EH - Polychorus

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EH - Polychorus

Postby ChrisFFTA » 30 Jan 2008, 07:28

-i

My old Polychorus which was working just fine a few weeks ago is playing up.

Basically the on-off switch makes a lot of clicking thump type noise when switched and no signal passes unless the blend switch is on. Otherwise there is total silence.

Now I cant look at it myself but I was wondering if anyone would have some 'clues' so that when I take it to Mr Fixit Man I dont sound like a gormless twit. :)

Thx
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Postby Dirk_Hendrik » 30 Jan 2008, 10:00

I have trouble determining, from schematic, as well as from online photo's of the thing, as well as from the real thing, which switch you refer to as the blend switch?
Sorry. Plain out of planes.

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Postby ChrisFFTA » 30 Jan 2008, 11:37

Dirk_Hendrik wrote:I have trouble determining, from schematic, as well as from online photo's of the thing, as well as from the real thing, which switch you refer to as the blend switch?


ok i am a schem noob so will describe as per looking att the box from above

the on-off switch is on the left hand side of the unit, the blend the right side. it is not a footswitch but similar to the on-off i would assume
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Postby Dirk_Hendrik » 30 Jan 2008, 12:58

So that would be the Sweep filter on switch?
Image
Sorry. Plain out of planes.

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Postby ChrisFFTA » 30 Jan 2008, 14:00

on that image it is sweep, on my pedal it is blend
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Postby paperhouse » 31 Jan 2008, 07:05

ChrisFFTA wrote:on that image it is sweep, on my pedal it is blend


that means you have an original pedal, not a RI. often the switches just go bad. i'd try replacing the switch first. i replaced the switch on my dlx electric mistress RI (the switches are the same, i beleive) with a radioshack switch. it's the exact same size except it isn't threaded so i had to buy some new nuts and bolts to attach it.

but i'd try just jumpering the switch so that it's stuck on one side before replacing anything. that way you know that it's not the switch stuck "in between" the two modes.
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Postby ChrisFFTA » 31 Jan 2008, 13:03

an old one? cool, i thought it was a reissue...

i will now speak with some authority when i take it to the tech
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Postby paperhouse » 01 Feb 2008, 07:44

ChrisFFTA wrote:an old one? cool, i thought it was a reissue...

i will now speak with some authority when i take it to the tech


yeah, see how the pic above says "stereo" above "poly"? that means it's a RI.
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Postby ChrisFFTA » 11 Feb 2008, 12:17

well apparently a few of the caps were buggered... tech is doing a few more tests to make sure its aok... he also said the older eh stuff had very poorly made boards and they suffer over time... is this others' experience(s)?
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Postby analogguru » 11 Feb 2008, 14:56

ChrisFFTA wrote:... he also said the older eh stuff had very poorly made boards and they suffer over time... is this others' experience(s)?


That´s true I got my Polychorus very cheap cause a lot of tracks were broken - especially near the potis switches. It is necessary to solder very carefully cause the glue which should keep the tracks on the board is very weak.

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Postby nelson » 14 Feb 2008, 12:12

Just for reference

http://electroconducive.googlepages.com/ehxpolychorus

The Schematic for the pedal is in the schem section.
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Re: EH - Polychorus

Postby Fernando JFET » 23 Mar 2009, 14:17

has anyone any guts from that pedal????? (my engish is very poor!)
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Re: EH - Polychorus

Postby sfx » 24 Mar 2009, 05:22

I have both the stereo reissue and an original Polychorus, I'd be happy to post some guts when I get the chance. Might be a fun project to convert to MN3007's or the Coolaudio chips...

The blend switch toggles between the wet/dry mix and wet only btw.

FWIW, the original seems like the better of the two to me.
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Re: EH - Polychorus

Postby sfx » 03 Sep 2009, 14:56

Here's a long overdue bump with a quick gutshot of my Polychorus. I can't seem to find my tripod at the moment, so you'll have to forgive the flash in the picture.

You can't see it but the jacks all use the chasis for ground and there are ICs hidden under a few of the pots as well.

Check out that one trimmer on the bottom left, it looks like it has oxidized itself completely. Weird.
sfx_polychorus_guts.jpg
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Re: EH - Polychorus

Postby borislavgajic » 03 Sep 2009, 16:30

it would be nice to see trace side also :)

thanks for the picture


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Re: EH - Polychorus

Postby sfx » 03 Sep 2009, 17:05

Here you go. Again, sorry the pics aren't the greatest. I'll replace them with better shots at some point.
sfx_polychorus_guts2.jpg
2polys.jpg
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Re: EH - Polychorus

Postby SonOfChaos » 03 Sep 2009, 18:03

Oddly, a polychorus is my dream build, of course I need a lot more experience and skill and knowledge first with simpler circuits but ONE DAY I will have one.
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Re: EH - Polychorus

Postby borislavgajic » 03 Sep 2009, 18:25

sfx wrote:Here you go. Again, sorry the pics aren't the greatest. I'll replace them with better shots at some point.
sfx_polychorus_guts2.jpg
2polys.jpg



pictures are great....!!! thanks a lot

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Re: EH - Polychorus

Postby SonOfChaos » 03 Sep 2009, 21:18

I keep thinking to myself, WHY does the Polychorus have to be so expensive.

Then I look at the guts and go 'OH'.

Anyone have a good comparison of the differences between the RI and the original. I heard the RI is true bypass somewhere.
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Re: EH - Polychorus

Postby soulsonic » 04 Sep 2009, 21:45

Hey! I've been repairing alot of these lately for a customer who collects them. I've worked on two Echoflangers, and now I'm working on a couple PolyFlangers. They really are incredible sounding effects.
I can provide some more photos if any are needed, though Nelson's pdf pretty much gives all you need, and I've found it a very useful reference while doing my repairs because his layout matches the original's very closely.

I've found that when fixing them up, replacing all the electrolytic caps will go a long way towards helping it to sound new again. Most of the chips seem to hold up ok, but sometimes you'll get a bad SAD1024... and that can be a problem to replace. One of the ones I'm working on right now appears to have a bad switching chip, but those are cheap and easy to replace.

I'd love to design a modern version that uses commonly available BBD chips.
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