Fender BJr repair

STRefugee said:
R35 and R36 don't look burnt. They both look healthy.
Ok, I'll wait.
Thanks
Click to expand...
I want you to test the voltage on pin 2 of the power tubes socket.
Output tubes removed.
Set meter for DC volts, 600. See where the V --- has a flat line?
Connect black probe to metal chassis.
Connect red probe to pin 2 of the output tube socket (or hold the probe so that the tip sticks down in the hole).
You can do this from the outside of the chassis (from the tube side). You don't need to do this from the inside.
Turn the power on just for a few moments.
Now we should see - 10 volts DC on pin 2 of the socket. Check both output tube sockets.
Turn power off.
 
syscokid said:
This is a damn good mod for these amps if you want to keep your amp as trouble free as possible.

And I would also like to add to my previous post that all these power resistors need to be installed with at least a 1/4” or 6 mm gap between the resistors body and the circuit board for better ventilation. Another Fender WTF!
Click to expand...


Very good advice. Heat is a Byactch
 
Amp Mad Scientist said:
I want you to test the voltage on pin 2 of the power tubes socket.
Output tubes removed.
Set meter for DC volts, 600. See where the V --- has a flat line?
Connect black probe to metal chassis.
Connect red probe to pin 2 of the output tube socket (or hold the probe so that the tip sticks down in the hole).
You can do this from the outside of the chassis (from the tube side). You don't need to do this from the inside.
Turn the power on just for a few moments.
Now we should see - 10 volts DC on pin 2 of the socket. Check both output tube sockets.
Turn power off.
Click to expand...
Hi @Amp Mad Scientist
Many thanks for the suggested testing and instruction. Much appreciated.
Didn't get round doing it yet, ther boiler packed up over the weekend and that took priority on all else. Always a pain when that happens.
(Here the "boiler" refers to heating and hot water system.)
Will have a look when back home later.
Cheers!
 
STRefugee said:
Hi @Amp Mad Scientist
Many thanks for the suggested testing and instruction. Much appreciated.
Didn't get round doing it yet, ther boiler packed up over the weekend and that took priority on all else. Always a pain when that happens.
(Here the "boiler" refers to heating and hot water system.)
Will have a look when back home later.
Cheers!
Click to expand...
If you look closely, you will see numbers stamped on the tube socket.
You can find pin 2 pretty easily.
We're going to go around and just make sure everything there is functional before we order parts.
(it probably is) but just in case something else is missing.
Trying to avoid making 2 parts orders / keeping the cost down if possible.
 
Don't order yet Mouser UK

1X Mouser Part No
594-2222-118-36101
100uF 25V 4,000 hr 2.54 2.54

1X Mouser Part No
594-MAL211838109E3 2.32 2.32
470uF 50V 4,000 hr

2X Mouser Part No
594-2222-118-36221
220uF 25V 4,000hr 2.88 5.76

2X Mouser Part No
594-5083NW2K200JA100 .308 .616
2.2K 2W Metal Film (1 spare)
Power supply

1 X Mouser Part No
5878-80-3-5 5.05 5.05
5ft 2mm Rosin Flux solder wick

1X Mouser Part No
71-RL20S-G-33K/R
33K 1/2W .54 .54
bias Resistor metal film

1X contact lubricant
Spray aerosol w/ wand
TBD
 
Amp Mad Scientist said:
I want you to test the voltage on pin 2 of the power tubes socket.
Output tubes removed.
Set meter for DC volts, 600. See where the V --- has a flat line?
Connect black probe to metal chassis.
Connect red probe to pin 2 of the output tube socket (or hold the probe so that the tip sticks down in the hole).
You can do this from the outside of the chassis (from the tube side). You don't need to do this from the inside.
Turn the power on just for a few moments.
Now we should see - 10 volts DC on pin 2 of the socket. Check both output tube sockets.
Turn power off.
Click to expand...
Oh Maaan!!
Can't find any numbering indicating pin 2. Looked with the magnifying glass and I wish I hadn't.
 
STRefugee said:
This looks unhealthy. Traces of overheating on the tube circuit board and pads lifting off View attachment 105252
I think I might need to order one of those.
@Amp Mad Scientist, please do let me know if you agree.


The job keeps growing
So glad I bought it 2nd hand for £240 about 10 years ago.
It would piss me off had I purchased this brand new.
Click to expand...
I can't see what you are talking about but if you think it's shot you can order a new board.
The boards in BJr do go sour sometimes. I have seen the pads break off the board before.
 
STRefugee said:
This looks unhealthy. Traces of overheating on the tube circuit board and pads lifting off View attachment 105252
I think I might need to order one of those.
@Amp Mad Scientist, please do let me know if you agree.


The job keeps growing
So glad I bought it 2nd hand for £240 about 10 years ago.
It would piss me off had I purchased this brand new.
Click to expand...
Is the pad actually broken off the board?
It's normal for the board to look toasty, it will still work.
 
Amp Mad Scientist said:
Is the pad actually broken off the board?
It's normal for the board to look toasty, it will still work.
Click to expand...
Hi,
Can't 100% sure. The soldering blob lifted off the board. But I will have to take the board out to have a better look at it.
I then though, well if I am to take it apart I might as well replace it.
I wonder if I ever really heard what that amp should sound like haha!
Thanks.
 
STRefugee said:
Hi,
Can't 100% sure. The soldering blob lifted off the board. But I will have to take the board out to have a better look at it.
I then though, well if I am to take it apart I might as well replace it.
I wonder if I ever really heard what that amp should sound like haha!
Thanks.
Click to expand...
Test the pin 2 voltage before you take it apart.
Do you see how there is 9 pins and a big gap between 2 of the pins?
The gap is where pin 1 and pin 9 are located.
Follow around the circle to pin 2.
 
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