Anyway to test a flyback?

kelleyphd

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I have a G07 giving me problems. It blows F901 shortly after coming on. I have new flyback and HOT. The tube glows briefly until the fuse blows. Does this mean the flyback is working correctly? Anyway to test it off the board?

Thanks in advance,
Daniel
 
When this happens it means that there is a short.

Verify that all caps have the correct polarity,

Make sure that the horizontal output transistor isn't shorted. Black lead of your meter to the frame, red lead on the case. Ohms setting on your meter. If you want to know what a short looks like, touch the two leads together.

Also check the voltage regulator.
 
Make sure that the horizontal output transistor isn't shorted. Black lead of your meter to the frame, red lead on the case. Ohms setting on your meter. If you want to know what a short looks like, touch the two leads together.

May seem obvious, but these tests are with power off. You can short the leads to see what the tests would look like with a short and compare to how it reads without a short.
 
When this happens it means that there is a short.

Verify that all caps have the correct polarity,

Make sure that the horizontal output transistor isn't shorted. Black lead of your meter to the frame, red lead on the case. Ohms setting on your meter. If you want to know what a short looks like, touch the two leads together.

Also check the voltage regulator.

I checked all the caps for polarity, checked the HOT for short and the voltage regulator. All test fine. I even took the HOT and VR off and tested them. What is the best way to track down a short?

Thanks for the help.

Daniel
 
Checked all caps for continuity to the next component. All check fine. I did find that S3 and S4, which hook up to the HOT have continuity with the frame. This doesn't seem correct to me but I got it on both of my non-working chassis. I also checked all the small transistors to make sure a couple of legs are not touching.
 
Checked all caps for continuity to the next component. All check fine. I did find that S3 and S4, which hook up to the HOT have continuity with the frame. This doesn't seem correct to me but I got it on both of my non-working chassis. I also checked all the small transistors to make sure a couple of legs are not touching.

If you have continuity between the HOT case and the frame, it is shorted. It should have a mica insulator under it and two plastic bushings around the mounting screws to isolate it from the frame. If they are all in place, the HOT is shorted internally and needs replacement.
 
If you have continuity between the HOT case and the frame, it is shorted. It should have a mica insulator under it and two plastic bushings around the mounting screws to isolate it from the frame. If they are all in place, the HOT is shorted internally and needs replacement.

Actually, with the HOT disconnected I checked continuity from S3 and S4 to ground and I got it. So, that seems to tell me that when the wires are hooked back up (emitter and base) it will ground the hot??

Daniel
 
ring tester (Lopt)

test FR401 and R908

Tested both and they were fine. In fact, everything so far is testing good. I tested all 900 series and all other transistors. I found D506 to be shorted when I tested it in circuit so I took it out and it tested fine. Should both sides of D506 have continuity with ground? I also get ground on both sides of C517, C518, and C521 along with R410. I am not the best at reading schematics but it seems all of these should not be grounded. D506 was hard to find on the schemos - it is northeast of X01.

Daniel
 
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