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June 13, 2024, 07:27:28 PM

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#11
Amplifier Discussion / Re: Repairing a Gibson G-105 G...
Last post by DrGonz78 - June 06, 2024, 01:20:00 PM
Q11 & Q12 caught my eye too but understanding each transistors role in a circuit is difficult. I don't know what Q11 & Q12 actually do but it never stops me from guessing. Are they current limiting the circuit in case of overload? Not sure if they are pre drivers for the outputs or what. I'm curious to know how bad of a guesser I am.  :o
#12
Yep, I get 23.2 Volts DC at the speaker output.  Still on the path that the problem is somewhere within in the Power Amp board.  Suggestions on where to test next?  Thank you.
#13
Amplifier Discussion / Re: Transformer mounting orien...
Last post by Jazz P Bass - June 05, 2024, 06:56:40 PM
Do it right!
#14
Amplifier Discussion / Re: Transformer mounting orien...
Last post by g1 - June 05, 2024, 02:14:38 PM
Ok, if it's your own amp you can leave it like that.
Just mentioned in case it was going to someone else.  Don't want to have to change your name from mr. to Dr.  ;D 
#15
Amplifier Discussion / Re: Repairing a Gibson G-105 G...
Last post by g1 - June 05, 2024, 02:09:32 PM
Q14 doesn't seem to be turning on, probably resulting in cross-over distortion which Dr.Gonz suggested.
Check through the components (and connections) on the path shown in red here:


You cannot view this attachment.
#16
Amplifier Discussion / Re: Peavey Bandit 65 transform...
Last post by mr.death - June 04, 2024, 02:28:18 PM
Fixed! All good. Thanks.
#17
Amplifier Discussion / Re: Transformer mounting orien...
Last post by mr.death - June 04, 2024, 02:26:50 PM
Quote from: g1 on June 04, 2024, 01:39:49 PMIt would be preferable to mount the other way if possible, with less exposed wiring.
The 2 black wires are carrying the 120V and you don't want any chance of a user being able to come in contact with them, or for them to get damaged.  Also, if those wires are not going through an original hole, the new hole can not have any sharp edges.
If you can, flip it over and mount so the 2 black wires are closest to the hole the wires route through.
Aside from that, the FM65 transformer is a great match for voltages and power capability (for Bandit 65).

I'm going to leave it as is. Its my amp and I'm careful with my stuff so I dont see me damaging the wires. I used the original wire hole that has a grommet so thats no issue. No sharp edges to be seen!! All good. Thanks.
#18
Amplifier Discussion / Re: Transformer mounting orien...
Last post by g1 - June 04, 2024, 01:39:49 PM
It would be preferable to mount the other way if possible, with less exposed wiring.
The 2 black wires are carrying the 120V and you don't want any chance of a user being able to come in contact with them, or for them to get damaged.  Also, if those wires are not going through an original hole, the new hole can not have any sharp edges.
If you can, flip it over and mount so the 2 black wires are closest to the hole the wires route through.
Aside from that, the FM65 transformer is a great match for voltages and power capability (for Bandit 65).
#19
Amplifier Discussion / Re: Repairing a Gibson G-105 G...
Last post by Timko - June 04, 2024, 01:14:46 PM
I captured some readings for Q10-Q18

Q10
C 1.175
B 39.94
E 39.42

Q11
C 0.941
B 0.095
E 0.091

Q12
C 0.012
B 0.088
E 0.088

Q13
C 39.72
B 1.097
E 0.561

Q14
C -39.74
B 0.270
E 0.082

Q15
C 39.83
B 0.565
E 0.80

Q16
C 0.082
B -39.89
E -39.84

Q17
C 39.83
B 0.565
E 0.97

Q18
C 0.082
B -39.89
E -39.80
#20
Amplifier Discussion / Re: Transformer mounting orien...
Last post by mr.death - June 04, 2024, 11:47:03 AM
pix