Sinclair ZX80 / ZX81 / Z88 Forums

Lardo Boffin wrote: ↑Wed Dec 06, 2017 5:16 pm Well, so long as they are polite!

I hope I wasn't unpolite.

Paul wrote: ↑Wed Dec 06, 2017 5:53 pm

Lardo Boffin wrote: ↑Wed Dec 06, 2017 5:16 pm Well, so long as they are polite!

I hope I wasn't unpolite.

No - you were very polite!

Lardo Boffin wrote: ↑Wed Dec 06, 2017 5:54 pm No - you were very polite!

Thanks for the feedback, it's always hard to tell for me because I don't usually communicate in english

Arrggghhhh!

The ZTX313s arrived today so I put them in (the right way round ), got a pulse and switched on.
I get a white screen and no K. Did I say argh?

The board was working - when I temporarily put the original TR2 back in earlier in the week I got a K. So I guess the question is - what have I broken while I was messing around? The ICs are Ok I think - I put them in another board and got a K.

Helllpppp!

Did you change resistor values?

sirmorris wrote: ↑Thu Dec 07, 2017 3:22 pm Did you change resistor values?

No - I left the original resistor in and removed the test ones.

The only thing I can think of is that I shorted something while soldering but cannot see anything.

I’m getting the same pulse on pin 6 of the Z80 on this board as another working one so it looks like that side of it is ok.

Edit - almost the same. The working board is pulsing and showing Lo at the same time. The non-working board is just pulsing. Not sure if that is significant.

Really wish I had left that ZTX313 in there...

Don't Panic!
Just start your fault finding investigation from the start...

• Test the +5V power rails
• Check for solder splashes using your eye (and maybe a magnifying glass)
• Test the Z80 CPU pins, A14, A15 plus /RESET, /MREQ etc...

You'll get there in the end

Mark

1024MAK wrote: ↑Fri Dec 08, 2017 2:53 am Don't Panic!
Just start your fault finding investigation from the start...

• Test the +5V power rails
• Check for solder splashes using your eye (and maybe a magnifying glass)
• Test the Z80 CPU pins, A14, A15 plus /RESET, /MREQ etc...

You'll get there in the end

Mark

Its more stress than panic. This was supposed to be fun but has rapidly developed into a ‘mare.

I have checked for solder with my eyes and a times 3 magnifiying glass (need a better one) and can’t see any. But that is not 100% proof.

Test results:-

There is always time for Excel! May extend that for all pins...

I do randomly sometimes get a pulse on A14 but not always. I never get a fast pulse on A15.

Its more stress than panic. This was supposed to be fun but has rapidly developed into a ‘mare.

That is why everything is called "work"!

"I have to work on something."
"i have to finish working on something."
"Something is not working, I have to work it."
"I am going to work."
"I wish that guy would work."
"I am tired of working on someone else's responsibilities."
"I am tired of repairing this, I wish it would work."

Don't Panic is a phrase on the cover of The Hitchhiker's Guide to the Galaxy...
Hence is the standard response to any situation...

Mark