I had a nice visit with #94 today until...

[ic-racer]

I looked back and saw that I had done a schematic on #094. I updated it with some info from these current pictures. Maybe more things can be updated or confirmed?

Or maybe someone can draw it up in current software. The software I used expired about 5 years ago and is no longer being supported and does not run on my current computer.

[Charlie Wilson]

Yeah ic-racer my list of details of the amp was in response to looking at your schematic. I tried to list all of the items that were assumed or otherwise incorrect. I made an error on the bass control tail but I am sure of the accuracy of all the other items.
CW

[Teleguy61]

They were packaged as Sprague Q-Line. I think the original manufacturer may be Draloric but don't quote me on that one.
CW

Yes as used by HAD (.6W, 1W, 2W) these are basically unobtainum now, pre Vishay (1988) aquired Draloric and made in Germany. It's no accident that he started to use these when most likely he could not obtain Pihers like he had in the past. The early Pihers and these Draloric CF's are similar in materials.

TM

Radio Shack used to carry these as their regular offering, and I bought many there.
No more.

[aflynt]

Did an attempt at a schematic. From the photo on the previous page it doesn't look as if there are any 22M resistors on the PAB.

[jam-mill]

To M Fowler, what I find interesting about your photo is that it looks like two of the nuts are missing from the holes. Ic-Racer, yeah I think I could do as good a job (or better ) than Dumble did(on the T nuts) and I am kind of leaning towards the t nuts after considering the other options but I guess I will have to let the customer decide if he wants more holes drilled.
CW

Charlie,

I am getting ready to drill a blank chassis and my engineer friend (builds 1/8 scale trains) recommend 'rivenuts'. Not sure of the size of the holes already in the chassis, but it might already be able to take a #8.

-jack

[Charlie Wilson]

Thanks Jack, yeah did a Fender style mounting with #94 and left it at that. I pretty sure it had perm nuts on the lower edges of the chassis and they were removed and the holes may be a bit to large at this point. I work for a structural steel company and my boss tells me that one of the problems is using steel perm nuts with a aluminum chassis. The aluminum oxidizes and the perm nuts break loose which seems to be a common problem around here. I still think that weld nuts screwed to the chassis rail is the most secure way to go. Aaron I never noticed it but you are right, no resistors on the PAB relay. I like your schematic. If I can find my note book I will give you some voltages.
CW

[jam-mill]

Hello,
I posted that the bass control tail resistor was 1k but now I am not so sure looking at my photo. It looks to me like 10K? Let me know what you think.
CW

That resistor looks like a 1K 2% to me (it is hard to distinguish 'orange' next to 'red'). Is there precedent for a 250K pot with a 10K tail?

[jam-mill]

Did an attempt at a schematic. From the photo on the previous page it doesn't look as if there are any 22M resistors on the PAB.

Aaron,

On the J/R switch is there supposed to be a connection node on the top-right side of the switch to the junction of the .01uF cap and top of bass pot?

-jack

[lovetone]

They were packaged as Sprague Q-Line. I think the original manufacturer may be Draloric but don't quote me on that one.
CW

Yes as used by HAD (.6W, 1W, 2W) these are basically unobtainum now, pre Vishay (1988) aquired Draloric and made in Germany. It's no accident that he started to use these when most likely he could not obtain Pihers like he had in the past. The early Pihers and these Draloric CF's are similar in materials.

TM

Radio Shack used to carry these as their regular offering, and I bought many there.
No more.

Does anyone have a recommendation for the best modern replacement for the q-line resistors?

[aflynt]

Did an attempt at a schematic. From the photo on the previous page it doesn't look as if there are any 22M resistors on the PAB.

Aaron,

On the J/R switch is there supposed to be a connection node on the top-right side of the switch to the junction of the .01uF cap and top of bass pot?

-jack

Yeah. The schematic software didn't make a little dot there because the switch contact is just an arc. It is supposed to connect to the switch there.

-Aaron

[aflynt]

Aaron I never noticed it but you are right, no resistors on the PAB relay. I like your schematic. If I can find my note book I will give you some voltages.
CW

Thanks Charlie! And thanks even more for the info and pictures of #94!

-Aaron

[Structo]

I find the OD trimmer (trigger) interesting that the value is 1M?

I remember there was some discussion about the OD trimmer in #124.

That it was a 500K trimmer that only measured 345 ohms.

It seems that #94 has a 1M trimmer and 100K OD pots?

And is measured 152K to ground?

[Charlie Wilson]

Yeah Structo and the amp sounds like it has a larger trimmer. Very gainy. Now the thing I noticed is that when I measure across the trimmer in my amp, even in OD mode with the amp on, it measure lower than what I know the value is. My guess is that it may be a higher value than the aprox. 750k and is a stock 1 meg(maybe a little on the low side).
CW

[lovetone]

I always set my OD trimmer with OD on and V2 pulled out thats the only way I cab find to get the true value.

Geoff

[Structo]

What are you measuring?

I thought you were supposed to check with amp on and OD on.

Measure resistance from wiper to ground.