Sinclair ZX80 / ZX81 / Z88 Forums

Hi,

Sorry, it's not the Spectrum.

It the printer alignment needle start.
There is a decay with the first or the second printing needle.
You had to check both printing needles and check if it touches the metallic shield at the right timing.
At least one needle must be bent, broken or too short. You have to equalize their length.

XavSnap wrote: ↑Sun Aug 14, 2022 1:11 am Hi,

Sorry, it's not the Spectrum.

It the printer alignment needle start.
There is a decay with the first or the second printing needle.

printer.jpg

You had to check both printing needles and check if it touches the metallic shield at the right timing.
At least one needle must be bent.

Hi,

Apologies but this isn't the printer with the styli. It's a thermal printer.

Regards,

Brett

Sorry again.

May be the thermal printing resistor.

The printer may be kaputt.

It’s definitely not the ZX Spectrum. Both the ZX81 and the ZX Spectrum use the built in support in the BASIC ROM to send the correct bit pattern in a serial data stream to the printer.

The Timex Sinclair 2040 and the Alphacom 32 printers receive the same serial data stream intended for a ZX Printer, but instead print a line at a time using thermal heating pads controlled by driver chips.

The fact that the self test does not work properly demonstrates that it’s the printer that is the problem.

If you test your Alphacom 32 printer using your ZX Spectrum, that will prove it.

Mark

1024MAK wrote: ↑Sun Aug 14, 2022 1:24 am It’s definitely not the ZX Spectrum. Both the ZX81 and the ZX Spectrum use the built in support in the BASIC ROM to send the correct bit pattern in a serial data stream to the printer.

The Timex Sinclair 2040 and the Alphacom 32 printers receive the same serial data stream intended for a ZX Printer, but instead print a line at a time using thermal heating pads controlled by driver chips.

The fact that the self test does not work properly demonstrates that it’s the printer that is the problem.

If you test your Alphacom 32 printer using your ZX Spectrum, that will prove it.

Mark

I think I may have sorted it out. I've been looking at the schematic and noticed a part marked SW next to the motor.

I believe this is the white plastic thing with teeth just below switch 1 (off button) and this was moved all the way to the left. I've moved this to the center position as seen in the attached pic and now it prints perfectly during the self test.

Need to do some further tests connected to speccy but it's looking promising.

Does anyone have any idea what that white bit with teeth is? Is some sort of alignment switch or something?

See attached pics for reference.

Thanks,

Brett

I can confirm that the toothed "switch" or what ever you want to call it does alter the print quality/alignment.

I have two Alphacoms and not afraid to experiment, moving the toothed thingy side to side slowly whilst printing does alter the print alignment.
as for your other problem sorry I have no idea.

Moggy wrote: ↑Sun Aug 14, 2022 9:47 pm I can confirm that the toothed "switch" or what ever you want to call it does alter the print quality/alignment.

I have two Alphacoms and not afraid to experiment, moving the toothed thingy side to side slowly whilst printing does alter the print alignment.
as for your other problem sorry I have no idea.

Looks like that was the actual problem. It was just out of alignment. Now it's back in alignment all 3 of my printers now print. The two alphacoms were printing OK anyway it was just the Timex one giving me some problems. Bit it looks like adjusting this has solved the alignment.

Thanks,

Brett

Yes, it’s a position sensor/switch.

Mark