Grant DX... floating final bias current?

[ExitThirteen]

I checked the MV1Y diode on the 2nd final, checks as it should. It matches the other MV1Y diode.

Just for giggles, I replaced the 2nd final.... everything is perfect now. Bias currents on both finals are stable, and adjust as they should. Was able to dial everything right up per the service manual. I put the suspect final on my transistor checker, and it seems to check fine, but maybe it has leakage at a junction? Truly odd.


~Cheers~

 

[bob85]

good news its fixed,
i have seen a few 2312 & 1969's measure fine on a dmm or hfe tester but pack in after a very short time under load, let them cool or spray freeze them & they work again,
never seen one with bias creep

 

[Low_Boy]

good deal

 

[Handy Andy]

And the Coach looks over at the Bench....

"You - 2312 - get in there..."

Another Player runs - arrives, onto the field...

 

[ExitThirteen]

I wonder how unusual it is to have a final with a bias issue like that.... just seems odd to me.


~Cheers~

 

[Robalo]

Good job E13

 

[bob85]

i would not say its common as its new to me but a shop that does lots of radio's may have seen it before,
even finals that measure good on a tester & break down as they heat don't turn up often here.