CS-3 quit working/ may have shorted out

[Bandera]

I was doing my mods and I was plugging in the power to make sure what I had just modded worked, and I think I shorted out the power to the case. The bottom was off and the power jack was floating around and it hit the case. Now effect will not work.  It stays bypassed.  There is signal when bypassed but effect will not come on. Where and how should I start looking?  Thanks

[diggum12]

Wow two in one week! (see the other thread about the BD-2 doing the same thing)

I don't think the jack hitting the case was the issue.  Since it works in bypass, you've still got juice at least through the switching circuit. 

All I can say is build an audio probe and start tracing.  See the "tools of the trade" section or do a search for audio probe.  That's the only way you're going to find it. 

Here's a schem that I found a while back that I traced & added all the part numbers to.

[Bandera]

Ok thanks. So far with an audio prob I found signal going into R3 and then none coming out.  The bands are red, black, green.  Thanks

[Paul Marossy]

The DC jack touching the case shouldn't have done anything, there's a polarity protection diode in the circuit to prevent direct shorts in the power supply. However, that doesn't protect anything that gets shorted on the wrong side of that diode.

It sounds to me like your FET flip-flop "bypass" circuit could be the culprit to me.

[diggum12]

Wow, that was quick!

Okay, that's good.  Everything on that same trace where R3 touches *could* be suspect.

Do you get any output between C4 - R9? 

edit:  Oh another question:  What kind of chip is in there?  Is it a THAT or a DBX? 

[Bandera]

signal out of C4 to R9 but out of R9 no.  And it is THAT.

[Paul Marossy]

Hmm... are you sure that the PCB doesn't have a broken track on it? Sometimes those can break while desoldering stuff, but they appear to be fine. Or maybe you have a cold solder joint that doesn't look like it is one.

If you measure the resistance of R9, does it measure what the value of the resistor is supposed to be?

[Bandera]

I really dont know what Im doing it but Im giving it my best  shot.  With the meter set to 200K it reads 32.8 and from the bands it looks like a 33k

[Paul Marossy]

I really dont know what Im doing it but Im giving it my best  shot.  With the meter set to 200K it reads 32.8 and from the bands it looks like a 33k

OK, sounds like your resistor is OK. I was thinking that maybe it was open and nothing was getting thru, but that's apparently not the case.

Maybe the PCB is damaged then?

[Bandera]

Thanks.  I have looked and looked at that board and dont see anything funky.

[Bandera]

I checked all the points on THAT and there is no signal.  There is voltage at 7. But I couldnt find signal on any of them. 

[Bandera]

I have modded about 10 pedals with no probs. I was maybe over-confident and I was checking 3 component replacements at a time. I just replaced the last 3 I did and it still doesnt work. I guess that power jack damaged something but I dont know.  I gotta step away. I appreciate any ideas from anyone. I gotta learn what the heck I'm doing.  Thanks

[diggum12]

signal out of C4 to R9 but out of R9 no.  And it is THAT. 

Dang that's exactly what I was afraid of.  I've got this EXACT same problem on an CS-3.  Once it gets past R9 then the signal is practically gone, if not totally.

I think that THAT chip is fried on both of ours.      If so those suckers must be really sensitive to static.  I really need to get that capacitor tester....   *sigh*

Can you also check that Zener on D9?  See if it spikes or anything when you switch the pedal on and off.  I'm not saying anything is suspect there but it's worth checking. 

What kind of voltage are you getting on pin 7 and pin 2?  Please be sure you're using a power supply or a verified good 9V.

Good luck! 

[Bandera]

Ok all th pins up to pin 7 have 4.6 volts or so and pin 7 has 8.94.  I could not get any volt reading out of D9 and I was touching ground and the pos end of the Zetner and flicking the switch and nothing.

[diggum12]

Well Paul still may be right.  I tried swapping the flip-flop fets (say that 3 times fast...) and it didn't help.  BUT now that I think about it I don't know if I used the right ones!  I need to do some more research on it and get back to you.