DOD - FX25 Envelope Filter  [schematic]

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MarcoMike
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Post by MarcoMike »

we are going to have 2 clone-topics this way... ;)

viewtopic.php?f=10&t=11582

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czech-one-2
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Post by czech-one-2 »

ok, back to the drawing board. I had the probe hooked up wrong [at the advice of a websight that said hook the clip to the board output,probe the input] Now the clip is to ground,and things are different for sure.
Now Q3 is not giving any audio. I had some ca3080's so I socketed and swapped those,so now all the chips are new.
I've always been able to fix a pedal by changing diodes,chips or sorting wiring,but thats not gonna happen here.
If theres anybody in the EU that can take a look at it let me know,It doesnt look like I'm gonna get this one working.

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MarcoMike
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Post by MarcoMike »

tomorrow before going to work I'll stop in czeck republick and have a look! ;)

just kidding... keep on probing the thing! make sure your audio probe makes sense: earphones (or whatever), shield to ground and tip to a capacitor and with that you "probe" the circuit. vintage style cap with long wires usualy are my choice for this, so I can use it holding it as a pencil from the cap body and testing with one of the lugs...

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MarcoMike
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Post by MarcoMike »

tomorrow before going to work I'll stop in czeck republick and have a look! ;)

just kidding... keep on probing the thing! make sure your audio probe makes sense: earphones (or whatever), shield to ground and tip to a capacitor and with that you "probe" the circuit. vintage style cap with long wires usualy are my choice for this, so I can use it holding it as a pencil from the cap body and testing with one of the lugs...

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czech-one-2
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Post by czech-one-2 »

I meant I would ship it ! :lol: [But feel free to stop by for a pivo!]
Anyway I got the probe sorted out,and I'm using a big old fender cap. I'm just not real clear on what points should be audible,what should sound distorted,and what should be silent.
Is the distortion from v- and the silence from grounds? :mrgreen:
And Q3 should have some audio on one of the 3 legs,right?

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rs
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Post by rs »

I think that's not the version czech-one-2 is after. The pedal has two CA3080's, and the schematic is from the version with a LM13600.

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andrewkirsanow
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Post by andrewkirsanow »

Shouldn't really see any audio on the legs of Q3, unless you've written the wrong number. Q3 is the switching transistor to drive the LED. If there's audio there, it must be stray coupled from the supply rails or somewhere like that!

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czech-one-2
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Post by czech-one-2 »

andrewkirsanow wrote:Shouldn't really see any audio on the legs of Q3, unless you've written the wrong number. Q3 is the switching transistor to drive the LED. If there's audio there, it must be stray coupled from the supply rails or somewhere like that!
Ok,its Q3 on the board,so no audio is ok. Still not sure where to go from here.
So heres what I have so far...
all ic's,footswitch and diodes have been replaced. Unit turned on when the 14007 was replaced.
Jacks are wired correctly.

Could somebody explain what the distortion is coming from the probe at some locations? Grounds or V- ? Sorry,I'm new to the use of this thing.

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MarcoMike
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Post by MarcoMike »

signal in the envelope generation part of the circuit won't be that clean... that part is supposed to turn your signal into a control voltage...

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Post by andrewkirsanow »

Aye, you would get very distorted audio at the junction of D4 and D5! Also, just realised that the posted schematic doesn't match the effect unit!! There's only 3 Ic's on the diagram as it uses a dual VCA chip, whereas yours has 2 seperate single VCA chips!

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Post by czech-one-2 »

andrewkirsanow wrote:Aye, you would get very distorted audio at the junction of D4 and D5! Also, just realised that the posted schematic doesn't match the effect unit!! There's only 3 Ic's on the diagram as it uses a dual VCA chip, whereas yours has 2 seperate single VCA chips!

Yes,I realized that schematic was from a later revision,but guess what?......... the original REV-A schematic is in the box! :applause: I will scan it and post it here this evening.

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Post by czech-one-2 »

But until then,heres some straight on photos for Borislavgajic - [these are post chip swapping and messing about]
Image
Image
Image

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czech-one-2
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Post by czech-one-2 »

OK, heres the 1st issue FX-25 schematic :thumbsup

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Post by borislavgajic »

but as you can see there are ca3094 ota on schem.....and you have CA3080 in your pedall........
si it is not the same......
Thanks for those pictures :thumbsup
I will look for error
Boris

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Post by MarcoMike »

boris, I was surprised when I read your post, I was sure I had seen 3094s... in fact in the first pictures he has 3094s, then he socketed some 3080 on the board...

czeck12, I think you're doing too many things at once...

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Post by MarcoMike »

and now that I see the schem, where is that 100k resistor connected?? it seems going from pins 5,6 to the transistor... but it should connect pin 8 and the transistor instead...

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Post by czech-one-2 »

MarcoMike wrote:boris, I was surprised when I read your post, I was sure I had seen 3094s... in fact in the first pictures he has 3094s, then he socketed some 3080 on the board...

czeck12, I think you're doing too many things at once...

Yes, I have stopped for the moment! :shock:
I read on line that the 3094 was an updated 3080 chip,and should be a match. If not then those 3080's are coming out fast! I've still got the 3094's so I can plug those back in.My reasoning for the chip swaps was since the 14007 chip swap fixed the switching,then maybe the other ic's were suspect.I know its rather archaic logic, but I tend to try possible fixes that I have on hand.And I've fixed maybe 10 pedals by swapping chips,so after diodes its my first instinct. I will put this thing back to [almost] original if I ever get it working!

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Post by czech-one-2 »

MarcoMike wrote:we are going to have 2 clone-topics this way... ;)

viewtopic.php?f=10&t=11582
Yes,I'm sorry about this! I was hoping the Moderators would remove the one that is in the wrong sub-forum.I feel bad hogging so much space! :block:

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borislavgajic
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Post by borislavgajic »

czech-one-2 wrote:
MarcoMike wrote:boris, I was surprised when I read your post, I was sure I had seen 3094s... in fact in the first pictures he has 3094s, then he socketed some 3080 on the board...

czeck12, I think you're doing too many things at once...

Yes, I have stopped for the moment! :shock:
I read on line that the 3094 was an updated 3080 chip,and should be a match. If not then those 3080's are coming out fast! I've still got the 3094's so I can plug those back in.My reasoning for the chip swaps was since the 14007 chip swap fixed the switching,then maybe the other ic's were suspect.I know its rather archaic logic, but I tend to try possible fixes that I have on hand.And I've fixed maybe 10 pedals by swapping chips,so after diodes its my first instinct. I will put this thing back to [almost] original if I ever get it working!
3094 is not same as 3080 chip!!!!!!
put back those 3094 if they still work......... :?
slow down.......3094 is like 3080 but have 2 transistors more inside, and different pinout.....

boris

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Post by andrewkirsanow »

Well, I've been following this thread for just too long to not find out how it's going!!! So, have you fixed it yet?

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