Recently, Somebody Somewhere wrote these words
>
> Now I better, although still not fully, appreciate your problem. I am
> not familiar with your programmer. On my programmer
> [1]http://www.xeltek.com/pages.php?pageid=5
> if I need another interface I pick the phone and order one. Then I
> run down the street and pick it up. No so with the Irish I take it.
> I also take it you are not able to extract a set of known good PALs.
No, unfortunately. If you have the correct phone number in
UK/Europe, you can find one. Needhams is about the best (in the
UK). Most parts companies are extensions to the multinationals'
components drawers.
> Are they soldered in?
No.
> No second machine?
Hell, no. The only other machine I know of is owned by the
Manufacturer, and they are having trouble with that :-/.
> Are the security links blown?
They tell me this is routinely done.
> None of my customers use fuse link PALs
> now but when they did most found it was more trouble than it was worth
> to blow security links. Something about needing two test programs, one
> for blown and one for unblown security links.
> I still think you are likely to have propagation problems since the
> old AMD pals are no longer made and the subs are much faster than the
> old.
That may well be. I have no way of checking, and no choice in the
PALs used, as they are programming for me.
> Do you have schematics?
ROTFL.
The only time manufacturers give those out is when they admit the
thing was an absolute disaster. I'm always playing to keep money
out of their pocket.
Declan.
> Fred Townsend
> Declan Moriarty wrote:
>
> Recently, Somebody Somewhere wrote these words
>
>
> I suggest you quit messing around with check sums and get to work. ;-)
>
>
> Unfortunately, that's a no can do. I need the checksum of that PAL
> to ever get a replacement from these guys in the future. This is
> to fix a 1999 version of a machine sold from 1992 - 1999. Those
> guys are 2 model revisions on.
>
>
>
> Who was it that offered the defination of insanity as repeating the
> same experiement and expecting different results?
> Your boolean equations, and therefore your check sums, must be right
> or couldn't get it to boot with one of the old PALs. Ordinarly PAL
> programmers automaticly checksum so if there was a problem I think the
> programmer would say so.
>
>
> Maybe my explanation lacked. One of my PALs has a pin blown (Pin
> 23) The manufacturers won't replace the one, they feel I should replace
> the four. They can't supply me correct PALs. Here's where the
> checksums of mine become relevant. They haven't a clue really, and
> I have the only working part for one of them.
>
>
>
> Your symtoms suggest you are running ripple logic with faster PALs.
> If so, you are trying to fix a bad design rather than a simple
> compoent failure. In short a hard road to hoe.
>
>
> I Agree totally - fixing a bad design is what I am trying to do.
> They do have 74BCT (Texas bus logic) all over the place.
>
>
>
> Here is where I'd start.
>
>
>
>
> 1. Check your power supply. Make sure it is absolutly clean. Faster
> devices are more sucesptable to noise. Add bypass caps if you
> don't see them on the PALS. Check out the power supply
> electrolytics.
>
>
> The power supply isn't perfect, but it's reasonably good. I'll add
> bypass. But this fault developed with heat (Cold everything worked
> - warm it failed) and then became permanent. I am not thinking of
> power supply issues, even thou that has had a ressurection.
>
>
>
> 2. See if you can find low power equivalents for your PALs. Quarter
> power versions are ideal. That does not mean switch to CMOS. The
> idea of using low power bipolar versions is they are much slower
> devices. It's not to save power. Remember speed kills.
>
>
>
> I can't choose the PALs they program! They won't give me the code.
> My guess is they are programming in the wrong files. I have reason
> to believe this (They hunted for weeks and then came up with these).
>
> So I'm about proving they have the wrong parts and pointing them
> at the right ones.
>
> References
>
> 1. http://www.xeltek.com/pages.php?pageid=5
--
With best Regards,
Declan Moriarty.
--
Author: Declan Moriarty
INET: [EMAIL PROTECTED]
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