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Man I LOVED that game, shame all the arcade machines are in the states!

Hmmm. I reflowed the solder on the headers and crimped the ribbon cable both ends. The voltage at the ROM is now 4.9 but still reporting the ROM error. The middle two LEDs are lit on the ROM board.

Thanks Ken, I'll take a look tomorrow. I'll crimp the ribbon cable tighter too (it was replaced but just in case).

Thanks local but the sound board is the one thing I haven't had to repair on this machine..

AAAARRRGGGHH. Got a new ROM 6 and it's still complaining of an error on ROM 6! I measured the voltage going into the ROM board as 4.9. The voltage at the ROM was 4.7 is this too low? Anyone have any ideas on where to go now?

Hi Ken, I'm not entirely sure of the etiquette here about contacting members and asking questions by messaging so if I've transgressed my apologies! You were very helpful in a post I started about trying to fix my Defender machine last year. I got the boards repaired and after a series of...

Order in to JROK and Ken has been fantastically helpful. Really nice people to deal with. Thanks for the recommendation.

Thanks Mark, I think I will rebuild the PS. It has had some work done on it already. Incidentally the game has started playing up. It currently stays in the settings page after reporting a ROM failure on ROM 6. I've ordered a new set and I guess I'll start checking the voltages from the PS. How...

Im going to fit a switching power supply I'd hate to have the boards fried if the original fails

Is jrok like a jammer board?

I replaced the ribbon cable anyway and it works!!! Finally! Man its every bit as good (and difficult! ) as I remember. Thanks for all your help guys. Still getting a rom check error (on rom 6) but it plays fine.

Thanks Do you mean the ribbon cable between the cpu and the control board?

It's been a while Hi Guys, It's been a while but I'm almost there with this damned willo the whisp defender machine! I had to send the boards away for repair in the end (every time I fixed a problem it revealed another). Got the boards back connected them up and found out that the monitor had...

Hmmm looking at the specs for the 74393 counter at 3C if pin 12 is high then pin 8 should be low? http://www.kpsec.freeuk.com/components/74series.htm#74393 Also it looks to me like this chip has been changed..

OK pin 4 at 3D is low, pins 5 & 6 at 3D are high. I can't check if pin 12 at 3C is pulsing as I borrowed an oscilloscope last time but pin 12 is high. I'll borrow a scope again and let you know if it's pulsing. Thanks again for your help. Andy

Wow thanks gavinyuill; that really does help!

Does anyone have a schematic that maps the circuit to the physical layout of the board? I can't find one anywhere and it would make life a LOT easier..

OK, looks like the reset circuit is OK, it's the watchdog circuit that seems to be low on startup. If I 'force' the reset by bridging the pins the watchdog pin and the reset pin are high and then the reset works as expected (both inputs are high until the reset switch is pressed then the reset...

Thanks.. Thanks guys for the prompt reply, looking at the schematics the board seems to be the old board layout so I've been using the 'defender_early_pcb_theory.pdf' circuit diagrams. The gate is labelled 5F in this document and 6O on the 'defender_later_pcb_theory.pdf'. Am I right in using...

Can anyone help me get an early Williams Defender working? Hi, I can't tell you how excited I am to own a genuine Williams Defender. It was always the game I loved to play in the arcade as a youngster (far too many years ago now) and I am pathetically desperate to get the thing working again...