Boss CE-2 problems.

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gurishka
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Post by gurishka »

Hey all,

Just got given CE-2 that didn't work and upon opening it up there's simply nothing wrong with it.

It gets power and upon turning it on, with the control on full there' simply no effected signal at all. :hmmm:

I've tried the trimpot inside it (marked it before moving it) but there's just no signal in there other than the clean.

Turning the trimpot I do hit the spots where it gets gritty etc but that's it.

Any suggestions are warmly welcomed. :thumbsup

P.S. I've also changed two of the FETs over to see if it was the switching circuit. No dice

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lolbou
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Post by lolbou »

Link to schem for reference.

Clean signal in both bypass and effect mode means Q1 and IC1 are ok. Your delayed signal is lost after being split at IC1 pin 7.

Audioprobe your signal (through C5, R9, ..., Q2 ..., R13, IC3, C10, R16... Q3 ... and up to R22 to see where it gets lost?
gurishka wrote:P.S. I've also changed two of the FETs over to see if it was the switching circuit. No dice
I'm afraid there is only one FET (Q9) :wink: and you have to make sure it works properly (it allows the delayed signal to make its way to the mixer stage (second half of IC1). I guess you've just changed the flip-flop transistors (Q6 and Q7)...

Let us know! :horsey:
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Fender3D
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Post by Fender3D »

Which "2 of the FETs" did you change?

CE2 has just 1 FET...
Find it and short its source and drain pins, then report...

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gurishka
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Post by gurishka »

Ah sorry guys, yeah I replaced two transistors in the circuit. Obviously working on little sleep and it being late at night, a brain fart occurred and nothing happened. :slap:
I'll report back after I find the stupid FET.

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gurishka
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Post by gurishka »

Well I shorted the drain and source of the 2SK30 and it's still very much the same. There is no delay signal going on there. Suggestions?

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Post by lolbou »

gurishka wrote:There is no delay signal going on there. Suggestions?
It does get lost somewhere after the splitter : audioprobe it! :secret:
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gurishka
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Post by gurishka »

So after mucking about with it and using my finger to short things, yes you heard right :shock:
I found a spot on a corner of the board, namely Q4 and Q5 and IC4 I think it is where if i short things around
the 150k resistor it works again... well more noticeably. :hmmm:

Measuring the spot where the 150k resistor is had it coming up at 109k so I changed that out.

Changed out the 47p cap too... but still no go...

And I've not got an audio probe.... :(

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Post by Fender3D »

If it comes back to life fingering IC4's neighbors, then IC4 is ok... (or it has horny neighbors :mrgreen: )

Does it also respond to rate and depth?

If this is the case, check for bad solders or lifted tracks.
Whether it doesn't respond to rate and depth, then it's LFO (IC2 and neighbors)

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gurishka
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Post by gurishka »

Had a look for cracked tracks and dry solder joints around that area, but nothing.

The pedal controls do react when I short the thing with my finger... which is very curious. :shock:

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Post by Fender3D »

Finger will alter resistance and/or capacitance...
first check resistors around, try subbing the trannies, (Q4 and 5), maybe D1...
It shouldn't be that far...

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Post by Gila_Crisis »

Yesterday I got a Boss CE2 to repair. Bypass on-off was working, but no chorusing effect was coming out of the box.
First I did the usual old electrolitic cap replacement with new ones, a proper and ACA to PSA power supply mod. Still nothing.

After doing some research in the internet I've found a guy stating he had a similar issue, and that it was a problem related to IC2, the TL022 responsible for the LFO.
I did unsolder it, put in a socket, and replaced the IC with a TL072: the chorus came back to life!
After I took the old TL022 and put it back into the socket: that worked as well!
So I suppose it was a bad soldering joint around that IC.
Zwischen Ordnung und Chaos fangt die Musik an

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Post by TWSpedals »

Do the mod to make it run off a normal 9V supply, always find they sound better afterwards.

I've known this before with the Boss analog choruses, the LFO op-amp fails. Seen it before in at least 3 CH-1s. I don't have an explanation for why it is a common fault though.
Have a nice day!

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