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Hello,
the unit does not give any reaction when addressed with correct IB? address. Have checked HB-IB clock which is OK. I do not have the special extender board, so further testing inside circuit is almost impossoble. So maybe best would be to change IC U6 (TMS9914AJTL), U30 (75161) and U31 (DS75160). Or any other suggestions?
Still wondering, what the options mean. Firmware ROMs are standard matching the serial prefix.

Regards Ernst.

Yes, Orin, you are correct. After taking a second (and third)? look, I see that I misread the 'B' for an '8'. Maybe I need some better glases...

At 2019-02-06 01:34 PM, dk1vi wrote:

the unit does not give any reaction when addressed with correct IB? address. Have checked HB-IB clock which is OK. I do not have the special extender board, so further testing inside circuit is almost impossoble. So maybe best would be to change IC U6 (TMS9914AJTL), U30 (75161) and U31 (DS75160). Or any other suggestions?
Still wondering, what the options mean. Firmware ROMs are standard matching the serial prefix.

I'm jumping into the middle of this, not having seen any preceding discussion, but here are some ideas:

1) The unit might have IEEE-488 disabled in firmware, either as a factory option, or as a user option. Can you see what address it thinks it's using on the local display?

2) Any chance you've flipped the sense of the address switches? It's not uncommon on IEEE-488 to see generic DIP switches labeled On and Off, and the On position pulls down to 0 whereas the Off position allows that bit to float to 1, so the numeric value is opposite to what you might expect.

3) If possible, have your bus controller poll all addresses one at a time. That might find the unit if it's not at the address you expect, for whatever reason. My KISS-488 includes that function, precisely for such a scenario. When your instrument recognizes itself as being addressed, it should pull \DAC low.

4) It's a bit tedious for extensive troubleshooting, but I've done such things as checking Vcc, checking chip clocks, etc., inside an instrument where I can't reach with everything plugged in, by temporarily tack-soldering some #30 wire wrap wire to pins, leaving it long enough to connect a scope or meter outside the instrument. You probably don't want a very long wire hanging off a high frequency line, but you can get away with this trick usually up to several MHz, which is usually plenty for these older instruments.

Steve Hendrix

Thanks for your commments. On startup the HP-IB address is displayed on the screen (18). I have tried to address it directly with no result. Same with polling.
I have already ordered the two different bus drivers U30 and U31, they are cheap. So changing them will be easy. If this does not work I have to dig deeper into the circuit.

There is another problem: BATTERY is displayed on startup. The battery is good and the battery voltage is present on the RAM ICs. So maybe one or more of the SRAMS are bad.
Howerver Self Test does not show any problem.

Ernst

I would still be inclined to look at the external cabling and the other end before opening up the instrument. Much more likely to be a problem with a connector than with the innards of the instrument, unless you have reason to suspect the instrument was abused. YMMV.

Steve Hendrix

At 2019-02-07 11:08 AM, you wrote: