Help Troubleshooting GGG VRM MUFF

[standingzero]

Hey all,
This is my first post and I'm pretty excited to be part of this learning community!

I've had one successful mod (Metalzone) and one successful build (GGG stratoblaster) so I decided to attempt building the GGG VRM MUFF. It isn't sounding quite right and I'm not sure why. Instead of being warm and fuzzy it's splatty and a bit brittle. The soldering joints appear to be good and the wiring / components have been triple checked. The only thing that looks "iffy" is the first color band on the 39k resistors looks more "bronze" in color than orange when compared to the orange band of other resistors. But since the project calls for three 39k and all three of them look the same I'm pretty sure they're right.

I have read the geofx and ggg troubleshooting guides already and have the tools to build the audio probe they talk about, but I don't know what to even look for with that, lol!

I've uploaded a video of the muff because I figured it would do a better job than my poor descriptions... thanks in advance!!

http://www.youtube.com/watch?v=KjNvGuVdGSs

BTW the LED isn't wired yet so that's why it doesn't turn on.


Also, I checked the voltage of the transistors don't match up with those on the GGG spec sheet:

*** The power supply used is giving me 9.4 volts to the dc jack

Q1: GGG                   Q1: My reading
Collector: 3.9             Collector: 3.86
Base: 0.6                    Base: 0.58
Emitter: 0.03              Emitter: Couldn't get a reading

Q2: GGG                   Q2: My reading
Collector: 3.8             Collector: 4.13
Base: 0.6                    Base: 0.59
Emitter: 0.03              Emitter: Couldn't get a reading

Q3: GGG                   Q3: My reading
Collector: 3.8             Collector: 3.83
Base: 0.6                    Base: 0.58
Emitter: 0.03              Emitter: Couldn't get a reading

Q4: GGG                   Q4: My reading
Collector: 4.0             Collector: 3.57
Base: 2.5                    Base: 0.59
Emitter: 1.8                Emitter: Couldn't get a reading

I have no clue what's wrong or how to move forward as I'm totally new at this. I read through the tech sheets on the GGG site

Any feedback / insight would be GREATLY appreciated.

Thanks and I'll post a full review when it's up and running correctly.

[petemoore]

  Clip to ground and try look for the DMM to 'beep', verifying every ground connection schown is physically connected on your board.
   You can measure/test at the same time:
  Find the farthest ground point available from the emitter resistor ground lead. Measure the emitter resistor value from the 'distant probe point' to the transistors emitter lead.
  This measures value and tests connections:
  Battery button to clipwire, battery clip - to Gnd., Gnd. trace, Gnd connection to emitter resistor, emitter resistor value, emitter resistor connection to emitter [or anything else 'put in there' such as an open trace or misvalue emitter resistor. 

[standingzero]

Thanks Pete....

I'll have a friend who understands electronics read over your post with me and help guide me in following the steps you've outlined.

I am still very new (but genuinely trying to learn) about all this: for example I have no idea what an emitter resistor is (guessing it's a resistor that comes before or after the emitter of each transistor) and how to exactly measure it. I'm sure he'll be able to guide me through your steps... I'll get back to you.

Once again I appreciate your time!

[LucifersTrip]

The soldering joints appear to be good and the wiring / components have been triple checked. The only thing that looks "iffy" is the first color band on the 39k resistors looks more "bronze" in color than orange when compared to the orange band of other resistors. But since the project calls for three 39k and all three of them look the same I'm pretty sure they're right.

hey...and welcome

I have to ask this question. If you have not definitely verified the 39K with a meter, how did you "triple check" the wiring & other components?

Did you check the wiring for continuity and other components with a meter?

It's not totally uncommon to kill a component as a beginner, especially when there's more of a tendency to hold the soldering iron on a joint for a longer time. So, verifying what is written on the side of a component is not the same as verifying with a meter.

good luck & please link to the schematic if you can