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Old 03-27-2013, 03:10 AM   #1
Evil Lurker
Warranty Voider
 
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Join Date: Feb 2011
City & State: West Tennessee, USA
Posts: 452
Default The fuhjyyu's in my monitor finally went tits up today.

7 years ain't too bad for them to last I guess considering it has probably spent the last 5 years powered on.

Basically over the last couple weeks I noticed the monitor would "grey screen" every time my PC rebooted, and the only way to get rid of it was to pull the plug on the monitor and plug it back in. Then it would work just fine. But today it was cold in the house, the power had went out for a few hours, and when it came back on, the monitor was stone cold dead... not even the LED was working.

Cracked it open, yanked off the PSU board, didn't even bother testing output voltages just started yanking caps. On the 12v rail there were three 470uF 25v TM series Fukiyoos, the two in parallel right after the rectifier diode measured 33 and 64 ohms each, and had absolutely no visible signs of failure. The third fukiyoo was after the low pass filter inductor and it measured 0.09 ohms... not dead yet but definitely on the way out. The only two half assed suitable caps I had were two ancient HFQ series panasonic caps... and when I say ancient they stopped shipping them in 2000. But, the ESR on the caps were below the max spec and the capacitance checked out OK so I slapped em on the board. Since I was a cap short, I put the fukiyoo with the low(er) ESR in after the low pass filter. Blech.

On the 5v rail, the single 1000uF 10v TM series cap after the rectifier measured 0.24 ohms, the other after the low pass inductor I didn't even bother checking. Had some NOS Rubycon ZL's laying around, so I slapped those in. On the power supply's main PWM controller subcircuit there was a lone 47uF 25v cap. Guess what the ESR was? 8.9 ohms. And of course it just had to be a low ESR TM series too. Only thing I could find to drop in its place was an Elna audio grade cap. I don't know what its specs were, but the ESR was .78 and it was rated 105C so I slapped it in. The last cap on the psu I replaced was a LE series Hermei rated 220uF at 25v or however you spell it on the inverter pwm controller subcircuit... it measured 2.4 ohms and just like the fuhjyyus it didn't show any outward signs of failure. I didn't have anything in this exact value, but I did have some ancient (and not to mention huge) NOS 220uF PL Nichicons laying around, and since there was room on the PCB to mount it I slapped it on the board.

After I got the psu pcb back in the monitor, plugged it in, turned on my pc, and the monitor fired right up.

But, alas I figure this is at best a temporary fix for everything but the ZL's which I figure can stay since their ripple ratings and ESR is lower than the fukiyoos TMs. So, I need to order some new caps... which ones should I go with to replace the TM series, Panny FR or FM, or Nichicon PW, HD, or HE?
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