The Amp Garage

sluckey wrote: ↑Wed Dec 14, 2022 1:56 pm

prairie wrote: ↑Wed Dec 14, 2022 1:37 pm I'm going to try and replace all jacks with non-shorting ones

You don't need to replace the jacks. Just remove the jumper between the sleeve and switch lugs.

Just snip it off?

Another update! I disconnected the shorting jacks last night and replaced one with a non-shorting jack (and then wired the 8 ohm tap directly to it, common to the ground lug of the jack). I was able to get guitar signal through the speakers, though it was very quiet (with the volume control nearly m...

UPDATE: My center tap/common from my OT (Heyboer HTS-5200) is going to the ground lug of my 8 ohm speaker jack. Look at your schematic. If when you say "center tap/common from my OT", those are two different leads. Your OT PRIMARY CENTER TAP should be connected to the power supply filter cap node (...

UPDATE: I ordered and installed a new PT (Heyboer HTS-5199) and everything fires up without issue (both through the limiter and directly into the wall). Though I don't have any guitar sounds coming through my speakers. That's not to say I don't have sound, however. When I turn the presence potentio...

sluckey wrote: ↑Sat Dec 03, 2022 7:25 pm

prairie wrote: ↑Sat Dec 03, 2022 7:12 pm Could I have my power switch wired wrong or have the wrong type?

The fact that you got voltage readings on the tubes eliminates power switch wiring. Looks like a bad PT.

Well that settles it. Ordering a new PT. BALLS.

martin manning wrote: ↑Sat Dec 03, 2022 6:48 pm The primary DC resistance will be very low, a few ohms. Does the fuse blow with all secondaries disconnected?

Yep. Disconnected the 6.3v and 300v taps. Same result.

Could I have my power switch wired wrong or have the wrong type?

I disconnected the primary leads and checked the impedance. Got 5 ohms, so that’s something (I think?). I was afraid of having an open lead or no reading at all.

Is there any other way I should be testing it?

If the fuse won’t hold with all secondaries disconnected, the PT is toast. It could have been damaged when you initially powered it up with tubes in and positive bias voltage. That would cause excessive current draw from the HV winding. Well that’s worrying. I’ll check the primaries in a bit here (...

sluckey wrote: ↑Sat Dec 03, 2022 12:08 pm Disconnect white wire from rectifier diodes. Still blow fuse when plugged straight into the wall?

I disconnected the above wires (300v windings) and the fuse still blows when plugged straight into the wall.

sluckey wrote: ↑Sat Dec 03, 2022 12:08 pm Disconnect white wire from rectifier diodes. Still blow fuse when plugged straight into the wall?

Will try this morning.

Unless I missed something (which is always possible :), it looks like your power supply has no shorts to ground all the way to V1. But something is drawing excessive current and taking out the mains fuse when you go off the limiter. How bright is the bulb when on the limiter and no power tubes? It ...

Pull the output tubes and plug the AC cord straight into the wall outlet. Recheck the voltages on the power tubes. Those readings are with no power tubes. And if I plug straight to the wall, I blow a fuse. Just to clarify the situation. Does the fuse blow when plugged straight into the wall with *o...

sluckey wrote: ↑Fri Dec 02, 2022 11:41 pm Pull the output tubes and plug the AC cord straight into the wall outlet. Recheck the voltages on the power tubes.

Those readings are with no power tubes. And if I plug straight to the wall, I blow a fuse.

Here are the voltages at the pins with the amp off standby (hooked up to limiter) V1 pin1: 260v pin2: 0v pin3: 1.4v pin4: 2.4vac pin5: 2.4vac pin6: 197v pin7: 0v pin8: 1v pin:9: 2.4vac V2 pin1: 293v pin2: 0v pin3: 2.2v pin4: 2.4vac pin5: 2.4vac pin6: not used pin7: not used pin8: not used pin:9: 2.4...

I took some voltage readings around the circuit. Numbers in parentheses are with the standby switched off (to the "operate" position). C21 + side: 0v C21 - side: -35v C22 + side: 0 C22 - side: -28 /// Without knowing which layout/schematic these R and C numbers refer to, it is difficult or impossib...