Galaga Issues (still) 2148 RAM... Where to get?

Scucci

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I'm try'ng to find a place that will sell a few 2148 RAM for cheap'sh, take paypal, and not have a retarded min. order?

I found a place that has them for @ 3 bucks a piece... but they want a $15 min. order... I'm only needing 2 for sure (Galaga fix, hopefully) and maybe a 3rd for any boo-boos.

If I can't find a place like that, is there anyone willing to part with a few?(yeah, posting here to save the trouble of a second post in the WTB section)

Anywho, besides that, I'm curious about the speed? What should I be looking for as far as speed with these guys go (for Galaga), or is it a non-issue?

I've got some weird boot issues (boots a little different every time I power it on). Sometimes I get a black screen now, sometimes the screen is filled with gibberish (mainly "M"s... or "W"s...) I've replaced sockets, cleaned legs (RIP Starfield generator... I hardly knew thee), replaced the 6116 rams, verifed the EPROMS, reseated everything, reflowed (reflown?) all the connector legs, verifed the ribbon cable is good, and I have no goofy resistor packets, voltage is correct, and I've hired a young priest and an old priest... still nothing, so... betting on RAM. If it's not the RAM... ... ug.

Any ideas on what it could be besides the RAM? And before you say the 74367 and the 74245 chips... please feel free to elaborate on them more. I've asked about them and gotten nothing back. I have their (and pretty much every other chip on Galaga)'s datasheets printed out right here, but without a decent flow chart or basic idea of what I should be looking for, in general (locked high, low, etc)... I might as well have a large stack of quilted 2-ply.

I'd REALLY love it if anyone knows of any Galaga flow charts for logic probes or anything like that...? I have them for Williams, but it's just a shame I haven't been able to find any for any other boards.
 
There's only 1 6116 SRAM on the board...

Did you replace the 2114 SRAMs?

If the 2148s are bad you won't have that symptom of Ws or Ms filling the screen.

RJ
 
There's only 1 6116 SRAM on the board...

Did you replace the 2114 SRAMs?

If the 2148s are bad you won't have that symptom of Ws or Ms filling the screen.

RJ

I can't tell... they were socketed to begin with (my thing is socketing everything I replace)... I'm pretty sure I've swapped them back and forth with Crazy Kong... but Crazy Kong was having issues as well... I guess I should make sure and get (and mark) a new set of 2114s.

Even before the machine started filling up with W (M)'s I was getting 2L errors and boot randomness. That's since gone away only because it doesn't even boot that far anymore.

Honestly, if repairs for these boards weren't so friggin' expensive, I'd've sent them off to be rid of the headache a long time ago.
 
It's expensive because it takes sooooo much time to do.

In general, I replace every socket that is 24 pin or bigger then clean all the chip legs and repair broken ones before putting them in the new sockets. After that all the resistor packs of the old/crappy style are replaced.

Once that's done then I can start troubleshooting any remaining problems. You'd be surprised at how many Galaga boards that fixes.

I put together kits with sockets and resistor packs but haven't put them on my site yet.

Now since yours has gone down hill I'd recommend looking at the legs on ANY chip or socket that you desoldered. If you see any coppery looking gunk on the legs then you pulled out a plated thru hole and you'll need to patch that. The traces and plated thru holes are easy to rip up & out on the Galaga boards.

If you give up, I can look at it. BUT, it's not cheap to work on Galaga. I do take trades on parts/boards towards repairs.

RJ
 
I checked the legs and sockets as I removed and replaced the chips, I didn't pull anything through from what I noticed. To make it easier on me, I just pried off the black cases on the sockets, then too my little bulb style desoldering iron... and used it in reverse and just blew the solder and pins out of the holes, so there was basically no pulling required. I checked the legs as I soldered the new sockets in to make sure I had a good connection, everything checked out. The machine actually behaved the exact same after I replaced some of the sockets as it did before I replaced them... but a few days later (after many more hopeful tries) it started the "M"/blank thing and it's pretty much been there every since.

Normally I'd say it'd be cheaper to get a new one... but for some reason, there are $250 Galaga boardsets littering Ebay... so I guess I can expect a price hike on them... thanks, Dale. lol
 
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