Boss CE-2 DOA HELP ASAP

[czech-one-2]

Hi i recently picked up a DOA boss ce-2, no led or signal wether 'on' or bypassed. the pedal is untampered with.
I'm new at this but my first thought was diode d7 or d5 was bad. I replaced d5 and the light came on for an instant,then nothing.
I replaced d7 and the light came on for an instant,then nothing! I'm stumpped. the battery is getting warm but not hot. I have a dvm and am getting voltages all over,including all opamps,but dont really know what i should be looking for. however there is no voltage on either side of what i beleive to be d5[attached to wire #4 - and wire #3] does this sound right?
Anyway what i thought would be an easy fix has got me stumped, can anybody help???
I'm including the schematic and a photo if that would be of any help.
thanks in advance for your time!


http://www.freeinfosociety.com/electronics/schematics/audio/bossce2.pdf

[czech-one-2]

for some reason my photos arent appearing.................working on it

[anchovie]

You need to host your pictures somewhere on the web and link to the URL. We can't see the contents of your "My Pictures" folder over the internet!

What's the voltage at the point where the battery meets the board?

[czech-one-2]

You need to host your pictures somewhere on the web and link to the URL. We can't see the contents of your "My Pictures" folder over the internet!

What's the voltage at the point where the battery meets the board?

its a full 8.5v where wire#9 [battery +] meets the board

[anchovie]

D5 should have zero voltage on both sides, it only does it's work if the wrong polarity adaptor is plugged in. D7 is optional, the circuit will be fine without it when using a 9V supply. What voltage do you get at the + side of C29?

[czech-one-2]

 What voltage do you get at the + side of C29?

8.25v  [ the battery is getting a little weaker]

[czech-one-2]

any suggestions as to where to start looking? I really thought it would be a diode or loose wire,but that doesnt appear to be the case.

[czech-one-2]

crickets ?

[anchovie]

Q6 & Q7 form the flip-flop for the switching. See if the voltage momentarily changes at the junction of C26 & C27 when you press the switch. If it does, see if the voltage on the collector of Q7 flips between high and low each time you press the switch.

[czech-one-2]

Q6 & Q7 form the flip-flop for the switching. See if the voltage momentarily changes at the junction of C26 & C27 when you press the switch. If it does, see if the voltage on the collector of Q7 flips between high and low each time you press the switch.

OK,i'll check tonight. However, being that the board components are not marked,could you help me identify Q6/Q7 by the photo of my board?
I appreciate your replies!!!

[anchovie]

I'm afraid I can't, you might have to identify them from the trace side.

[Quackzed]

check out the input jack as well, wiggle the input chord, twist it, see if it feels like a solid connection??

[czech-one-2]

ok, i checked the junction of the two 220pf caps c26/c27,the voltage pulses when the switch is depressed. the collector of Q7  flips between .01 v and .59v..
Also, the led is switching on and off now when powered by battery,but not by adapter,that may be due to the ACA vs PSA thing though.
I'd say the input jack was a great suggestion,but without a 1/4'' plug inserted the led does not work,so its ok.
the process of elimination continues, but I have no idea where to go next???

any    

[anchovie]

You'll see from the schematic that the Q7 collector point connects to various FETs the control the switching of the audio path between effect and bypass. It may be that one of these FETs no longer works. An audio probe or oscilloscope in conjunction with the schematic could be used to trace the signal from the input to the point where it dies.

However, I appreciate that you're new to this and a CE-2 with a mystery fault may be a bit too much to deal with this early on for you. You might want to gain a bit more experience with components and circuits in general and save this one for later, or simply sell it on as faulty and pick a project you might enjoy more!

[czech-one-2]

actually, I would greatly enjoy getting this pedal to work ! I'm a novice electrical tech,but thought this might be an opportunity to learn a few things.
I guess i was hoping that some one out there had a similar problem with a ce-2,or that the problem was an easier,more common fix like a wire,diode,footswitch,jack,etc.

[anchovie]

Cool, I'd recommend you start tracing the audio path in that case.

[Quackzed]

after having fixed a few broken pedals i usually start with moving parts.. pots switches.. jacks..wires , then look at the board for any signs of rot rust cracks etc.. then onto reverse power problems, protection diodes, transistors audio probe..
    but 90% of the time its a worn jack or a wire that broke off or even an intermittent pot. you know, something that people turn, touch, plug in,unplug.. something that can be abused my reasoning is simply that all the parts soldered to the board are untouched and in a sort of time capsule...one thing that can damage those untouched things is electricity... things can get fried!
    so, before replacing transistors and diodes etc... i'd plug in a guitar plug it into an amp ,check the volume without the pedal, (make sure its the pedalthats not passing sound and not a cable etc..) and with it all hooked up, wiggle the plugs jacks battery wires, anything and everything... see if you can get just a bit of sound out of it...if not then its on to tracing the power to look for things that may be fried...
...yelling and profanity can also make dead pedals work... sometimes.

[czech-one-2]

GOOD Advice!  
I'll spend some more time with it tommarow and try your suggestions,makes sense to me.
I've fixed at least 20 pedals and never had a fried component,but theres a first time fore everything! I guess I was getting a little over-confident,now the reality of my inexperience is upon me
at least I CAN play the damn guitar!

[anchovie]

the led is switching on and off now when powered by battery,but not by adapter,that may be due to the ACA vs PSA thing though.

But still no audio with the battery?

[czech-one-2]

no audio 
sorry for the delay,but i wont be able to work on this till thursday. thanks for the suggestions!