I am trying to repair a Line 6 Spider III guitar amplifier, for which replacement parts sadly no longer can be ordered. The problem is a flawed DSPB56362AG120, which overheats and seizes up at normal operating temperature. This was apparently a common problem with a whole batch of these chips (date code 1J21D). There is a video on youtube where a tech makes the amp operable again by evaporating a drop of alcohol directly on the DSP! I have already unsoldered the DSP, and I have bought a new one to replace it. However, I have no way to clone the instruction set from the original DSP to the new DSP. I have seen DSP56 EVM kits for sale on the internet, and I could probably learn to use one if I gave myself a while to study. But, perhaps you guys could just steer me to a person who could clone my DSP? Thanks!
The 56362 data sheet is here:
Joe mentions, it contains a 30k word program ROM. In those days (15+
years ago) it was very expensive for OEMs using Motorola DSPs
to customize the onchip ROM, plus that precluded fixing bugs, which were pretty much a given to occur. Assuming that was the case with your amp mfg, you can look around on your PCB for
Flash chips. They tend to be socketed, as in this 56362 board pic:
Or they might be soldered on, as in this 56367 board pic:
In the soldered-on case they would have been made by Atmel, AMD, or Fujitsu
(the latter two became Spansion), and they were usually wider with pins
on only the sides (i.e. not square with pins all the way around).
If you find one or more Flash chips, then chances are good you can solder on a replacement 56362 and your amp will run fine. You do need to make sure that part markings match your original chip -- there can be significant differences in silicon revision, clock rate, and temperature rating.
That is excellent news! There is a SST25VF512A 512K serial flash on the board. I will see if I can find somebody with better SMT rework skills than me to swap the part. Thanks!
Does it look something like this:
replacement.com.tw/sst49lf008a.jpgand it's socketed ?
The DSP56362UM.pdf "users manual" says (in part)
18.104.22.168 Program ROM
The program ROM contains customer-supplied code. For further information on supplying code for a customized DSP56362 program ROM, please contact your Motorola regional sales office.
I think this means that the ROM is a mask-programmed device with the programing done in the final metalization mask of IC fabrication. If this is correct, then there is no way of transferring whatever code might be in the part you removed into the replacement part.
On the other hand, there is a "bootstrap" ROM area as well. If the DSP56362 in your product gets a program transferred in from some external memory (e.g. "flash" or similar) via the bootstrap program, you might be lucky and just need to solder in your part and go.
I agree with Joe West on the programming issues.
Have you considered a huge heat sink on top of the DSP to keep it cool. Lots of wings.
Maybe it requires some clever addition of a cooling fan blowing onto the heat sink as well.
Just a thought.
P.S. There is one for sale on Ebay for about $70.00. That's equivalent to no more than 2 hours of your effort I would think.
Thanks for the reply. Yes, I tried heatsink first (fan assembly harvested from PC video card). Unfortunately, ambient temp above about 75 degrees still means no go. I thought about a peltier, but they draw so much current!