Products > Test Equipment
Fluke 8500A, 8502A(T), 8505A, 8506A modules
m k:
Included list has partnumbers combined from few manuals and some pictures.
It even includes the famously missing option -04.
If there is a mfg number it's from manual.
If mfg number is present but Fluke stock number is missing they are the same.
If there is no option ID then it's from picture.
Rest are eighter way.
Some variable module placements.
8506
Thermal true
RMS Multimeter
Instruction Manual
P/N 638858
MARCH 1983
page 8-8
Slot A
DC Signal Conditioner
8505A
DIGITAL MULTIMETER
Instruction Manual
P/N 638841
March 1983 Rev.2 2/91
page 8-8
Slot C
DC Signal Conditioner
here and xDevs have pictures where
D DC Signal Conditioner
C AC/DC Converter (RMS)
B Ohms Converter
A Current Shunts
Disclaimer
Included list is a totally new intervention.
And so can be taken as a clean second guess.
E,
Cal Memory
Addressing
ID A_Cal
7 - 7
6 - 6
5 - 1
4 - 2
3 - 3
2 - 4
1 - 5
0 - 0
Read is actually not Write so Address and Enable will read and both will create their own ACK.
E2,
--- Code: --- Input
-----------------
| | | |
| Ohms Currents |
| \ / \ |
| RT1 RT3 |
\ / \ \ /
DC--- ----AC
\ /
----------
|
RT6
|
Active Filter
|
RT5
|
Fast RR A/D
--- End code ---
For 8506A the Thermal TRMS is not mandatory per se, but among ACs it is.
So you can leave it off and the machine is fine with simultaneous Ohms and Currents.
In case you hack 8505A to be 8506A remember button placings.
U18
A0 - A11
A1 - A12
A2 - A13
A3 - A14
A4 - memory cycle or not
O1 - U24
O2 - U23
O3 - U22
O4 - U20
--- Code: --- 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111
0000 1110 E 1110 E 1110 E 1110 E 1101 D 1101 D 1101 D 1101 D 1011 B 0111 7 1111 F 1111 F 1111 F 1111 F 1111 F 1111 F
.......
1000 1110 E 1110 E 1110 E 1110 E 1110 E 1110 E 1110 E 1110 E 1101 D 1101 D 1101 D 1101 D 1011 B 0111 7 1111 F 1111 F
.......
--- End code ---
Rest are F, so the whole DM74s287/N82s129 is programmed and can't be reused.
(TBP14s10N on schematics)
Since A13 is directly wired to U24 and 2nd set has double area for U24 one can guess that they have had some bigger ROM chip thoughts.
U18 ROM can be replaced with 74159 and 4 pull up resistors.
original A4 to _G1 and _G2
with pull up
0-3 outputs to U24
4-7 outputs to U23
output 8 to U22
output 9 to U20
27256 ROM is a drop in replacement for 2764.
Then U23 can be left out, but changing jumper W3 wont work since RAM location changes.
Combining and doubling U24 and U23 is fine but U18 content must be changed.
Rewiring A13 and lifting chip leg wont do either since _CS is not serviced.
Replacing U18 with 74159 will do, then its outputs 0-7 are combined to socket's _CS.
If replacement 74159 is used then remaining empty ROM socket can be used for extra software.
Then A-F outputs are combined to empty socket _CS and extra ROM space is available.
In case of extra software keep in mind that it's of course also possible that original software is testing that originally unused address space.
m k:
One Front/Rear more for 8506A and corrected A11 stock number typo.
Can't find a reason why I thought elsewhere that DC Signal Conditioner was universaly interchangeable.
Early and late part numbers are different.
E,
ods to xls
Martian Tech:
For reference, here's the inside of an 8500A.
m k:
IEEE-488 is not last, how the external connection happens?
m k:
One 8500A manual added.
Controller is one module but two parts.
Maybe CPU and ROMs were so expensive.
My guess for dual PCB controller is 8502A/AT and its extra needs.
Though the manual has only single module controller listed.
8502A/AT
(manual p/n 577049)
includes calibration memory(-04) as a standard feature.
Same with all A22 to A30 modules.
Operates with 400Hz mains.
Error A is illegal Thermal TRMS controller switches selected
Error E is more than one Thermal TRMS controllers installed
Boot
HI-3.0.0
C2454A 8
Cal Memory module has a battery and 2 RAM chips.
(429860 P5101L and 408757 P5101L-3)
8502A
(manual p/n 471466 rev 1 7/81)
Figure 8-7
A6 Controller PCB Assembly - Single PCB version
CPU and ROMs are blank, no component numbers, chip rectangles are present.
2 last of 6 RAM chips are completely missing, empty space in picture.
Figure 8-8
A6A1 Controller PCB Assembly - Double PCB version
1 ROM socket, no chips.
All ROMs are labeled as not used.
4th is also labeled as double PCB version interconnection.
2 last of 6 RAM chips are labeled as not used.
A6A2 Controller PCB Assembly - Double PCB version
5 of 6 ROM chips are without sockets.
6th is missing but socket is present, location like 3rd in A6A1.
Schematics has no address lines for that 6th ROM.
BTW, I have a strong feeling that I've seen a picture of Cal Memory module recently.
Can be a fake memory but if that lateral top edge battery is black and those two panduits are still strapped then it can be somebody's published but unknown feature.
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