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.
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?
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
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.
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)?
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.
analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
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.
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.
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.
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.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran
