So. It's my first real troubleshooting investigation. I'm really good with instructions and I'm very careful, so I've never really had to troubleshoot before. I'm sure it's great that I get to, since it'll help me learn. But, that's the thing, I'm almost totally electronically illiterate. So, I need help. Bad.
Here are the relevant build docs from GGG:
Schem:
http://www.generalguitargadgets.com/pdf/ggg_dnr_ross_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
Layout:
http://www.generalguitargadgets.com/pdf/ggg_dnr_ross_lo.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
Problem:
No signal when effect is engaged (but bypassed signal is fine. LED works correctly)
What I've done:
- Checked and reflowed all solder joints. There are no bridges, cold, or dry joints
- Checked ALL wiring, it's correct according to the layout
- Whipped up an audio probe and went at it
Here's where I'm lost. I built the audio probe, but have no idea, really, how to read a schematic. (I know, I know, I'm embarrassed...) Anyhow, I started with the IN pad on the board -- joy. Then C2 -- joy, R1 -- joy, C1 -- joy, R2 -- joy, R3 -- NO JOY. Also there's no joy on any of the pins of Q1. Nothing on R5 or C6 or anywhere else.
I replaced R2 and double-checked its value (metered 9.9k). Same thing. So, it seems to me (and I'm well aware that I can be, and likely am, WAY off base) like the signal just isn't getting past R2. I even checked for continuity between R2 and R3, which there is.
Am I on the right track? What's next to hunt down? I just don't know where to go from here and am REALLY frustrated. Lil' help?
Thanks!
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Cam
Sounds like you're doing great man :) I would start by doing a continuity check and make sure everything is connected to where they have to be and not shorting anywhere. This would be done with your meter bascially touching with one probe point A and the other probe on point B, if you get a Beep, you're good to go...Also, on the same test, probe each trace to ground. If you test a trace and it's grounded then your problem lies within one of those components. Check for either a blown component (like a diode) or maybe just a solder bridge to ground.
If all of this passes, try swapping out Q1. From your testing sounds like you got close to Q1 and maybe that's your culprit right there.
I'm sure there's tons of other things to check but at least this is a good start, in my opinion :) Good luck!
-Kaleb
Shot in the dark: have you adjusted the trimpot at all? If not, set it around 50%. If I recall, full CW & full CCW will 'kill' the effected signal.
Problem is at Q1? that means that any of the parts in an around Q1 might have a cold joint or something along that line. Can you get voltages on Q1 and we can tell if you they look right. Also, double check the orientation of Q1.
And yes, you NEED to bias the circuit properly using the trimmer.
Jacob
Quote from: jkokura on April 07, 2011, 03:11:53 AM
Problem is at Q1? that means that any of the parts in an around Q1 might have a cold joint or something along that line. Can you get voltages on Q1 and we can tell if you they look right. Also, double check the orientation of Q1.
And yes, you NEED to bias the circuit properly using the trimmer.
Jacob
Thanks, guys. WILL do! I've replaced the trimmer in favor of 2 1k resistors. It's what Keeley does and the circuit and board are set up for it.
BOM:
http://www.generalguitargadgets.com/pdf/ggg_dnr_ross_bom.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
"TR1 – Trimmer - 2k - Can be replaced by two 1k resistors as shown in the layout"
I'll look around the transistors for bad joints. As for checking their voltages, which voltages do I want? Wow -- that's a dumb way of asking that...what I mean is, do I measure the voltage from each leg to ground? Or leg 1 to 2 or 1 to 3, etc.?
Thanks again!!!
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Cam
Put your black lead on your DMM on ground, then measure each pin of the transistor. Write them down and post them for us. If you can look up a datasheet and tell us which pin is which, that's very helpful.
Jacob
Quote from: jkokura on April 07, 2011, 04:16:01 AM
Put your black lead on your DMM on ground, then measure each pin of the transistor. Write them down and post them for us. If you can look up a datasheet and tell us which pin is which, that's very helpful.
Jacob
Yahtzee! Will do in the morning!
¡GRACIAS!
Think I figured it out! I subbed some NOS Toshiba 2SC1849s for the 2N5089s. It looks like my 2SC1849s are pinned out differently. The 2N5089s are EBC, while the Toshibas are BCE. I should just be able to carefully bend some leads and be fine.
Took HOURS of web scouring to figure this out. Turns out that the 2SC1849 comes in both pinouts. I found some legacy BYOC docs that explained that trannies with "C1849" have a different pinout than the ones labeled "2SC1849." The ones with the "C1849" label have to be turned, blah blah. Then ANOTHER legacy BYOC build doc out and out says that some 2SC1849s have the BCE pinout, which makes sense of the other build doc...Anyhow. I think that's it. I'll put it together in the morning and report my mileage.
Thanks again for the help, fellas!
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Cam
Welp. It appears I was wrong...
I've put installed these trannies in damn near EVERY configuration -- exact same problem. As I poke around with my audio probe, I get signal at Input, C2, R1, C1, and R2 (though it's quite quiet there...). Then -- NOTHING! If I'm reading the schematic correctly (and that is questionable...), then I should be getting signal AT the base of Q1, but I get nothing...And nothing at the emitter either.
I'm almost certain, after much testing and scouring, that the pinout of my trannies is standard (that is, EBC, looking at the flat side, pins down). I've reflowed every solder joint and 20-tuple checked the wiring. I've exhausted my imagination about what might be wrong. So...here's what's going on.
Same thing -- no output when engaged (bypass is fine). Switch works correctly. LED fires as expected. The only subs I've made are 2SC1849s in place of 2N5089s. IC is CA3080E (not a sub). Here are the voltages I'm getting on the trannies (Trannies are labeled differently on the schematic than they are on the layout. The following accord to the schematic)...
Q1: E - 2.38v, B - 2.94v, C - 6.86v
Q2: E - 2.09v, B - 2.65v, C - 7.13v
Q3: E - 0.4mv, B - 0.5mv, C - 9.11v
Q4: E - 0.5mv, B - 0.8mv, C - 9.1v
Q5: E - 8.63v, B - 0.5mv, C - 9.15v
So...uh...yeah. I have no idea what that all means, but there it is. What's my next move?
Thanks again, fellas!
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Cam
Do you have any 5088/5089's to try? You can use them to eliminate the pinout confusion of the other transistors and see if the problem lies there or elsewhere. Also, try just one 1K resistor in place of the trimpot as I'm pretty sure I remember setting the trimmer full on and full off = no sound. Subbing two 1K resistors is the same as a 2K trimpot full on.
One more shot in the dark: is the IC orientated correctly?
Quote from: maysink on April 21, 2011, 01:24:27 AM
Do you have any 5088/5089's to try? You can use them to eliminate the pinout confusion of the other transistors and see if the problem lies there or elsewhere. Also, try just one 1K resistor in place of the trimpot as I'm pretty sure I remember setting the trimmer full on and full off = no sound. Subbing two 1K resistors is the same as a 2K trimpot full on.
One more shot in the dark: is the IC orientated correctly?
Thanks! That's kind of what I was planning. I just hate to irder a buck worth of transistors and pay the shipping...but it's what I think I must do.
I replaced the 1K resistors with a 2K trimmer. I set it to half way. I guess I can monkey with it and see if it's the problem. I considered the IC also. It's oriented correctly. And I'm losing signal before I even make it to the IC. So...poo...
Thanks for the help! I gotsta get this fixed!
Did you check all your diodes? If not you should make sure none of them are dead.
If you live near a radio shack, they should have 5088/5089's. They'd have replacement diodes, too, if needed.
Q's 3-5 look suspicious to me, but if sound isn't even getting by Q1...
Yes, you NEED to have a trimmer in there, not the 2 1k resistors. There's a sweet spot for the trimmer, and you'll need to be able to dial it in. If you haven't got a trimmer in there, install one and begin to try again. Once that's done, you should be able to hear things. If not, use the recommended transistors instead of the ones you're using.
Jacob
I put this same project together this weekend, used a trim and it worked on the first try. Adjusting the trim was easy, I'd get those resistors out of there.
Still no go. Now I've REALLY tried everything. Well, obviously not, I guess -- since it still doesn't work. But everything I could think of, which I admit, is very little. Anyhow. Here's what's up now.
Replaced the 1k resistors with a 2k trimmer.
Replaced all the transistors with 2N5088s.
Now, I get signal...but only if the sustain and level controls are both DIMED! I double-checked my pots, they work and are of the right values and in the right places. So it's not that...but wouldn't it have been great if it were...
But I have some more data! I found some voltages taken off a Ross. Here are the working Ross voltages, compared to mine (RQx = Ross, MQx = Mine):
RQ1: E - 1.65v, B - 2.10v, C - 7.98v
MQ1: E - 2.39v, B - 2.97v, C - 6.84v
RQ2: E - 2.34v, B - 2.87v, C - 7.28v
MQ2: E - 2.37v, B - 2.93v, C - 6.87v
RQ3: E - 9.5v, B - 0v, C - 0v
MQ3: E - 9.2v, B - 0v, C - 0v
RQ3: E - 9.5v, B - 0v, C - 0v
MQ4: E - 9.2v, B - 0v, C - 0v
RQ5: E - 9.0v, B - 9.32v, C - 9.50v
MQ5: E - 8.7v, B - 9.20v, C - 9.24v
Now, slap me if I'm wrong...but they all look good 'cept Q1, right? Q2 is off, but it doesn't look like too bad -- the greatest difference is about .4v on the collector.
Also - here are the IC voltages from that same Ross and my build (pins 1 and 8 are unused).
R2: 4.92v
M2: 4.76
R3: 4.91v
M3: 4.76
R4: 0v
M4: 0v
R5: .633v
M5: .633v
R6: 2.76v
M6: 2.92v
R7: 9.5v
M7: 9.23
Looks good to me, but what do I know?
Also, here are some photos of the front and back sides of the board.
(http://img580.imageshack.us/img580/7439/topvy.jpg)
(http://img23.imageshack.us/img23/6683/bottompo.jpg)
Lastly, here again are the links to the layout and schematic:
Schem:
http://www.generalguitargadgets.com/pdf/ggg_dnr_ross_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
Layout:
http://www.generalguitargadgets.com/pdf/ggg_dnr_ross_lo.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
What next? I feel like I'm getting SO close! But I'm plum OUT of ideas, save pull and replace every compoent one-at-a-time...
Thanks again, fellas!
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Cam
Is it so obvious that it's not worth telling me (like what my wife says when I don't know 'what's wrong')? Or have I stumped y'all, too?
I guess, what I really mean is....
Bump ;)
Thanks again, guys. Hope you don't mind me bumping this.
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Cam
Well, it´s just a guess....but I would change all the tantal caps (especially the ones in the circles on the pcb) to electrolytic caps.
C6 needs to be polarized, the panasonic cap definetly isn´t.
Tell me, if I´m right...or wrong.... :)
regards
Good catch fish!
(see what I just did there...)
Yes, C6 looks like it's supposed to be polarized. The tants might be fine, but I like Electrolytics better soundwise in this circuit anyway.
Perhaps try changing C6 and see if that fixes things.
Jacob
Thanks, guys!
I subbed the tants because that's what Keeley uses in those positions and that's what my buddy wanted. He uses the non-polarized 1uf in C6 (as far as I can tell, based on a photograph and trace on FSB), too. But I'll swap it out for an electrolytic and see what it does :)
Just for the sake of understanding -- why willn't (generally -- theoretically...) non-polarized caps work in place of polarized? I'm happy to know THAT they won't, but would love to understand WHY they won't.
Thanks again, fellas! In due time, I'll be more of a contributor and less of a leach...
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Cam
Well, remember that the keeley one isn't necessarily the same schem... Whenever you build a project, you should rely on that schem and layout, not one for a different pedal.
Keeleyky likely uses the tantalum caps because of reliabilty reasons, not sonic ones. at least, if he claims sonic ones I'd like to see the data on the differences, cause I certainly don't buy that kind of stuff much.
Polarized caps are directional. How they operate is to release power in a specific way but only one direction. Non polarized caps go either way, so in some circumstances they can't always be used where a polarized caps are expected.
Don't know if that's the case here, but we'll find out soon.
Jacob
Thank you, sir! I appreciate your help!
Bummer is, though, that it didn't help. Replaced the poly cap with an electrolytic -- still no joy. What next?
(On another note. I think Keeley has a bit of an affinity for the tantalum caps. He considers them an 'upgrade' to some extent. I don't know why -- for reasons of reliability or some kind of phonic preference, but I decided to use them where he did for my buddy's sake. It's what he asked for :) )
Oh yeah, lastly, when I dime the SUS control, at the very end of the sweep it makes a 'woosh' sound, like when biasing a transistor. No idea how relevant that is, but thought I'd mention it.
Many thank yous!!!
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Cam
Dude, don't know what to tell you.
You have the wrong value resistors in R4 and R3... You have 470R resistors there, and you should have 470K. That explains the wrong voltages on Q1 and that explains the bad results when trying to make the pedal work.
Check it out, you should get immediate results assuming that there's no other errors.
Jacob
Son. Of. A. Bee sting! That was it!!!
To top it all off, I made the mistake on TWO levels. First, I didn't read the resistor code correctly (but I'm not fully color-sighted). Second, when I measured those resistors before I put them in, they measured .470k, not .470m. But, I didn't read the measurements correctly.
Dang! SO glad it's fixed!!!
Thanks, guys!!!!!!!! It sounds GREAT!
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Cam
Let this be a good (and gentle) lesson to ALL of you guys out there debugging. It is VERY important to follow the suggestions in the "How to debug" tips found here in the sticky. Checking parts is easy to skip over because we all assume we did it right. It's the easiest mistake to make, and what's worse is that we all often rely on the places we buy these parts from to get the value you right on the packaging. Even in this case, when the guy building it still has spent time double checking his part values BEFORE installation, there was still a mistake made.
Really, don't assume your parts are right. The first step of debugging should ALWAYS be the double and triple checking that all the right parts are in place. Get a friend or spouse to help you read the codes, measure them, and then measure them again. It never hurts to check again, and you know what happens when you assume you got it right.
Great that it's working. I'll get off my soapbox now...
Jacob
This may not be relevant, but on my last project (Egodriver) I finished and did not have any output. Before I S$#t a brick I pulled the shaft out on each pot (as if to clean) and found that my gain pot was faulty. I took it apart and found that the two tabs that are supposed to scrape the inner circle werent touching unless the shaft was pulled out. IE, Check your your pots.
Good job Jacob! Thats a catch! Good to see your builds working! I always check the resistors, and use the color code as a guideline.
Quote from: jball85 on June 05, 2011, 04:40:14 AM
This may not be relevant, but on my last project (Egodriver) I finished and did not have any output. Before I S$#t a brick I pulled the shaft out on each pot (as if to clean) and found that my gain pot was faulty. I took it apart and found that the two tabs that are supposed to scrape the inner circle werent touching unless the shaft was pulled out. IE, Check your your pots.
You can test it with a ohm-meter. Touch lug 1 and lug 3 for full resistance. Then from lug 2 to lug 1 turn the pot, it should go from 0 to the value. Do the same for lug 2 to lug 3.