systech phaser with vactrols.... help will be appreciated!!

[pinkjimiphoton]

anybody gotta schematic?
no, really...

here's a bunch of gut shots from this obscure beast... i sent dino a silver one a year or so ago to trace, figure someone may find these pics handy.
it's a double phaser... two speeds, kinda ramps between them.

it passes audio and bypasses, and i can hear the clocks working particularly when taking meter readings. but it won't actually "phase"... the trimmer for the feedback control will let you hear the phased sound (and even feed it back) but no sweep.

the blue electros are 100u @16v, the yellow are 10u (pcb says 5u, the 100's say 50u on the board) the tant is 22u, the tropical fish is .047u. little yeller things are links, diodes are in914, the round chip is a ca3080, the rest seem to be just dual opamps. i'll try and list the parts when i get a chance, and see if i can get a contiguous shot of the pcb so maybe someone can make a pcb.

i had one of these years ago... it's chewey and thick and to my ear sounded just like page on achilles last stand.

anyways.... uttsgay!!! lots of 'em... tried to get backlit shot of front and back of the board too. would LOVE to see this thing resuurected as a diy.

also would love any help/advice on where the hell to check  why this thing isn't phasing... i can hear the clock, it's passing audio and effecting it, but no sweep. i am still wayyyyy too newb to figure this out i'm afraid.

anyways... guts:

[ZZ$$$$$$$]

replace all the electrolytics with the same value capacitor. it should work.

[pinkjimiphoton]

what was in there, or what's marked on the board? the 22u tant is marked 10u on the board, and the two 10u axials say 5u on the board.

replaced all... no change. still passes signal, can hear the clock in the background but no phase shift to the audio signal. i have an old polyphase doing the same thing.

all the voltages seem to be good, all the chips in the various stages seem to be working, i'm getting modulated voltages that change with the effect settings, even the jfet seems to be ok.

wondering if it's the vactrols themselves? i mean, if they don't light, the effect will still work but have no sweep, right?

sorry for the questions, this is only maybe the 3rd or 4th phaser i've ever messed with. thanks!

[Fender3D]

Hi Jimi

Vactrols there, are connected in series, it means if one LED fails no Vactrol works anymore...

[armdnrdy]

With the effect on...check resistance from the center pin to each of the outer pins of the Vactrols. (side with three pins)

The resistance should move up and down.

If you get a constant resistance, check voltage on the other side of the Vactrols. (LED side with two pins)

Try one pin to ground...then the other pin to ground.

The voltage should swing up and down. As Federico stated...if one of the Vactrols is bad, the circuit for all is opened...just like the old Christmas lights. 

[pinkjimiphoton]

sorry, been dealing with life again.
i did try the vactrols with my meter. i get nothing, but i can hear the tone change so i'm assuming the filter and stuff is ok. i'm betting on the vactrols. i have two bags of them, but none have 5 terminals. guess i need to find some vtl5c 4/2's somewhere.


thanks bros... larry what range of resistance should i be looking for? my meter goes up to 20m, but i got nothin on any ranges.

[armdnrdy]

Hey Jimi,

I would imagine from a few K to the area of 100K...give or take a bunch of Ks! 

[pinkjimiphoton]

 

k






i'll try again

[pinkjimiphoton]

ok, now sheet be gettin' downright weird and there's like, spirits flying across my basement and the dog is covering her ears, but it is phasing. i have no idea WHY...
let me explain.

i checked this thing again, but for voltage instead of resistance. one of the vactrols was reading way off from the others, like dead... on the led side.

so i was like.... danggitall... i don't wanna wait to find the proper part, i wonder what would happen if...

so i took a bog standard generic vactrol thing i got in a bag from electronic goldmine a couple years ago, and decided i'd try and parallel the defective (?) vactrol with one of these other ones.

so i hooked it up on the led side first... and suddenly it started phasing. w... i mean wtf?

then i was thinking about it, if the led was dead somewhere... i just bypassed it. but i think that means i'm losing out on this particular stage of the phaser, right? i can't see how it can possibly "see" the light from another component.

definitely the vactrol, good call guys, thanks. i'm gonna try and see if i can parallel this with the ldr side too and see if it will still phase. the 5th (center) connection is just a center tap anyways, right?

hope i don't let the magick smoke out...

[pinkjimiphoton]

i'll be a sonoma beech... it worked.
definitely better with the third one hooked up. it'll do til i get the correct piece in.

thanks gents!

[armdnrdy]

Yep...it sounds like you completed the circuit of "Christmas lights"

I can't see in the images you posted.....what is the model number on the Vactrols?

[pinkjimiphoton]

vtl5c4/2

mammoth has 'em for like 8 bucks, small bear has 'em for 11. neither has a picture so i'm  not buying any yet.
the unbalanced bit with the wrong vactrol actually sounds kinda cool

[armdnrdy]

I saw some decent images of the vactrol model on the other site but...the vactrols are installed to where all you can read is 'Vactec Vactrol'...instead on the model number.

You can actually read VTL5C4/2?

I would have thought that they would have been the dual VTL5C3/2 like in the Phase 100 and Mutron Bi-Phase.

[pinkjimiphoton]

yep, i can read it. it's printed in white on the side of the vactrols.
i think the only dif is a center tap on the photo resistor side.

could probably make a workalike with two photo resistors and an led if push came to shove.. just put the resistors in series i guess.
i found a few vendors for the proper parts, but they're not cheap.

[duck_arse]

if yer original vactrol is led dead, can you maybe surgery the old led out, and surgery a new one in? if it's dead now, you'll have lost nowt, maybe gained some ldr ....

[pinkjimiphoton]

Naaaaah, it actually works good like this, believe it or not!! very cool lopsided swishyness.