Hot Rod deville Bias??

[nosaj]

I've had 2 go open circuit. I guess I've been bitten by the Taeyda cheap caps. Have some Nichions on the way.
nosaj

[Helmholtz]

ESR is not critical here as currents are low.
Leakage current shows as a DC resistance and can be measured with an Ohmmeter.
Meter reading should settle at several 100k for an ecap.

[nosaj]

93uf .14 esr using atlas cap tester. c43 was open, got some better caps on the way.
nosaj

[Helmholtz]

To be fair, C37 is part of a charge pump.I just wouldn't say the cap is pumping.
Forget what I wrote above.
What I meant is that the cap just does what all caps are supposed to do: It stores and releases charge depending on applied voltage.
Either a loss of capacitance or excessive leakage current will impair it's ability to do so.
Same with C43.

[g1]

I believe voltage doublers are often referred to as an example of 'charge pump' type circuits.

[Chuck H]

"Pumping" doesn't make sense to me here.
Check C37 and C43 for capacitance and leakage resistance.

???
As in C37 isn't holding and releasing charge as it should (pumping?). I had no trouble with the adjectives. C37 isn't performing. (<period) That said, I always appreciate corrected terminologies so I might not be misunderstood by the engineers and techs here. So, thanks. But go easy please..

[Helmholtz]

Does anyone concur or am I barking up the wrong tree?
nosaj

"Pumping" doesn't make sense to me here.
Check C37 and C43 for capacitance and leakage resistance.

[g1]

Does anyone concur

Yes, try replacing C37.

[nosaj]

cr15 anode side is -35.75 so that means c37 is not pumping enough enough electrons for voltage doubling?
nosaj

Does anyone concur or am I barking up the wrong tree?
nosaj

[TomCarlos]

I am following along on this thread. Here is the schematic: hotrod_deville_schematic.pdf

[Helmholtz]

Is there a reason for not posting the complete schematic?

[nosaj]

cr15 anode side is -35.75 so that means c37 is not pumping enough enough electrons for voltage doubling?
nosaj

[Jon Snell]

Read the service manual diagrammes and cross reference the voltages. Bear in mind, the voltages are just a ball park number.
The Cathode voltage on CR15, (CR10 side), is meaningless as it is swamped with chopped AC from the capacitor and CR10. It is a voltage doubler circuit.

[nosaj]

Heres what else i got cp15-cp17 57.8 Vac
cr10 shows .097 Vdc
CR15 one side -35.75 other side 3.5Vdc

So based on these I presume is either a bad solder joint or a bad cap I really should remember to check them before i solder them in.. So another fun job of removing the pcb.
nosaj

[nosaj]

Here's what i got no tubes installed.
plate 509
screen 507
control grid -24.69

voltage across c38 -25

Sorry for delay this notification stuff cat wait to get fixed.
nosaj