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Home  /  Arcade • Tech / Repair  /  Teenage Mutant Ninja/Hero Turtles RAM fault
23 November 2016

Teenage Mutant Ninja/Hero Turtles RAM fault

Written by S11
Arcade, Tech / Repair Comments are off

This one is a simple fix but I thought I’d use it to demonstrate a technique for making minor track repairs.  I received a TMHT PCB today which on testing showed this mess:

tmht_fix1

While the screen is a complete mess, you can make out a number of ‘OK’ and ‘BAD’ messages.  With this many problems and one ROM affected, it seemed best to start with address lines on the ROMs.  Immediately the one at J15 turned out to have a disconnected pin 4.  The address lines are shared between ROM and RAM near the CPU, which meant there needed to be a broken track somewhere.

tmht_fix2

And this is what I found tracing a track just hidden under J17.  This is very likely to be the result of someone trying to do a 4 player to 2 player ROM conversion, and being careless with a screwdriver.  There’s a somewhat tidy way of fixing small track breaks like this without leaving a big jumper wire on the game.

tmht_fix3

First scrape some insulation off the track and ‘tin’ some of the copper – liquid flux will help here, just a tiny bit.

tmht_fix4

Next you need a couple of strands of thin wire – here I just split two off from some fine gauge multicore and twisted them together.  Tin those too.

tmht_fix5

More liquid flux, and solder the exposed tinned wire to the tinned tracks.  It’s usually easier to do than this but the socket was kind of in my way, and I didn’t want to go through the invasive and time consuming process of removing and refitting it.  This is why we leave some insulation on the wire, to use as a handle.

tmht_fix6

Then use a razor blade to cut the handle off, leaving a few strands of wire as a track repair.

tmht_fix7

Tidy up your work by cleaning away the flux and using some masking fluid to cover up the exposed track.  Again this can be done a little tidier when you don’t have a socket in your way.

tmht_fix8

Looks fine though when it’s all back together, and the game is repaired!  Actually it did have a sound fault too, it would sometimes make intermittent rumbling pops, the 12v filter capacitor had been knocked, damaging it.  Another easy fix.

tmht_fix9

S11

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