[Amps] THP HP-2.5 Help

[Manfred Mornhinweg]

Hi Will,

I don't know anything about your specific amplifier, but I do have 
experience working with PICs.

> I have a THP that on startup is displaying the message? "PSE STBY 
> OPERSW!"? after it gives me the THP/firmware version? message. Doing
> a bit of troubleshooting with a friend, it appears that it is the 
> processor or timing PIC. We checked the reference crystal and that
> was dead on..

It would be hard for a PIC to be partially bad. If it's bad, it won't 
run at all. It's not completely impossible to have a partial failure, 
but very rare. So the culprit is unlikely to be the main processor PIC.

> The second chip next to the processor actually had a felt or
> permanent marker across it. U9. It is? NOT listed anywhere (parts or
> schematic). 

Is it perhaps part of an optional extra?

> The second chip is a 12F683 (8-Pin Flash-Based, 8-Bit
> CMOS Microcontrollers with nano Watt Technology). It may be the real
>  culprit... What little reading I have done, it is a timing function
>  device. It looks like it is supposed to supply the timing..

Very possible. Small PICs are inexpensive enough to make them a very 
practical alternative as soon as a PIC can be used to replace just a few 
standard logic ICs.

> Anyone have the ability to read/program the 12F683 chip??

I have it, but I'm in Chile...

Anyway, making a reader/programmer for PICs is very easy. There are many 
schematics on the web. I built one that uses just one CMOS buffer IC and 
  a few resistors. The required software is available for free. I use a 
program called "PICPgm Development Programmer".

You can also buy ready-made PIC programmers. They come in various levels 
of functionality and performance.

However it's often not possible to read out a PIC, because at the time 
of programming they can be configured to allow or disallow readout, and 
most manufacturers choose to disallow it, to protect their proprietary 
software from being copied. So you might read out just zeroes, even if 
the PIC is perfectly fine and correctly programmed.

Manfred

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