #8
steve c
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Default Re: JVC HR-S8700 dead PSU

Sorry -- yes I did mean C5102
I hope the attached helps
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Old 9th Sep 2021, 10:09 pm   #9
Scott5591
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Default Re: JVC HR-S8700 dead PSU

Quote:
Originally Posted by willow5 View Post
Thank you Steve. The strange thing is that the machine eventually fires up after a few minutes like there is no fault. Could this be related to this faulty capacitor or could it be also be a diode?
i suspect mine must have the same fault as it does the exact same thing, takes around 10-20 seconds to power up.

Did you ever get this fixed, the machine is a real pain as you cant access the underneath of the pcb, you literally have to take the whole mechanism and pcb out of the chassis.
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Old 10th Sep 2021, 11:18 am   #10
steve c
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Default Re: JVC HR-S8700 dead PSU

Hi Scott
I had an email back from willow 5 saying it sorted the issue
This is or was a very common problem on this model
If you need a manual give me a shout back

Steve
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Old 11th Sep 2021, 3:43 pm   #11
dj_fivos_sak
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Default Re: JVC HR-S8700 dead PSU

I'm not familiar with this model, but many JVC machines have IC protectors on both the power supply and the main board. They look like transistors but they only have two leads and they act as fuses. Many times they blow for no apparent reason.

Fivos
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Old 20th Oct 2021, 10:00 pm   #12
Scott5591
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Default Re: JVC HR-S8700 dead PSU

i just picked up another one of these machines for £2 a couple of weeks ago.

Fortunately this one was working perfectly

amazing how undesireable these great machines seem to be.

In my opinion this is the best VHS deck JVC ever made, the TBC and DNR on these make tapes look better than any other VHS player ive owned.
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