Adventure! Excitement! Explosions! Electrohome G05-802 repair log

ieure

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Adventure! Excitement! Explosions! Electrohome G05-802 repair log

Monitor: 15" G05-802, s/n 9-182553, purchased dead 2011-11-07. Recapped prior to purchase, in an attempt to get it working. Defletion board is in rough shape, missing the two back corners where the screw holes anchor it to the frame. Two traces which passed through these areas have been repaired.

Symptoms
No neck glow, no HV, no deflection chatter, spotkiller on, no image.

Repair log
Swapped in known good deflection board, powered on. R718 immediately and literally burst into flames. Looking at the frame, found Y Q608 (2N3716) & X Q709 (2N3792) transistors had been swapped. Pulled all frame transistors, tested; good. Reinstalled in correct positions, tested to make sure insulators were functioning; they were.

Examining the deflection PCB revealed many cold/broken solder joints on the P500, P600, P700 & P701 headers. Additionally, a patch from D100 to P500 (repairing a broken trace) was tacked on & not conducting well; fell off when handling.

All the header pins looked like this:
e8mJo.jpg


Reflowed all header pins, reinstalled D100->P500 patch, powered on. Good neck glow, HV & chatter present, spotkiller still on. Image is present, squashed into the top of the display, with a bright vertical line in the top center.

Since monitor has partial vertical collapse, I focused on the Y deflection circuit, section 6xx. Pulled Q601/2/3/4/5/6/7, tested, good.

Started testing every resistor & diode in 6xx section, comparing against the schematic. Some resistors tested below spec in circuit. Compared against another board, and they read within range, so assumed this was normal and did not remove from circuit to test.

Found D606/D607 both shorted, replaced. Powered up and I have full deflection. Adjusted pots to get the image correct, monitor is now fully working.

Here she is, looking good:
WbJ2m.jpg
 
Nice repair log. Funny how, to an outsider, those header pins wouldn't seem like a "good" thing to find....man I love it though. It's almost like opening a present "Ooooh look! Cold solder joints! Haha!" Thanks for posting. :)
 
Indeed! When I see cold joints, it's more like "Boo Yaa! Smoking Gun!"

Mointors still scare me, but now that I'm through three of them, the fear is subsiding to more of a quiet mutter.
 
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