Fender Super Champ XD - No Sound

[earache]

Hello

I'm looking at a Fender Super Champ XD that makes no sound. The two 6V6s and the 12AX7 light up, as does the power indicator light, but the channel indicator LED does not. No sound comes with any controls or switching the channels and no "pop" when plugging into the amp.

How to go from here? What is the next trouble shooting step? Are these amps known for having their DSP circuits just die?

[Leo_Gnardo]

Hello

I'm looking at a Fender Super Champ XD that makes no sound. The two 6V6s and the 12AX7 light up, as does the power indicator light, but the channel indicator LED does not. No sound comes with any controls or switching the channels and no "pop" when plugging into the amp.

How to go from here? What is the next trouble shooting step? Are these amps known for having their DSP circuits just die?

Channel indicator not working might be a failure in low voltage supply. Look inside, make sure all those connexions to the board are plugged in, none loose. Poke & prod with a chopstick or similar non-conductive item, that may reveal in intermittent connection. Look carefully at all the components (assuming the board is component-side-up) to see if anything looks burnt, loose, or out of place.

Also,

How's the speaker? And the speaker cable - I forget on the XD whether it's wired direct to the amp. If it has a plastic speaker cable plug, they sometimes fail. Once speaker & cable are checked next question: Is there a working hi voltage supply?

[The Dude]

Those things notoriously have a bad DSP board. I've seen many. Schematic below.

Super-Champ_XD_schematic.pdf

I just had another one in last month. Check power supplies. Check for signal into the DSP board, but no signal out. If that is the case, you are hosed. I contacted Fender and the board is no longer available. I had to go to plan B. Attached below.

DSP Mod.pdf

Edit: Of course, if this is a customer unit, you'll want to explain and get approval for the mod, first. The mod basically turns it in to a useable amp, but single channel w/volume and tone. No more channel switching or effects. The last one I did was for a guy who used it to amp a Line 6 modeler, so he didn't care.

Edit (again): Credit to dbtech for putting together the mod and documentation.

[Enzo]

And just because the DSP in these fails more often than it should doesn't mean that is what is wrong with THIS one.

No LED points to no +5 supply. Are ALL power supplies present?

[The Dude]

Oh, I completely agree, Enzo. That is why I said, "Check power supplies. Check for signal into the DSP board, but no signal out." I wasn't suggesting we modify the amp without troubleshooting and verifying the problem first. My recollection is that most everything in this amp is controlled by the DSP board, including the channel indicator LED. The collective symptoms are why I suspect the DSP is bad. Even the volume and tone controls are digital controls. But again, YES, test first.

[lowell]

I got one in with no sound. +5v is there, as well as other supplies too. There is only 1.2v on pins 9-11 on the 4051B. No signal out to U3, but there IS signal out of U7. Bummer. I'll see if he'll go for the mod.

Also, where are the VDD and VSS for the 4051B in the schematic? I can't find em. I have 5v on VDD and 0v on VSS. I used the datasheet for the pin numbers. But still, can't see them on the schematic, and would like to confirm that this is correct.

Thanks for sharing the mod Dude!

[earache]

So after having found that the various voltages were present on the DSP board, I chose not to mod the amp but gave the required parts to the owner, who is thinking about making the mod himself.

Thanks for the input everyone!

[The Dude]

......Thanks for sharing the mod Dude!

No problem, but the real credit goes to dbtech who is a member here. I only reposted his work.