MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

roman 245/246 happiness
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge  
Author roman 245/246 happiness
levelhead3
So there have been numerous threads here and on emcloned discussing the two main problems with the roman 245 and 246 - first that there is a "null" zone on the CV pots' travel from about 3:00 on, where the output voltage maxes out at around 9.4v and after that no additional voltage gain occurs, and second that adjacent stage outputs "blend" together and do not independently trigger a 281r.

I'm happy to say the Dave Brown has come to the rescue and successfully addressed both issues. The CV null zone required the replacement of the CV banks' summing opamps, and a reduction in the the sustained voltage level on the stage pulse output waveforms allowed the 281r to "see" the independent pulses.

He also looked into the pulser & reference waveforms and the clock. These modules are now 100% operational as far as I can test.

As usual complete details of these mods are posted on his website, and I just want to repeat the sentiment of an earlier thread and express my gratitude for his continued support of our community.

Thanks Dave!
Peake
SlayerBadger! SlayerBadger! SlayerBadger!
diophantine
Nice!

Do you know if this was this a problem with the first 245 PCBs that were made available on emcloned? (Not made by Roman, but another user.) I have two, but haven't built them yet...
davebr
diophantine wrote:
Nice!

Do you know if this was this a problem with the first 245 PCBs that were made available on emcloned? (Not made by Roman, but another user.) I have two, but haven't built them yet...

I am aware of another 245 PCB but I don't know if it what you are referring to. Is there any nomenclature on PCB2? You can either post or send a photo to me of PCB2 component side, and a BOM would help.

If it doesn't use 24V or have a DC-DC converter to generate 24V there should be a dead zone, but with the right resistor values, can be pretty minimal. That was my "better" solution on my website.

Dave
diophantine
davebr wrote:
I am aware of another 245 PCB but I don't know if it what you are referring to. Is there any nomenclature on PCB2? You can either post or send a photo to me of PCB2 component side, and a BOM would help.

If it doesn't use 24V or have a DC-DC converter to generate 24V there should be a dead zone, but with the right resistor values, can be pretty minimal. That was my "better" solution on my website.

Thanks Dave - it has cj3000 written on it. I only see a +5V regulator, with a jumper for internal/external +5V. The BOM is around here somewhere...

Will try to take a look at your mod notes this weekend!
davebr
diophantine wrote:
davebr wrote:
I am aware of another 245 PCB but I don't know if it what you are referring to. Is there any nomenclature on PCB2? You can either post or send a photo to me of PCB2 component side, and a BOM would help.

If it doesn't use 24V or have a DC-DC converter to generate 24V there should be a dead zone, but with the right resistor values, can be pretty minimal. That was my "better" solution on my website.

Thanks Dave - it has cj3000 written on it. I only see a +5V regulator, with a jumper for internal/external +5V. The BOM is around here somewhere...

Will try to take a look at your mod notes this weekend!

I am familiar with that and can post the reference numbers on my website. You'll have to double check them as I have no way of doing that. Some of the mods are already done. The stage CV outputs are dual op-amps so I'll have to find an affordable rail to rail dual. There aren't many available in DIP.
davebr
diophantine wrote:
It has cj3000 written on it. I only see a +5V regulator, with a jumper for internal/external +5V. The BOM is around here somewhere...

Will try to take a look at your mod notes this weekend!

I do not have a BOM nor reference diagram for this PCB. If you find the BOM please send it to me. I would also appreciate you scanning your unpopulated PCBs, both sides, and send them to me so I have traces and can make reference diagrams. Scanning works better than photos as the distortion is minimized.

Dave
kashmir
diophantine wrote:
davebr wrote:
I am aware of another 245 PCB but I don't know if it what you are referring to. Is there any nomenclature on PCB2? You can either post or send a photo to me of PCB2 component side, and a BOM would help.

If it doesn't use 24V or have a DC-DC converter to generate 24V there should be a dead zone, but with the right resistor values, can be pretty minimal. That was my "better" solution on my website.

Thanks Dave - it has cj3000 written on it. I only see a +5V regulator, with a jumper for internal/external +5V. The BOM is around here somewhere...

Will try to take a look at your mod notes this weekend!


I have the same set of PCBs, there are still unpopulated so I can scan them if yours are already built. I also have BOM and schematics in case you didn't find them yet.
davebr
kashmir wrote:
I have the same set of PCBs, there are still unpopulated so I can scan them if yours are already built. I also have BOM and schematics in case you didn't find them yet.

Please do. PM sent.

Dave
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge  
Page 1 of 1
Powered by phpBB © phpBB Group