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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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Dead Mitsubishi 1998e Monitor
The chassis has "Acer ELECW 2 94v-0" stamped on it.
Power led lights up. It has HV but no picture. The heater looks a bit dim compared to other models ive worked on. Heater voltage is 5.5v and resistance at the pins is 5.3ohms. The other voltages at the crt pins are, G1 -183v G2 166v R 39v. G 33v. B 37v. Ive checked esr on all the caps, and tested big resistors, HOT, diodes, transistors, dry joints etc. |
#2
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Your G1 voltage is way too negative which biased off the picture tube.
I would trace the circuit down and check the parts. There is usually some way to feed a variable positive adjustment voltage into the G1 circuit. This may be defective. I would expect the G1 to be about -40 to -60 volts in normal operation. Try connecting a variable resistor box to the G1 pin on the neck board and ground. Then starting at the highest resistance, slowly reduce the resistance and see if the picture comes back when you reduce the G1 voltage. The G2 voltage seems low. This is an high-impedence circuit and your meter may be loading it down. I use an 100 to 1 probe on my meter when I check G2. I would expect 300 to 450 volts. Video cathode voltages also seem low. I would expect 50 to 70 volts here. Is your B+ voltage to the CRT neck board OK ? Hope this helps. John |
#3
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