Intermittent black squares printing from Pioneers to 82240B

[Dave Britten]

(06-07-2017 05:16 PM)Geoff Quickfall Wrote:  It is beginning to sound like a noise problem. Either to much data (black square) or to little data (missing print or space command)

So the noise is being interpreted two ways, ignored (missing) or printed (black square). Internally the oil filled caps filter noise and would be my first suspect in the hardware. Especially since the self test functions. Of course the self test prints code directly from the rom therefore no IR test is involved so my second thought would be the IR diode or a cap in that circuit.

Diodes have a shelf life, but up in the 'I won't see it in my lifetime' age.

So now that you have ruled out positional error (too close, too far, receiver and transmitter angles) it would seem that its receive range has narrowed considerably. Again capacitors come to mind as an aging component.

Geoff

Noise (or a faulty cap) might explain the black squares (i.e. mis-received characters) at close range, but the omitted characters are consistently at the beginning of lines. And I don't see the problem with my 48s. Is there a big difference in transmitter power between the Pioneers and 48? Maybe a slight clock difference, and the Pioneers are just a bit outside of what this particular printer can handle?

(06-07-2017 05:35 PM)BobVA Wrote:  Just to make sure I'm understanding that, is the printer at rest when that comes in, and it doesn't respond to a single <LF>? Or did it get a <LF><LF> at the end of the preceding print line and didn't execute the second one?

Right. The sequence is like this example:

Code:

BALANCE=  4,715.68120945<LF>
<LF>
PMTS:13-18

The line feed between the two lines to add an intervening blank line gets skipped. The printer just sits there waiting for the next line to be sent from the calculator (which pauses between lines so as not to overrun the buffer). So far, I've yet to detect it skipping characters anywhere within a line, only the first one.

(06-07-2017 05:35 PM)BobVA Wrote:  Did you try a second Pioneer? If so, which model?

What would be perfect is if you could pick up another 82240B *and* another HP-27S then do some comparisons :-)

I tried it with my 17BII a little bit, and was getting similar results, at least as far as the black boxes. I'll have to test again to see if it's dropping initial characters too. What I do know is that the 27S is printing flawlessly to the 82240A, and the B is having no trouble with a 48SX and 48GX.