HP 82162A printer HP-IL Transmit Err

[SilverGreen93]

Hi,

I just reworked a battery pack for the HP 82162A printer and wanted to use it with my HP-41CV calculator, but unfortunately whatever I try to do, I always get TRANSMIT ERR message on the screen. It was definitely working 10+ years ago.

What did I test:
1. I connected the HP-IL cable in a loop without any device and executed PRX => this gave NO PRINTER message, which is expected.

2. I connected the HP tape drive to the HP-IL interface and it works fine, DIR shows the files on the tape. So the HP-IL adapter must be good.

3. I connected both the HP tape drive and the printer in a loop. Any command I issue gives TRANSMIT ERR.

4. I thought that the printer does not transmit the HP-IL data out, so I measured with an oscilloscope the RX and TX HP-IL pins on the internal chip from the printer and signals do get in and out of the printer. See this signal here:


5. I also checked the IRD, IRW and ISEL pins of the HP-IL chip. The IRD and IRW receive low pulses from time to time, indicating that the CPU is accessing data from HP-IL. ISEL is tied permanently to ground as far as I can tell.

6. I measured the clocks: the CPU has a 4.00MHz clock signal, the HP-IL chip has a 1.917MHz clock signal. I know it must be 2MHz, but I think 1.917 is good enough, is it?

7. Pressing the Paper advance button does properly advance the paper. Pressing the Print button does nothing.

Do you have any other suggestions what could be wrong with my printer?

Here is a view on the internals:


Thanks,
Mihai