Electronics > Repair
Series defect on agilent 167xx boards?
John_ITIC:
The update for this weekend is that I assembled DogP's adapter cards and managed to burn up both one of my 16754A cards as well as my 16700B main frame! It was my fault as I missed DogP's comment not to use 80-wire cables as those short together some 6-7 pins on each cable. So I'm putting this in here as a warning to others: Only use 40 pin connectors and 40 pin flat cables.
https://github.com/pdaderko/16702B/blob/main/card_extension/README.md
I looked into the 16700B issue and found that it does not detect any (known good) boards. The back plane does not have any sensitive electronics so I assume its the main interface board that somehow got damaged. I did find a replacement main interface board on Ebay so I picked that up as that would be a quick and easy fix if it resolves the issue.
Now, having learned my lesson, I tested the 16700 extension boards in another 16702A unit with 40 wire flat cables and I can report that they work fine with 21" cables. They are a little too short for my work bench arrangement so I put in an order for very long 52" cables. I think that will work well for the pv self tests as no major data is transferred over the cables. I would assume that actual data capture and upload will stress the cable interface more - I will try that out once the long cables arrive.
Finally, I attached a couple of pictures for the curious...
Thanks.
/John.
dorkshoei:
--- Quote from: John_ITIC on March 04, 2024, 04:42:13 am ---I did find a replacement main interface board on Ebay so I picked that up as that would be a quick and easy fix if it resolves the issue.
--- End quote ---
Thanks for the order though I hate giving 13% to those eBay bloodsuckers. I have several other boards from the same 16700b for sale. All working. PM me here.
DogP:
Ouch! I guess that's good to confirm my suspicion that damage would occur from the wrong cable... would have preferred to have kept that unconfirmed though. :-/
To track down what likely got damaged... those 80-pin cables internally short pins 2,19,22,24,26,30,40. Pins 19 and 22 are unused on the extension, leaving pins 2,24,26,30,40. That would cause backplane pins 2, 20, 22, 26, 36 to short together from one cable, and pins 38, 56, 58, 62, 72 to short together from the other cable.
I'm not aware of the backplane pinout being published anywhere, but simply using a voltmeter may find the obvious culprit (e.g. finding +12V, -5V, etc. which would have likely damaged a data or control signal). Or maybe a voltage rail got shorted to another, possibly popping a fuse. No idea if they buffered anything, or if the lines went directly to FPGAs/ASICs/etc. though.
I'd definitely be interested to hear how the long cables work out... another option is popping the bottom cover off the unit like MarkL mentioned, putting the unit on its side, and then using the extension out the opening. That's how I tested cards on my workbench, shown in this pic: https://github.com/pdaderko/16702B/blob/main/card_extension/in_use.jpg .
DogP
MarkL:
--- Quote from: DogP on March 04, 2024, 07:16:18 am ---...
To track down what likely got damaged... those 80-pin cables internally short pins 2,19,22,24,26,30,40. Pins 19 and 22 are unused on the extension, leaving pins 2,24,26,30,40. That would cause backplane pins 2, 20, 22, 26, 36 to short together from one cable, and pins 38, 56, 58, 62, 72 to short together from the other cable.
I'm not aware of the backplane pinout being published anywhere, but simply using a voltmeter may find the obvious culprit (e.g. finding +12V, -5V, etc. which would have likely damaged a data or control signal). Or maybe a voltage rail got shorted to another, possibly popping a fuse. No idea if they buffered anything, or if the lines went directly to FPGAs/ASICs/etc. though.
...
--- End quote ---
I've done a little poking at the backplane about a year ago, and was able to take some reasonable guesses at some of the signals by direct measurements and looking at a broken 16531A scope module. The 16531A is thru-hole, so it was a lot easier to see where various traces were going.
Here's what I have so far. Any pin where I didn't have a good guess is not listed. I would think shorting the -5.2V supply did the most damage, since it's also responsible for supplying the power-hungry ECL on the modules.
From service guide, power supply has:
+5V -5.2V -12V +3.3V +12V -12V -3.3V
Connector: AMP 1-534204-4 (pin 1 has a square pad)
Pin(s) Signal
------ -----------------------
1-5 +5V
6-8 +3.3V
9-10 +12V
11-12 -12V
13-14 GND
15 D7 bi-directional (D7:D0 based on 16531A DAC)
16 D6 bi-directional
17 D5 bi-directional
18 D4 bi-directional
19 D3 bi-directional
20 D2 bi-directional
21 D1 bi-directional
22 D0 bi-directional
23-24 GND
26 from backplane
27 from backplane
28 from backplane, A1 on DAC
29 from backplane, A0 on DAC
30 from backplane, 138 both decode select C
31 from backplane, 138 both decode select B
32 from backplane, 138 both decode select A
33-34 GND
35 from backplane, R/nW, select which 138 decoder
37 from backplane, 134 both G2A not enable
43-44 GND
53-54 GND
55 100MHz system clock
56 100MHz system not clock
62 from backplane, 138 decode G1
63-67 -3.3V
68-72 -5.2V
John_ITIC:
--- Quote ---Thanks for the order though I hate giving 13% to those eBay bloodsuckers. I have several other boards from the same 16700b for sale. All working. PM me here.
--- End quote ---
PM sent.
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