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

August 16, 2022, 12:33:36 AM

Login with username, password and session length

Recent Posts

 

Searching schematic fender GDEC 3 thirty.

Started by scoobynuts, June 17, 2022, 10:01:14 AM

Previous topic - Next topic

scoobynuts

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

mandu

Is this the resistor attached to the 12 volt regulators?

dmeek

It's in this schematic: 130 ohms/1W

You cannot view this attachment.

mandu

One schematic with 3886 output with +/- 31 volts supply has 130 ohms in the PSU circuit.
The other schematic with 2050 output with +/- 22 volts supply has 10 ohms in PSU circuit
No mention about the output power in both the schematics.

Regards

scoobynuts

#4
progress so far:
I managed to get the service manual from fender by invoking the new EU "right to repair regulations" It wasnt any help as regards troubleshooting, apparently the board is non-repairable. It did however have full schematic and component values. So, I replaced the 130 ohm resistor. The new one turned red hot and fried as soon as voltage applied.
i then replaced u40, the regulator. resistor no longer frying but burnt my finger when touched.
i have now found shorted capacitor c285. 220uF 25v. waiting on replacement part to arrive.
fingers crossed, that will do the trick

Loudthud

Where can I find out more about the EU's Right to Repair regulations ?

Den.

Quote from: Loudthud on July 16, 2022, 05:05:02 AMWhere can I find out more about the EU's Right to Repair regulations ?
I found it here.

Tassieviking

#7
Scoobynuts, please take note of the fp before the 130 on the resistor.
This might mean the resistor should be fireproof, if it fries again it will not go up in flames as long as you use a fireproof resistor.
I could be wrong, but would you chance it. Some of the more knowledgeable people here might pipe in and I and others might learn something important if they know what it stands for. :)
If it might get hot, make sure you leave some space under the resistor for airflow, also makes the PCB less hot.
There are no stupid questions.
There are only stupid mistakes.

phatt

Yes TassieVikingman,, fp is short for Flame Proof. ;)

@ Scooby,
Those resistors often run warm but as they drop a fair amount of voltage they cop heat, if the 130-Ohm resistor has burnt then the resistance may have dropped and then  C285 has likely been running over the voltage rating and died, as you have found. I'd replace C286 while you are there. Even better replace with 35volt caps.

If those 2 resistors are running very hot that can shorten there life.
If excessively hot in normal use you can use 2 watt resistors which will run cooler and hence last longer.
Phil.