Products > Test Equipment
Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
Neptuni:
Found someone in Sweden that sells and burn eproms, so now a set is on the way in the post.
garrettm:
--- Quote from: Neptuni on November 15, 2021, 06:22:25 pm ---Hi,
The 8505 is ok now after removing and insertion of the IEEE and isolator card.
The 8506 is still rebooting…
[...]
Mikael
--- End quote ---
It sounds like the microcontroller isn't getting stable power during turn on. I had a unit that would exhibit similar behavior due to the 5V supply being too low and a bad capacitor.
Check the +5V power supply (unguarded Vcc) at the Controller module (using test points TP1 and TP3) or at the PSU (this method does not account for voltage drop to the Controller). If it's in spec (5.05 +- 0.05 V), check the electrolytic caps on the Controller board. If those are okay, try raising the voltage a little bit higher, say 5.1V.
Good luck with the firmware upgrade, I'm happy to see people using the bins I uploaded. That said, I doubt you will notice much--if any--difference in operation of the DMM using the new FW unless you are controlling the meter remotely. I've never seen a unit with 5.01 FW out in the wild. Your 8505A has the oldest FW I have ever seen for an 850xA. If you're willing, I would love to see photos of the DC Signal Conditioner module for comparison. Fluke revised the DC Signal Conditioner multiple times, and I'm curious to see what one of the earliest iterations looked like.
m k:
It seems that somebody has read xDevs repair story since ebay was full of .156 spaced edge connectors.
Thoug Vectorbord 3682 was best for the riser part I found, ready made HP extenders were also available but not very decently priced.
But there is also an arcade world and they have a JAMMA adapter and it has .156 spacing, clean fingerboards are also available.
So next idea for empty controller slot, a sniffer board.
Nowadays an MCU can fit in empty space of skeleton type of DIL-socket, quite fast and easily implemented serial buses are also available.
So the operation of a sniffer is mainly in the extra controller slot and from there a shielded serial cable connects to CPU riser of the main controller board.
It can easily be also a concept and so implemented anywhere.
Full software simulator implementation of a meter seems to be pretty irritable, occacionally.
(personal opinion)
Neptuni:
Hi again,
One set of EPROMS received today and now I have the 8505A working with 5.05 fw:)
Yes, both 8505a and 8506a will be used with GPIB, so thanks for the files!
I will look at the power supply and also the caps on the controller as well, the reboot has came back…
I can post a picture on the conditioner board later.
garrettm:
--- Quote from: Neptuni on November 17, 2021, 06:29:58 pm ---Hi again,
One set of EPROMS received today and now I have the 8505A working with 5.05 fw:)
Yes, both 8505a and 8506a will be used with GPIB, so thanks for the files!
I will look at the power supply and also the caps on the controller as well, the reboot has came back…
I can post a picture on the conditioner board later.
--- End quote ---
Are you sure your new EPROMs have 5.0.5? 5.0.6 is the newest FW for the 8505A and 6.0.7 for the 8506A (though CT models use different FW, newest IIRC is 1.0.1).
For future reference, an inexpensive programmer like the XGecu TL866II Plus will work with lower voltage UV EPROMs such as the M2764A. That said, it might still be cheaper to pay someone else to program them if this is a one-time job. I've found it helpful to have a programmer on hand, that way I can read chips and upload FW for others to use, test ICs (e.g. 7400 series), as well as programming ROMs. For 35 USD, I feel I've gotten my money's worth out of the TL866II.
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