Defender tech help urgently needed!

[retroshaun]

[ukvac] Defender tech help urgently needed!
OK Guys, heres my situation!

A while ago I was asking about replacement power supplies for a Defender
which died (got power up sound but nothing else, no picture etc). Anyway
after a lot of hassle I have fitted a switching power supply kit from
Bob Roberts. Powered it up, got start up sound OK, looked at screen and
now I get a picture as if the machine is trying to go through the "rug
pattern tests" buy it hangs there with a "sort" of rug pattern but not
as random (the screen is filled with garbage but in kinda "stripes"
vertically down the screen, across the entire area. These are kinda
"flickering"). To make matters worse, after leaving it like this for
perhaps 30 secs I noticed a smell of kinda burning "rubber" (likely
circuit board!) and switched off. None of the LEDs are on on the game
boards at all. The power is working fine. Bob said it is probably a
short someplace but can offer no more help... at the moment I'm backed
into a corner here.

**** H--E--L--P **** !!!!!!!!!

This has been going on for ages now and as I'm gonna move away out of
the country soon I would like it fixed before I go. Can anyone offer ANY
help/solutions to this nightmare?

Cheers guys!
Shaun

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[Ravage]

[ukvac] Re: Defender tech help urgently needed!
Oh dear Shaun - tales of woe...

how about this for the stripes:
PROBLEM:
Rug pattern incorrect. Instead of being a random pattern, it is a very
uniform horizontal line pattern. Keeps repeating.
SOLUTION:
Bad output on pin 5 of 7474@6E (CPU board). Replacing the IC solved the
problem.

Taken from the most excellent http://www.nanonano.demon.co.uk/arcade/pr
obsa_i.htm#Defender (Williams)
hosted by Scott green

Just make sure the pcb ties up (theres two types, silver-ground edged
ones and all-green later reevisions), so check that the actual chips is
a 7474

As for the burning.... hmmm and an extreme EEK!

Hope this is of some use

Rav

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[Ravage]

[ukvac] Re: Defender tech help urgently needed!
DOH!

Re-rread and noticed you did mention vertical... so....

PROBLEM
Vertical colour bands across screen.

SOLUTION:
No output from 74LS74 @ 6E. Replacing the IC fixed the problem.

Rav the hasty

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