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June 25, 2022, 06:25:07 AM

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#11
Amplifier Discussion / marshall 3210 lead Mosfet trou...
Last post by Jdomi - June 20, 2022, 02:23:56 AM
Hi,
I am looking for advices on troubleshooting a Marshall 3210lead Mosfet.
The problem is this: adjusting the bass in "normal" mode has almost no effect.
Everything else works fine. I found the diagram on the web but I don't see what element could cause this defect, in particular around the bass potentiometer. The potentiometer it self or maybe a capacitor?
Has anyone already  seen this problem or have a clue?

Thanks in advance.
(I am french and my English level is not so good, so thanks google translator!)
#12
Amplifier Discussion / Re: Do Electrolytic Caps Age ?
Last post by g1 - June 19, 2022, 08:22:18 PM
Quote from: mandu on June 19, 2022, 10:23:46 AMI would suggest you experiment with those old electrolytic capacitors before throwing out to learn something and acquire some knowledge out of it. Regards.
Yes this is a good idea.  And running the charger with a limiter lamp will avoid the overheating that you experienced, and sometimes bring them back to life if you are patient.
#13
Amplifier Discussion / Re: Do Electrolytic Caps Age ?
Last post by mandu - June 19, 2022, 10:23:46 AM
Quote from: Tassieviking on June 19, 2022, 08:58:36 AMThanks guys for the answers, I think I will not keep the Electrolytic caps since I don't know the age of them.
Better be safe then sorry.

I would suggest you experiment with those old electrolytic capacitors before throwing out to learn something and acquire some knowledge out of it. Regards.
#14
Amplifier Discussion / Re: Do Electrolytic Caps Age ?
Last post by Tassieviking - June 19, 2022, 08:58:36 AM
Thanks guys for the answers, I think I will not keep the Electrolytic caps since I don't know the age of them.
Better be safe then sorry.
#15
Guitar News / Re: Soldano releases first sol...
Last post by Loudthud - June 18, 2022, 10:22:03 PM
The Soldano SLO Mini 30 runs off of a 24V 2A switchmode brick like you might find on a laptop computer. Inside there are three PCBs. One runs across the back where the input DC jack, the effects loop jacks and the speaker jacks are mounted. There are a couple of diodes and an LM7809 TO-220 Voltage regulator without a heatsink. All connections are made with flying leads through 2 or 3 pin connectors.

The main PCB is through-hole technology with the input jack, the pots and the two mini-toggle switches soldered to it. The power switch is mounted to the front panel with leads back to the back PCB. The Class D power amp is a small PCB mounted to the main PCB with standoffs. The power amp PCB is all surface mount components with leads soldered to it. The power amp chip is TPA3106D1, there is also a quad TLO74 opamp and several small transistors and surface mount diodes. The power amp PCB is branded PM30 (SYNERGY)_V03. The preamp has three TLO72 opamps and a chip, TC1044S that converts +9V to -9V to run the opamps.

The Effects loop Send gets it's signal from the preamp output, the Return goes straight to the input of the Power Amp Board. There is roughly 12V on both sides of the Speaker output with no signal. The speaker output is rated for 8 or 16 Ohm loads only.
#16
Guitar News / Re: Soldano releases first sol...
Last post by Loudthud - June 17, 2022, 01:28:48 PM
Just got a msg from my local shop. The amp I ordered has arrived and the main guy there, who is a diehard tube amp guy, says it is amazing and he has ordered one for himself. You can't get a bigger endorsement than that.
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#17
Schematics and Layouts / Searching schematic fender GDE...
Last post by scoobynuts - June 17, 2022, 10:01:14 AM
Hi all
My first post!

I've got a fender GDEC 3 thirty. It's got very attenuated volume.

There is a fried resistor on the main board beside a voltage regulator. It's Crispy so I can't read the colour bands.  It's R269 so I'm looking for a schematic to see what it's value is.

I found a schematic but it must be  older/newer since it didn't have that resistor.
Any help much appreciated.
Cheers
#18
Schematics and Layouts / Re: G-K Gallien-Krueger MB112 ...
Last post by anotherfuzz - June 17, 2022, 08:54:05 AM
Quote from: jetstuff on August 29, 2020, 06:34:41 AMI've been working on a G-K MB112 200Watt Bass amp, but G-K can only offer a preamp schematic (see attached....HOW?).
They use an ICEpower 50ASX2-BTL 'bought in' board from Denmark.
Does ANYONE have a schematic for this board?
I have got the amp working by replacement of the board from Profusion Ltd. (UK)

thanks!

Hi, could you please send me the preamp schematic?
#19
Amplifier Discussion / Re: Do Electrolytic Caps Age ?
Last post by mandu - June 17, 2022, 08:47:27 AM
I had a pair of new 6800mf/80 volts caps in shelf for 10 years. With capacitance meter both measured good above 6800 mf. To clear doubt I connected a 40 volts DC supply and left for 30 minutes. The capacitors became very hot and I have to throw them away.
Either the capacitor becomes dry (lower capacitance) or have lower dielectrics (high leakage current).
You can connect a DC power supply to it and check if they survive as I did.
If the physical look is bulged, then throw them away.
Regards. 
#20
Guitar News / Re: Soldano releases first sol...
Last post by Loudthud - June 15, 2022, 03:51:21 PM
I was thinking it's really a great idea for novice amp builders because they don't have to deal with Mains wiring. With one of those switchmode supplies that are common now, they don't even have to worry about Mains Voltage. They work on anything from 90 to 250 VAC. Just get the power cord that will work in your country.