Midway Sea Wolf repair question(s)

gwarble

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Hey all,

I'm waiting for some parts ordered to continue diagnosis/repair of my new Sea Wolf (links to "score" thread):


and i found broken legs on an ic at C5 in the pcb diagram labeled:
"3235
3245"

from here

is this the correct replacement part? (links to arcadechips.com item D3245)


and would this "clock driver" being dead give me no CPU activity/clock?


Also, any tips for removing the edge connector between the 2 boards of the 8080 "L" stack? I'm tempted to cut it and try to desolder sections... i'm skeptical of being successful removing the solder enough on all those pins to pull it out in one piece... any experience? a few pins are jacked and overall not very tight so i'm planning to replace it (though i may try C5 above first and hope to get back to getting garbage on the screen)
mtkr4BX99tAF399toSZFZmw.jpg


Thanks in advance,
gwarble

edit: ok i'm pretty confident that D3245 will work...
 
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This is a description of the chip and It's function.

The DS3245 is a quad bipolar-to-MOS clock driver with TTL
compatible inputs. It is designed to provide high output current
and voltage capabilities necessary for optimum driving
of high capacitance N-channel MOS memory systems.
Only 2 supplies, 5 VDC and 12 VDC, are required without
compromising the usual high VOH specification obtained by
circuits using a third supply.
The device features 2 common enable inputs, a refresh input,
and a clock control input for simplified system designs.
The circuit was designed for driving highly capacitive loads
at high speeds and uses Schottky-clamped transistors. PNP
transistors are used on all inputs, thereby minimizing input loading.

So it looks this chip was design drive MOS memory on the board.
So replacing the board might not get you the clock back.

You might want to pull the CPU and check if the clock is pulsing..
 
I'm waiting for parts to fix some sockets, replace that chip, and improve the L interconnect, but here's a quick recap of my attempts to fire it up

After fixing a broken fuse holder and wire splice, i fired it up
First try, spark on the monitor chassis, flicked off quickly
Monitor inspected, nothing so i fired it again and got garbage on the screen
http://forums.arcade-museum.com/attachment.php?attachmentid=130464&d=1357780394

Voltages test good, got some different garbage a few times...
http://forums.arcade-museum.com/attachment.php?attachmentid=130466&d=1357780473

Pulled pcbs, reseated two boards again (and found some suspect pins, but reseated and ordered new edge connector)
Also reseated 8080a in screw down blue socket, and reseated C5 finding broken legs
http://forums.arcade-museum.com/attachment.php?attachmentid=130276&d=1357539587

Now i can't get anything back on the screen
Voltages check out fine on the CPU, but i dont see a clock signal on pin 19 i think it was
I don't know if i had a clock signal when i was getting screen garbage, but i'm trying to get back to that point at least

Thanks for the info, i agree it sounds like that chip would use the clock signal but not help create it
 
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I have been try to find a complete schematics to give you a hand.
But I have yet to find one. so i do not know if the 7400 around the crystal has to do something with the clock.
 
Thanks will do...

Do you know if i could have got screen garbage (or the vertical bar RAM test w/o ROMs installed) without the cpu clocked?

If so, i may have never had clock
If not, then i must have a poor/intermittent connection or killed a component to lose my clock
 
I wish I was more help to you. If I had one I could step you through the whole game.
I can just give you a best guess. Someone really needs to make a website for this game like they do for the space invaders.

Do you have a logic proble or a scope?
 
Thanks, you're already being a help... and actually the Space Invaders threads/logs are very helpful and way more abundant than SW...

I have a feeling once i change these connectors/sockets/chips i'll be better off diagnosing these issues...

No scope or ESR meter, and i'm an amateur on the logic probe... i bid on an ESR meter, never needed one before, i may just start changing out caps though
 
So the 8080a datasheet tells me the clock output signal, as well as CLK1 and CLk2 inputs, from the xtal circuit i guess?

It says non-TTL clock signals, can i probe to see if they are getting to the CPU? Also will my probe being rated 17mhz be inadequate for this board running at 20mhz?
 
8080a CPU

If it is an 8080a -2 it runs at 2.6 MHz
If it is an 8080a -1 it runs at 3.1 MHz
If it is an 8080a with no dash number behind it it is a 2 MHz

Have you tried removing the CPU and using the logic probe to PIN number 15 and PIN number 22
 
So when i realized the edge connector i ordered from china so i'm gonna have to wait a few weeks... I started checking continuity on the old one, from pins below main board, to edge trace on the daughter board, and only one pin with actual circuitry on both sides was open, so i stuck a thumbtack behind the pin and got continuity

Then i pulled the D3245 and pushed it deep into a new socket, verified continuity on all pins, and reinstalled it... also did this with a suspect ic near the cpu

I was able to get vertical bars on the screen again... reinstalling the ROMs sisn't bring back the first garbage i got, but at least i got video signal back

I probably have to shelve it for a few days as i have to return to work tomorrow (been on vaca), but i think i should be able to get a little farther now (check the RAM pairs and figure out which are bad)

Lastly there's a schematic pack overpriced on the bay, should i drop 25 bucks on it?
 
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