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

[Dave Frederickson]

Is the Printer Function Switch on the HP-IL module in the ENABLE position?

[MeindertKuipers]

Summarizing, you get the TRAMSIT ERR whenever the printer is in the HI-IL loop. Most likely this is an indication that the physical loop is somehow disturbed.
First test would be to check the electrical continuity of the IL loop and cables at the printer side with an Ohm meter, and if that is rougly the same as for the cassette drive. If that checks out good do the same for the loop's pulse transformer block of the printer (part identified with 9100-4226). This part is described in a document 82166-90020 HPILkitTech. Verify continuity of all transformer coils and connections.
If that checks out verify if all components between the pulse transformer and the HP-IL IC are functioning correctly.
I once had an issue with one of the transformer wires broken (of another HP-IL device) at the soldering joint, and resoldering solved the issue.

Good luck!

[SilverGreen93]

(03-17-2024 02:19 AM)Dave Frederickson Wrote:  Is the Printer Function Switch on the HP-IL module in the ENABLE position?

Good remakr, but yes it is. If it weren't, the print function would not be existing.

(03-17-2024 09:02 AM)MeindertKuipers Wrote:  Summarizing, you get the TRAMSIT ERR whenever the printer is in the HI-IL loop. Most likely this is an indication that the physical loop is somehow disturbed.
First test would be to check the electrical continuity of the IL loop and cables at the printer side with an Ohm meter, and if that is rougly the same as for the cassette drive. If that checks out good do the same for the loop's pulse transformer block of the printer (part identified with 9100-4226). This part is described in a document 82166-90020 HPILkitTech. Verify continuity of all transformer coils and connections.
If that checks out verify if all components between the pulse transformer and the HP-IL IC are functioning correctly.
I once had an issue with one of the transformer wires broken (of another HP-IL device) at the soldering joint, and resoldering solved the issue.

Good luck!

Oh, I was measuring the signal on the component side of the IL transformer... Now I measured on the connector side and there is indeed no signal at the output.

I measured with the ohm-meter the resistance of the coil and it is open, compared to the Tape drive on which it is about 1 ohm.

Initially on visual inspection it looked ok, but after touching the coil wire with a pointy needle the wire had immediately showed that is it not connected to the pin! What a coincidence! The same issue as on yours!

I could have not imagined that the coil wire could ever go loose. Might it have been a vibration problem from transporting the printer from one place to another?

I tried my best to solder back the (now much shorter) wire, and... surprise! The printer works!
Do you have any suggestion to make sure that it will stay there and not break loose again?
I am not certain I did a good job with the solder, because it was very hard to get it to grip and stay put. The measured resistance is 0.8ohm.

Here is a photo of the wire soldered back (the first pin on the left):


Thanks!