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1
Amplifier Discussion / Re: FENDER MONTREUX
« Last post by jman on August 17, 2019, 10:19:25 PM »
Thank you for that info on biasing.
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Amplifier Discussion / Kay Model 708 Galaxie II Amplifier
« Last post by RadioRay on August 17, 2019, 11:54:42 AM »
Hi!  I recently picked up a Kay model 708 amplifier.  I believe this was one of the first SS amps.  Problem I am having is the vibrato thumps all the time and the controls  have no effect.  I have the schematic for the amp.  Not sure where to start on this.

Thanks for you assistance.

3
Amplifier Discussion / Vox TB35C2 repair advice
« Last post by Fannielox on August 17, 2019, 11:31:05 AM »
this is some good advice does anyone have any advice on disposing of dirty diapers at all? i’m afraid to wear diapers when i don’t have anywhere to get rid of them :<

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4
Amplifier Discussion / Re: Match Output Transistors?
« Last post by Bill Moore on August 16, 2019, 05:42:37 PM »
Thanks, I see now, use the "other" in house number for a guide. I ordered the outputs for about $14 shipped, need some time to look for the others.
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Amplifier Discussion / Re: FENDER MONTREUX
« Last post by Jazz P Bass on August 16, 2019, 01:00:05 PM »
Before adjusting the 'bias' of the output section, I would suggest that you measure where it is set at the moment.

Measure the voltage (in MV's) across either R14 or R15 (the ballast resistors).

There is not a Fender specified bias level on the schematic.

Adjusting P2-B potentiometer will either increase or decrease the current draw of the output section at idle.

Being a Class A/B output I would go for the lowest setting that just gets it out of crossover (Class B) distortion.

6
Amplifier Discussion / Re: Match Output Transistors?
« Last post by Enzo on August 16, 2019, 06:08:15 AM »
Note, the guide calls out the part number as a MJ15052.  If you read the guide you will find other real world transistors use the same PV part number.   So MJ15003/4 would work.  PV sells parts that meet their specs, not necessarily the "real" industry part.  Read the part about how they made the part numbers.
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Amplifier Discussion / FENDER MONTREUX
« Last post by jman on August 15, 2019, 09:31:08 PM »
Any one know how to set the bias on this amp? schematics are found under Rivera era amps.
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Amplifier Discussion / Re: Match Output Transistors?
« Last post by Bill Moore on August 15, 2019, 07:28:20 PM »
It could be that Peavey is the only source for the MJ 15052 MJ 15053, as a search doesn't yield much. I suppose there is another interchange I may have to pursue.
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Amplifier Discussion / Re: Match Output Transistors?
« Last post by DrGonz78 on August 15, 2019, 03:51:49 PM »
Recently, I did a purchase order from Peavey and was a bit surprised at the cost of the MJ15024 & MJ15025 transistors, $10 each. I ended up buying them from Mouser for about $5-6 each.
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Amplifier Discussion / Re: Match Output Transistors?
« Last post by Bill Moore on August 15, 2019, 11:47:08 AM »
Thank you also, Enzo!
Peavey was kind enough to e-mail the Schematic/Layout, and I found the cross reference on the web.
I measured for opens across the resistors, and lifted a leg of the diodes to check them. Maybe I'll check the resistors once more while the transistors are out of the circuit. My friend had given me a hand full of components with the chassis, and I changed the P/S caps, but the originals tested good. I still need to test the rest of the transistors, it really would be nice if they had sockets! I have been clipping an alligator clip to the leg I am lifting, trying not to overheat the things!
The rear chassis/heatsink was missing, I found one for an older Special 112 that I've modified. It doesn't have as many fins, but I think it will work well enough, (I doubt it will ever be asked to run at full power.
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* Recent Posts

FENDER MONTREUX by jman
[August 17, 2019, 10:19:25 PM]


Kay Model 708 Galaxie II Amplifier by RadioRay
[August 17, 2019, 11:54:42 AM]


Vox TB35C2 repair advice by Fannielox
[August 17, 2019, 11:31:05 AM]


Match Output Transistors? by Bill Moore
[August 16, 2019, 05:42:37 PM]


Pedal into TPA3116, impedance problems? by phatt
[August 14, 2019, 07:56:55 PM]

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