Riddled TV Repair Forum

Mike · Guest

buddy of mine called me about a 46" mitsubishi VS-4506R today.
he said one day it shut down, and he attempted to power back on. a quick multi-color flat horizontal line would blink up and shut back down. it was a quick half a second ordeal. he repeated his attempts to power it on, and a horizontal line would blink up and shut down.

Well i was thinking a vertical output caps/IC failure, whcih is common in those mitsus, but then he said after trying a few times, it just died completely. no cliks, no power, no anything.

So, only thing i can figure was the repeated attempts to fire the set up with a possibly shorted vertIC, it could have opened the hot, or a fuse, or anything.

any ideas? I havent seen the set yet, but before i go out there, figured i would ask here.

Google

Steve · Guest

Usual vetical IC and check caps and 30v zener in circuit. Here are the notes and typical shutdown causes for this model:
1. SHUTDOWN CAN BE CAUSED BY NO VERTICAL DEFLECTION. SINCE THE VERTICAL CIRCUIT IS POWERED BY THE SWITCHED POWER SUPPLY THE UNIT MUST BE TURNED ON TO TROUBLESHOOT THE CIRCUIT. THIS CAN BE ACCOMPLISHED BY TEMPORARILY DISCONNECTING THE VERTICAL INPUT TO THE X-PROTECT CIRCUIT. ** TO PREVENT DAMAGE TO THE CRT'S YOU MUST UNPLUG THE CRT PCB'S. ** TO DEFEAT THE X-PROTECT CIRCUIT, UNSOLDER D4A1 LOCATED OFF THE COLLECTOR OF Q4A1. IF THE UNIT POWERS ON AT THIS POINT, YOU HAVE CONFIRMED A VERTICAL FAILURE AS THE CAUSE FOR SHUTDOWN. ** D4A1 MUST BE REINSTALLED IN CIRCUIT TO PREVENT CRT DAMAGE. **

2. WITH VERTICAL PROTECTION DEFEATED (D4A1 OUT OF CIRCUIT) WHEN THE UNIT POWERS R514 (PIN 11 OF THE FLYBACK) OPENS. CHECK PARALLEL CAP. C512 .33 UFD 400 V IF C512 IS GOOD REPLACE THE FLYBACK PART # 334P191020 ON THE MAIN PCB. 3. CHECK PIN 1 OF IC401 FOR 10.7VDC. IF LOW OR MISSING CHECK FOR SHORTED D4000 (PART #264P487030) LOCATED OFF PIN 1. (PCB-MAIN) 4. CHECK PIN 8 OF IC401 FOR 28.4VDC. IF MIS!
SING CHECK FOR OPEN D520 AND R540 AT PIN 5 OF FLYBACK TRANSFORMER T503. (PCB-MAIN) D520 PART #264P102020 R540 (1.2 OHM 1/4 W) PART #103P398010 5. CHECK FOR DEFECTIVE IC401, PART #272P239040 ( PCB-MAIN) 6. CHECK R540 1.2 OHM 1/4 W OFF PIN 5 OF FLYBACK (PCB MAIN). 7. EXCESSIVE 130V SUPPLY. CHECK C911 47 UFD 100 V AND C914 47 UFD 50 V, IN THE IC900 CIRCUIT.

Steve · Guest

Remember the noisy power supply is what kills the vertical. So check number with the7 (C914 and C911)or just replace them with 105 degree caps then test the rest further.

Mike · Guest

ok thanks for the info. just one question. when the repeated attempts of
trying to power on with the failed vertical circuit, the set eventually died
with no signs of life.

im assuming it opened something in the SMPS since you say the vertical B+ is
derived from the main SMPS instead of the flyback is that correct?

im thinking a B+ supply fuse, or something in the chopper controller
circuit.

Mike · Guest

welp i just junked it out to the trash. about 95% of the electrolytics were
shot. it would have costed more to change over 300+ in caps. than to get a
new one. LOL.

Google