Fender Champion 30

[gbono]

I need a knob for a Champion 30 - they look like the same knobs used on the Stage 100 and Princeton dsp?? Does anyone know if the knobs are interchangeable or did Fender orient the D shaft differently? THX

[Enzo]

The princeton 65 DSP aqnd Deluxe 90 use the 054419 knob, described as "180 degree", or most likely backwards from regular ones. It is the same knob as your Champion 30.

[Jazz P Bass]

Fender Amp Knob Rotary 180 SS w/CHR 0054419000

[gbono]

Thank you Enzo. Do you happen to have a schematic for the DSP version of the Champion 30? I'm just getting into this amp. The Champion 30 I have has a odd potentiometer for the FX selection - the pot appears to be a normal wiper/resistive not a encoder. Doesn't seem correct?

[Enzo]

Why yes, yes I do...

A pot wired across 5v or whatever is a variabloe voltage which is easily interpreted by an ADC as a control signal. Good as an encoder. That is what they do here.


Here is your file:

[gbono]

Thanks for the manual - cheap and cheerful encoder design though the owners manual shows numbers around the FX select like there are detents to "find" when turning the knob. This unit is supposed to make random noise after its been turned on for awhile (when it was demoed to me the amp didn't make any strange noises - go figure). I'm guessing it is a cold solder joint or ? I will use the headphone output to monitor the problem and see if its in the preamp section vs output - hello mr chop stick.

[olddawg]

Thanks for the manual - cheap and cheerful encoder design though the owners manual shows numbers around the FX select like there are detents to "find" when turning the knob. This unit is supposed to make random noise after its been turned on for awhile (when it was demoed to me the amp didn't make any strange noises - go figure). I'm guessing it is a cold solder joint or ? I will use the headphone output to monitor the problem and see if its in the preamp section vs output - hello mr chop stick.

If it is a DSP unit. Do a hard reset per the owner's manual and return it to factory presets before you do anything else. It can clear up a lot of wired or intermittent problems. It annoys some customers but it reduces callbacks.

[gbono]

There is a undervoltage sensing chip - U11 (MC34064) that provides a reset to the DSP. I didn't see any other refernces on how to rest the DSP. I don't like to ground pins on these older digital designs - so if someone has a procedure for resetting the DSP in this amp it would be appreciated.

For some reason I can't upload files .................. see the service manual Enzo uploaded above - page 13/16

[Enzo]

Power up reset only guarantees the DSP starts from step 1 of its program. Reinitialization only comes in if a digital circuit has memory that is alterable. That is to say user patches or such. If there are no alterable or stored patches, there probably won;t be a reinit function.

[olddawg]

Power up reset only guarantees the DSP starts from step 1 of its program. Reinitialization only comes in if a digital circuit has memory that is alterable. That is to say user patches or such. If there are no alterable or stored patches, there probably won;t be a reinit function.

Sorry Enzo, my bad. I assumed it had user programmable presets.

[gbono]

The DSP in this design does have onboard memory for the config code/program. I'll talk with the DSP guru here to see if there is a way to reinitalize the code. I'm going to assume that Fender loads DSP code at the contract manufactuer's site and that's it - no firmware updates in the field.

[Enzo]

Olddawg, it was a perfectly reasonable thing to suggest, I didn;t know either way, I was speaking to the general case. SInce gbono finds no reset, I will assume there is not one.

One does not reinitialize the code, one reinitializes the memory - the RAM. And that would only be that memory that you can alter. ROM is burnt in and not subject to reset.

[gbono]

This design has both an external PROM and SRAM (U4 and U2). The pins 20-22 PS,DS and IS (BAR) are kept high until you need to access a particular external memory space. The RS (RESET) pin stops the DSP and when RS is brough high the execution of the program in memory stats at location OFF80h. I'm working on the reinitalization process and will pass it along when done.

[Enzo]

I think we are not using "reinitialization" in the same way. I mean it as "restore factory settings", in other words erasing any user patch edits and restoring the original programming. All that is stored in volatile memory, if it has any. That is totally separate from making the program start at step one at power up or some such. If you cannot edit the thing, there is nothing to reinitialize.


It has to have ROM for the factory program to live it, yes. But if you cannot ALTER any of that from the panel, then there is nothing for it to remember in volatile memory.

U11 is a power up reset IC. It creates the signal /RESET at power up. They run that through a couple schmidt inverters to create DSP_RST. DSP_RST is sent to pin 98, the /RS input of the U3. Once power is on, the thing runs constantly. /RS on U3 looks to be active low to me, not active high. But either way, the only thing that controls the reset line is U11, the power up. The FX are constantly running, you only need bring up the FX level control and there they are.