In message <m1BBzzA-000JAXC_at_p850ug1>
ard_at_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_at_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.
Received on Fri Apr 09 2004 - 13:41:01 BST