Products > Test Equipment
Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
joeqsmith:
As I mentioned, I had been running with the display turned off both asynch and synch and both ascii and binary. I've tried them all. As I understand it, the sync output should pulse on every conversion. You can see that from the data I have collected, I never see it get anywhere near the claimed conversion rates.
--- Quote ---I suspect if all three are in place, we will see rates closer to what Sales & Marketing are saying.
--- End quote ---
This is where I saw the fastest numbers but again, no where near the claimed numbers.
--- Quote ---For most purposes, it is probably easier to just let the meter do the averaging internally!
--- End quote ---
And again, just to be clear, I was running averages as well while monitoring the sync output assuming that when the meter would average, it wouldn't throttle the conversion speed. It wasn't even close.
I looked in my stock of ICs and have some brand new 128s. So I looked at the schematic and I notice U24 routes A13. Then we see U23 ties pin 26 high. Looking at my original manual, it is also routed like this. They must have planned on adding some features to U24 at one point and decided to support the 27128. More odd is U18 (74S287) which is a PROM that they are using as part of their decoder logic. Then they have jumper W3 (mine is strapped 1-2) which would change the decoding.
I started to look at the TL866CS programmer. It's cheap enough but after seeing the comment about reading the parts three times to make sure they are right and then there were several posts about the company having malware in their software. But, then again, you get all these crazy adapters and such for under $100. What's been your experience with it?
SilverSolder:
--- Quote from: joeqsmith on February 07, 2021, 10:55:04 pm ---As I mentioned, I had been running with the display turned off both asynch and synch and both ascii and binary. I've tried them all. As I understand it, the sync output should pulse on every conversion. You can see that from the data I have collected, I never see it get anywhere near the claimed conversion rates.
--- End quote ---
OK, perhaps the explanation for Sales & Marketing's 500 reading per second claim is that the speed of 500 readings per second is only possible inside the instrument itself, as part of an (internal) averaging process? Perhaps this instrument NEVER returns a result that is not the outcome of an averaging process of some kind?
Maybe it is possible to put the scope on the ACK line of the digital part of the R2 board, to get an idea of how many A/D conversions per second are actually occurring? - that has to be the ultimate limitation of how fast it is running, right?
--- Quote from: joeqsmith on February 07, 2021, 10:55:04 pm ---I started to look at the TL866CS programmer. It's cheap enough but after seeing the comment about reading the parts three times to make sure they are right and then there were several posts about the company having malware in their software. But, then again, you get all these crazy adapters and such for under $100. What's been your experience with it?
--- End quote ---
I just installed the latest software yesterday (which I got from the company's web site (http://autoelectric.cn/MiniPro/minipro_setup685.rar) and my antivirus did not balk at anything, nor do I see any evidence of phoning home - there is no need to register or sign up for an account or any of the BS we typically get from Big Tech nowadays. Considering how popular this programmer is, and the amazing amount of devices it supports, it seems a no brainer.
I originally bought it to program Atmel ATTiny chips, but never actually used it for that... so I am dusting it off for this Fluke Boat Anchor Project! :D
I'll have a go at extracting some EPROMs with it maybe later tonight and let you know how that goes.
[Edit] It was very easy - this thing is a winner (for this job, anyway)!
bdunham7:
If you look at the line synchronous spec of 4ms, that is 250 per second. If you take the amount of time it takes to average the max number of samples, 217, divided by 250, you get about the right number of seconds to match the 9+ minute acquisition time or output rate at that setting.
SilverSolder:
--- Quote from: bdunham7 on February 08, 2021, 12:14:03 am ---If you look at the line synchronous spec of 4ms, that is 250 per second. If you take the amount of time it takes to average the max number of samples, 217, divided by 250, you get about the right number of seconds to match the 9+ minute acquisition time or output rate at that setting.
--- End quote ---
You get even closer if you divide the 60Hz period by 4. I think we have this right!
It is pretty cool that it samples 4 times per mains cycle, on the flanks. Maybe it is less noisy there than at the peaks (not to mention, 2x more of them!).
SilverSolder:
I was able to use the TL866CS to read the EPROMS from a controller out of an 8505A. The firmware is revision 505/606. A binary comparison with the files posted by @garrettm showed zero differences.
The cover says part no. 660563 but inside, the PCB had no. 638544 printed on it... not sure if some replacement/swapping has occurred in the meter's life.
It is a Rev W, not sure we have seen one of those before!
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