Fred's "my wife thinks I'm crazy" 700B conversion

[FredR]

We're you a dairy farmer growing up?? You sure get up early...

My alarm goes off at 3:50 am

 

[laatsch55]

Internal or external?

 

[FredR]

Working the front panel. The stock knobs are nice solid aluminum but not very deep. Means you have to fritz with the pots to make sure the knobs will fit flush. Combo of padding them from behind and dremeling them from up front.

Back side of the front panel shows a really weird meter sensitivity switch. Cleaned it up and seems to be working fine. Same with the power switch. Wondering if I should replace them. What do you guys think? Replaced the volume pots with these:

http://www.mouser.com/Search/Produc...tualkey65210000virtualkey652-PDB241GTR02104A2

 

[FredR]

Internal or external?

External. Internal a couple hours later.

 

[laatsch55]

That's a standard meter range switch for a "B"....same with the power switch..

 

[laatsch55]

External. Internal a couple hours later.

We call that AC and BC here...(BEFORE coffee, and AFTER coffee..)

 

[laatsch55]

20% tolerance?? How did they match up?

 

[FredR]

20% tolerance?? How did they match up?

Have to check. Only thing I saw for a 3/8 inch hole. What do you use?

 

[laatsch55]

I use the Bourns pots too but I haven't bought any in years and I couldn't tell ya what the tolerance is, but I do try to match them. They'll vary from 95 to 105K. I take 3 readings, minimum, 1/2 way and maximum. They seem to be fairly consistent at least...

 

[FredR]

I use the Bourns pots too but I haven't bought any in years and I couldn't tell ya what the tolerance is, but I do try to match them. They'll vary from 95 to 105K. I take 3 readings, minimum, 1/2 way and maximum. They seem to be fairly consistent at least...

96 and 101K.

 

[laatsch55]

What are they at max volume setting Fred, 0.00??

 

[FredR]

What are they at max volume setting Fred, 0.00??

2.5 and 3.5 ohms.

 

[laatsch55]

Close enough...

 

[FredR]

Close enough...

Excellent! Really wanted to use these vintage guitar amp pots as they go to 11.

 

[FredR]

Back at it. Photo of the wiring for the DC protect board. Note the tie mount that the boards AC runs through to avoid having it drop down into the rca input area.

 

[FredR]

Mounting the control board is next. This is one of Joe's preassembled boards. At first I ordered them to save time. Now I order them because I can't come close to this quality.

 

[FredR]

Control board wired in. Getting close to first power up.

 

[FredR]

For the first power up I have only the first 3 rows of outputs populated. If all checks out I'll do the last 3 rows and test again. For the more cautious out there Joe's best practice is to do one row at a time.

 

[FredR]

Dim bulb test passed. Bias set to 380 mV per Joe's precedures. Time to populate last three rows of outputs.

 

[laatsch55]

Good man Fred!!