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Major Title pcb repair
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ben76 View Drop Down
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    Posted: 05 February 2015 at 12:06am
Hi all,

I recently got a Major Title pcb however it was faulty! Which was good as I've not been well recently and needed something to focus on. The pcb arrived on Monday 2nd Feb and I had time to get straight on it!

1st plug in gave out a ram problem.





That was the pcb saying which rams are bad and also the Major Title logo was messed up and over too the left.

I looked online for the schematics and couldn't find any Ouch so I looked for repair logs and one on Aussie Arcade by IG/VG sort of matched so I piggybacked a ram and the logo appeared back where it should and one of the red '1' had gone back to a '0'... result I removed it and socketed in another 6116...





I was getting somewhere... This then led me to piggybacking ram to see if any difference occurred. Not much happened then I realised the ram maybe working in pairs so tried piggybacking multiple rams. Slowly I started getting somewhere.... (and forgot to take pics of the roms!)

Anyway....

After a total of 7 6116 rams changed (thank you sf2 boot pcbs!)





Enjoyed that one Smile now to rtype it.... Big smile

- Ben

P.S. I think I am right with the 6116 ram being tied in lots of 2 and also it seems to like 2 of the exact same (I did try the same speed marked but it didn't like it so had to change both!)
P.P.S. Not sure why it had 3 faulty ram chips reported and I had to change 4 locations overall Confused
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mr_ppp View Drop Down
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 Post Options Post Options   Thanks (0) Thanks(0)   Quote mr_ppp Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2015 at 12:13am
Nice one Ben! Hope I'll be able to do things like this one day Smile
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Nimajamin View Drop Down
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 Post Options Post Options   Thanks (0) Thanks(0)   Quote Nimajamin Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2015 at 1:49pm
Now to Par-Type it Big smile ..gosh, I better pull my finger out & get that guide sorted.
Join the resistance..! (Lead solder is preferable)
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 Post Options Post Options   Thanks (0) Thanks(0)   Quote tb2000 Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2015 at 1:53pm
Originally posted by Nimajamin Nimajamin wrote:

Now to Par-Type it Big smile ..gosh, I better pull my finger out & get that guide sorted.
Please! Big smile I've got one to do for myself and one for Olly! I've also got a faulty Major Title 2 which I think is ripe for a R-Type Leo conversion! LOL
Currently looking for: 14" and 19"/20" Hantarex/WG/Electrohome/Kortek etc. monitor frames
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Nimajamin View Drop Down
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 Post Options Post Options   Thanks (0) Thanks(0)   Quote Nimajamin Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2015 at 1:55pm
The basic trick is to use a pair of 74LS157's (basically each one is a 4 way switch (two sets of 4 inputs, 4 outputs & an A/B select) to route the 5 (iirc) pcb mods to be either modded - or not, based on the Hi/Low Rom select signal routed around the board. (The Bydo Orange wire in the original post)

The reason I dont have a guide prepared was that I just went through each mod in turn. Wish I documented the second one I did, it was much neater, using more of the original traces - in place of patch wire.

I did photo it tho, so I should be able to retroactively doc it.
Join the resistance..! (Lead solder is preferable)
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ben76 View Drop Down
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Points: 20952 		Post Options Post Options   Thanks (0) Thanks(0)   Quote ben76 Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2015 at 4:20pm
Originally posted by Nimajamin Nimajamin wrote:

Now to Par-Type it Big smile ..gosh, I better pull my finger out & get that guide sorted.
Still waiting.... TongueLOL got enough chips sorted to do 1 dual conversion

- Ben
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nice, thanks for sharing
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GadgetFreak View Drop Down
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Points: 25 		Post Options Post Options   Thanks (0) Thanks(0)   Quote GadgetFreak Quote  Post ReplyReply Direct Link To This Post Posted: 18 November 2016 at 12:47pm
Hi,
I know this is an old post but I have a MT that is showing exactly the same ram errors, yours is the only repair post I have managed to find for this problem.
Do you remember which rams you replaced to clear those 2 ram faults?
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