10BP4 with a G1 Short

[Chris K]

Filament is fine...a bit of cutoff and good emissions. No HK shorts but G1 reads shorted on my Sencore CR31A Super Mack. I tried the clear G1 shorts function with no change. Comments or suggestions???

[Alex KL-1]

If CRT is doomed, well, some risky tricks are ok then, since is "already lost"...

Try to charge small caps with ~ 100V (from 47nF up) to see if clean shorts. Or perhaps more µF with less voltage (some electros)?

Probably people here, having far more/longer field expertise than me, can suggest some less dangerous approach

[Chris K]

The Sencore has a welding function on the rejuvenate/restore side of the tester. I forget how many milliamps it hits it with but there's a bright, blue flash. What I didn't do was tap the CRT neck with the back of the screwdriver while hitting it with the blast. This is the first 10BP4 I've encountered with a serious issue. They have always served my restorations well. I wouldn't call them bulletproof but they are pretty rugged.

[Electronic M]

I would try the tube in a working TV set before trying something as risky as remove shorts. I had a 10BP4 like that and it worked fine in an actual TV with the short to the point I'd have never guessed if I had restored the TV without testing it.

When you have good emissions don't risk it until you have seen picture on screen to know you have an actual problem.

[Chris K]

Got it. Thanks Tom. I thought it was a bit weird everything else was fine on the tester. I think I'll reflow the pins first then try the Sencore again.

[jr_tech]

What do you measure with an ohmmeter between the G1 pin and the other pins?

jr

[Yamamaya42]

Originally Posted by jr_tech

What do you measure with an ohmmeter between the G1 pin and the other pins?

jr

That may be tricky, cause it may or may not change as it warms up / cools off, if it is indeed shorted, the measurement may change as the heater warms it up and things move ever so slightly.

[Chris K]

A quick stupid question, this tube is in an RCA 630T and has an electromagnetic ion trap. It’ll work like any other 10BP4 if I try it in another set and put a passive dual magnet trap on it correct?

[jr_tech]

Originally Posted by Yamamaya42

That may be tricky, cause it may or may not change as it warms up / cools off, if it is indeed shorted, the measurement may change as the heater warms it up and things move ever so slightly.

Indeed true... but a quick ohmmeter measurement may provide useful information.

Originally Posted by Chris K

A quick stupid question, this tube is in an RCA 630T and has an electromagnetic ion trap. It’ll work like any other 10BP4 if I try it in another set and put a passive dual magnet trap on it correct?

the type of trap shouldn’t matter.

jr

[Chris K]

Originally Posted by jr_tech

What do you measure with an ohmmeter between the G1 pin and the other pins?

jr

No continuity with any other pin

[Chris K]

Filament looks really, really strange.

[Yamamaya42]

Well. I'd do as EM suggested, try it in something known good, and it it acts weird, THEN PANIC!

[jr_tech]

Originally Posted by Chris K

Filament looks really, really strange.

Possibly contacting the grid cup when warm?
Could you repeat the ohmmeter test with the heater warm?

jr

[Chris K]

Checked just after turning it off. No continuity from G1 to any of the other pins. I'll try it in a TV