Defender Power Supply needed urgently

[G-man]

[ukvac] Re: Defender Power Supply needed urgently
At 19:13 05/01/2000 +0000, you wrote:
>At 18:59 05/01/00 -0000, Rob H wrote:
>>Maplin are c**ts! At least they are at my branch. I get my bits from
Swallow.
>
>Swallow are WAY overpriced on many items, although I WILL say that their
>JAMMA fingerboards are brilliant.
>Yes I know Swallow are probably reading this.
>Use Maplin mail order, or get a CPC account.

Bear in mind that each Maplin is a franchise, they only pay to use
the name, so the quality of the shops can vary hugely.

Our local Maplin in Aberdeen is pretty good at
having stuff in stock, even fairly obscure items. As others have
said, mail order is top notch.

Graham

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[Nivelo]

[ukvac] Re: Defender Power Supply needed urgently
I tend to use Farnell for all my bits, they are usually cheaper than Maplin
(although you do have to buy a bit more in bulk for wire etc.). Using a
credit card and ordering from the net/phone, delivery is almost always next
day. You can obtain a catalogue from their site.

Andy

 

[Dave2084]

[ukvac] Re: Defender Power Supply needed urgently
At 03:59 am 5 01 2000, you wrote:
>You can use a bog standard arcade switching PSU easily enough, the only
>drawback being that the CMOS gets reset occasionally wiping out your
>hi-scores and game settings.

Yeh and a pain in the arse that is ... my 10,000,000+ on robotron only
lasted one on off cycle (

>I think Sinistar PSU's do protect against overvoltage (Dave?) so you
>could consider that option too.

Robotron, Joust and Sinistar all used the same PSU, that had over-voltage
protection (OVP). You can identify these by the two power transistors
being on a separate heat-sink as opposed to on the main (and only) PSU
board as in Defender and Stargate.

Stargate (allegedly) had an in-line OVP circuit board. I have drawings for
this and its quite a simple circuit. If anyone wants to build one I'll
scan the document in and put it on-line.

I hope this helps ...

For my 10p worth ... in the long term I plan to convert (non destructively)
one of my boards to use 4164 RAM as it only uses +5v, NO -5v or +12v ...
therefore PSU failure will only cause game to power down, NOT frying the
RAM ... if you loose -5v using 4116 (standard) RAM you risk killing some or
all the RAM. Once I have made the RAM more voltage tolerant, I hope to use
a Sinistar PSU to run my Defender without a switcher (Remember Sinistar
PSU's have OVP) and therefore keep my high scores for ever, or at least as
long as a CR2032 lithium cell lasts ... BTW have many of you guys tossed
out the 3x AA cells yet??? Battery acid will kill your williams game ... a
lithium cell not leak (???)

Hope this helps ....

Dave Langley

Williams Documents + More On-line!!
http://freespace.virgin.net/chad.gray/DaveLangley/index2.htm
Coming soon ... Williams Documentation site @ www.robotron-2084.co.uk

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