Subject: breathing life into old chips

From: Jules Richardson<[email-masked]>
Date: Fri Apr 4 03:07:00 2003

hi,

this is sort of off-topic as it applies to my TV and not a computer, but I bet
some of the folks here can offer advice... :)

the microcontroller in the set seems to have developed a fault which only
appears when the set's warm. Tracking down a replacement seems to be easier
said than done as the chip was obviously discontinued a while back (and then
I'd have to worry about the on-board ROM anyway).

At the moment though there's no heatsink on the chip - if I do stick a heatsink
on it in the hope that it keeps it cool enough to operate, is it still likely
to fail at a later date anyway? Once a chip's started to exhibit heat-related
problems is that basically the end of it even if something's done about the
cooling? I figure some of you people will likely know about these things :)

(the chip in question is a ST9293J9B1/AEL for the record, but no infomation
appears to exist on the web or on ST's site for it; wish I could get pin-outs
to check that it is the chip and not surrounding circuitry that's failing)

cheers!

Jules
For a better Internet experience
http://www.yahoo.co.uk/btoffer

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From: Jochen Kunz <[email-masked]>
Date: Fri Apr 4 11:59:01 2003

On 2003.04.04 11:04 Jules Richardson wrote:

> the microcontroller in the set seems to have developed a fault 
> which only appears when the set's warm. 
Are you sure it is the microcontroller? Problems of this kind are "cold"
solder points much more often then failed components. => Resolder
everything on the PCB, especially where the PCB gets hot. 
-- 

tschüß,
       Jochen

Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/

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From: [email-masked] (Tony Duell)
Date: Fri Apr 4 18:39:25 2003

> appears when the set's warm. Tracking down a replacement seems to be easier

Possible. I assume you've checked for dry joints, that the IC's power 
supply is good (check decoupling caps too), that the reset line is right, 
and that the crystal is good (a suprising number of crystals fail in TVs...)

> I'd have to worry about the on-board ROM anyway).

Have you tried a TV spares place? You might still be able to get the 
original part, correctly programmed.

> to fail at a later date anyway? Once a chip's started to exhibit heat-related

In my experience it will get worse :-(

-tony

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From: [email-masked]
Date: Fri Apr 4 20:11:11 2003

> to check that it is the chip and not surrounding circuitry that's failing)

What is this TV model & brand?

FYI: Most TV shops has scraps laying around waiting for a donor to 
fix yours.

I know of this because I work for a tv/projo/video camera etc. shop.  
I mainly work on projos and TVs.

Sharp is notorious for failing micros/jungle ICs.

Cheers,

Wizard