no pulses on pins3 of IC35 and IC36. On C11 there is only 1.5V
This is very strange.
As a reference please check the pulses on pin 3 of IC37.
There is continuous pulses and a burst of fast pulses when you click the sine button down.
One problem may be the cable. Is it really a 25 lead printer cable (not a serial port cable) ?
yes, pin 3 of IC 37 works as you wrote. Cable is pin to pin lead, about meter long, checked with multimeter.
But no pulses on pins 3 of IC35 and IC36 even if you repeat to click the sine button on and off ?
Please check that there is no short circuit from these pins to the input section’s ground.
If not short circuited, what is the DC voltage on these pins to the input section’s ground?
yes, as you wrote. IC35 pin 3 is about 3.3V constantly. IC36 pin 3 is 0V. Measured against computer ground. Seems something wrong with my LPT? How must be serial port configured in BIOS?
It is not critical. - The ECP mode seems to work in my test PC with Windows XP.
If you are using Windows XP, please check the check box “Disable LPT Plug-and-Play (Windows XP only)” in the PcLab2000SE user interface. Then click the OK. - Then you are requested to restart the PC.
okay, thank you for your help, I will probably try it on another PC in a few next days.
and I will test the thing you wrote
OK.
The problem is now isolated - but the root cause is still unknown…
hi,
I have two laptops here. I’m trying to get some pulses directly from LPT. I have oscilloscope connected to ground, live wire to pin1 of LPT - getting here burst tone. Pins 7,8,9 do nothing when I’m pressing sine button. Is my measure config right? Or I’m doing something wrong?
[quote]Pins 7,8,9 do nothing when I’m pressing sine button. Is my measure config right?[/quote]When the sine button is pressed down, pin 7 should give two pulses and pins 8 and 9 should give a 400ms long burst of pulses.
From pin 9 there also comes one 5ms negative pulse every 100ms.
Is it possible that the LPT port data lines 2-9 are configured as inputs?
[quote]
Is it possible that the LPT port data lines 2-9 are configured as inputs?[/quote]
how can I check configuration of my LPT, please?
First you have to check the LPT port mode in BIOS.
Select the Compatibility Mode, also known as Centronics, standard or SPP. It is a uni-directional.
Laptops has only EPP or bi-directional mode. Desktop PC have also EPP+ECP and “Normal” mode.
So now I’m on my desktop, LPT set to normal. When pressing sine button, getting right pulses on pin1 and pin9 of LPT.
Pin7 is 3.3V all the time and pin8 is 0V.
I will try to check it with another desktop PC
The LPT port mode should not be very critical.
I tested with a desktop PC the following modes: Bi-Directional, EPP and ECP.
The K8016/PCG10 works well in all modes (in Windows XP).
okay,
I think now I’m getting correct pulses to pins 1 and 3 of IC22. Still dont know whats wrong with pin 2 of IC22. It seem there is instantly 5V without any pulses. Circuit now works this way - LED “ready” switches on and off when I’m pressing sine button. Also voltage on “signal out” is changing when I’m moving offset bar.
But still no waveform on output.
There are only two very fast negative pulses on pin 2 of IC22.
I think the pulses are there. You shouldn’t get the offset setting to work if there are no pulses.
Now you have to check if data is loaded to the RAM IC10.
Can you see the data on the data lines?
Is the address data running?
yes,
D0-D7 on IC10 shows data activity when sine button is pressed.
but pins A0-A14 are 0V all the time.
Please check the RESET signal on pin 1 of IC48, IC49…
Should be high.
Only one negative pulse is there when the sine button is pressed.
both pins are LOW all the time