Z80A for a Punch-Out boadset?

[MaximRecoil]

I bought a "complete but non-working" Punch-Out boardset for about $50 less than they have been selling for in working condition on eBay lately, and well, when I got it, I noticed it wasn't "complete", but it was pretty close. The only thing it is missing is its Z80A main CPU; just an empty socket there. I also noticed a broken ceramic .01uf 50v disk capacitor on the CPU board.

The easiest place to get a Z80A and know it is the right one is MikesArcade IMO, but he is out of stock for the Z80A (well, he stocks the NEC D780C-1 clone actually) - http://www.mikesarcade.com/cgi-bin/store.pl?sku=Z80ACPU

So I came across some in an eBay store - http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7555490921

Does anyone know if those are the right ones? They are genuine ZiLOG Z80A's @ 4mhz, which is correct, but I don't know about that "SIO/0" part. I came across this site which shows Z80 SIO/0, SIO/1, and SIO/2. What is the difference? How can I tell which one I need?

[Ken Layton]

Jameco Electronics (www.jameco.com):

# 35596CH        Z80A (cpu) 4 mhz   $1.99

# 15230CH      .01 uf @ 50 ceramic disc capacitor (6 cents each with a minimum order of 10)

[MaximRecoil]

Thanks Ken. How about those Z80A's in the eBay store link that I mentioned in my original post? Are those the right ones as well? I'd rather get those because they are new rather than refurbished (how do you refurbish an IC anyway? and as cheap as a Z80 is, why would they bother?) plus they are cheaper (2 for a dollar rather than 1 for $2). Cheaper isn't a big deal since it is a small amount of money either way, and it might even out with shipping cost (I can't see how much shipping is from Jameco) but I do like the idea of getting 2 of them that are brand new for a dollar. The same eBay store also carries the .01 uf @ 50 ceramic disc capacitor that I need (25 pack for a dollar) and they automatically combine shipping on multiple items.

[Ken Layton]

The chips in that ebay link are NOT Z80 cpu chips! Those are support chips for a Z80---definitely not what you need. The chips I linked at Jameco are exactly what you need. Jameco has reasonable shipping charges (not anything like Happ!).

[MaximRecoil]

Thanks again Ken, I'll order from Jameco. I came to about the same conclusion after some Google searching right after I posted. It looks like the one on Ebay is a microcontroller while I need a microprocessor (CPU) like the one you linked to at Jameco...or something like that. I'm still wondering what is up with them being refurbished but as long as it works I suppose it doesn't matter.

[D_Zoot]

The "refurbished" parts Jameco sells are pretty much just pulls.  I guess they test them and clean them up (clean legs), justifying the "refurbish" label.

I've ordered a lot of "refurbished" chips from Jameco, most were  items that just aren't readily available as NOS anymore.  I've never had a bad one from Jameco and wouldn't hesitate to continue buying pulls or refurbished parts from them.


D

[fredster]

Bob Roberts keeps those chips.  I always go to him first.  He keeps a lot of odd and obscure chips.

Try finding an MB3731 sometime.

[MaximRecoil]

Got the parts from Jameco today, the Z80A and the capacitor. I installed them, plugged the boardset into my cabinet and it fired up fine. I played it for about 20 minutes and the "non-working" boardset I bought works 100%, no problems with either the video or audio. So that was a pretty cheap way of acquiring a working Punch-Out boardset.

Something strange with that cabinet that I noticed before and have now confirmed; both coin slots only work if you have the shield cage cover installed. With both my SPO and now with my PO board, if you just slide the board into the cage, and press the card edge connector from the harness directly onto the board's edge connector, only the left coin slot works and the right does nothing if you insert a quarter. If you install it properly with the shield cover which actually does have some electrical componentry on it, beyond just being a card edge connector extension, then both coin slots always work fine.

Does anyone have an explanation for this? Something to do with ground maybe?

[ChadTower]

Has to be completing the ground loop that the coin chutes are connected to... look for the ground wire from those chutes, probably goes to one of the screws on the side of the cage.

[MaximRecoil]

Has to be completing the ground loop that the coin chutes are connected to... look for the ground wire from those chutes, probably goes to one of the screws on the side of the cage.

No wires going to any of the screws, or any part of the cage at all. I agree that the cage cover must complete a ground somehow, but I can't see how it does it. On RGVAC a few weeks ago, someone posted that they had a Punch-Out machine for sale and that one of the coin slots didn't work. I'll bet he was missing his shield cage cover.

Now, I've noticed another thing. I've been playing that PO boardset quite a bit today since I got the Z80A and capacitor installed in it and everything is perfect, no problems with the gameplay, audio, or video at all. Just a few minutes ago, just for the hell of it, I started it up in service mode and for the ROM test, it is showing "NG" for location 8H ("OK" for everything else in the ROM and RAM test). According to the manual, "NG" = "failed". This doesn't make any sense because like I said, everything is working perfectly. So I'm assuming that is CHP1-C.8H. Anyone know what that particular ROM is responsible for?

It is kind of funny; when I was having audio issues with my SPO board, its service mode showed everything to be OK; and now I am having no issues with this PO board and its service mode is telling me there is a problem.

I'm not sure if I should try to fix something that is only broken in theory, lol.

[fredster]

I have an Rtype I'm having trouble with that says "NG" and points to "work ram".

Those boards must be getting old. I can't find the ram for it.

Ken is da man when it comes to finding parts.  How much did that chip and shipping and all cost you from Jameco? (if you don't mind me asking)

[Ken Layton]

Jameco's shipping prices are pretty good. When I place an order with them (since I mostly order lightweight stuff like chips and transistors) I select good old US mail for shipping. I think it was only $5 (considerably cheaper than other methods and faster too).

[ChadTower]

Not if you have my mailman... cheaper isn't any good when he leaves it on the ground 40 feet from your house.

[MaximRecoil]

I have an Rtype I'm having trouble with that says "NG" and points to "work ram".

Those boards must be getting old. I can't find the ram for it.

Ken is da man when it comes to finding parts.

[MaximRecoil]

Do you have any thoughts on this, 2600? (assuming you read this thread). I was thinking of trying a different ROM at 8H because even though there are no problems with the game play, audio, or video, this will continue to bug me until I get to the root of it. Can you burn that 8H ROM, and if so, how much to send it my way?

[2600]

That ROM is CPU code.  What it does I dunno.  What type of chip is it?  If verify my burner can burn it after the break.  If so you pay for the part and shipping(to me and back to you) and I'll do it for free.  If you want to send me yours, I'll read it to see if it's the part.

Have you tried taking the chip out and cleaning the contacts and/or check for any bad solder joints first?

[MaximRecoil]

That ROM is CPU code.

[2600]

Let's say the test code does a checks the contents of the ROM.  One bit off and the test would fail.  One bit could be as severe as making a machine crash, be as benign as making one pixel of a sprite have a slightly different color, or making a change in part of the code that isn't even called.

Looking at the Z80 would probably be one of the last things I look at.  I'd start with what the test says is failing.

 

[MaximRecoil]

Let's say the test code does a checks the contents of the ROM.  One bit off and the test would fail.  One bit could be as severe as making a machine crash, be as benign as making one pixel of a sprite have a slightly different color, or making a change in part of the code that isn't even called.

Ah, okay, that's good to know.

Do you have any 2674 Eprom's on hand that I could pay you for or should I send you one? I have that one which is a 2764 that I got for the Super Punch-Out board that I ended up not needing but it doesn't have a window, so I don't know if it can be reprogrammed or not?

[2600]

Sorry, I don't have any spare chips and can't find my UV eraser, which I would need.

You can try hobbyroms.com.  I've heard people use them before and the prices don't seem that bad.