The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

Hi All,

What I have here is a Zenith P-202 Speech Processor, circa 1982, made by Zenith Electronics here in the UK.

I have managed to figure out and re-wire the in and out's to suit my Lincoln (with the addition of a relay to stop the Lincoln's display going weird when it's plugged in) and it's sounding great, But...

One of the pre-amp chips has started getting noisy and wants replacing. The problem lies in the fact that none of the chips have identification on them. (edit: all the chips now found to be- TL061CP op-amps)

If anyone has any info on this Processor - schematic, part layout, user manual, anything! It will be greatly appreciated, as this box of tricks (along with a Telex NC450D microphone) makes my Lincoln sound awsome.

Thanks All,

Norm (aka Warf135)

used to have 1''brief. two 9v batts held with pink bands poly caps front tuning knobs very crude with resistors.may have 1 in bits could be anyware? didnt perform mega fantastic as i remember. indiff to wire to uniden or cybernet wired 1 to a lincoln once as i remember the 13.8 wire needed to switch the unit to work? ie pos. neg. you see them all the time on ebay. used cmos ic's?.

Thanks for your reply Warhorse,

you describe it to a tee. The guy I got it off said it could be powered by batteries or the power supply. Didn't take too long to figure that it needed both forms of power for it to work.

since my last post I was getting reports of a pretty bad buzzing coming through. The buzz got worse as I increased the RF power on the radio. After initially checking my PSU, and all ground connections along the mic line, I realised that it must be caused by "RF Feedback".

I then added C1 and C2 to decouple the audio in and out of the box and that has sorted it. (i'll post the updated wiring diag)

If you do ever come accross your old one, I'd be willing to buy it from you for spares.

Many thanks,

Norm.

still looking for schematic, part layout, user manual.

not alot!


http://thecbmuseum.blogspot.com/2008/06 ... essor.html

Thanks warhorse!


UPDATE 12-05-2009: I rebuilt my speech processor and now it's working fine again. I found out that ALL of the 8 pin DIL chips are very cheap TL061CP low power J-FET input op-amps.