Agilent 54845A Failing all trigger self tests

[ARF]

So... I started studying the acquisition board design and ran into a rather stupid problem. The board contains a lot of logic manufactured by Motorola in PLCC packages. However, when I downloaded datasheets for some ICs, they did not have a description of the pinout for the PLCC housing. Quite strange.

https://www.mouser.com/datasheet/2/308/MC10H105-D-21730.pdf

I assumed that the pinout would be the same for the DIP and the PLCC, but it appears that this is not the case. There are no data for the PLCC. Maybe I'm too tired and need to sleep...

[MarkL]

Look back in this thread to Reply #20 on May 09, 2018, 12:48:59 pm.  You will find the pin mapping.

[ARF]

The fact that the guys have not been able to solve this problem for many years is a completely disappointing. I'm not smart enough.

However, I found an interesting thing that I did not see on the forum (or I missed it). Like many others, I have an error with all triggers, including Logic Trigger.
According to the internal help, Logic Trigger is easy to test; it is sufficiently isolated from other blocks  of the ACQ board.

I did the Logic Trigger self-test separately and the first error I received was: "Logic trigger memory test is failing".

The help says:

"The logic trigger memory is tested by writing out test patterns to all setable bits accessible over the serial IO port, reading data back in and comparing all setable bits. The two test patterns 0xAA and 0x55 are used.  Not every bit of every word is writable. Fifty bytes of the sixty-four byte memory are tested."

This means that the error is completely digital! Between the PCI board and the ACQ board. Serial data is not written(?) to the memory registers of the Logical Trigger.

The help says:

"The logic trigger self test includes tests to check the integrity of the serial data port, the startable oscillator which includes parts external to the logic trigger IC and a group of tests which are contained entirely inside the logic trigger IC except for circuitry to read and write from the serial port. The logic trigger self test consists of 11 separate tests listed and described in order of execution:"

It shows how to check these dependencies:

"
The logic trigger test is somewhat self contained but does depend upon the serial input port and the 100 Mhz startable oscillator. The startable oscillator is used for pattern duration and range. 

To check the 100 Mhz startable oscillator:
1. Check the enable line toggles during the test.   U84 pin 15
2. Varify that the oscillator is running during the test.   U84 pins 18,19

The logic trigger also provides holdoff for the trigger system. A 50 Mhz free running oscillator is used as the holdoff clock.
1. Verify that the 50 Mhz osc. is running.   U81B pin19
"
Everything that is described is present on my board: turn-on signals, 100 MHz, 50 MHz. This brings us back to the digital problem.

Now comes the fun part. Where is this chip with internal memory located on the board?

Considering that I see turn-on signals and clocks during the test, the problem is most likely with reading from this digital interface. It looks like the registers are being written correctly.

[ARF]

Presumably this is so, but there are probably errors there.