The Amp Garage

Sorry Evan, I must be thinking of another customer. I just forwarded an email to you that explains the process for attenuating the clean channel by 10dB. Just ignore the fact that it starts off with Hi Dan.....

Yes, please post pics of the switches; as well lit and as close up as possible. I am sure these issues are caused by miswiring.

Also, it would be nice to see a straight-on, clear view of the footswitch programming jumpers.

Ciao,
Lou

double post.

The gain channel is very different from what I'm used to and I need to work with the trimmers to balance its EQ and relative output level. It's very aggressive and bright, which aren't bad things just different. Maybe it's the clarity and note definition being retained in the gain that hits my ear ...

Hi Evan, If you hadn’t wired the efx loop jacks before you played the amp, that’s your problem. You would need to run a short jumper from the send point to the return point (like your red jumper at the standby switch connector), otherwise the preamp output is not connected to the power amp input, an...

xtian wrote: ↑Fri Mar 27, 2020 12:11 am I'm not suggesting it's good practice to discharge with a bang. However, I've never heard it's bad for the caps, either. References?

A BSEE client told me this.

xtian wrote: ↑Thu Mar 26, 2020 10:56 pm Any voltage over ~20vDC will give a good SNAP if discharged across a low resistance path like a probe or screwdriver.

I have heard this is unhealthy for electrolytic caps, so should be avoided if possible. It’s always best to bring them down with a resistor in the range of 200k to 470k, 2W.

The board has a bleed resistor at each capacitor. If you turn off the amp, unplug it, wait about a minute, then measure the DC voltage at each of the test points as Phil suggested, you should find that all voltages have fallen to safe levels. Phil suggests 5V, and that’s what I look for as well. Tho...

It's definitely possible that some things got mixed up. As I may have mentioned, this is well beyond what I know electronically. When I got the board, I thought this was going to be a bit more "paint by numbers" esque and so I'm wildly confused on why the tech didn't just plug in the wires where th...

Hi Jason, No worries. We use reference designators for electronic assemblies. So you will notice on the board, all resistors have a unique number near them starting with “R” followed by a number. For example R45, R66, etc. Likewise for capacitors; for example C47, C16, etc. inductors start with L, t...

Alright, I think I got them. Looking into the amplifier from the control panel inwards: Left Tube: 1 - Resistor in series with R8, L3, R7 to ground (chassis and center of screw down terminal) 2 - White wire - connected to R1 3 - Yellow wire - connected with R2 - Resistor in series with R7, L1, R8 t...

We can work through the bias supply changes shortly. First, I want to get an accurate understanding of the nomenclature. As Phil stated, the R and L designations are confusing at beat, But I have not looked at the schematic yet, so I am hoping this will become more clear once I do. I will check back...

Hi Jason, Yes, that wire could be the reason you’re not getting full power. The new photo is too dark around the tube socket to see the pin numbers, which are embossed in the plastic right next to each terminal. Can you get a flashlight in there and read and report back with the pin numbers for each...

Yep, you called it... When doing it right, I got 41.2 off of 1 2 measured 18.7 3 measure 18.6 Hi Jason, These voltages should be as follows: 1 40-ish VAC 2 This is a NEGATIVE DC Voltage (with respect to Chassis GND), in the range of about 50 to 55 VDC 3 This is a POSITIVE DC Voltage (with respect t...

xtian wrote: ↑Tue Mar 24, 2020 4:21 pm Here is the Rev A schematic. First, that mod to R60 is totally wrong. Put that back to stock.

Schematic, HRD TO ODS, Rev A.pdf

Correct, there should not be a wire from the top end of R60 to anything.