HP86 problem

[Paul Berger (Canada)]

(07-19-2019 09:43 PM)Alexkumt Wrote:  this is the motherboard, in red I highlighted the dip-switches

https://imge.to/i/5oR86

You can find the service guide for 86B at http://www.akso.de/fileadmin/Series_80/A...ce_86B.pdf on page 4-24 of the manual the settings for SW2 are defined, I cannot tell from you picture which way the switches are set, however in my experience the rocker type can be especially flaky you may want to rock them back and forth a few times to make sure they are closed, and verify the connections using a meter. Unfortunately the scan of the schematics in that manual are pretty poor but you can see that on one side of that switch is connected to non-inverting buffer outputs and the inputs are grounded. There is another signal connected which is likely an enable signal, so my guess is that when the 86B starts up the buffers are enabled and the switch read and then the buffers are turned off. Near as I can tell from the schematics the switch is connected to some of the column lines, so that would be the reason for the non-invert buffers, so it could be read and then get out of the way. Best guess is the non-invert buffer chip is the 1820-1402 (74LS365) right behind the switch but you could confirm with a meter.

If the enable signal never arrives or one of the buffers is defective it could lead to the LANG warning. That switch is unfortunately missing from Tony's schematic, perhaps it only appeared in later revisions of the 86B, and the schematic section of the service guide for the switch is pretty blurry.

I also happened upon a manual "Introduction to 86B Local Language" on hpmuseum.org and found your message in there "101 (Warning) LANG UNDEFINED Computer hardware is not properly configured for local languages - the computer requires servicing"

Paul.