G07 & 4600 question

mcandrewsoun

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I have just replaced the HOT and Flyback on a G07 that was killed by a power surge.. Havent done done a cap kit yet..This is a repair for a friend, and I dont have the origional tube/yoke.. My test tube appears to have a resistance in the ballpark.. (50 V, 2.5ish H). When I fire it up, I get a tiny image, maybe 3/4"H by 8"V.. Would this likely be the yoke mismatch, or is there something else fried on the board?. B+ was around 125v.

Now the 4600 has a problem on the XY board. Im getting no horizontal oscillator, therefore, no HOT squeal, no HV. The Horizontal drive transistor looks ok on the meter. Has anyone seen any common causes to look for?

Andrew
 
Got the G07 figured out...but still working on the 4600.. Im gonna cap it and see if that changes anything. All the transistors seem to be ok..
 
So the main horizontal drive transistor (on the daughter board) is ok, I swapped in a known good one, and its the same. Im getting like 520v on the case of the HOT, wheras with a known good board its close to 1000v (peak to peak). This doesnt feel like a transistor...seems more like a diode or bad ground somewhere? I did put a cap kit on it also.
 
Kickin my butt!

Switched the Horizontal drive and horizontal oscillator transistors, pulled the protection circuit.. It looks like the oscillator is outputing more then it should.. I measure 2.4 pp whereas the manual has .8v. Im gonna check the diodes upstream..they appear ok.. Has anyone seen any wierd failures like this before?

Andrew
 
Fixed!

After literally checking every resistor in the horizontal circuit, I found R360 to be out of spec.. Supposed to be 27 ohms, measured out at 39. I paralleled two 52 ohm resistors, and she fired right up.

Andrew
 
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