Super Champ XD Red light on. Channel select light off. No Sound.

[PowerToTheTubes]

Ok I did a stupid thing... A really stupid thing... I moved to Europe from the US with my SCXD. The amp has been sitting for a year before I used it. I plugged it straight in with an adapter and the fuse blew. I then realized that I need to get a step down converter transformer. So I replaced the fuse and got a the transformer that was rated for the amp. The amp is rated at 90 watts so I purchased a 100 watt step down converter. I plugged it in and now the light turns on but the channel select light is off and there's no sound. Well there's buzzing and whistling. Almost like tuning an old radio. I unplugged everything and looked at my tubes the preamp tube looks ok but both power tubes are black and one has a brown gook around it. So now I'm wondering if I just need to change the power tubes and I'll be ok or could there have been more damage done to the amp...

Any help would be really appreciated!

thanks

[52 Bill]

Welcome to the place.

I doubt that the tubes are the problem here. I would first look to see if there are any internal fuses for the low voltage power supply.

[PowerToTheTubes]

Thanks 52bill! I've been a long time lurker on here.

I will open up the amp and see if I see any fuses internally in the amp. I'll be back in a few.

[PowerToTheTubes]

I opened up the amp and looked at it from top to bottom. I can't find any other fuse.

Do you think those power tubes look ok?

Jaime

[PowerToTheTubes]

I found this at another forum...

"BTW, the SCXD has a second fuse--a 7 amp fusible link soldered down like a resistor. So if there's a major problem and some clown tries to jumper the glass fuse, it'll blow. That may be a safety standards requirement in some countries."

I have no idea where that would be...

[52 Bill]

I found this at another forum...

"BTW, the SCXD has a second fuse--a 7 amp fusible link soldered down like a resistor. So if there's a major problem and some clown tries to jumper the glass fuse, it'll blow. That may be a safety standards requirement in some countries."

I have no idea where that would be...

Looking at the schematic, there are two fuses for the 20 volts supplies, one for the 5 volt supply and the 7 amp one for the tube filament supply. Unfortunately they are all marked as PICO fuses, which are solder in fuses and are not easily changed.

Do you have a multimeter? Do you know how to use it?

[PowerToTheTubes]

Unfortunately, I did not bring my multimeter to Europe. Yes, I basically know how to use one. I'm guessing these other fuses can't not be visually identified as "blown"?

[The Dude]

...... I'm guessing these other fuses can't not be visually identified as "blown"?

Generally not. You'll need a meter or at least a some sort of crude continuity tester.

[PowerToTheTubes]

Generally not. You'll need a meter or at least a some sort of crude continuity tester.

Alright, tomorrow I will go out and buy a multimeter... It's 12:30 am here.

[The Dude]

In a pinch, I've used a battery, some clip leads, and a light bulb (if you can't wait).

[PowerToTheTubes]

Ok guys. I purchased a multimeter. Now where do I need to test...? Sorry for the rookie questions. I don't know my way around a schematic..

[PowerToTheTubes]

Alright guys... So I'm assuming I have to check continuity on those Pico Fuses... So in that document I attached in the above reply, I see there are 4 of them. I checked continuity for F2 through F5. They all ring except for F3... Is that a bad sign?

[oc disorder]

Depends how you look at it .. well I think it's good as it's a positive starting point..that fuse eventually supplies the "brains" as it were (U4 U5) so that's why there's no one home even though the light is on ! As it blew we hope it did it's job and protected the chips. If you want to do it yourself and run the risk of further damage
get a 1.6 A and a 2 A glass fuse (any size) and using short jumper leads with mini crock clips hook the new 1.6 across the leads of the existing blown one and stand back ... If the channel select doesn't come on within 3 secs that would be a bad sign.

EDIT: Oh the brown gunk on the tubes is just glue from slack manufacture "they dont make toobs like they used to"

Also may pay to remove all the tubes and measure F2 again the 7Amp heater fuse. As the transformer and the heaters
are all in series with the fuse - even with the fuse blown it measures a very low reading as if the fuse is intact.

[PowerToTheTubes]

Well I definitely don't want to do it myself... I prefer to buy the pico fuse and have someone install it for me.

So do tubes that are fine look black like that picture attached above?

[oc disorder]

Well I just meant the above as a temporary test I'll just have a look at the photo
It seems they are made like that with a black coating , JJ tubes etc as far as I know don't have this....

I suspect marketing !




If you are going to take it to a pro he will be able to check other components regulators etc prior to powering it up.
As you can see from the manual Fender don't pay to have these repaired under warranty and replace the whole unit.