The elusive Indextron

[mbates14]

Originally Posted by jhalphen

Hi to All,
Hi Mbates14,

Found this illustration of the Sony CX22011 PWR control IC in my archives.
Unfortunately, spec sheet searches yield nothing and i've never had a full Sony data sheet, even in 2007.

Also, there is no Theory of Operation in the KVX-370 Service Manual so it's going to be a difficult task to assess what voltages & how many the CX22011 supplies.

Sorry! not to be more helpful,

Best Regards
jhalphen
Paris/France

Yeah, that's all the same information I had and i could find as well. they are only using one of the two error amplifiers, and they aren't using the HV or LV shutdown protections in this design, either.

Also this chip appears to use a 1.2V reference, which there are very few PWM chips that do.

What cuts a lot of the market is the fact that they are using this in locked-frequency sync mode which again very few available chips can do. the SG3525 was attractive to do this, but it requires a modified feedback network due to the differences in reference voltage, and the other problem I ran into is its a push-pull design. I tried to sum the output using gates but it did not work well with the glitching and phase compensation issues.

I assume they phase-lock the 22011 power supply section for noise reasons, but they also pick off the R/C timing circuit ramp that runs off to the horizontal deflection stage to an extra winding on the yoke. idk if its a pincushion/horizontal parabola circuit or what.

So i put it aside for now, I did find a couple different ICs i can tinker with which have single-ended outputs and can phase-lock.

I attached the insanity that ensued haha. The picture is hard to see because the forum software is still expecting attachments stuck in 1992.

[jhalphen]

Hi to all,
Hi Mbates14,

Thanks! for the reply.
You have well analyzed the PWR circuitry and your engineering skills are far above mine.

Are you sure your CX22011 is dead; i sent one one of my Indextrons to Andy C. and it was a corroded trace under the IC (electrolytic leakage) which caused the PSU malfunction.

Andy left the VK forum for personal reasons.
He's on ARF (Antique Radio Forum) though and signs "AC".
Might still be willing to repair Indextrons.

see this thread for instance :
https://antiqueradios.com/forums/vie...?f=15&t=427760

Best Regards
jhalphen
Paris/France