Accidentally plugged in wrong tube and now no sound. [resolved]

[starnerd67]

Its been a while since i used my Bottlehead Crack (standard) and i accidentally plugged in a 274B rectifier in.
No sound comes out from the headphones.
The amp was working before so i know its the wrong tubes that messed something up.

Went back to the manual and put back in the original tubes.

Tubes DO light up.
LEDs DO NOT

amps pass OHM check

Volt check:

1: -.52
2: -.52
3: 0
4: -.52
5: -.52
6: 0
7: 4.4 mV
8: 0
9: 3.3 mV
10: 0

Is there a way to fix it?
I have the Speedball upgrade that i haven't built yet, since it appears that i'd be removing much of the wires around the tubes, would just doing the speedball upgrade remove the broken parts and fix it?

[Doc B.]

Could be blown rectifers. Check the UF4007s with your diode test setting or ohms setting on your DVM.

Here's a quick instructions -

https://sciencing.com/test-diode-rectifier-7378447.html

[Paul Birkeland]

Is there a way to fix it?

Replace the blown fuse first.

I have the Speedball upgrade that i haven't built yet, since it appears that i'd be removing much of the wires around the tubes, would just doing the speedball upgrade remove the broken parts and fix it?

This is not going to be helpful.

[starnerd67]

The fuse isn't broken

and the UF4007s all read about .46 to .47 volts. Which seems to be okay right?

[Paul Birkeland]

Are you absolutely positive that the fuse isn't blown? Have you checked it with a meter? That tube would short the B+ to ground in the amplifier through the heater of the 274B, so the fuse should have blown almost instantly.

[Doc B.]

Presumably that is the forward voltage test on the diode checker setting of your meter. Did you test the diodes in the reverse direction and verify that they measure open/very high resistance? That is the critical measurement to verify they are OK, because they fail by shorting. A bad diode would read conductive (low resistance) in both directions.

[Paul Joppa]

The OP said the tubes do glow, so the fuse must be intact.

[Paul Birkeland]

Oops, my mind had made up that it said "do not glow". 

Measure the 270 ohm resistors and see if one of them is open.  The next failure mode would be one of those resistors just opening up so quickly that it doesn't look burned.  This would also mean that you could potentially see DC voltage present on the first capacitor mounted by the UF4007 diodes, so be careful and double check that back there.

[starnerd67]

The UF4007 diodes all read about .47v in the forward direction and .0L in the reverse.

I hope testing the 250 ohm 5w wirewound resistors is the same way i test the UF4007 diodes.
the results are the same backwards and forwards doing the test this way:
1) .29v
2) .0L

[Doc B.]

Nope, resistors are not tested with the diode test. Just measure resistance across the resistor, one probe to each of the leads with the meter set to ohms. If the resistor is bad it probably shows signs of overheating. But you have to measure it to know if it is good or not.

[starnerd67]

Okay i think we may have found it.

One of the 270 ohm resistors is measuring 0.0L
The one going from 15U to 21U

The other resistors are measuring correctly.

So i take it i should start by replacing that one.

[Paul Birkeland]

That's a good first step.  You can jumper over it with a piece of wire temporarily to check the operation of the rest of the amp, but it will be a bit noisy if you try to use it setup like that.

[starnerd67]

Replaced the resistor and everything works again.

Thanks everyone