New Amp: Purple Flashes, No Sound

[The New Steve H]

I got my Bassman 5f6a clone put together and fired it up. I have a transformer with 2, 4, and 8 ohm outputs, and the 8 ohm output was connected to a 1 x 12 cabinet. I had a single-coil guitar on the input.

I got some purple flashes from the rectifier, and I didn't like that very much, so I turned the amp off and looked it over. I found that I should have used 2 1n4007 diodes on each side of the rectifier instead of one, so I fixed that. I also found some stuff that looked like it might be close enough together to cause shorts, and I fixed that, too.

I took the rectifier out and turned the amp on again. The heaters all lit up, and there were no flames or explosions, but I got no sound at all. I shut it down and put the rectifier back in, and for a while, it looked nice, but then I got a couple of purple flashes, and I shut it down quickly. I never got any sound out of it.

Any idea where to start looking for problems?

One of my 12ax7 sockets is a little messed up. I found that solder had gotten into one of the holes. I gouged it out of there, and it appears that the tube is seating right and making good contact. I don't think this is the problem.

I also have a problem with my standby light. I took an old 125V job I wasn't using. It has two wires on it. I connected each wire to one contact on the power switch, figuring the light would be in parallel with the amp. When I turn the amp on, the light goes off. It goes on when I turn the amp off. I'm starting to wonder if I'm going crazy.

[selloutrr]

Is your PT center tap correct?
Is the Rectifier wired correctly?

You might have boogered your PT and / or OT during the start ups. I'd go over everything again and make sure polarity is good check voltages. Then start testing tubes and iron.

Did you use a variac or bulb limiter on power up? this probably would have pointed out a fault before it could cause damage.

Is your Rec tube still ok?

[The New Steve H]

The power transformer has two center taps (red/yellow for the big voltage and yellow/green for the filaments) and they are grounded to the same bolt on the chassis.

The rectifier is definitely wired correctly. I am no longer using it, because I want to get the amp working before installing it again. I am hoping it's not fried, and the diodes should do the job just fine without the rectifier tube.

I truly hope I didn't manage to destroy two transformers. Wouldn't there be smoke or heat or something?

I will check the voltages.

I'm wondering if the phase inverter tube socket is too messed up to function.

I guess I better build a current limiter tomorrow.

[The New Steve H]

Rectifier socket voltages with tube removed:

4, 6: 153V
5, 7: 379V

[Firestorm]

Rectifier socket voltages with tube removed:

4, 6: 153V
5, 7: 379V

???

4,6 should be high voltage AC;

2,8 should be 5V filament w/Hi-voltage DC on pin 8.

Where are your 1n4007s?

[The New Steve H]

The diodes are between unused pins (5, 7) and high-voltage pins (4,6). The reds from the PT go to 5 and 7, and the diodes go to 4 and 6.

The filament on the rectifier looks fine.

I checked the phase inverter socket, and I don't think it's out of commission, because the damaged pin hole goes to the filament, and it's getting 3.5V. The filament lights up.

[Firestorm]

Got it. And how are you getting your B+ out with no tube in the socket?

[The New Steve H]

The diodes are supposed to do the actual rectification and supply the juice. The tube is just there for sag and to look cool.

[ToneMerc]

For the sake of clarity, is this how it's wired?

[The New Steve H]

Thanks for the picture. I'm going a little crosseyed at this point. I will try to make sure it compares favorably with what I have.

[The New Steve H]

Is it okay if I never tell anybody what I did wrong?

Thanks for the help. I'm about to do a little soldering that should bring some sort of result.

[ToneMerc]

Is it okay if I never tell anybody what I did wrong?

I think you stated it above, that's why I posted the picture so that you could confirm how it wasn't wired.

[ToneMerc]

I would imagine your layout is similar to this.

[The New Steve H]

I'm working from a Fender layout and a Weber layout, but I'm sure they're fundamentally the same as that one. I don't have a capacitor on the rectifier, though.

I fixed the obvious problem, but the frigging thing still blew the fuse. I'll get on it in the morning.

I also realized the light ain't going to work in parallel with the power switch. It's funny how you can start getting weird ideas after working on a project for too many hours straight.

[diagrammatiks]

did you make sure to get the right light?

you can power a mains rated light from ac mains.