Problem with an IBANEZ CS505

[azhari]

I'm trying to salvage this old pedal which was given to me by my uncle.

It powers up alright (18V).

Here's the issue :

With the pedal OFF -

When the amp is plugged into the mono output, I get the clean bypassed tone but the output has seemingly dropped as compared to the guitar being plugged directly into the amp.

With the amp plugged into the stereo output (the bottom one), I get a true clean bypassed signal as it should be with no volume drop.

With the pedal ON -

I get the same low volume clean (dry signal) at the mono output; no wet signal (or it could be really soft).

When I plug an amp into each of the stereo outputs, I get a low volume wet signal at the upper output and a clean signal normal volume dry signal at the bottom output.

What gives?

My experience with pedals has been minor troubleshooting/revival of dead pedals and some modding (to Keeley/Monte Allum/etc specs).

Appreciate your thoughts/advice on this as I would really like to salvage this pedal.

Thanks, guys!

[azhari]

Here are some photos of the guts (seems to have been repaired before but me uncle got it from someone else some time ago so he's in the dark about it as well) :

http://s584.photobucket.com/albums/ss284/0azhari0/b.jpg
http://s584.photobucket.com/albums/ss284/0azhari0/e.jpg

[Ripthorn]

I don't have much experience with stuff like this, but I think those old pedals weren't true bypass, so my best suggestion is to see if there are any damaged FET's in the switching path.  The low level clean signal sounds like a dead FET (shorted connection internally).  I don't know if the mono jack would affect the stereo one, but I would take a DMM to any FETs in the switching section.

[azhari]

It's been a long time since i studied electronics but thanks for the refresher.

It seems strange that I'm still getting a weak wet (chorus) signal in stereo mode from the upper jack - i assume in stereo mode, the dry signal comes out from the bottom jack and vice versa.

Should i look at voltages on the FET outputs?

Pardon me but it's been a lonnngggg time...thanks!

[azhari]

Ahhh...went back to my oldddddd textbooks...I will DMM the base/collector/emitter and see how it goes...but the odd thing is that there is a wet signal in stereo mode; albeit soft in volume.

So I think the FETs are working (but i'll check anyway) but somehow I have the impression that the mono (top) output jack or related/connected components is the culprit.

This is due to the low volume output i get from it in both mono and stereo mode.

In stereo mode, the bottom jack clean signal output volume is fine; however the top jack wet signal output volume is very low....I can hear the chorus tone if i increase the amp volume really high.

I'll see how it goes and update...but at the same time, if anyone is able to chime in with any ideas, I'm all ears.

I'll be replacing the mono (top) output jack just in case