Help with Mutron Micro V Build - first post

[newb622]

Hey all!

I'm shoulders deep into this:http://tagboardeffects.blogspot.com/2013/11/mutron-micro-v.html

And have no effected sound.  When the board is bypassed, I have fine output, but nothing's coming out when the effect is engaged.  I've already checked all my links for solder bridges and my parts were good right before I soldered them in.  Short of unsoldering each piece individually to test, what should I do?  I did this on stripboard, and also measured my voltages, they are as follows:

IC 1:
0 0
.78 .78
.78 1.49
.78 1.36

IC 2
.67 .79
.66 .57
.78 .71
0 .78

Q1:
C: 9.47
B: 8.7
E: 5.8

Q2:
C:1.35
B:.71
E:.78

Q3:
C:9.46
B: 8.80
E:.78

Let me know if there's anything you can help me out with!

[img][/http://imgur.com/a/NOovh]

Is there a better way to upload pictures??

[balkanizeyou]

first of all, it looks like you've got the wrong transistors - your voltages would suggest that you're using PNP transistors for Q1 and Q3, not NPN like 2n5089.

Second, seems like you don't have appropriate power rails conections on your board - pin 7 of IC1 should be at supply voltage (9.47V in your case), the same with pin 8 of IC2. Both pin 4 of IC1 and pin 4 of IC2 should be at 0V. Check those connections (those two vertical jumpers in the middle of the board - the blue dots in the sixth and seventh row suggest that the jumpers should be also soldered to the points indicated by those dots).

[duck_arse]

newb622 - welcome.

we always like to see pictures of what people have built, in this case, what you've built. sometimes we can even spot build errors for you ....

[newb622]

Hey duck_arse!

Thanks for welcoming me, this seems like a great community and you all have already helped a lot.  Attached are a few pictures of my build, as well as images of my tester with the three transistors, and my readings for voltages for balkanizeyou.

balkanize:

I realized that the two blue dots between ICs 1 and 2 must mean a leg attached to the jumper, which would get my 9.4V to the correct pins.  Am I correct?  So the jumper has three legs then.  I measured the voltages after adding these, and got this:

IC 1:
0     0
0     9.44
0     0
0     4.74

IC 2:
0     9.44
0     0
0     0
9.35   0

Q1:
C: 9.44
B: 8.66
E: 9.44

Q2:

C: 4.74
B: 0
E: 0

Q3:
C: 9.44
B: 8.85
E: 0

D1: 0 & 0
D2: 0 & 0

Are these transistor voltages weird?  I verified the part numbers, and they appear to be correct, and they are also reading as NPN on the tester, and Q2 is a PNP.  Is anything weird there?  I thought it was strange the circuit uses a PNP at all, is this normal?

I still have no output from the affected sound.  Let me know what you think!

Heres the link to my images, is there a better way to upload these?

http://imgur.com/a/NOovh

[balkanizeyou]

PNP transistors are not very popular in the negative ground setup that is the industry standard for guitar effects, but they are sometimes used (like in this build). Your transistors look fine, though.

I suspect an iffy ground connection OR a short between the power rails somewhere. Now that you've connected the jumpers to those additional points, you should be getting 0V at pin 4 of IC1 (which you do), but also 0V at pin 4 of IC2 (you have 9.35V there). Considering the fact that those two points are connected by a jumper wire, they should be at the same voltage, but obviously they are not. Check this connection.

[duck_arse]

I've just spotted an interesting problem - you have an LM386 stuck in where you should have an LM1458. the two are very dissimilar in form and function, if not appearance.

it might be better if you pull both IC's from the sockets and then do voltage measures on the socket pins. this way, your precious, where power amp or dual opamp, won't fry. there are still missing voltages on those pins, and the CA3080 can be kilt with a slip of the meter probe.

may I ask, how did you do the track cuts on the vero? they don't appear very clean, like we want them. perhaps go over all your cuts with an exacto knife, and trimm those little hanging cresents of copper around the cuts. we usually use a 3.5 ~ 4.5mm drill bit in some sort of handle to do quik and clean/accurate cuts (but we still trimm them under a magnifying glass to be sure).

also, yes, the blue spot on those layouts indicates that that hole will have one end of two links in it.

(imgur is fine for image hosting. when you want the image to appear in this thread/page, copy/paste the individual image addy imgur gives you into the img tags mona gives you . make sure the link you post ends with an image extension [.png, .jpg etc] and not html - or no extension.)

[newb622]

duck arse -

will a MC1458P work?

http://smallbear-electronics.mybigcommerce.com/ic-mc1458p-ti/

It says its a replacement.  I'd prefer to order from smallbear, as they ship a lot faster than mammoth, but if I should use the real deal, I'll just go with mammoth.

[newb622]

balkanize -

just adjusted the jumper there, and pin #4 on both ICs are connected now.  Here are my new readings.  It seems a lot of pins have charge now, is this correct?  also, D1's anode has a charge now.  Let me know what you think, I also have to get an IC as I had the wrong one.

IC1:
0     0
9.46 9.46
9.46 0
0     7.66

IC2:
0     9.46
0     9.03
9.46   0
0     9.46

Q1:
C:9.46
B: 8.92
E: .96

Q2:
C: 7.67
B: 7.85
E: 9.41

Q3:
C: 9.46
B: 8.82
E: 9.45

D1:
A: 7.82
C: 0

D2:
A: 0
C: 0

[duck_arse]

newb - an LM1458 or an MC1458 or probably a JRC1458 or a uC1458 ......... they are all 1458's, dual bipolar opamps. you need to watch the suffix, which will often/usually indicate the package, DIL, SMD, etc.

the datasheet, it's your friend. and there is a shirtload of dual opamps, I won't go into the different numbers, but they all have the same pin functions at the same pin numbers, so they become somewhat interchangeable.

but not with the LM386.

and if you are reading those voltages with the IC's in their sockets, I'd again suggest you remove them, and leave them aside UNTIL you get those voltages right. [balkanizeyou will be along any moment now to help you sort that .....]

[balkanizeyou]

good idea about taking the chips out of the sockets - the CA3080 are pretty sensitive, so it would be nice not to fry them (assuming it's not fried yet).

For reference, I'm looking at this schematic:


Now that you have the power rails connected to the ICs, it's time to check the virtual ground thing. There's a 22k/33k voltage divider setting the Q3 base voltage to about 5.4V. Silicon transistors, as mentioned, have a ~0.7V voltage drop from the base to emitter, which would put the emitter a little bit above half the supply voltage, 4.5V. This voltage is then applied to a few different points in the circuit.

That's theory. In reality, you have 8.82 at Q3 base. Not good, but even worse is the fact that the VB, instead of being 0.7V lower than that, is at full power supply potential! That suggests a short somewhere. I'd suggest looking for a short somewhere around the Q3 emitter and two other rows connected to it by jumpers.

[newb622]

Ill check for those shorts, and I've been removing the ics, so hopefully no fried ones there.  Balkanize, I think the layout on tagboard uses both sides of the LM rather than two separate, and I also noticed it appears that the diodes are in different places on the madbean schematic.  Does that change anything?

[balkanizeyou]

the schematic above also uses one LM1458, but the symbol is split into two separate opamp blocks for drawing convenience. It's a common practice with dual and quad op-amps. And you don't need to worry about diodes at the moment, because the problem lies somewhere else. It's important to get the virtual ground to about half the supply voltage.
BTW, it looks to me that they are in the same place (from the range pot to pin1 of the opamp, and from pin1 to pin2).