Calling all zaccaria owners

[Retropin]

I have a CPU board that will not boot... the CPU2650 nevers starts up.
OPREQ has a LO pulse and this should have a steady HI.
Now before i start thinking about replacing the 2114RAM ( has seen some acid damage) i need to make sure all other requiremets on CPU are in place.

Essentially, for CPU to run there are only 3 things it really requires.
5vDC
Ground
 and good CLOCK.

My clock is a LO pulse and im not sure that this is correct.... i thought it was active HI not Lo.

So anyone with a working ZAC game.. can you place a logic probe on TP2 and tell me if its HI/LO or not

Thanks guys..

[Steevsee]

I'll be happy to check this on my Blackbelt machine in the morning if still needed.

[Retropin]

Oh yes - still needed. Im pretty sure it should be Hi/Lo pulse.. but i need to confirm this

Thanks mate!

[Steevsee]

Ok Gav, before I let you know the readings, I have to confess that this is the first time that i've actually used my logic probe. 
It's a pretty cheap DSE kit probe that I put together quite some time ago. Anyway here are the results I got.

TP1 - HIGH(solid red led)
TP2 - LOW(solid green)
TP3 - PULSE(Solid red, green and yellow)
TP4 - LOW
TP5 - HIGH/PULSE (Solid red and yellow)
TP6 - LOW/PULSE(Solid green and blinking yellow)
TP7 - LOW
TP8 - LOW
TP9 - LOW

Alot of these look different from the Zacc website but I did check each TP a couple of times to confirm my results.
Not really too sure on my interpretation of the various led combinations. .
Happy to help further if I can.

Also If you happen to be around Chermside sometime, you would be welcome to come and have a look for yourself, if that would help.

[Retropin]

thanks for that.... odd readings which is why i wanted someone with a working Zac to confirm these for me.
I find that the Zac sites dont give you all the information.

The reading i was most interested in was TP2 - CLOCK... Zac sites state that it should be PULSING... i get a LO PULSE... you get a steady LO 

Every other reading on you probe is correct with the Zac sites bar the CLOCK... what im assuming here is that the clock on your logic probe is not fast enough for the CLOCK on CPU and shows only a LO.
On my CPU i have a LO pulse but at only about 2hz.

mmmmmm has the fog cleared??? er... no!

Thanks though mate... much appreciated!

[ajlaird]

The reading i was most interested in was TP2 - CLOCK... Zac sites state that it should be PULSING... i get a LO PULSE... you get a steady LO 

Every other reading on you probe is correct with the Zac sites bar the CLOCK... what im assuming here is that the clock on your logic probe is not fast enough for the CLOCK on CPU and shows only a LO.
On my CPU i have a LO pulse but at only about 2hz.

This does sound like a problem (unless your probe is reading wrong) - every clock pulse I have seen in real life for a CPU is in the MHz range.

[Retropin]

The reading i was most interested in was TP2 - CLOCK... Zac sites state that it should be PULSING... i get a LO PULSE... you get a steady LO 

Every other reading on you probe is correct with the Zac sites bar the CLOCK... what im assuming here is that the clock on your logic probe is not fast enough for the CLOCK on CPU and shows only a LO.
On my CPU i have a LO pulse but at only about 2hz.

This does sound like a problem (unless your probe is reading wrong) - every clock pulse I have seen in real life for a CPU is in the MHz range.

Agreed... clock seems real slow.... need to put my CRO on this but i went to use it and the probe fell apart! With CPU board out of cct and on bench clock should be 6mhz