[sdiy] Karaoke boom-box echo chips

[anthony]

I have been systematically collecting those karaoke boomboxes that have an 
echo feature to make cheap slapback echo and reverb effects. Part of my 
making cool effects and synths out of mostly junk - Gomitronix (tm).

But damned if I can find datasheets on many of these. It mostly involves a 
lot of work using the karaoke machine (if it still works...) and figuring 
out what is input/output, clock, etc.

The only datasheet I've found is for the Semicon CD3699, but most of it is 
in Chinese. If anyone can read and translate Chinese, it would be cool to 
have an English version of this datasheet - not to say that's impossible to 
follow - the salient features are sort of in English. It's easy to find the 
datasheet on Google. It's a good thing the datasheet is available easilly, 
because divining what each pin does just by following PCB traces would be 
fruitless, I'd wager. The datsheet is also nice in that it shows a couple of 
different application configurations.

I have a few others (5 or 6 of these boomboxes), but one that pops up in my 
mind as one I can't find a datahseet to save my lfe has the CD3197. The 
others are in boxes so I can't see the part numbers. The first one I got, I 
made the mistake of removing most of the parts around it so as to have a 
small PCB - without first testing the unit as it was first intended. I sort 
of got it to work, but I lost interest because I actually have a nice 
collection of studio quality gear.

I'm guessing that the difficulty in finding datasheets is that these are 
custom chips and the datasheets stay mostly in China or or Taiwan or Korea. 
Parts by Japanese manufacturers (like Toshiba) tend to have easy to find 
datsheets, but I have yet to find one in a disused karaoke boombox.

If anyone else has been traversing similar avenues, maybe we could pool 
info?

Although the PTXXXX parts are pretty cheap, experimenting with a free part 
is more economical and you get to follow the Reuse part of the "Reduce Reuse 
Recycle" liturgy.

Cheers,
Anthony