Philco Experts: Model 87 Grid Condenser?

[Winky Dink]

Reese,
As it looks to me, "E" is the detector plate voltage. At the filter block I read 8.9V (versus 30V specifiication) and at the power transformer I read 6.5V (versus 30V specification).

If 1AF is pulled, there is no sound.

I went carefully through my filter block reconstruction, and it seems to be OK.

I also found some Philco "field service data" that gave several causes for Hum. Two items were defective condensers, which I think I've ruled out. One item was bad friction contacts on the range control, and I've ruled that out. The final item was neutralization, which I haven't dealt with yet.

Dave,
The diagram at the lower right of the schematic is a filter block schematic with numbers for the terminal strip to the chassis. It was that easy.

Thanks, All.

[old_coot88]

OOPs! Double post.

!@#$%^&*

[old_coot88]

Originally Posted by Winky Dink

Reese,
As it looks to me, "E" is the detector plate voltage. At the filter block I read 8.9V (versus 30V specifiication) and at the power transformer I read 6.5V (versus 30V specification).

Um.. "at the power transformer" Don't you mean at the plate of the '27 detector?
What happens with the point E voltage if you pull the '27? If it stays low, then something is lugging it down. There is a cap in the filter block that goes from point E to ground. Is there any chance that cap could be installed backward? (That's assuming you've replaced the original caps with electrolytics.)