The Amp Garage

Thanks Martin, that’s exactly how I wired them (plus the caps). I guess I’m clear to do the initial PI setting and continue wiring everything else in then. Looking forward to hearing how this circuit sounds as well as the unusual OT I’ve used. Hopefully I got the relays/board/pots right. Triple chec...

Yep, obvious.

The DIN plug needed a ground reference to actually work, lol. Ran the wire back to ground 5 (as it’s labeled in the layout) and the FS magically works now.

Getting good at catching my own f-ups; now if I could get a little better at not making them…

I guess that makes more sense thinking about it. Re-checked my relay wiring at the din and switches back to the negative side of the coil and everything seems right. The runs from the relay PS board to the switches/DIN seem correct, as does the regulator side - 12v to both relays. I’m using the same...

Power amp check complete - the power amp is fully operational. B+1: 477 V5 plate: 472 biases at 38mvDc V4 plate: 472 biased at 40mvDc Bias pot sits a little past noon - right in the middle 👍 V3a plate: 297 V3b plate: 294 V3 cathode: 44 Not hearing any weird noise from the PI or OT, so I guess V3b pl...

Been playing “Operation” with the main board for the last couple hours and I’m getting close to being at the next test point. I was hoping to get some feedback on the PI lead dress if possible before I nail it. Took a gander at the Livesey site and the documented Bluesmaster builds here - most notab...

martin manning wrote: ↑Wed May 15, 2024 2:16 pm Yea, sorry for the diversion. If you went ahead and wired the rest of it up you'd have been fine. Hopefully the learning was worth the trip!

Always worth it Martin; and appreciated

sluckey wrote: ↑Wed May 15, 2024 3:50 am Sorry for the filament string wild goose chase. I missed you saying you had correct voltage between the filament pins.

No worries! I appreciate any feedback and any opportunity to learn. It’s all very good

I’ll have to look and see. If so - shame on me for forgetting that lesson. I can still remember the serial number of every weapon that was ever assigned to me (going back ~30 years now), but I can’t remember what I ate for dinner 3 days ago. Age, TBIs, too much Laphroaig, all of the above? :lol: Onw...

Do you have heater leads connected between the two sockets? If not that would explain it. I thought I saw a back/white twisted pair. I added the twisted pair late last night to perform sluckey’s test; but they weren’t soldered in to V4. I was measuring from the loose leads. I took them out a little...

martin manning wrote: ↑Wed May 15, 2024 1:45 pm That says that the 150R from 2 isn't connected to ground.

I’ve actually got that resistor on pin 2 of V4. Should I move it or connect the heater bridge and see if the voltage balances out?

Measuring across the two heater leads coming out of the transformer with the bulb limiter in place gives me 6.4vac.

Understood.
I get 150 from 7 to ground, but open from 2 to ground. When the heater leads were attached, I was getting 150 on either/both sides. Here’s a close up of the socket:

I’ve got the ACT, bias pot resistor, and ground wire from the bias supply board all sharing the same ground lug. Pin 7 has the 150R ACT, the blue wire to the resistor side of the LED terminal strip, and a green heater wire. If I detach the heater leads and measure across them, aren’t I essentially r...

I’ll go over everything one more time, but I’m fairly certain that I don’t. Is it safe to measure heater voltage with the leads off the socket and just hanging in the air? The only other thing I wonder about is the terminal strip where the LED connects. Could the phenolic part have absorbed flux and...

One thing I noticed was having the diode and resistor for the lamp going to the wrong pins - so I fixed that. Measuring as sluckey advises gets me 6.4vac and has always been right around that. It’s when I measure each pin to ground that I get the stated discrepancy. If measuring that way isn’t relia...