polychorus

[Gus]

Someone I know asked me to look at an polychorus that does not work.
The effect was bought in 81 and did not work.

I plugged it in and had no led but did have voltages the interesting thing is the foot switch turns on the led because it is wired to the power by the foot switch.  The schematic I found on the web does not show the foot switch being connected like it in the one on my bench.  The schematic shows the foot switch controlling an analog switch

So before I start tracing (I will mark the wires and take pictures because the wires are all the same color and look easy to break)  
I thought I would ask if people know about this problem with the chorus.  I was told it was bought like this and it looks like no one was inside after it was built.  

[Govmnt_Lacky]

Gus,

Could you possibly be a bit more descriptive about the problem? Is it just the LED not working?

This box was either the father or the son to the Echoflanger and I have had quite a bit of experience with that unit. Would love to see the schematic and layout for this box.

Oh yeah... Would like to help fix your problem too   

[Gus]

It looks like it might be miswired if the schematic I found is correct.  I thought I would ask if someone had found this before. 
I can trace it and figure it out.
I was just asking if someone found this before. 

[theehman]

That wiring is correct.   The footswitch operates the 4053 switching ICs.

[Gus]

To be clear the story is the effect was bought in 81 and never worked

Board has EH7700E marked on it and no IC numbers marked on the PCB most the off board wires are white with a brown stripe.

I opened it up and the LED is not wired like in the schematic anode goes to +15 the cathode goes to the foot switch the other pin on the foot switch goes to ground

I am guessing some of the wiring might be wrong.

I took pictures, marked the board and wires with tape.

Anyone have a picture of where the input jack, output jacks, blend switch, foot switch and LED wires land?

[theehman]

Are you looking at the Echoflanger schematic?

[Gus]

I am looking at the echoflanger schematic.

[theehman]

There's a thread with pics at the "other" forum.

[theehman]

http://photobucket.com/images/echoflanger?page=1

[Govmnt_Lacky]

@Gus

I don't know why you want to keep everything so close to the vest but....

I did successfully clone the Echoflanger and if I remember, the LED was used not only as a power on indicator but, it was also skillfully used to provide a proper power bias to at least one of the BBDs.

Without any more information from you, I can only provide limited info 

[Gus]

Thanks for the pictures, unfortunately the unit I am looking at has a different PCB layout.  The PCB is marked 7700E


Govmnt_Lacky
I am not building a clone.  I offered to look at a non working stock from 1981 EH polychorus for someone.  I was told it was bought in 81 and it never worked. 
I posted here because I thought someone might have a picture of where the wires go.

[Govmnt_Lacky]

Govmnt_Lacky
I am not building a clone.  I offered to look at a non working stock from 1981 EH polychorus for someone.  I was told it was bought in 81 and it never worked. 
I posted here because I thought someone might have a picture of where the wires go.

OK. I understand what you are saying but...

If you posted some photos of the board you are working with it might help the cause. You are talking about a 30+ year old pedal and you will be hard pressed to find someone who recalls the wiring inside of it without some kind of reference.

Help us to help you 

[Gus]

Looks like this one is wired a little different than the schematic I found.
 
The 1024 does not use the led this version has two Si diodes in series from the +15 to the 1024s V1

It also looks like the LED is wired to the foot switch to indicated the effect is on.  

Checked the wires for continuity

Found one solder short between two pads

Taking my time tracing it

First I want to get the bypass to work input gain stage to analog switch to out

Does anyone have a Polychorus from around 1981 that can check if the LED turns on and off with the foot switch?

[Govmnt_Lacky]

Good luck!

[theehman]

Pulled out my Polyflange from storage today and it is wired like that with the LED to the footswitch.  If that LED doesn't light, then either it's dead or the power supply is bad.  The Memory Man stereo echo/chorus uses the same arrangement.  If the LED is bad, there'll be no effect.

[Gus]

Thank you for checking the Polyflange

[analogguru]

There were two versions:
The older version - which has printed "power" on the case - uses the LED as described only for power indication.
The newer version - which has prined "status" on the case - uses the LED as status indication (Effect On/Off)

In the newer version there is from V+ a 2k resistor to pin 10 of U4b (4053) and the anode of the LED.  The cathode of the LED is connected to one lug of the footswitch, the other lug is connected to ground.