I will try this... thanks!

Best regards,
Reiner.

> -----Original Message-----
> From: Dante [mailto:dante@yuggoth.org] 
> Sent: Friday, November 21, 2003 11:18 PM
> To: BUEHL,REINER \(HP-Germany,ex1\)
> Cc: port-pmax@netbsd.org
> Subject: RE: Maxine graphic card hardware problem
> 
> 
> Greetings, I tend to lurk on this list, as generally I have 
> little of value to contribute. However I do have some 
> electronics experience, and have been researching the DS1287 
> RTC for you. The DS1287 is no longer available, but the 
> DS12887 is a pin compatible RTC with a bit more RAM. I 
> understand that it may not be a drop in replacement for all 
> applications, but that is anecdotal. According to the chip 
> spec, and given that the DS1287 and DS12887 would work in a 
> very similar fashion, it is *possible* that you can get a 
> battery reading by placing the positive lead of a VOM on pin 
> 24, and the ground on pin 12. I am not certain that this will 
> work; here is why.
> 
> The chip has the integrated Lithium battery as previously 
> noted. The operating voltage on pin 24 (VCC+) is +5v (> 
> +4.25v). If VCC drops below
> +4.25 volts the RTC functions are no longer accessible. If 
> VCC drops to
> >+3v then "the external VCC switched off " (their words) and 
> the lithium
> battery is used to power the RTC and RAM.
> 
> I am unable to locate anything which would tell me how the 
> switching mechanism works, and as a result I am not certain 
> that it is possible to directly measure the voltage on the 
> battery.  Therefore with out a second system with the same 
> RTC to test the suspected faulty unit, is not possible to 
> measure the battery voltage, and have full confidence that 
> you are performing an accurate test.
> 
> Additionally it should be noted that the DS12887 (and I 
> suspect) the DS1287 have a shelf life of 5 years.
> 
> The data sheet is avalible here:
> 
http://pdfserv.maxim-ic.com/en/ds/DS12887.pdf


I hope this helps,

Keith Blankenship


On Thu, 20 Nov 2003, BUEHL,REINER \(HP-Germany,ex1\) wrote:

> Since I have no access to the console or the system at all, I was 
> thinking more of tests like "measure voltage at pin x of the chip". If 
> I can not find a way to get to the prom prompt, I might have to 
> replace the chip and hope.
>
> Best regards,
> Reiner.
>
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