Electrohome G05-802 Yoke Resistance and Monitor Help

Jet

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Electrohome G05-802 Yoke Resistance and Monitor Help

Can anyone help me out with what the resistance readings should be on my G05-802 yoke? I've been battling with the monitor in my Asteroids Deluxe for months now (blows fuses and transistors), and have narrowed it down to either the tube or the yoke. The tube tests bad on the cutoff test (according to my Sencore CR70), but passes everything else. I'm not quite sure what to do. I have searched high and low, but haven't been able to find what the yoke readings should be.

The reason I have narrowed my problem down to the tube or yoke is because I have tested literally every component on this chassis and replaced all of the recommended parts. I even sent the chassis off to PNL Video and they said it worked perfectly for them. I have also read through the B&W XY FAQ several times and studied many of the G05 repair threads here on KLOV. Maybe I'm missing something really obscure, otherwise it has to be my yoke or tube. Any thoughts?

P.S. I also bought a working chassis off ebay a while back. It worked for about half an hour and then R100 and R101 were super hot and several small resistors burned. At that point I checked the voltages coming from the power supply and they're fine. I'm ready to pull my hair out :). Thanks in advance to anyone that can help me out!
 
Do you get any image on the screen?

I don't have exact readings, but yoke resistance is typically very low for vectors, I think the Amp is <1Ω.

If the yoke is an issue, it should be very obvious by metering, even if you don't know the exact value. Anything dead short or high (>15Ω) resistance is going to be a problem.
 
Yellow-black is around 2.5 ohm, red-blue is around 1.6 ohm.

You should remove R100 and R101 and replace them with jumper wires, as Electrohome did in later revisions of the deflection board.

When you sent the chase off to be checked, did the frame (and frame-mounted transistors) go with it? Which transistors are blowing?
 
Thank you both for your help. I just tested my yoke. Yellow-Black tests 2.5 ohms and Red-Blue tests 1.5 ohms. So my yoke is just fine after all.

I just got an Asteroids board and plugged it in. The monitor is now working, so it's not an issue with my tube or yoke. Back to the drawing board :). I must have an issue with my Asteroids Deluxe board that'll I'll work on next. Thank you again for your help!
 
If it's the board, and it's playing blind, one quick and easy thing you can do to start is just feel the chips in the video output section (lower right corner) with the back of your finger. Particularly the TL082's, which are the final output amplifiers.

They are a relatively common failure, and sometimes get very hot when they go bad, which is a dead giveaway. There could be other issues, but that's a quick and easy one to check.

Also, if you have a logic probe or DMM, you can check to make sure signaling is present on both the XOUT and YOUT test points. If one or both are missing, this will cause the spot killer LED to light on the monitor deflection board. If you measure 0V AC on either of them, that will help you narrow down which chain of chips to focus on (as the X and Y paths are basically the same).
 
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