Maestro FZ-1A

[duck_arse]

quackzed - please note:

Resistance between minus terminal and each collector - I'm not getting a reading on any of these. Is that normal?

this can't be right, either circuit or measuring method is failing here.

[Quackzed]

true, i'm guessing measuring method, due to voltage measurements being close?, but who knows... time for ze audio probe!
** man i really thought that cap was goin' downtown!!! **   

[Riinehart]

yea, i think probably safest to assume i screwed something up or somehow didn't measure correctly. i remember trying all of the different resistance settings on my meter and only seeing a "1" no matter where i turned the dial. but i will try again when i'm home and see if i can figure it out. i'll also get the audio probe put together. i didn't have a capacitor on hand but it should be arriving today.

[Quackzed]

the cap on the schematic says 1uf, but the cap in your picture actually reads 106 which is a 10uf cap...you can always swap em later it wont effect the circuit working or not...

[Riinehart]

i think i need to take a step back and ask a stupid question: when i measure resistance between the minus terminal and each collector, should i have the battery in place or not?

[Quackzed]

doesn't matter. either way, the resistance should be the same... voltage measurements need the battery in...

[Riinehart]

hey, thanks quackzed for all the quick answers!

i'm still stuck on this situation of resistance between the negative battery clip and the collectors. duck_arse had asked me to make this measurement, and i wrote back that i wasn't registering anything on my meter, and he responded back that that couldn't be correct.

so now as i am measuring again, i realize i get different measurements depending on whether the pedal is on or off and whether the battery is in or out:

- 1.8m with battery in and pedal turned off (via on/off switch on volume pot)
- 1.0m with battery in and pedal turned on
- with the battery out, i can't get any reading. my meter is not auto-ranging, it's the kind where you turn the dial depending on the amount of resistance, but no matter where i turn the dial the reading stays at "1"

does that make sense? is there anything i should try?

fwiw, i'm building the audio probe now ... hopefully that'll help figure things out.

[Quackzed]

you can try measuring  the 10k brown black orange resistor closest to the yellow purple yellow resistor then measure the other 10k resistor right next to it  ... set your meter for closest setting above 10k...probably the 20k setting and you should get @ 10k for each one... if you get a reading of "1" on your meter set it to the next higher setting till you get a reading... it helps if you look up the color codes on the resistor and know what resistance to expect and set your meter accordingly... but you CAN just go up setting by setting till you get a reading of 'some'  resistance value... a 1 with no decimal usually means the resistor is too high for that setting...

[Quackzed]

also, looking at your pics, i can see some dried up schmutz on the top of a transistor and in other spots... its possible something got spilled into the box and dried up... might be a good idea to get some alchohol and q- tips and clean the board and around all the parts(with the battery OUT  )... if the spill was beer or juice or soda it's conductive and will mess up accurate resistance readings as well as prevent the circuit from working... if it worked before and now it doesn't it's possible something got spilled on/in it and dried and that might be why its not working now... might come to life after a good cleaning...

[Riinehart]

ok, more embarrassingly stupid questions ...

how do i measure the resistors while they're in the circuit? do i just take the battery out and measure from each side of the resistor?

if so, they are 7.42k and 8.14k respectively.

or is there a different way i should be measuring?

[Riinehart]

fortunately no spills or anything. it's just the dried fiberglass from the insulation that's stuffed into the pedal.

but cleaning it sounds like a good idea regardless. will try it.

i also just finished making an audio probe. any ideas where i should start?

[duck_arse]

measuring resistance - the multimeter puts some known volts across its probes, and Ohm's Laws the resistance resulting. I think. this is why we always measure resistance with the power OFF. the circuit supply will just confuse the meter. when measuring in circuit, just probe each leg. other circuit connections may affect the reading, but it will only ever read lower than the marked value. the most accurate way is to desolder and lift one leg of said resistor, then measure.

I should have been clearer in what I wanted earlier. the circuit shows the collectors connected either hard-to or via 10k resistors to the battery minus terminal, no? so, take the battery out, switch the unit on, plug in a plug if it has that type power switch, then measure the resistance fro the battery clip itself to each of the collector pins of the transistors. they can't be O/L or -1- or open circuit if the circuit is going to work.

and how to use an audio probe. there is 2 way to do, fit battery, switch on, etc, then either monitor the output and inject/probe Q3 base, then Q2 base, then Q1 base, or inject into the input jack, and monitor at Q1 emitter, then Q2 collector, then Q3 collector. Q1 E should be same loud as input, but each next collector will probably be louder. start with monitor amp volume low, turn it up till you hear good/bad, then turn down again before next probe point.

I should probably point out that I have only ever used a cro, never an audio probe, but I've read nearly everything GibsonGM has typed about correct use.

[Riinehart]

duck_arse, thanks so much again.

re: resistance, in that case the measurements i last posted are true, regarding the two 10k resistors that quackzed was asking about:  7.42k and 8.14k

i also had a chance to try the audio probe, using the first way you suggested.

at Q3B, i have barely audible signal (the same that i get when i try to use the pedal). at Q2B, it is the same. but at Q1B, i have full signal (clean, no fuzz).

any idea what this could mean, or how i could troubleshoot further?

[Riinehart]

possible breakthrough ...

i don't even have audio coming out the other end of the stomp switch when the switch is on.

in other words, with the audio probe, i can verify that i have audio going into the switch (it's the first thing that the input cable hits), but when the pedal is on i have nothing (or very very little) coming out of either terminal on the other end of the switch.

when the switch is off, i have audio coming out of the terminal that goes directly to the output jack for bypass.

bad switch??

[Quackzed]

that could be it. if you have an alligator clip you could clip around the switch to check, one side to the terminal that goes to the effect and one side to the input terminal... make sure the switch is switched to the effect on side so that the signal isnt also going directly to the output jack... ill cross my fingers for ya!

[Riinehart]

damn ... unfortunately no.

even when it's alligator-clip'd around the switch, i get the same lack of signal on the effect side of the switch.

[Riinehart]

even if i bypass the volume pot, and jumper from the input cable to the output of the volume pot, same thing happens. i'll have full signal on the end of my alligator clip, but as soon as i clip it into the circuit, signal is dead.

i'm lost ..... 

[Quackzed]

damn! another close but no cigar... onward!!!  ok , seems like you have a better handle on measuring resistances so lets figure out q1.

how do i measure the resistors while they're in the circuit? do i just take the battery out and measure from each side of the resistor?

if so, they are 7.42k and 8.14k respectively.

thats pretty close to 10k ,your meter battery might be getting low...
ltes do some measuring...
the other 10k resistor:
the 1M resistor near it:
the 100k at the input(br bl yel):
hell... go ahead and measure the other 3 as well... first we'll check that all the resistors are close to their right values...

[duck_arse]

and, plug something into the mt jack, so I don't need to worry which is the captive cable. now measure resistance from the input tip to the output tip. result? work the byapss, what now? then, measure from the input tip to the R1 100k on the board. result? work the bypass, what? then, do the same for the output tip, to the vol pot wiper. result, work bypass and result?

[Riinehart]

Sorry for the LONNNG absence. Life got in the way for a bit, but today I'm finally back at it. Thanks to all for the previous help and suggestions ... and if by any chance you're still around, I'm going to post the answers to the last round of questions below. Still stumped!

At Quackzed's suggestion, I measured all the resistors, and many of them are significantly off from what this schematic says they should be (hope this image works):



And duck_arse, here are the answers to the questions you last asked. I was a little unsure of what you are referring to as the "input tip" and the "output tip." Do you mean the input  and output tips of the cable inserted into the mt jack? Or do you mean, once a cable is inserted into the mt jack, to measure from the tip of that cable to the tip of the other cable (the instrument cable)?

I tried to check for both:

Resistance from input tip to output tip of cable in mt jack: No resistance. When in bypass, also no resistance.
Resistance from tip of cable in mt jack to tip of instrument cable: No resistance. When in bypass, no connection at all.

Resistance from tip of mt jack cable to R1: 115k. When in bypass, no connection.
Resistance from Tip of instrument cable to R1: 115k. When in bypass, also 115k.

Resistance from output tip to volume wiper: Full connection, no resistance. When in bypass, no connection.

Sorry again for the long silence in this thread. If anyone is still interested in helping, I'd be extremely appreciative. I'd love to get this guy working. Thanks so much again!