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Old 01-02-2013, 07:57 PM
Dan Schafer's Avatar
Dan Schafer Dan Schafer is offline
Danny in Cleveland
 
Join Date: Nov 2004
Location: Cleveland, Ohio
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MGA Mitsubishi CS-1945R Cold Shock!

Hi All,
Needed to use my (I thought...working) spare MGA TV stored on a cold porch (just below freezing) New Year’s Eve. I guess I didn’t allow enough time to let the set get up to room temperature and upon turn-on, the 1 Amp flyback power supply fuse opened. I wonder if it was from too much, sudden condensation? There was a substantial blanket of dust and people skin cells covering the circuit board, which may have become conductive. I’m crossing my fingers that the fuse opened up before any real damage to output transistors or flyback. I’ll put an ammeter in line with that fuse (F902) and monitor the current as I bring up the line voltage on a variac. Any other caps I should make sure to replace that may have got stressed? Sam's Photo fact’s only lists a model CS-1944R. I hope not too different from the CS-1945R. I want to look at the print and guess as to parts most likely stressed. I think I'll just flat replace any cap rated over a certain voltage. Any other kind suggestions and or anyone’s 2 cents, before I go forward with my troubleshooting approach?
Danny in Cleveland
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Old 01-02-2013, 08:19 PM
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radiotvnut radiotvnut is offline
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I would check the horizontal output transistor for shorts before replacing the fuse because there's a good chance it's shorted. There are several things that can cause a HOT to short; such as a bad flyback transformer, loose solder connections, and bad electrolytic capacitors in the B+ and horizontal driver circuits. Instead of a fuse, you might wish to use a 100 watt standard incandescent bulb in place of the fuse. If there is a short, the bulb will serve as a load that will help protect other components.
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Old 01-02-2013, 08:36 PM
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StellarTV StellarTV is offline
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I'd wager on a shorted HOT due to intermittent solder joints exacerbated by the cold.
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