My take on a 2nd Gen ODS

[martin manning]

What program do you use to draw your circuit board layouts? Corel Draw?

Now, don't laugh... PowerPoint. I've done faceplates with it too, just need to save as .pdf.

[Matt J]

What program do you use to draw your circuit board layouts? Corel Draw?

Now, don't laugh... PowerPoint. I've done faceplates with it too, just need to save as .pdf.

No judgment from me since I still use Microsoft Paint for most things!

I do need to look at Powerpoint now. There are some faceplate ideas for other projects I've been kicking around I would love to try sometime!
Matt J.

[GAStan]

Never mind...

[dbharris]

What program do you use to draw your circuit board layouts? Corel Draw?

Now, don't laugh... PowerPoint. I've done faceplates with it too, just need to save as .pdf.

No judgment from me since I still use Microsoft Paint for most things!

I do need to look at Powerpoint now. There are some faceplate ideas for other projects I've been kicking around I would love to try sometime!
Matt J.

There is a bit of a learning curve, but a combo of inkscape (think Illustrator) and gimpshop (think Photoshop) have served me well for graphics, face plates, pedals, logos, etc. They are open source and free. Can do pretty much anything you might want.

-Dan

[Matt J]

BTW - I'm cleaning up some wiring and double checking some of the connections. While I'm in there with my soldering iron I would like to address the issue of not getting enough negative bias voltage. Which resistor should I adjust first? The 3.9k on the board, or the 27k running from the bias pot lug to ground?

Currently I'm only getting about -43 max negative DC voltage and cannot go lower than 63mA when trying to bias, which is way to hot for these 6L6GCs.

Matt J.

[martin manning]

I recommend adjusting the 3k9. Start by clipping or tacking another 3k9 across the one that's there and see where that gets you.

[Matt J]

I recommend adjusting the 3k9. Start by clipping or tacking another 3k9 across the one that's there and see where that gets you.

Update: It's alive!

Well, sort of.... Dropping the 3.9k down to 1k gave me enough negative voltage to bias the 6L6GCs at about ~38mA at 440 VDC plate voltage. I rewired some of the preamp and may have cleared out an error grounding out the preamp I just could not find at first. The amp will now produce sound, but it is intermittent and will cut out. Preamp switches and tone stack work, so does the PAB, but switching on the OD causes the signal to cut out completely. I'm going to try to roll some tubes and just keep digging from there.

Matt J.

[Matt J]

I've rolled several tubes but keep getting the same result, OD goes in and out, then out completely.
I'm starting to suspect I have an error in the relay wiring. The PAB is working fine, but I would appreciate another set of eyes on the OD relay board I'm using from Taylor at AN.
From left to right:
Shielded cable with the black heat shrink connects to the Master Volume.
Green wire feeds into the 220k OD entrance.
Grey wire feeds out from the clean 10nf coupling cap.
Ground connection follows next.
Shielded cable with the green heat shrink leads to the wiper of the OD Volume pot.
Matt J.

[GAStan]

Something I noticed and am curious about. The green wire goes to the 220k OD entrance, then to a 33k then to OD1 input. The junction of the resistors is tied to ground on the layout. Is this really supposed to be grounded? With it grounded the signal is only passed by the 1m2 resistor.

[GAStan]

Found a Gen 3 schematic and it matches the layout.

[dbharris]

I've rolled several tubes but keep getting the same result, OD goes in and out, then out completely.
I'm starting to suspect I have an error in the relay wiring. The PAB is working fine, but I would appreciate another set of eyes on the OD relay board I'm using from Taylor at AN.
From left to right:
Shielded cable with the black heat shrink connects to the Master Volume.
Green wire feeds into the 220k OD entrance.
Grey wire feeds out from the clean 10nf coupling cap.
Ground connection follows next.
Shielded cable with the green heat shrink leads to the wiper of the OD Volume pot.
Matt J.

I believe your channel relay is wired like the traditional 2nd Gen, but needs to be wired like a bluesmaster since you have the hybrid setup with independent channel master volumes. Check Martin's board PDF in files and follow the bluesmaster connections.

-Dan

[Matt J]

I've rolled several tubes but keep getting the same result, OD goes in and out, then out completely.
I'm starting to suspect I have an error in the relay wiring. The PAB is working fine, but I would appreciate another set of eyes on the OD relay board I'm using from Taylor at AN.
From left to right:
Shielded cable with the black heat shrink connects to the Master Volume.
Green wire feeds into the 220k OD entrance.
Grey wire feeds out from the clean 10nf coupling cap.
Ground connection follows next.
Shielded cable with the green heat shrink leads to the wiper of the OD Volume pot.
Matt J.

I believe your channel relay is wired like the traditional 2nd Gen, but needs to be wired like a bluesmaster since you have the hybrid setup with independent channel master volumes. Check Martin's board PDF in files and follow the bluesmaster connections.

-Dan

Thanks Dan!
I had thought about going that direction, but wanted it instead to be more like 102, 124, and 183 with an OD ratio control and single master. I may revisit that though.
Matt J.

[dbharris]

Sorry I misunderstood! Good luck tracking it down.

[Matt J]

Sorry I misunderstood! Good luck tracking it down.

No problem! I'm actually second guessing myself and wondering now if I should have gone with a hybrid design with the separate masters.

Matt J.

[Matt J]

The more I have thought over, the more I am leaning towards changing it to have the separate masters for OD and Clean.
The design I have seen the most for this is in the attached PDF.
I have two questions on this;
1. Why is the clean master not connected to the ground bus? The outer (brown in this drawing) wire runs to COM 2 which, from Martin's relay layouts, should just have the OD entrance running to it.
2. Is there any benefit to switching from the 2nd Gen Deep Switch to the to the version from the 4th/5th eras as this design does? From trying it when this amp would work, I was not that impressed with the 2nd Gen's function.
Matt J.