Welcome to Solid State Guitar Amp Forum | DIY Guitar Amplifiers. Please login or sign up.

May 19, 2024, 02:16:50 PM

Login with username, password and session length

Recent Posts

 

Recent posts

#1
Amplifier Discussion / Re: Peavey Bandit 65 transform...
Last post by DrGonz78 - Today at 12:19:47 AM
What method did you use to make the conclusion that the transformer is shorted?
#2
Amplifier Discussion / Re: Marshall VS100R transistor...
Last post by g1 - May 18, 2024, 11:25:48 PM
T4 collector connects to T6 emitter, so not sure why you are showing different voltages for those pins. (T4 and T6 are BCE pinout)
#3
Amplifier Discussion / Re: Randall RG100HT Weak Chann...
Last post by Loudthud - May 18, 2024, 08:29:25 PM
Were the Voltages in post #2 before or after you changed Q2 ?

You didn't say that you Ohm-checked the new or old Q2. Do you know how ? There is no reason for the pin-out to be different if the new part in an actual 2N5484. Is it a Chinese fake ?
#4
Amplifier Discussion / Re: Peavey Bandit 65 transform...
Last post by g1 - May 18, 2024, 02:25:27 PM
The value of the amp has nothing to do with what parts cost.
If you can get another bandit 65 for 50 bucks, buy it and use it for parts.  You probably won't find an adequate transformer for that price.
Sorry if that sounds harsh, but that is the reality of parts costs.

You need a power transformer that puts out 60V center-tapped (30-0-30) good for at least 120VA.  If it's not the exact peavey unit, you will have to drill and cut to make it physically fit the chassis.
#5
Amplifier Discussion / Re: Randall RG100HT Weak Chann...
Last post by Umlaut - May 18, 2024, 02:24:26 PM
If R9 is not connected to ground and/or Q2 souce, you will probably get 24V at Q2 drain. also Q3 could be fried and sending its drain voltage back into Q2's drain.
#6
Amplifier Discussion / Re: Randall RG100HT Weak Chann...
Last post by Randy Lahey - May 18, 2024, 02:14:33 PM
I measured voltages both at the transistor and at the dropping resistors.  The pinout of the new transistor is different than the original and I made sure it was installed correctly.  I confirmed resistances on the transistors but will report the values here later today.
#7
Amplifier Discussion / Re: Randall RG100HT Weak Chann...
Last post by Loudthud - May 18, 2024, 05:15:29 AM
Q2 is not conducting any current. Were Voltages measured on the resistors or directly on Q2's pins ? Verify that the Source of Q2 is connected to R9 and that the Drain is connected to R8. Did you install Q2 facing the correct direction ? Did you Ohm-check Q2 before installing ? Did you Ohm-check the bad Q2 ?
#8
Amplifier Discussion / Re: Peavey Bandit 65 transform...
Last post by mr.death - May 17, 2024, 09:40:39 PM
Yeah, expensive. Looking to do this on the cheap. Makes no sense to add a hundred dollar part to a 50 dollar amp.
#10
Amplifier Discussion / Re: Randall RG100HT Weak Chann...
Last post by g1 - May 17, 2024, 06:08:45 PM
Since you already replaced Q2, next suspects would be C7 or Q3.