Maestro FZ-1A

[duck_arse]

riinehart - you'll have to try harder than that to get rid of us. it has been a long time, and I have forgotten what we were looking at .......

anyway. when I same "mt jack", I mean "the empty jack", that which has nothing plugged in. and when I say "input (or output) tip", I mean the hot/signal/tip connection of the jack, or of a cable plugged into. they are named tip in both cases, with the ground on the sleeve connection. so measuring from tip-in to tip-out is to check that the signal will get from in to out when bypassed, and that at least something happens to that connection when you un-bypass.

and then I wanted to know from tip-in to the board-in when un/bypass, and from the board-out to the tip-out as well. these are the basic steps to find where you may have made a switch/jack wiring error.

115k to R1 is ok, if the reading is 0 at the other end of R1, the board input. are you measuring with the battery disconnected? and if you can lift one end of the 470k and the 1M, and remeasure, that'd be nice.

[Riinehart]

Ha -- that's a huge relief!! I'm so grateful for the help!

Just a reminder/recap -- so far I haven't changed anything on the pedal. It used to work. But I didn't use it for a while, and it stopped working. In bypass, full sound gets through; but when the pedal is on, there is only the faintest little bit of signal (almost inaudible).

Also, yes, I was measuring resistance with the battery disconnected -- and indeed I am getting a reading of 0 at the other end of R1.

With one leg lifted on both the 470k and 1M, they both read correctly!

Tip-in to board-in ... 115k. With bypass, I get no reading.

Any idea what this means??

Thank you again!

[Riinehart]

Also -- I'm sorry, I'm still not sure what you mean by "tip-out".

Please excuse my crappy MS Paint drawing, but hopefully this makes sense:



Thanks again!

[duck_arse]

ah-hah. I was thinking you had an input socket and an output socket. so which has the captive cable, the input? then the output socket tip connection would be "tip-out". can you audio-probe the transistors again, post findings? I'm hopping for quakzed to come back and help.

[Riinehart]

Yes, it's kind of a strange cable set-up on this pedal.

The captive cable goes to instrument, and the mt-jack goes to amplifier.

When I'm home from work tonight I'll do the audio probe test again.

Thanks!

[Riinehart]

OK, I checked the transistors again with the audio probe.

I get full (clean) signal at Q1 base and collector, and no signal at any other leg of any of the transistors.

[duck_arse]

not the collector, surely, it's connected to supply. well, I'd say replace the 1uF's between stages, use poly if you have them. but that's only if you've got good voltages on Q2 ..... and you could try injecting your test signal into the base of the second transistor, via a known good cap, and listen w/ probe at its collector. same for third transistor, will prove they are still good.

[Riinehart]

Thanks, duck_arse -- I'll start searching for some poly 1uf's.

Could you advise what good voltages should look like at Q2?

[duck_arse]

mmmmm, well, maybe. with grounded emitter, the base can only ever get ~-0V3, both those transistors. my theory, such as it is, fails at the collector voltages when the E is grounded, I'm afraid. it'll be more than -1V5, less than -0V3, though.

[Riinehart]

OK, thanks again! I'll check when I get home later and will post.

[Riinehart]

OK, good news, I suppose: -1.3V at Q2 collector.

Any idea what to look for next?

Thanks again!!

[duck_arse]

well, to measure the DC's, I just put a transistor on the bb in the Q1 circuit, then as Q2, then Q3, if you follow. with -1V66 battery, I got:
* Q1 C=-1V66 B=-0v4 E=-0V3
* Q2 C=-1V27 B=-82mV E=0V (fuzz at maxx)
* Q2 C=-1V63 B=-10mV E=0V.

so my -300mV at the bases was way off. your Q2 C looks ok by my figures. did you try the signal injections?

[Riinehart]

I'm sorry, I have to once again show my ignorance ... I'm not sure what some of these things mean.

Could you explain a little more? Also, what do you mean by signal injections, and how would I do it?

Sorry for the extra questions and thanks again for being so helpful.

[duck_arse]

when you do signal tracing w/ the audio probe, you inject signal into an input and listen/monitor at an output. so, you can apply signal to the input cable tip , and listen at the output socket. but! nothing comes out the third stage, leading us on this merry dance, no? so, back up, listen at the output of the second stage, Q2 collector. nothing! so go to the first stage output, Q1 collector. something there, but not Q2?

well, now you can inject your signal into Q2 base, via the audio probe's blocking cap, and monitor at the output socket. anything? if not, monitor Q2 collector. this will prove/disprove the Q2 stage workings.

and then, for completeness, or because we still haven't found the prob, inject your signal at the base of Q3, listen to the output. if each stage input provides stage output, but there is no thru-put from Q1-in to Q3-out, you'll now know what and where and why.

each transistor is a separate stage, the signals (out-in-out-in etc) are joined by those caps. so test each stage functions as some sorta amplifier by self, then string them all together for a working fuzz.

[Riinehart]

can't thank you enough for taking the time to explain this.

makes total sense. i'll get back on it tonight.

thanks!!!

[Riinehart]

duck_arse, thanks to you I think I may have this figured out.

When I inject signal into the base of Q1, I get no output (of course).

But, when I inject signal into the base of Q2, I DO get output. And likewise, when I inject into the base of Q3, I get output.

After Q2 is the 1uf cap. If I inject signal before the cap (between Q1 and the cap), I get no output.

However, if I inject signal after the cap, I get output.

So ... replace the cap?

Please let me know if that makes sense to you.

Also, if so, anything particular I should look for in a replacement? The markings on the cap are:

1064+
1MFD+
6v

I don't know a lot of the terminology, so I'm having trouble finding an exact match online.

Thanks so much again.

[duck_arse]

if by

After Q2 is the 1uf cap. If I inject signal before the cap (between Q1 and the cap), I get no output.

you mean "after Q1 is the 1uF .... ", then yes, this is exactly what I have been leading you to.

as for the cap, if you want the real 100% mojo, replace with a similar (replace both those 1uF, take the first fail as a warning) size/type. if you just want the pedal working again, replace with "a 1uF capacitor". a 6V, 10V, 16V, 25V, 35V, 63V (etc) electro will be OK. but, if you want to not worry about those caps again, find a 'plastic' type, a box-cap or a grrencap or an orange drop or a tropical fish ...... any of the non-polar types, 1uF, will do. again, they might be 50V, 63V, 100V ...... some like using 630V.

whatever you can get, that fits, that you like the look of, that you can afford, marked 1uF or 106 (don't worry too much about tolerance, J, K, 5%, 10%, 20%, like that), at any voltage, will do the job. even disc ceramic. and I think that "1064+" may well indicate a cap made 10th week of 1964. it is not quite as old as me!

[edit :] oooopppss!! obviously, as you've spotted by now, not "106", but 105. you don't want a 10uF in there.

[Riinehart]

Thanks so much, duck_arse. I'm so excited to finally have a potential solution.

Do you think these would be good replacements?

http://www.ebay.com/itm/METALLIZED-POLY-FILM-CAPACITOR-AXIAL-1UF-400VDC-220VAC-NEW-2-PKG-/190816529448?hash=item2c6d8d2c28

[duck_arse]

those will do, yes, but they show shipping to australia as $21.25 !!

I also found this on hebay:
http://www.ebay.com/itm/2x-105MPW400K-Metallized-Polypropylene-Film-Axial-Capacitor-1UF-400VDC-220VAC/121280140273?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D33278%26meid%3Dd1c79c2535184c60af3ff07e4f5af86b%26pid%3D100005%26rk%3D1%26rkt%3D3%26sd%3D190816529448

but really, maybe smallbear. I found these, all are ok:
http://smallbear-electronics.mybigcommerce.com/tropical-fish-1-mf-250v-10/
http://smallbear-electronics.mybigcommerce.com/tex-cap-1-mf-axial-200v-10/
http://smallbear-electronics.mybigcommerce.com/sec-mpc2s-1mf-50v/
http://smallbear-electronics.mybigcommerce.com/roederstein-mkt-series-1-mf-250v-5/

[Riinehart]

This is great -- thanks so much again. Excited to post some results!