MarkK wrote:
OK, seems like a good place to ask this question...

I have a Tek 2712 spectrum analyzer and one of the Philips PLS157 PLA is
bad. It is in the trace blanking logic. I can buy an unprogrammed PLS157
on E-bay.

Anybody have any ideas where I can get the program info or even better a
pre-programmed part. It is A9U308 PN 160-5005-00 Man code 8009 which is
TEK .

Or failing that, anybody have an idea of what the logic is that is used to
create the blanking signal, there are about 4 or 5 inputs to this chip and
only one output is bad so I might be able to wire up some combinational
logic to re-create the function.

If anybody out there has any info about this, I could use it.

TIA

Mark



Any way you can disconnect the output and look for glitches when
it should switch? work the logic backwards.

Blanking shouldn't be too hard to figure out??

Don't know anything about the chip...assume it'd read locked so you can't
get out the contents???

I've fixed a 308 logic analyzer with a bad prom. Wouldn't run at
speed, but worked well enough to read out the bits.