Replaced blown stk-391-020's, 3, also str-m6811 regulator Ic900 got all B+ back ,hv comes back but in shutdown.How to bypass shutdown to trouble shoot set?
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Check and replace the main power regulator [SMPS] board to your TV. Contact any service technician, or the authorized service center for Mitsubishi. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy. http://electronicshelponline.blogspot.com/
On this tv there are a few things more common. Usually a bad regulator will be shorted which will not allow even a click when you attempt to turn it on. A vertical i.c. bieng bad will cause a double click at power up. My best guess after repairing about 300 of this model is to solder the connections on the yokes first. These are reached from the front of the set and you have to usually loosen the yoke tension screw and turn it to be able to solder the connections.( When you get the set to come back on you will have to adjust them slightly). If that doesn't take care of the problem I would look for leaky capacitors around the 5,9 and 12volt regulators. These are located on the signal pcb and I think it's C2P05 that is the most common one to fail. Third thing to check is cold solder around the convergence i.c.s You may even replace these chips just to be safe. Surely one of these should fix the set. Good luck, Russmann.
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.CHECK PIN 1 OF IC401 FOR 10.7VDC. IF LOW OR MISSING CHECK FOR SHORTED D4000 LOCATED OFF PIN 1. (PCB-MAIN) D4000 PART #264P487030 3. CHECK PIN 8 OF IC401 FOR 27.7VDC. IF MISSING CHECK FOR OPEN D955 AND L961 AT S1 TERMINAL OF T902. (PCB-POWER) D955 PART #264P102040 L961 PART #411P012010 4. CHECK FOR DEFECTIVE IC401. IC401 PART #272P239040, OR INSTALL PT# IC-401, THIS KIT CONTAINS CAPACITOR C920, D4000 AND IC401. BE SURE TO MOUNT C920 ON FOIL SIDE OF PCB. 5. EXCESSIVE 130V SUPPLY. CHECK C911 47 UFD 100 V AND C914 47 UFD 50 V, IN THE IC900 CIRCUIT.
Good Luck, big IRISH.
The VS5043 shuts down for many reasons. The most common are power supply issues. Bad caps, open resistors, shorted regulators, and missing voltages will cause the set to shutdown.
In my notesI have a location of components known to cause your problem( R5A03,L5A00,D5A21,Q5A04,Q5A03,C5A19,L902,IC900.IC700) All the parts listed are available. As I stated above there are many reasons for shutdown such as a bad flyback transformer that may not be available anymore. However, this type of failure needs to be properly diagnosed by a qualified technician. Good luck!
I usually find that symptom you describe is caused by cracked solder joints on the power regulators or vertical output IC. I have also seen that symptom caused by loose solder joints on the vertical windings up inside one of the yokes. If you have experience in repairing TV's then you can disassemble the set and pull the main chassis, flip it over and resolder all of the parts mounted on heat sinks. If you do not have experience in repairing projection TV's then allow a qualified tech to handle it for you.
Most likely the convergence output IC has shorted out and has overloaded the convergence power supply, which has stopped working. The computer senses that the convergence power supply is not running and shuts the set down. The convergence IC should be replaced, the power supply restored and the convergence circuits realigned by someone experienced in Mitsubishi projection sets. When I do a housecall for a set like that I charge $150, but shops in your area will vary so ask around.
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