JVC JX-S900 120 Hz Hum Bar Problem

[CharlieMax]

Google has a link to a thread on this forum pertaining to my proble
with my JVC JX-900 A/V Switcher, but it is a dead link.

Can anyone direct me to the thread or know the solution to th
problem.

I am guessing it is a bad power supply capacitor but would like t
verify that deduction.

Thank

 

[[email protected]]

CharlieMax:
The best way to verify your probably correct deduction about a bad
capacitor in the power supply is to take it apart and test it or
substitute a replacement. Also could be a bad diode, bad regulation
circuitry, bad solder joint or something shorted after the power supply
that is dragging down the regulation.
It is all guesses until you do some testing and troubleshooting at your
end.
electricitym
..

..

 

[carlot]

Google has a link to a thread on this forum pertaining to my problem
with my JVC JX-900 A/V Switcher, but it is a dead link.

Can anyone direct me to the thread or know the solution to the
problem.

I am guessing it is a bad power supply capacitor but would like to
verify that deduction.

Thanks

I have the same hum problem on my JVC JX-S900 and additional to that
If I want to open the switch manually without the remote, light jus
blink and nothing. I can switch on only by its remote control. Is tha
related?

VCR connected to that switch sometimes not often picture become black.

Carlo

 

[carlot]

I have the same hum problem on my JVC JX-S900 and additional to that:

If I want to switch on manually without the remote, light just blin
and nothing.

I can switch on, only by its remote control. Is that related?

VCR connected to that switch sometimes not often picture become black.

I want badly to fix that machine because I beleive it is a top of it
class

 

[[email protected]]

There is a good chance I wrote that original thread.

I had the 120 Hz hum bars (black bands) and FINALLY I replaced the
power supply caps.

1) 3300uf 16V
1) 2200uf 16V
2) 470uf 16V

I used Nichicon Ultra Low Impedance (ESR) from Digikey and used higher
voltage caps. The 2200 had a lead spacing that was 2mm wider, but I
tapered the PCB hole with a rat tail jeweler's file and it worked just
fine. The big thing to consider is that there is another board above
these caps and they can't be more than about 1 inch tall.

The big caps oozed a dark brown hard substance that I thought might
have been a cement to stabilize the big caps. But it appeared to be
cap guts.

Had the parts on my bench for maybe 1/2 year and FINALLY finished the
job.

Image is now perfect.