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Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)

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SilverSolder:
Turns out the TL866CS can't maintain 21V programming voltage on these particular chips...

19.38V is as good as it gets.

No wonder these particular EPROMS are having "learning difficulties"! :)




The latest model - TL866II  - has a more realistic 18V max specification...   I'm pretty sure the power supply didn't change!

bdunham7:

--- Quote from: SilverSolder on February 15, 2021, 04:06:22 am ---Turns out the TL866CS can't maintain 21V programming voltage on these particular chips...

19.38V is as good as it gets.

--- End quote ---

https://pinside.com/pinball/forum/topic/program-21v-25v-roms-in-lower-voltage-programmers

joeqsmith:

--- Quote from: SilverSolder on February 15, 2021, 04:06:22 am ---Turns out the TL866CS can't maintain 21V programming voltage on these particular chips...

19.38V is as good as it gets.

No wonder these particular EPROMS are having "learning difficulties"! :)
..
The latest model - TL866II  - has a more realistic 18V max specification...   I'm pretty sure the power supply didn't change!

--- End quote ---

Good to see you put the scope on it.  It's very telling.  I guess I'm not too surprised.   I think I paid around $300 USD for my last programmer.  Spread that over the 20 some years I had it and it's about $15/year.    Pins were short circuit protected.   I did manage to damage one once but other than this and the lightning strike, I've had no problems with it.   I had to hack their code a few times to keep it running and add a few parts, so it was really beyond it's life anyway.

For the 100M range test, eyeballing, it looks like the average temperature changed about 0.5degC during the night, while the resistance changed about 5K .    It's a 10ppm part, so I expect 500ohms of that drift is contributed by the Caddock part.    Looks like the meter has a  TC of 0.02% + 10X 0.5 counts in this range.   Seems like it should be roughly 10K.  Even if we look at p-p, its a wash.   Maybe a bit high. 

Also shown is the last hour or so of data.   Foil did a nice job taming the signal.  Without that part being shielded, winter, rolling on a chair creating all sorts of HV, those readings would be all over the place. 

SilverSolder:

And the temperature is measured inside the meter? -  the results look pretty good.  And if you use the mean or the median value out of the bell curve, it looks like you will get a statistically valid precise value out of it.

I have a humidifier running in the lab during the winter - I got tired of destroying sensitive parts despite precautions!  - it barely manages to keep the humidity in the 25% range, despite being refilled every night with 4 buckets of water...   25% RH is just about good enough to avoid the worst of the static, though, so overall it is still a win.

Re programmers - the TL866 is hard to beat in terms of the number of devices supported, and it is generally reliable apart from high voltage NMOS parts obviously.  I think it might be possible to add a barrel jack to it and get it to work reliably at 21V, assuming the problem is that its internal DC/DC converter runs out of breath.   That is the subject of another thread, though...

I ended up ordering one of these:  https://www.batronix.com/shop/programmer/BX32P/index.html   -  at EUR 159, it seems a relative bargain if it is really is professional grade (which indications are that it is...  5 year warranty, 30 day money back guarantee if you don't like it, etc.)  - I also like that it is small, similar to the TL866.  Let's see how that works out!

joeqsmith:
I've been fairly lucky in my home lab and only remember damaging a few cheap handheld meters (part of my testing).   I normally wear a strap and work on the mat.     

I would like to have the ability to program some of the old 40 pin parts (8051) along with the 6811e9.  Some of the serial PROMs for the FPGAs were not supported with my old programmer.   Biggest problem was having to boot the new PC up in DOS to run it!  lol. 


The readings are not moving around much now.  I have attached the 16 plus hours of data if anyone would like to do their own post processing.   Same format, ohms/temp in ASCII.   Like before the readings are every 4.9 seconds.     

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