Re: Anyone have any troubleshooting advice?

> Probably a stupid question, but did you check ALL pins, especially the
> power supply pins?

Yes, I checked all pins on the DACs and the analog multipliers.
Voltages are good.

On the AM6012s, 5.27v on pin 20 (v+), -15.01 on pin 17 (v-).
On a DC scale, I get 0v on pins 14/15 (VR+/VR-) for both DACs.

On test screen 4 (crosshatch), read 0.4V on pin 18 (IO) of the Y DAC (F10),
reads zero volts on the same pin of the X DAC (A10). On the scope, this shows
up as a noise like waveform.

>From looking at the schematics, pin 18 is what feeds into D11/E11 which
eventually feeds into the multipliers, so I was *assuming* pin 18 was the
analog output of the DAC.

But where I'm getting confused is that pin 18 also splits off into the BIP
circuit, from the schematic, it almost looks like the BIP circuit feeds
into the DAC (as an input) on pin 18.

Before I started looking at the digital inputs to the Y DAC I figured I needed
to understand what pin 18 is and get some basic explanation as to how this
part of the circuit works.

The following is a JPEG of what the screen running the crosshatch test pattern
http://www.tonyjones.com/temp/tempestbady.jpg

thanks!

Tony

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Received on Sun Feb 9 14:06:02 2003