Fender G-Dec Jr - not powering up - Pico fuse?

[speedyrazor]

I have just aquired a old G-Dec Jr 15, which is not powering up. Upon oipening it, I can see someone had aleady removed the glass tube fuse, I can't see any other issues visually.
I used a multimeter and can see 240v coming out of the trasnsformer (im in the UK).
I know I shouldn't do either of these, but just as a quick test, I made a temporary connection accross where the glass fuse should be, still nothing. I then came upon multiple threads online suggesting that the pico fuse, which is in position T2, just behind the two brown wires, is a common known issue, where in the factory a 500ma fuse is fitted, but in reality, this is too low, and it's suggested a 1amp fuse is fitted instead, so I also soldered a temporary connection across this Pico fuse (T2), but still nothing when pluged in and turned on. My questionn is, making a connection across where these two fuses should be, if one or both of them were the issues, should this bring it to life? Or is there something else a pico fuse is doing? Or is there something else I could try please? I am obviously taking great care and precations when doing this stuff.
Great little amp, shame to throw it away. Any help in next steps would be greatly appreciated.

Kind regards.

[Jon Snell]

Pico fuse??? Please explain. Is it F1 or F2?
F1 must be 250mA T for UK.
F2 1A F

[Helmholtz]

I used a multimeter and can see 240v coming out of the trasnsformer (im in the UK).

That looks like your mains input voltage, so doesn't tell if the PT is working.

I know I shouldn't do either of these, but just as a quick test, I made a temporary connection accross where the glass fuse should be, still nothing. I then came upon multiple threads online suggesting that the pico fuse, which is in position T2, just behind the two brown wires, is a common known issue, where in the factory a 500ma fuse is fitted, but in reality, this is too low, and it's suggested a 1amp fuse is fitted instead, so I also soldered a temporary connection across this Pico fuse (T2), but still nothing when pluged in and turned on. My question is, making a connection across where these two fuses should be, if one or both of them were the issues, should this bring it to life? Or is there something else a pico fuse is doing?

It is a very bad idea to jumper a fuse with a wire.
Fuses either have a safety purpose and/or protect expensive components like the power transfomer.
A fuse doesn't blow without a reason. So jumpering it without curing the problem often makes things worse.
Also doubling the current rating may take the PT at risk.
(Always test fuses out of circuit.)

Consider building a bulb limiter and please post the amp schematic.

Replace fuses with original specs and see if if you get correct secondary voltages.

[speedyrazor]

Apologies, I got the fuse ratings wrong, F1 (glass fuse 250mA T for UK), T2 (Pico fuse) was T 1A 125V. Here is a link to the service manual containing schematic, etc.

https://drive.google.com/file/d/1U78...ew?usp=sharing

[Jon Snell]

Apologies, I got the fuse ratings wrong, F1 (glass fuse 250mA T for UK), T2 (Pico fuse) was T 1A 125V. Here is a link to the service manual containing schematic, etc.

https://drive.google.com/file/d/1U78...ew?usp=sharing

Because I will not allow the gargler to use my personal information to target me as a shopper, I am unable to open your link.

[Helmholtz]

I guess it's an axial leaded miniature fuse.
https://www.fusesunlimited.com/products/picofuse

[g1]

Because I will not allow the gargler to use my personal information to target me as a shopper, I am unable to open your link.

See attached

[The Dude]

That looks like your mains input voltage, so doesn't tell if the PT is working.




It is a very bad idea to jumper a fuse with a wire.
Fuses either have a safety purpose and/or protect expensive components like the power transfomer.
A fuse doesn't blow without a reason. So jumpering it without curing the problem often makes things worse.
Also doubling the current rating may take the PT at risk.
(Always test fuses out of circuit.)

Consider building a bulb limiter and please post the amp schematic.

Replace fuses with original specs and see if if you get correct secondary voltages.

^^^^^^ Yes, that. Follow power supply in from transformer secondary voltages. Then, if secondary is good, check DC supplies and find out what is there and what is not there. Fender is kind enough to include test points and expected voltage in their schematics.

[Jon Snell]

See attached

Ah, thanks for that but I already have the service manual. It read as though it may have been different.