WinPic+Tait+16F84A

[Sh@dow]

I measured everithyng with Vdd turned on and:
Vdd +4.88
MCLR +13.17
DATA +4.88
CLOCK +4.88

 

[Nigel Goodwin]

And do Data and Clock switch between 0V and 5V as you switch then ON and OFF?, and does the Input pin follow the Data pin?.

 

[Sh@dow]

I found another schematics,which is a bit different.I Modified my programmer ant it works.
I attached the modifications i made.They are the same for Data,Clock and ACK line.

 

[Pommie]

But, the original circuit already had the pullups. Didn't you fit them?

Mike.

 

[Sh@dow]

Original circuit has pinups between chip 74LS07 and PIC.There are no pullups between LPT ant 74LS07.I installed pullups between LPT and 74LS07.

 

[Nigel Goodwin]

Original circuit has pinups between chip 74LS07 and PIC.There are no pullups between LPT ant 74LS07.I installed pullups between LPT and 74LS07.

The pullup resistor is absolutely essential, as the buffers are open-collector, and (as expected) it is shown on the original Bob Blick circuit - I just checked the link in your first post!.

Presumably you must have missed it?.