[volt-nuts] Solartron 7081 NVM FAIL

[Fabio Eboli]

> I will try looking in monitor mode tomorrow, but suspect that I will  
> see binary zero or FF depending on HOW the EAROM has failed.

Yes, probably you are right.

>
> Do you have a scanner, it might be interesting to see how they  
> propose doing the zener calibration for the 7061?  I guess you need  
> an environmental chamber, an accurate controllable current source  
> and a logging voltmeter (at least I can provide one of the three, as  
> my other 7081 still works OK).

I had scans already done.
The instructions are very crude:
http://img842.imageshack.us/img842/8948/7061100.png
http://img6.imageshack.us/img6/5324/7061101.png
Here the schematic of the reference:
http://img843.imageshack.us/img843/2945/7061235.png
http://img402.imageshack.us/img402/8248/7061236.png

I imagine that the second order temperature compensation can
be problematic in the process, maybe this is why they
don't provide instructions to recalibrate the zener.

> The quote from Ametek for a FULL calibration including zener is  
> rather eye watering, and I doubt they would do a zener only  
> calibration (or if they would it would be equally expensive).

Just a question, you can also answer privately, but what is the usual
price on the used market for a 7081, good or broken?
I've only seen one on ebay (other than the ones at >1k euro that
never sell), and I've never seen one here on the surplus resellers.

> A question for the other 7081 owners:  The zener diodes in this 7081  
> and a 7071 are 1N829 in an orange glass DO7 (I think) case.   The  
> zener in my original 7081 is quite different as it is in a  
> hermetically sealed metal can that looks for all the world like it  
> should hold a crystal.  What is more, it is thermally connected to  
> the AD590 temperature sensor while the other two the diode is about  
> 3/8" away!
>
> What are your zeners like?
>

That's interesting! Have you some photo? :)

Fabio.

----------------------------------------------------------------
This message was sent using IMP, the Internet Messaging Program.