Newbie GGG Rams Head build

Started by Hard Road, December 30, 2012, 05:05:44 AM

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Hard Road

Hey Guys have been trying to debug my GGG Rams Head big muff all day to no avail  :icon_cry:, I do know more stuff now than I did 12 hours ago so all is not lost  :icon_rolleyes: I think I am at the point where I have to put it down for a while. After reading debugging stuff 101 I checked the Voltage on Q1 through Q4 with the following results
Q1
C= 0
B= 0
E=0

Q2
C= 5.02
B= 0.82
E= 0.08

Q3
C= 1.72
B= 0.80
E= 0.09

Q4
C= 2.37
B= 1.95
E= 1.46

So as you can see I have some problems? I am at a loss why I have no power at Q1? I am hoping someone has come across this before and can nudge me in the right direction, any help greatly appreciated, I am a stomp pedal virgin, so please be gentle with me  :icon_biggrin:, Cheers Paul.

Kesh

R5 or the traces to it are open- maybe a dry solder - or shorted to ground, as the ground trace is close to one end of R5

Maybe you have some issues with Q3 and Q4 too. Collector looks low.

Hard Road

Thanks I will check it out, Yeah I know the other values are out, thought I would work out what is going on with Q1 and work from there first???cheers Paul

Hard Road

Ok yep bridged solder joint on r5 and q1, latest readings, still not working? But progress never the less thank you, any ideas on what next? cheers Paul.

Q1
C= 9.3
B= .83   That is low - right?
E= 0.05

Q2
C= 5.92
B= .93
E=0.09

Q3
C= 2.03
B= 0.95
E= 0.09

Q4
C= 3.02
B= 2.51
E= 1.82

Kesh

now it looks like you have shorted C of Q1 to 9V, so across R5

B will always be about 0.5 to 0.8V above E

Devius

q1 2 and 3 should all be close to
c 4
b 0.6
e 0

and q 4 is a bit higher
c 4
b 2.5
e 1.8

Devius

I built the violet rams head from ggg. I found it a bit easier to break it off into 4 sections so I could understand a bit more about what they do. Everything turned out fine aside from the unity gain issue but I believe I have it sorted out now. It can be frustrating but not all hope is lost. You'll get it man. Just take your time and start from one end.

Hard Road

Thanks mate, I will put it down for a few days and have a few New Year frothies  :icon_biggrin:, and attack it in the new year. I make guitars and I reckon they are easier than making stomp boxes  :icon_rolleyes: