Ludwig Phase II Clone Tech Notes

[R.G.]

i am suspecting that you're right, of course, and that from your explanations that it is indeed q6 that is shorted. later on, would it be helpful if i bit the bullet and took some voltage readings from it?

If and when you get the motivation to go get at the console board, you can do the necessary voltage readings from the solder side. The big thing would be to measure the voltage between the collector of Q6 and its emitter. If that's zero, it's shorted. If it's less than about 0.5V, it's saturated and is letting ripple get through. It needs a minimum of a couple of volts across it to be able to work out the ripple on the collector and make the emitter quiet.

i'm thinking maybe it would be better on the work/soundalike (face it, a strict clone of this thing will be cosemetically impossible anyways) to add a couple more stages of filtering,

Maybe. In the simulator, with about five volts of ripple at the Q6 collector, the ripple at Q6 emitter is under 10 millivolts, which is pretty good for such a simple circuit.

There may be lower-cost (in terms of rip-up and re-do) ways. Making C11 be 220uF or 470uF would cut the incoming ripple to half and 1/5th roughly. Changing to a darlington device for Q6 ups the effective ripple rejection of the transistor so much that simulations show ripple under 2mV. Simulations are **always** suspect until tested in the real world, but this matches what my gut tells me. So changing out Q6 and C11 may make a difference. And it will be so good that a fancier regulator might not offer any significant improvement.

a true bypass rather than the buffered one it appears to have now,

I would advise a better buffer rather than going to true bypass. It could be made very good indeed with all the power available in this box. A dual opamp running from a 24V three-terminal regulator would give you very clean buffering and lots of room for big signals without distortion. Kind of a "make the world safe for the Ludwig" circuit.
True bypass is a solution for limited problem we had forty years ago. There are better answers that really should be considered.

and maybe make a couple of the trimmers that control the formants and pedal range made external for tweaking goodness...also, going with standard rotary pots will make it easier to build, take up less turf, and in general be less crap to break or try to source.

You could do that. I hate all the wire going off board, but it's purely a matter of choice. The pads on the PCB I did are big enough for wires to come off to external pots easily enough.

[R.G.]

found this looking for subs for that regulator (q6) on the control board...i have ZERO understanding of this stuff, so forgive me if it's a dead end...
http://www.onsemi.com/pub_link/Collateral/TIP110-D.PDF

It'll work fine. I only recommended the TIP112 because Mouser has them a dime cheaper than the other NPNs in the series. Any of the NPNs in that group will be fine.

[pinkjimiphoton]

i will open her up this evening, and have at the circuit board to see what's up. if it's shorted or saturating, obviously i'll replace it.
i may just say screw it and fly to the parts store this morning to get the regulator you reccomend, and a 470mf 100v cap now, so i have them on hand in case it is shorted.
i would LOVE  to have this thing be quiet enough to run it into a dirty amp, and am concerned about the leaking component damaging something else.

if a 470mf cap would kill the ripple that much, to me it seems a no-brainer!!!

please note tho: i HAVE been accused of having no brain, so....................

[R.G.]

I also suspect a grounding problem in your unit. Just a guess.

It might save you a trip if you could bear to open it up and test voltages first, then leave it open overnight.

[pinkjimiphoton]

i can definitely do that if i have to.

i am having a prob anyways...i know they sell a proper or at least compatible part at cnc here, but no idea which of these may be the proper match...any chance you could help a bruddah that's completely confused out and try to tell me an nte part # please?

this is the page i get for "compatible" replacements, but i can't tell which is right or wrong with my limited knowledge.

http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/69d5aa3584d015ce85256e780056e56f?CreateDocument

it looks like the nte 160 is the one i want, but it doesn't seem to be right to me, and why use expensive germanium if not necessary for tone?

or am i wrong?

here's the cross ref part finder i'm forced to use for the local stuff i buy:
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?openForm

i have to go visit my girlfriend, she's in the hospital again...long story you don't wanna know about.

if i can hit the part store before it closes, IF i get the regulator, whether i need it or not, at least i have it on hand to make the repair...and if not needed, well, there's always room in the junkbox for another component. i definitely wanna replace that filter with a bigger cap anyways, one way or the other, i need to get that ripple quieter.

thanks r.g., i reallllllllly appreciate the help!!!!

[pinkjimiphoton]

will this work?

http://www.nteinc.com/specs/200to299/pdf/nte261.pdf

Silicon Complementary Transistors
Darlington Power Amplifier
Description:
The NTE261 (NPN) and NTE262 (PNP) are complementary silicon Darlington power transistors in
a TO220 type package designed for general purpose amplifier and low–speed switching applications.
Features:
High DC Current Gain: hFE = 2500 Typ @ IC = 4A
Collector–Emitter Sustaining Voltage: VCEO(sus) = 100V Min @ 100mA
Low Collector–Emitter Saturation Voltage:
VCE(sat) = 2V Max @ IC = 3A
= 4V Max @ IC = 5A
Monolithic Construction with Built–In Base–Emitter Shunt Resistor
Absolute Maximum Ratings:
Collector–Emitter Voltage, VCEO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100V
Collector–Base Voltage, VCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100V
Emitter–Base Voltage, VEB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5V
Collector Current, IC
Continuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5A
Peak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8A
Base Current, IB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120mA
Total Power Dissipation (TC = +25°C), PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65W
Derate Above 25°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.52W/°C
Total Power Dissipation (TA = +25°C), PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2W
Derate Above 25°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.016W/°C
Unclamped Inductive Load Energy (Note 1), E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mJ
Operating Junction Temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65° to +150°C
Storage Temperature Range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65° to +150°C
Thermal Resistance, Junction–to–Case, RthJC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.92°C/W
Thermal Resistance, Junction–to–Ambient, RthJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.5°C/W
Note 1. IC = 1A, L = 100mH, P.R.F. = 10Hz, VCC = 20V, RBE = 100Ω.
Electrical Characteristics: (TC = +25°C unless otherwise specified)
Parameter Symbol Test Conditions Min Typ Max Unit
OFF Characteristics
Collector–Emitter Sustaining Voltage VCEO(sus) IC = 100mA, IB = 0, Note 2 100 – – V
Collector Cutoff Current ICEO VCE = 50V, IB = 0 – – 0.5 mA
ICBO VCB = 100V, IE = 0 – – 0.2 mA
Emitter Cutoff Current IEBO VBE = 5V, IC = 0 – – 2.0 mA
ON Characteristics (Note 2)
DC Current Gain hFE IC = 0.5A, VCE = 3V 1000 – –
IC = 3A, VCE = 3V 1000 – –
Collector–Emitter Saturation Voltage VCE(sat) IC = 3A, IB = 12mA – – 2.0 V
IC = 5A, IB = 20mA – – 4.0 V
Base–Emitter ON Voltage VBE(on) IC = 3A, VCE = 3V – – 2.5 V
Dynamic Characteristics
Small–Signal Current Gain |hfe| IC = 3A, VCE = 4V, f = 1MHz 4.0 – –
Output Capacitance
NTE261
Cob
VCB = 10V, IE = 0, f = 0.1MHz – – 300 pF
NTE262 – – 200 pF
Note 2. Pulse Test: Pulse Width ≤ 300μs, Duty Cycle ≤ 2%.
NTE261

[digi2t]

If and when you get the motivation to go get at the console board, you can do the necessary voltage readings from the solder side. The big thing would be to measure the voltage between the collector of Q6 and its emitter. If that's zero, it's shorted. If it's less than about 0.5V, it's saturated and is letting ripple get through. It needs a minimum of a couple of volts across it to be able to work out the ripple on the collector and make the emitter quiet.

I measured mine, I'm getting 13.45 volts between E and C.

[R.G.]

will this work?
http://www.nteinc.com/specs/200to299/pdf/nte261.pdf
Silicon Complementary Transistors
Darlington Power Amplifier
Description:
The NTE261 (NPN)

Yep, that will do.

[R.G.]

I measured mine, I'm getting 13.45 volts between E and C.

Yours is working right.

[pinkjimiphoton]

i got the nte160, couldn't get a 100 volt axial 220-470mf cap, so i'm doing the old tube-amp trick of piggybacking 3 100mf 100volt caps... since caps in parallel act like resistors in series, that should give an effective capacitance of 300mfd @ 100vdc....close enough for rocknroll to hopefully nuke that hum.

so...gonna open her up, again, and measure q6...if it looks like it's shorted, then i'll take her apart and replace the regulator when i add the caps. hopefully that will take care of the ripple causing the hum problem...if nothing else, it'll be well-filtered. if the hum doesn't go away, i guess i'll have to work thru each board a component at a time and see what i find.

while i have her open, i'll take voltage readings at all the transistors on the control board, too, so we've got them. for the sake of continuity, which thread is better to post in?
or should i post in both?
ultimately, i hope to archive all of this so all the info will be in one humongous zip file for future generations of diy'ers.

i am really honored and humbled to be a small part in this undertaking, and grateful for all i've learned since i posted the schematics i'd found. this has been one hell of an experience!! thanks r.g., dino, keppy, and everyone else who's either been driving the bus or along for the ride.

anywho, more later...
peace

[R.G.]

i got the nte160, couldn't get a 100 volt axial 220-470mf cap, so i'm doing the old tube-amp trick of piggybacking 3 100mf 100volt caps... since caps in parallel act like resistors in series, that should give an effective capacitance of 300mfd @ 100vdc....close enough for rocknroll to hopefully nuke that hum.

One thing's for sure - it won't hurt!

so...gonna open her up, again, and measure q6...if it looks like it's shorted, then i'll take her apart and replace the regulator when i add the caps. hopefully that will take care of the ripple causing the hum problem...if nothing else, it'll be well-filtered. if the hum doesn't go away, i guess i'll have to work thru each board a component at a time and see what i find.

Yep.

while i have her open, i'll take voltage readings at all the transistors on the control board, too, so we've got them. for the sake of continuity, which thread is better to post in? or should i post in both?

Whichever. I was thinking that this thread would contain more of the techie, down-in-among-the-farads stuff.

ultimately, i hope to archive all of this so all the info will be in one humongous zip file for future generations of diy'ers.

Good idea!

i am really honored and humbled to be a small part in this undertaking, and grateful for all i've learned since i posted the schematics i'd found. this has been one hell of an experience!! thanks r.g., dino, keppy, and everyone else who's either been driving the bus or along for the ride.

You're welcome. I was always interested in this thing, since the schemos first came up. I decided based on the complexity that without a live unit, cloning was futile. Then you came up with a live one. That's an important part. Don't discount your contributions - it wouldn't be here without you.

[pinkjimiphoton]

ok guys, i'm inside the top....i forgot i'd soldered all the wires on, so she should be a bit more robust than i had thought.

just checked q6

readings to ground (one of the holes in the fall plate

e  35.5
b  36.0
c  44.8

between e & c  9.2
between e & b  .4
between b & c  8.6

r.g., does that look about right?

gonna lurk a bit and hope you check in, measure the other trannys in the mean time.

[digi2t]

Crap, never thought to check the other voltages across the other Q6 legs... DOAH!!

But it looks like you're getting a lot less voltage across E and C than I am.

[pinkjimiphoton]

control board transistor voltages all sliders @ min, bypass on, fx on

q1
e 33.8
b 31.2
c 35.5

q2 is oddball, it has TWO BASES
i don't know what the first terminal is, so...

?   7.2 - 4.9 keeps cycling
b1  14.4
b2  .3

q3

e  0
b  .5
c  10.9 - 0 keeps cycling

q4

e  0
b  .5
c  15.6 - .1 keeps cycling

q5

e  0
b .5
c  6.4 - 5.4  keeps cycling

q6

e  35.5
b  36.0
c  44.8

[pinkjimiphoton]

Crap, never thought to check the other voltages across the other Q6 legs... DOAH!!

But it looks like you're getting a lot less voltage across E and C than I am.

for real...wonder if i should just go for it and swap it out?

or wait for r.g. ?

[R.G.]

Sorry - I had an email that had to get out, and it kept me away from the fun stuff.

Actually, with a collector-to-emitter voltage of about 9V (44.8 - 35.5), your Q6 is doing fine. It's definitely not shorted. That was the test. Also, the difference from base to emitter is about half a volt, which is what it should be. Bag the replacement, you don't need to swap it out, not on this evidence.

I was thinking that the collector and emitter would be at the same voltage, or maybe the collector half a volt higher than the emitter. That's not the case, and the transistor is all that could make the voltages be that way, so it's likely OK.

Sorry - the hum comes from somewhere else. Maybe a grounding issue.

[pinkjimiphoton]

i think i found the hum prob...the green filament ires on the control board were running parallel with the white/red stripe wire that carrys audio...seems that may be the problem.
regardless, it now has 300mf @ 100v for the power supply filtering...hopefully that will help nuke it down some.

[R.G.]

I wanted to get that last one out quick if you were still watching.

q1
e 33.8
b 31.2
c 35.5

That's strange. The base is lower than the emitter. Any chance you swapped those readings emitter for base?

q2 is oddball, it has TWO BASES
?   7.2 - 4.9 keeps cycling
b1  14.4
b2  .3

This one *is* an oddball. It's supposed to be cycling, and it is. This is what generates the animation rate. It's OK.

q3
e  0
b  .5
c  10.9 - 0 keeps cycling
q4
e  0
b  .5
c  15.6 - .1 keeps cycling

Q2 drives these two to cycle. They're workign fine.

q5
e  0
b .5
c  6.4 - 5.4  keeps cycling

This one is driven by the foot pedal and the animation. If you flip the animation footswitch off, it ought to sit still and only move when the pedal moves.
Looks OK.

q6
e  35.5
b  36.0
c  44.8

And this one's OK, as I noted earlier.

Sorry if I false alarmed you. It seemed like a bad Q6 could explain stuff. It appears that this was not the case.

The added capacitance can only help, though, so it wasn't wasted. We'll track down the hum. Could be grounding, or it could be the AC lamp wiring either capacitively leaking into the circuit, or through a wiring problem.
>You posted about the filament wires as I was typing this! < 8-)
Is that schemo with the "TIP29" note on replacing Q6 from your box?

[pinkjimiphoton]

no, but i can take a pic from my box, maybe i can get a cleaner shot of the schem. i took some more gut shots, will post shortly...tried to get some good shots of the switches.

i'll check q1 again real quick i could have read it backwards...
gimme a sec..

c 35.3
b 35.3
e 33.8

the readings changed a little after adding the other caps. getting much better formants, too...but a bit more noise in the background....less hum, but a ticking. could be cuz it's dissassembled.

[R.G.]

Q1 is what does the slow start on the animation when it's set to "slow start". I suspect that if that control is working, so is Q1.

Good to hear the hum and formants are improved.

I just wondered about that "q6/TIP29" note. No biggie.