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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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JVC JX-S900 120 Hz Hum Bar Problem
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 |
#2
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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 .. .. |
#3
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CharlieMax Wrote: 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 -- CharlieMax 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 just blink 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. Carlot -- carlot |
#4
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carlot Wrote: 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 blink 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 its class. -- carlot |
#5
Posted to sci.electronics.repair
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JVC JX-S900 120 Hz Hum Bar Problem
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. |
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