Author Topic: 1st time build - glitching, dying sound at less than full volume - transistor?  (Read 398 times)

tefanone

Hi all,

First build and have read the common faults that will inevitably occur with such forays into building.
I've used exact matching components, checked the joints (yes I know some are a bit messy) but have v little / glitchy output at low volume and gain, only sounding viable when vol and gain are maxed.  Seems like it is a biasing issue.  I've checked all the other components which match their stated values. 

Details as per the reporting format as below.  Those two resistors seem to be the culprit, unless I am missing something...

1.  Interstellar Overdriver clone, PCb bought on eBay

2.  Schematic (parts list) emailed by the seller, as per the picture

3. Adhered completely to the layout, including exact values of components

4. No modifications

5. Polarity as per the schematic, I don't believe it has been hacked to work with negative ground

6. It powers up fine but is glitchy at low gain or low volume (fades out quickly), improving only at max gain and volume

Voltages:

C1
: .547
: 0

Q1
C: 0
B: .547
E: .049

R2
: .545
: 9.1

R3
: .049
: 9.1

C2
: .545
: .049

Q2
C: 0
B: .547
E: .058

R4
: .547
:  9.1

R5
: .058
: 9.1

C3
: .545
: .058

Q3
C: 0
B: .547
E: .058

R6
: .547
: 9.1

R7
: .547
: 9.1

R1
: 0
: 0

R8
: 0
: 0

R9
: 9.2
: 9.2

C4
: .058
: 0

C5
: 9.1
: 0

D1
A: 9.35
K: 9.32









« Last Edit: January 18, 2021, 03:39:55 PM by tefanone »

GibsonGM

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Hi Tefanone, welcome!    In order to help you out, we need you to provide some info about your build. It could be biasing, yes, but there's no solid way to know without some measurements.   

Please read this thread, and do your best to post the info requested back here :)    https://www.diystompboxes.com/smfforum/index.php?topic=29816.0
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tonyharker

Hi tefanone, What exactly is it you are trying to build.  Did you get it as a kit or just a bare board and bought the components separately.  You could have faulty components Do you have a schematic?

tefanone

Thanks for the replies, just updated my original post.  Even if I can't get this working it has been a useful learning experience for a newbie!
In answer to the question above: I bought the board on its own and then separate components.
« Last Edit: January 18, 2021, 04:09:40 PM by tefanone »

GibsonGM

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The voltage on D1 suggests a problem; you should read 9v on the + side and nothing on the other.  It is there as a protection for reverse polarity...remove it and see what happens (hey, the damage is probably already done, LOL).  Do NOT get + and - power leads confused when you try it or you WILL destroy the transistors.  But right now, they have no voltage at the collectors, indicating a problem upstream.   Reflow the sketchy solder joints visible in the board bottom pic, too, before trying it...just a thought.  No schematic = hard to say, but the gnd side of the diode shouldn't be hot! 

Actually before removing it, check for continuity between + and - with that function of your meter or measure resistance (ohms)...should not have continuity.  If you have continuity, remove D1 and check again.  Don't wreck the solder pads...
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antonis

they have no voltage at the collectors, indicating a problem upstream.

I beg to differ with your Highness, Sir..
Particular effect DOES call for grounded Collectors.. :icon_wink:
(reverse active mode..)
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GibsonGM

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they have no voltage at the collectors, indicating a problem upstream.

I beg to differ with your Highness, Sir..
Particular effect DOES call for grounded Collectors.. :icon_wink:
(reverse active mode..)

Ok...I am not familiar with the thing (no schematic).     What about 9V on both sides of the clamp diode?
MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

tefanone

Hi all,

Thanks for your input. I swapped a couple of components around but I think resoldering each join helped. Itn now works perfectly, as does another simple build following the same treatment. Onwards and upwards!

iainpunk

great to hear that it works,
bad solder is often the culprit of non working pedals,

cheers, Iain
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