Sparta A20(2) Broadcast Console: info/schematic?

[Schmilsson]

A friend is in need of a schematic - or any info really - of  a Sparta A20 console. Any radio dorks got any goodies in their secret stash?

 

[PRR]

You are giving me flashbacks.

That console is super easy EXCEPT (the one I had) was powered with ground on black and NEGATIVE 30V on RED. I stupidly thought red would be positive, and it was 6 months finding my mistake.

The mike amps are just 3 transistors and easily traced-out. Bus masters are similar. Speaker amp is antiquated, go chip-amp. Power supply was fragile and I would cut-back to PT secondary, new rectifier bulk-cap chip-regulator and get the polarity right.

Perhaps the biggest problem is how easy it opens. All kinds of crap gets dropped inside. That is probably why my power supply failed.

 

[Schmilsson]

Much appreciated!

Yes, look really simple indeed.

 

[wrc.radio]

I do have some of the schematics for this. They are a bit light, but i'll try to scan them. Reply if you want them or not. i could email you pdf's.

 

[envelope]

Hello, I am working on another Discrete Sparta mixer, the A-15.
The Preamp cards are the same, and the mixer also runs on reversed polarity. 
The external power supply outputs +30VDC via LM317, and then the polarity is reversed within the mixer.
The output transformer in this A-15 is a UTC A-37.

To: wrc.radio  I would love to see any information you have relating to the A20, for reference and information gathering.


thank you kindly.

 

[LeoP]

hello I have Sparta as-40b,dont know anything about power supply. There is 6pin connector on back side, is it 110V ? and whats pins?

 

[hornGary]

Take a look at steampoweredradio.com, lot's of information around Sparta products:

https://www.steampoweredradio.com/manuals/spartam.html