Dead Lexicon PCM70, need some help.

[radardoug]

I am working on a Lexicon PCM70, it has no reverb, otherwise everything functions. I bought an HP signature analyser and went through it with that, all chips give right signatures except two, but replacing those chips does nothing. I am starting to suspect two programmed chips in there, U48 and U49. I do have a reader, but need a working unit to read the chips in. Can anyone help?

 

[cavedata]

I am working on a Lexicon PCM70, it has no reverb, otherwise everything functions. I bought an HP signature analyser and went through it with that, all chips give right signatures except two, but replacing those chips does nothing. I am starting to suspect two programmed chips in there, U48 and U49. I do have a reader, but need a working unit to read the chips in. Can anyone help?

 

[radardoug]

Awesome Cavedata! I was thinking about this unit this morning and thinking I might have to declare it unfixable. Back to work! Thank you so much.

 

[radardoug]

An update on this one. The 74s288 has one byte wrong out of 32. I will get another one burnt and update.