9 Apr
2004
9 Apr
'04
6:41 a.m.
In message <m1BBzzA-000JAXC@p850ug1>
ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
Have yuou checked _all_ the electrolytics, even the
low-value ones? On
both sides of the isolation barrier.
I've replaced all the electrolytics on the
LV side that I could see. I've
just noticed a 1uF 50V that I missed - I don't think I've got a 1uF 50V 105
deg C in stock though.
Have you looked for a current sense
resistor that's gone high?
There is some visible heat damage around some
fusible resistors, but they
checked out fine. There are two diodes in the vicinity of the FRs that I
haven't checked yet. I really need to get this thing back on the bench for
testing.
This may mean they didn't actually design it, but
bought it in from
somebody like Astec who didn't supply schematics.
Looks like that's what
happened - the PSU bears the logo of a company called
Phihong.
What really annoys me is that they went to the trouble of picking a plastic
that would shatter when you removed the case screws. Needless to say, the
case will no longer hold together - the screw posts shattered when I removed
the screws. I hate manufacturers that do that sort of thing.
I know the CTS256 was copy-protected (or at least all
the ones I have
are...).
Sounds about right.
There is some info in the data sheet on the algorithm
(it's
pretty simple) since you can extend it with your own rules in an external
EPROM. I guess I now need to find that data sheet...
I think it's available
online somewhere, but I'll be damned if I can find it.
LA = 'Logic Array'??? Maybe a ULA for address
decoding, etc?
That's one possibility - Commodore used an LA05 (with a different
number
after the dash) in the Magic Voice and Currah used one (again, different ID
number) in the Microspeech (aka uSpeech).
(the list of the
3 chips sounds like something Greenweld were selling about 15 years ago...)
That's where I got mine from - I bought one set back in '97, then bought
another three sets in 2001, while Gweld were still selling them at ?3 per
set.
Thanks,
--
Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem(a)dsl.pipex.com | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.dsl.pipex.com/ | 48xCD, ARCINv6c IDE, SCSI
... Where there's a will, there's an Inheritance Tax.