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john

MPS 1 7 segment digit (topshot)

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Hello,

I recently go me a Topshot with a MPS1 board inside.

after removing the leaking battery, reparing tracks on the board, placing a new battery, replacing IC16 I got down to the last failure code where the segment at the right bottom is lit.

the manual says:

BB/PTR  on =PTR

 

does anyone know what this means?

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Edited by john

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I'm sure I had a Dutch board with a Dutch game that run with this segment on all the time. Nick?

 

BB is black box, prt is printer. Which is to do with the communication port. You could try running a uk program to see if it goes out ok.

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thnx,

i'll check out the communication port tomorrow.

Perhaps some waste of the soldering is causing a connection there.

there was al lot of it on the board when I was removing IC16.

I don't have a UK program to test it.

there is a same cabinet for sale in the naberhood but that's also not running and can have the same problem.

Edited by john

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After a good clean up of the board.

The machine started up.

Now there's the following the machine runs and the game is playable.

But none of the lights go on.

None in the buttons and none in the upper and lower glass.

the TL's are on

Also there is a strange humming coming out of the speaker.

the digit segment of the printer is still on.

Edited by john

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Can't say I'm much use on MPS1. I'm better with MPS2, but here goes on MPS1...

 

Check lamp supply voltage is hitting the MPU (4 pin connector from PSU to MPU)

 

 

Can't quite tell if the left 7 segment has the lower right segment on or off... for mux timeout (multiplex lamp timeout)

 

Also have a look around IC23 pin 13. I've seen C58 go bad and half lights would not work but no mux timeout was indicated. On the CRO you should get a wave form like \\\\\ on the screen at the cap, but it was falling too fast and chopping the second half of the wave, which in turn chopped the lamps.

 

think there are one or two other caps across LS123 Multivibrators on MPS1 that cause faults, but seem to recall they hold the board off running at all.

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I was going trough the manual and saw that all the light signals went trough IC14.(pic)

I think there 's the light problem..

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Edited by john

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IC14 is the buffer for all the data lines (like IC 11 and 12 buffer the address lines).

 

Don't  think the MPU would run with a bad IC14 as all the data lines go to all 4 PIO's and the RAM (IC8)... not just the Lamp PIO (IC38) but could be wrong. MPS2 won't run with a bad buffer chip.

Edited by Louie Bee

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