Concentrating on power supply.pcb-dbf board. Everything seems to be okay by that I mean voltages on transitors up to dbf drive transitor. At this point have 5.08 volts on base, calls for 5.3v, have 5.7v on emitter calls for .7v, have 2.7v on collector, calls for 5.9v. Have checked resistors and caps in vicinity. They seem to be okay. Have desoldered and checked to make sure. Other two high voltage transistor values following way off. These are designated dbf drive transistor also. One has values of 11.50v on base calls for -571v has ll.o8 on emitter, calls for -570v has 840v on collector calls for .2v. Other drive transistor has 2.5v on base calls for .7, has 2.4v on emitter has 2.4v has 10.96v on collector, calls for 10.6v. The dbf output transistor has 837v on base this connector to collector of other drive trans.supposed to be .2v, collector has1060v, supposed to be 522v, 0v on emitter. All of these transistors have been removed and checked via diode test. Seem to be okay. I'm an amatuer with enough knowledge to be dangerous. Everyone tells me to pitch this tv because its obsolete but I want to fix it.
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Re: rear projection mitsubishi vs5042 no high voltage
Are you talking about the LV power supply or the HV power supply? The terminology your using is related to the horiz drive circuit. Have you checked the B+ off the regulator which should be about 120v or, it will on the pc bd for the correct voltage. Do you have sound? If you do then you will have to use use your scope to see if you have proper drive at the base of the Horizontal Output Transistor. Then we can go from there. Oh, by the way I can tell by the voltage readings you stated both of those transistors of turned off.
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you might need to have voltage checking at this time. if their is a dc output voltages at the power supply board.if none the main board will not turn on.then probably their is bad component at the power supply board.
This sounds like it could be a High voltage shutdown, a bean detection shutdown, a short in the sweep circuits, or a power supply issue.I have found 1. SHORT DETECT SHUTDOWN (PIN 13 OF IC700) CHECK FOR OPEN L902 PART # 351P155010 OFF Q904 C (15 V SUPPLY) ON THE MAIN PCB. 2. SHORT DETECT SHUTDOWN (PIN 13 OF IC700) CHECK FOR SHORTED D913 PART # 264P722010 AND OPEN Z901 PART # 283P039020 (Z905 AND Z900 M 3. CHECK FOR LEAKEY D5A21, PART # 264P045040, IN THE BEAM PROTECTION CIRCUIT ON THE MAIN PCB 4. CHECK PIN 6 OFF IC5A01 FOR 22.2 VOLTS DC IF LOW CHECK D5A09, PART # 264P244030 ON THE MAIN PCB. Or possibly the crts have leaked fluid and damaged the system or convergence board. It would be a total shot in the dark to say what is wrong with this set without looking at it. You are going to have to call in a tech to give you an estimate. Expect anywhere from 150 to 600 bucks. depending on what the problem is.
The high voltage is supplied to the screen via the flyback transformer. However this does not necessarily mean that the flyback is bad. It could be the circuit feeding the transformer, or the screen itself. There are Hazardous voltages floating around in this set. Be careful, if you are trying to fix this yourself, especially if you don't have an electronics background...
Do you get the high voltage coming up? You can check for this by measuring if there's any voltage at DL231 or/and DL221 (diodes off secondary of flyback). If there is voltage momentarily then the hv is trying to come on and the Flyback is likely at fault (excessive highvoltage detected) if not then usually power supply problem is indicated - Start there - tip-use the tuner shield as ground/return
You have a power supply decaying; it will likely get worse.
There may be board repair of this available so locate the power supply board - look at the assembly that seems closest to the AC cord, check the board number and search on it.
NOTE: There may be more than one number on the board since the bare board may have its own but it will be obviously a part of the board. The assembled board number will look much more temporary and may even be on a label.
If you locate a service company that claims the ability to service it, pick their brains a little since it may not be a main power supply failure but rather another, possibly separate board that produces the high voltage for the CRTs.
If you do find a separate board that seems to be servicing the CRTs, note that board number too and ask them about both.
1. SHORT DETECT SHUT DOWN (PIN 15 OF IC700) CHECK FOR OPEN L902 PART # 351P070010 OFF Q904 C (15 V SUPPLY) ON THE MAIN PCB. 2. SHORT DETECT SHUTDOWN (PIN 15 OF IC700) CHECK FOR SHORTED D913 PART # 264P722010 AND OPEN Z901 PART # 283P039020 (Z905 AND Z900 MAY ALSO BE OPEN BECAUSE OF THIS). 3. X-RAY SHUTDOWN (PIN 55 OF IC700) CHECK FOR A LEAKY D5A09 PART # 264P244030 OFF PIN 6 OF IC5A01. 4. X-RAY SHUTDOWN (PIN 55 OF IC700) CHECK FOR LEAKY D5A21, PART # 264P045040, IN THE BEAM PROTECTION CIRCUIT ON THE MAIN PCB. 5. CHECK FOR LEAKY Q5A03 AND/OR Q5A04 BOTH PART # 260P559050, IN THE HIGH VOLTAGE DETECT CIRCUIT, ON THE MAIN PCB.
This model is equipped with a self-diagnosis feature to help with diagnosis of shutdown problems.
To activate this turn the unit on let it shutdown then press the input and menu buttons on the front panel simultaneously and hold them in for 5 seconds after 5 seconds the power LED on the front panel will blink a two digit sequence.
This will be one set of blinks a short pause then another set of blinks, this will repeat 5 times.
1 - 2 = no error detected
2 - 1 = X-ray protect (high voltage or beam current) 2 - 2 = Short protect (short protect monitors low voltage supplies)
2 - 3 = Deflection protect (this could be loss of vertical or horizontal deflection)
2 - 4 = Vertical protect (usually loss of vertical from the source)
1. SHUTDOWN AT POWER WITH SELF DIAGNOSIS ERROR 2 2. CHECK FOR LEAKY C9A60 470 PF 1000 V PART # 154P400030, PARALLEL TO D9A57 ON THE POWER PCB (NOT SHOWN IN THE SCHEMATIC).
2. SHUTDOWN AT POWER WITH SELF DIAGNOSIS ERROR 2 2. CHECK FOR OPEN FUSES F9A04 AND F9A05 PART # 283P043090 ON THE +24 AND -24 VOLT LINES. IF THE FUSES ARE OPEN THE CONVERGENCE OUTPUT CIRCUIT WOULD BE SUSPECT.
3. SELF-DIAGNOSIS INDICATES SHORT PROTECT. CHECK FOR A SHORTED IC4B01 PART # 270P261020 (VERTICAL OUTPUT) LOADING 24-VOLT SUPPLY LINE. LOCATED ON THE MAIN PCB