Ludwig Phase II Clone Debugging and Miscellany

[Govmnt_Lacky]

UGG!!!

Spent the last 2 hours adjusting trimmers and listening to LFO noise 

No matter where I adjust to, the tick does not dissipate. Maybe it is inherent in the system and I am just being fickle???

It sounds phenomenal as long as you continue to strum or play 

If anyone has any other ideas..... I am open to suggestion.

[Keppy]

Have you verified the zener fix with a meter? If you meter the R39/40/64 junction, it should never rise above ~15V. If that's not the case, you will get bleed. I spent a bunch of time with the animation off, triggering the flip flop manually when diagnosing that problem. The zener is intended to keep that junction at 15V at all times. Without it, when you use one animation mode (not both), the voltage at that point jumps from 15V to 30V causing LFO bleed. Actually not straight LFO bleed, but the inability to turn fuzz repeats or FFM off completely.

Do you get a smooth sweep from the animation? If C6 was faulty it could cause the filters to change instantly instead of sweeping. That would also account for it changing when you adjust R26.

We all feel your pain about listening to noise for hours. We had to figure out the trimming procedure from scratch, remember?

[Govmnt_Lacky]

Have you verified the zener fix with a meter? If you meter the R39/40/64 junction, it should never rise above ~15V. If that's not the case, you will get bleed. I spent a bunch of time with the animation off, triggering the flip flop manually when diagnosing that problem. The zener is intended to keep that junction at 15V at all times. Without it, when you use one animation mode (not both), the voltage at that point jumps from 15V to 30V causing LFO bleed. Actually not straight LFO bleed, but the inability to turn fuzz repeats or FFM off completely.

Just to make sure, the 15V 0.5W zener diode I installed went from (cathode) to R5/Q2/C2+ junction and (anode) to R7/C2-/R24 junction. Is that correct orientation?

Do you get a smooth sweep from the animation? If C6 was faulty it could cause the filters to change instantly instead of sweeping. That would also account for it changing when you adjust R26.

The sweep is smooth and the formants sound great! The problem is when the strings are muted I am getting what I consider a great deal of noise. Ticking, tocking, sweeping, swooshing, etc. I know the sweeping and swooshing are typical in this unit. My issue is with the Tick tocking and its level. I do get what I would consider a "seperate" tick/tock when I put it in Repeats mode but the original noise is there too.


EDIT: I used the 2N2646 UJT for Q2 and did not install the Ralt resistor. Just for clarification

[Govmnt_Lacky]

Have you verified the zener fix with a meter? If you meter the R39/40/64 junction, it should never rise above ~15V. If that's not the case, you will get bleed. I spent a bunch of time with the animation off, triggering the flip flop manually when diagnosing that problem. The zener is intended to keep that junction at 15V at all times. Without it, when you use one animation mode (not both), the voltage at that point jumps from 15V to 30V causing LFO bleed. Actually not straight LFO bleed, but the inability to turn fuzz repeats or FFM off completely.

So, I just checked this junction with the Animation ON and the switch in FFM and I am definitely seeing voltages go up to about 30VDC. I lowered the Rate pot to minimum and adjusted the rate internal trimmer as low as I could go. My meter was jumping between 17 and 30VDC.

I did install a 15V 0.5W zener as instructed above in my last post. Is the orientation that I specified correct??

[Keppy]

Awesome! You're describing the textbook zener problem. It sounds like you have the anode of the zener connected to ground just as it should be, but the cathode is in the wrong place. It needs to go to the R39/40/64 junction. Good luck!

[Govmnt_Lacky]

Awesome! You're describing the textbook zener problem. It sounds like you have the anode of the zener connected to ground just as it should be, but the cathode is in the wrong place. It needs to go to the R39/40/64 junction. Good luck!

Installed the 15V zener between C8- (anode) and the cathode went to the R39/40/64 junction.

I am now getting a constant 14.65VDC on the junction when Animation is on and I am in FFM mode.

However, I am still getting the tock, tock, tock, tock, tock on all formant channels with the strings muted.... and still fairly loud 

Am I being too picky??

[Keppy]

Did it change at all? I'm shocked that you didn't describe any change after installing the zener correctly, even if it didn't completely fix the problem.

You've verified that Q8 base and collector are at correct voltages, which basically rules out the percussion repeat path and past known design problems.

Since you said that the ticking only occurs with the formants on, it seems like the tick is getting in through the filter CV inputs. These are smoothed by the C9/C10 shunt caps. The formant switches are fed by Q5, which has C6 as a smoothing cap on the base. These three caps are responsible for turning the ticks into sweeps. Maybe try metering/poking at these caps and associated resistors. Frankly, though, I'm out of obvious ideas.

[pinkjimiphoton]

greg.... the ticktock crap is normal and part of the sound of the circuit. my original did it, dino's clone did it, my clone does it.
the only way to get it to stop completely is to turn the switch to ffm only, and decrease the depth of the fuzz repeat pot.
its SUPPOSED to make that damn noise. you're just not supposed to stop playing.


seriously, noisy noisy beasts. if it were an lfo issue, it would be whining, not ticktocking. its a fuzz repeat, or percussion repeat like on an old organ.

of course, maybe you guys will find a cure, but it IS inherent in the original units.

[Govmnt_Lacky]

So, I made the last few changes (removed a misplaced zener in the circuit) and it still sounds the same. I guess it is an inherent thing.

One final question....

When I have Animation on, and a formant selected..... NOW.... I am not getting any modulation in Repeat mode. It works fine in FFM and Both (I get Bow-wow, Yoy-yoy) but when I flip to Repeat mode.... I get no modulation..... just sounds like a flat filter.

I don't remember it doing that before I removed the misplaced zener 

[Keppy]

FFM = Formant Frequency Modulation.

You're not supposed to hear auto filter sweeps without the FFM on. Manual movement with the treadle should still work.

When I have Animation on, and a formant selected..... NOW.... I am not getting any modulation in Repeat mode. It works fine in FFM and Both (I get Bow-wow, Yoy-yoy) but when I flip to Repeat mode.... I get no modulation..... just sounds like a flat filter.

I don't remember it doing that before I removed the misplaced zener 

The zener fix exists to stop the LFO bleeding into the filters in Fuzz Repeat mode (and also to stop it from bleeding into the fuzz repeat section in FFM mode). Without the zener fix, it's impossible to turn either mode off, though the switch will make one mode or the other stronger.

[pinkjimiphoton]

that switch should choose formant filter modulation, fuzz repeat, or both.

it SHOULD sweep the filter only if the footswitch is on for the modulation, other wise you need to use the treadle to sweep the filter.

the ticktockticktock crap from the fuzz repeat is a "feature".

you guys who haven't played an original may think its a bug, but thats the way they work.

[Govmnt_Lacky]

Thanks for all the help Dino, Keppy, and Jimi! I think this is a wrap!

One final thing....

Anyone happen to have a copy or link to the original user manual? Something that explains all the controls?

[pinkjimiphoton]

AFAIK there never WAS a user manual for these things.

i think ya were supposed to just drop some kinda chemical in your eye or something, crank it up and mess with the knobs, greg

the only thing i've ever seen were some advertisements for it way back. the one i got originally had sat at windham high school unused and unopened until i enqured about it around 76 or 77. no paperwork.

the band director had no idea about it. said it was a left over from the electronic music class that had been canned in 1972 or so.
the sad thing is that a couple other local schools had them as well, and they were simply thrown away (along with synths and modules... i scored an electrocomp eml 101 "pseudo poly" analog for 50 bux from a "rival" high school that had been put out for trash).

[digi2t]

Thanks for all the help Dino, Keppy, and Jimi! I think this is a wrap!

One final thing....

Anyone happen to have a copy or link to the original user manual? Something that explains all the controls?

Email sent.