polyphase gut shots....

[pinkjimiphoton]

i got the pics scruff, thanks mate.

ok. now we're getting somewhere. the "thing" i thought was a thermistor MUST be a cap.
here's a pic of the thing, no idea what it was, tho now if its a cap at least i can test it.

its just a plain silver can, with no markings, and sits right by the three vactrols



the pots are snapped off right where they bend. right now i've got 'em tack soldered together. if i change 'em, they're yours.

gonna go down and poke around. luckily i kept all the original parts, so now that i have a decent cap/component tester, i'll figure out that part hopefully and get this thing beginning to go again.

appreciate the help bro!

[Scruffie]

That's an electro alright, it's just missing its 'wrapper' 22uF I think i'm correct in saying.

I think I can actually see the original thermistor in there.

[pinkjimiphoton]

soon as i get some grub in me.... damn, where's my sausage on a fork???

i'll go down and solve this mystery... or at least a little piece of it.

[idy]

The schematic you posted (and the other I have seen) both have a vactrol. I'm pretty sure I noticed one inside mine....

[Scruffie]

The schematic you posted (and the other I have seen) both have a vactrol. I'm pretty sure I noticed one inside mine....

That's those 3 black cans with 3 wires coming out of them.

[StephenGiles]

JP51J1 wasn't it?

[Scruffie]

JP51J1 wasn't it?

That's the one, I swore I had the datasheet but I can't find it right now but i'm 99% certain it was 100k at 25c.

[pinkjimiphoton]

oh man, this is a LOT of data to type. i took voltages on everything, i was kinda surprised how much easier it was
to find my way around this circuit than years ago when i gave up. i was like, shaking in mortal trepidation back then.. "i can't possibly follow this shit!!! "

the "mystery cap" reads 33uF on my meter. + side goes towards the vactrols

anyways. here goes. some voltages look fine to me, some seem weird as hell. i don't get anything seeming to sweep or modulate which is making me suspect a bad 4013... i think. anyways...

regulator
(left to right)
1  16.07
2  20.0
3  15.4
u1, 4558 (input stage)
1  7.69
2  7.69
3  0
4  0
5  7.53
6  7.73
7  .01
8  .01

phaser stages, all 4558

u2
1  1.32
2  3.45
3  2.26
4  0
5  2.25
6  2.27
7  3.20
8  15.48

u3
1 1.35
2  2.26
3  2.23
4  0
5  0
6  2.24
7  3.14
8  15.48

u4
1  3.26
2  3.58
3  2.19
4  0
5  2.18
6  2.89
7  2.55
8  15.49

u5
1  1.86
2  2.20
3  2.18
4  0
5  2.18
6  2.19
7  2.85
8  15.49

1458
1  12.7
2  6.33
3  6.78
4  0
5  6.33
6  12.58
7  1.91
8  13.39

lm324
1   6.32
2  6.46
3  6.33
4  15.48
5  6.32
6  6.45
7  6.48
8  6.34
9  6.39
10 6.34
11  0
12  6.33
13  6.34
14  6.64

3140
1  .03
2  6.33
3  6.33
4  0
5  .03
6  6.33
7  15.49
8  7.68

4013be
1  15.5
2  0
3  0
4  .55
5  0
6  15.33
7  0
8  0
9  0
10  0
11  0
12  0
13  15.5
14  15.5

q1 , 5088
c   .55
b  1.17
e  .53

q2 5087
c  11.26
b  11.17
e  0

q3 5088
c  15.36
b  0
e  0

q4 3904
c  11.20
b  .74
e  0

q5 5088
c  11.20
b  1.04
e  .70

all three vactrols are reading 2volts on the ldr sides that are sticking up. i forgot to check the led side.

these settings with all knobs on full and switch "on"

too much info. i see some stuff that looks way wrong to me, but i don't really know much beyond fuzzboxes really

thanks for the help !!

[Scruffie]

Right... well first things first, before attempting to fix the LFO (if it indeed needs fixing) all your phase stage ICs are mis-biased, the reference voltage for them is provided by U1.

You have 0V on pin 7 & 8 of U1, if that's correct rather than a mis-reading then i'd say U1 is dead, it should have ~15V on pin 8 and ~7.5V on pin 7.

The problem could also be the 22uF cap that feeds from a 100k resistor from pin 7 of U1.

[pinkjimiphoton]

thanks scruff,
i will check and confirm today and post back.
its possible my meter leads didn't make a great connection, some of the other pins i had to kinda "wipe" to get connections.

i will start there tho.... be back asap.

[pinkjimiphoton]

yeah, i just had a bad connection. pin 8 is 15.5, pin 7 is almost 8 volts.

its passing audio thru it. dicking around looking for bad solder (hah, 70's eh pedal, bad solder lmao) and found a point where i could hear an oscillation, and it changes via the pot so i assume the lfo is ok.

could it be over voltage? the regulator should have 0 volts on pin 2, correct? i'm reading 20. the output side reads 15.5-ish, the other side is around 16. to me this seems kinda off.

while holding each of the chips to short 'em with my skin (hey it works sometimes to see if stuff is working) and then touching the leads to the vactrols, every single one swept a little bit... just while i was shorting it.

so i'm thinking it may indeed be the vactrols after all. i'm gonna proceed gingerly and solder some new ones in and see if she will fire.

also replaced the 10k bias trimmer cuz it just... seemed wonky.

i will check back for thoughts and report my findings asap.

thanks again scruffie!

[Scruffie]

The regulator confused me for a second but it's a transistor based regulator, not a 7815 type so the base isn't grounded, you're getting 15.5V on the output so that's fine.

Okay so the voltages on U1 are okay, are all the phase stage ones still the same though? They should all have about ~7.5V on pins 1,2,3,5,6 & 7. At the last readings the voltages were way off. Did you test that 33uF can with no label to make sure it was good? As that's part of the bias chain for the phase opamps and vactrols it's pretty important.

You can test if the LFO is sweeping by putting an LED in parallel with one of the vactrol LEDs. I'd also test the vactrols with the continuity meter for internal shorts before replacing any of them.

[pinkjimiphoton]

The regulator confused me for a second but it's a transistor based regulator, not a 7815 type so the base isn't grounded, you're getting 15.5V on the output so that's fine.

Okay so the voltages on U1 are okay, are all the phase stage ones still the same though? They should all have about ~7.5V on pins 1,2,3,5,6 & 7. At the last readings the voltages were way off. Did you test that 33uF can with no label to make sure it was good? As that's part of the bias chain for the phase opamps and vactrols it's pretty important.

You can test if the LFO is sweeping by putting an LED in parallel with one of the vactrol LEDs. I'd also test the vactrols with the continuity meter for internal shorts before replacing any of them.

gonna go down and check the voltages again... so everything on the phaser stages should be about the same? definitely not whats happening

i did not replace the 33uf cap. it is good, but it doesn't show a polarity... maybe its unpolarized and thats why it had no wrapper?
i will stick that in and see if it comes back to life, right now its a 22uf in there i think.

i'll also try and bypass the vactrols with an led and report back shortly.

thanks bro !!!

[pinkjimiphoton]

ok!!
i replaced that 33u cap, now the voltages are looking much better.
for the sake of brevity, i'll just post the changes

phaser stages now as expected i think

across  u2     u3     u4     u5
1       7.77    7.74   7.8    7.72
2       7.9      7.8    7.82   7.73
3       7.69    7.65   7.66   7.63
4       0         0       0       0
5       7.65    7.65    7.65   7.77
6       7.72    7.73    7.77   7.72
7       7.72    7.73    7.76   7.73
8       15.38     *        *       *

minimal changes on a couple of the q's

q2
c from 11.26 to 11.17
b        11.17     11.07
e        0       

q3
c from  15.36 to 15.31
b  0
e  0


q4
c from 11.20 to 11.12
b from .74     to 1.70
e  0

q5
c from 11.20 to 11.12
b          1.04 to 2.11
e            .70 to 1.69

all other voltages stayed the same
tried bypassing the led's on the vactrols, no luck. i did get about a 1.3 voltage drop from 15.30 something as i went across making me suspect the leds are working.
ldr side all read about 2.10

also noticed i'd subbed a couple paralleled 100u's for the two 220's. replaced both with 220u@25vdc. on fireup i heard ONE partial sweep. i think.

so somethings still off, but it looks a lot closer. should the 1458 be seeing 15v on pin 8 too? reading about 13.39

<sigh> and of course the 33u? well i had replaced it with a 22u years ago. AND i got it in backwards. <slaps head> all fixed now. put the original cap back in.

so... still stumped!!

[Scruffie]

Excellent, that's looking much better

No, the 1458 has a voltage divider going to its power pin so it's slightly lower supply so 13V is all good there.

So it's not working in either envelope or LFO mode and the Envelope/LFO slide is definitely wired up correctly?

You can forget about the 4558, 1458 and 324 for the moment, the main focus is on the sweep mode, the 4013 and transistors for now.

There's definitely a problem with whichever transistor Q3 is, they should all have a voltage on their base.

Looks like there's something up with the 2N5087 too, it has 0 on its emitter but that should have power on it.

It'd be easier if I knew how you were designating them regarding the schematic.

Edit: Also, what happens to the transistor voltages without the 4013 in? Or the much lazier version, if you have a spare 4013 stick it in, see if it works and if not, see what happens to the voltages.

[pinkjimiphoton]

i will try another 4013, i believe i have a couple kicking around. something weird is going on, for sure, but we'll get it.
i will try another play with it in a little bit and see if it will fire with the new chip.

i am using the designations in ariel's revised drawing that used to be posted here before botophucket screwed the pooch for the whole net.

q1 is a 5088

q2 and q3 are  5087 aand 5088 pair

q4 and q5 are 3904 and 5088 pair if it helps any. i've gotta do a couple things today before i can revisit.

i am NOT sure the switch is wired correctly in fact. i will investigate that too.

also will check the circuitry around q3. wondering if i messed up and put a cap in backwards there too someplace. hey, where i'm concerned, ANYthing is possible!

you rock pete. thanks so much for everything brother!

[pinkjimiphoton]

ok, so i spent some time unsoldering and measuring resistors and caps. everything is within 10% of what its supposed to be.
i have been using this:

and the old hand drawn schematic.

i DID replace the vactrols with no effect of course. it was the only other thing connected to q2 and q3 that was left to check, which leads me to the conclusion that either the slide switch dealio is way @#$%ed up, or either the 5087 or 5088 its tied to are dead. i don't really see where the hell a b voltage will come from coming off e of q2. that should be 0v i would think, all thats there is the connection to q3 b and the voltage divider of r44 and r45.

q2 i'm reading only 1/10th of a volt drop between c and b, do you think that pnp is bad? i mean, to my limited understanding its gotta be either that or the 5088 that are dead. there's really nothing else there!! or am i perhaps missing something?

stumped, scruff!!!

q1 looks really funky to me, too... i should be getting about 15v to c i would imagine, its only got a 100k resistor between  it, pin 4 of the 4013 (which i replaced with a fresh one, 3140 too) and i'm reading .55 v there.

man, this thing is as @#$%ed-up as a soup sandwich. i guess the next thing to do is start replacing q's?

[Scruffie]

Test Q3's base and emitter with a continuity tester to confirm it has an internal short and if it does, replace it and see if the voltages clear up.

[pinkjimiphoton]

will do so now, be right back

[pinkjimiphoton]

checked it with a continuity tester, go one way, no go the other. took it and the 5087 both out and tested both with my meter and tester, and both checked out fine.
also traced and checked the switch wiring to the schematic, its on par with what it should be. getting a little messy cuz that solid core crap wire EH used breaks every time ya look at it.

made an "led tester" with a green led and a 10k resistor with a roach clip to ground. felt around the circuit to see if i could find modulation. i get it across the speed pot, and i think it was pin 3 of the 3140 light swells in and out, and on pin 5 it pulses on and off and i can change it with the rate pot, so i guess that means the oscillator is working. thats a good thing.

so the lfo works, and it passes audio.

also tried the led across the 3 vactrols. i can get it to light, but there is no modulation happening.

looking at the voltages i'm lost at this point. it seems to me q1 c should be wAYYYYyy higher than .55... shouldn't it be more like 15v there and pin 4 of the 4013?

shit, the only thing left i think is that 100k resistor feeding pin 4 and c of q1. i'll check it tomorrow, its 12:30 am here.

stumped but determined!! this thing WILL live again!!!!!