Tektronix 4054A Calibration (with Option 31)

[stepleton]

At long last a friend and I have started to undertake the 4054A calibration procedure (PDF page 99-138). There is a lot of detail, but we find that certain parts are unclear or even obviously wrong. The most outstanding example of this is the mislabeling of the standard and Option 31 HV boards (PDF pages 105 and 106). More subtly, the BASIC program on PDF page 129 has bugs: instances of "16,25" on line 140 should be "16.25", and the last "5," on line 150 should be deleted. Some procedures just seem silly in their difficulty: on our machine --- how are you supposed to access the 12V and 20V rails (positive and negative) on J530 (see PDF page 116), since the Display Controller Board doesn't use those and blocks off your access?

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Anyway, we've made it about halfway through --- we're especially glad to find that our voltages look good, with our HV apparently exactly at -6000V. It's on to the display calibration now (PDF page 118+), and we're not quite clear on what we're supposed to do here. Perhaps @nikola-wan will know, as I believe he's carried out this calibration before.

We're stumped right away by the instructions for the storage board. It's not clear to me when we are supposed to carry out this procedure. Are we supposed to:

1. Turn on the computer, let it sit for 30 minutes (see bottom of PDF page 102 for why), then do steps 1-12 before pressing the PAGE key to clear the display for the first time

OR, should we

2. Turn on the computer, wait 30 minutes, press the PAGE key to clear the display, and then do steps 1-12?

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The confusion comes from steps 5-10. We're supposed to twiddle R295 (OP LEVEL) until "the crt gets bright but does not store". It's clear from step 8 that you're supposed to see the pattern the flood guns make on the screen, which you do see as a pattern of stored overlapping pools the first time you turn on the computer (before pressing PAGE). But after you press PAGE, the pools are gone.

I would assume that the storage board calibration is asking you to temporarily boost OP LEVEL so that you can see the flood gun pattern (so option #2 above). The mystery here is that I can't find any instruction later on to revert OP LEVEL to a value that no longer allows you to see the flood gun pattern --- which would be distracting once you finished calibrating the 4054A and just wanted to use it.

This wouldn't be the first time the calibration procedure tells you to make a change and then never tells you to undo it. PDF page 104 describes changing the jumpers on the HV board, and the configuration described there is different to how the 4054A here was originally configured. It's not clear when or whether we should change them back.

Does anyone have any more clarity about what we do with OP LEVEL during the display calibration procedure?

 

[nikola-wan]

At long last a friend and I have started to undertake the 4054A calibration procedure (PDF page 99-138). There is a lot of detail, but we find that certain parts are unclear or even obviously wrong. The most outstanding example of this is the mislabeling of the standard and Option 31 HV boards (PDF pages 105 and 106). More subtly, the BASIC program on PDF page 129 has bugs: instances of "16,25" on line 140 should be "16.25", and the last "5," on line 150 should be deleted. Some procedures just seem silly in their difficulty: on our machine --- how are you supposed to access the 12V and 20V rails (positive and negative) on J530 (see PDF page 116), since the Display Controller Board doesn't use those and blocks off your access?

-----

Anyway, we've made it about halfway through --- we're especially glad to find that our voltages look good, with our HV apparently exactly at -6000V. It's on to the display calibration now (PDF page 118+), and we're not quite clear on what we're supposed to do here. Perhaps @nikola-wan will know, as I believe he's carried out this calibration before.

We're stumped right away by the instructions for the storage board. It's not clear to me when we are supposed to carry out this procedure. Are we supposed to:

1. Turn on the computer, let it sit for 30 minutes (see bottom of PDF page 102 for why), then do steps 1-12 before pressing the PAGE key to clear the display for the first time

OR, should we

2. Turn on the computer, wait 30 minutes, press the PAGE key to clear the display, and then do steps 1-12?

-----

The confusion comes from steps 5-10. We're supposed to twiddle R295 (OP LEVEL) until "the crt gets bright but does not store". It's clear from step 8 that you're supposed to see the pattern the flood guns make on the screen, which you do see as a pattern of stored overlapping pools the first time you turn on the computer (before pressing PAGE). But after you press PAGE, the pools are gone.

I would assume that the storage board calibration is asking you to temporarily boost OP LEVEL so that you can see the flood gun pattern (so option #2 above). The mystery here is that I can't find any instruction later on to revert OP LEVEL to a value that no longer allows you to see the flood gun pattern --- which would be distracting once you finished calibrating the 4054A and just wanted to use it.

This wouldn't be the first time the calibration procedure tells you to make a change and then never tells you to undo it. PDF page 104 describes changing the jumpers on the HV board, and the configuration described there is different to how the 4054A here was originally configured. It's not clear when or whether we should change them back.

Does anyone have any more clarity about what we do with OP LEVEL during the display calibration procedure?

Wow! Does this mean you have your 4054A working?

Glad you are doing the calibration steps. Sorry that you found those errors in the Technical Data Manual. I went looking through my files to see if I had a later one - and -03 was the latest file. However the manual you are looking at was scanned by dvq.com. I had asked vintagetek.org for the latest parts and schematics for the 4054A and the scans I received from them were the same version and date as the ones from dvq. I then checked my bound hardcopy (obtained from a manual seller around 2000) of the 4052/4054 4052A/4054A Technical Data and it was two revisions newer - October 1983. The Nov 1982 version was the first version to add information on the 4052A and 4054A computers.

May 1983 revised page 5-31 - but I don't see what they changed. They still have commas between the 16 and 25 in the DATA statement.

Oct 1983 Revised: pages xi, xv, 3-25, 4-5, 5-7, 5-8, 7-7 and 15-10
Added: pages xvi, xvii, xviii, 15-11 through 15-15

I'll scan the revised or new pages and post them (or try to edit them into the pdf).

I assume the storage board adjustments are done after turning the 4054 on - since the previous page step 1 turns the 4054 off and step 4 turns it on and step 5 checks the high voltage.

 

[stepleton]

Oct 1983 Revised: pages xi, xv, 3-25, 4-5, 5-7, 5-8, 7-7 and 15-10

Thanks for the quick reply and for checking newer versions! Revisions to pages 5-7 and 5-8 suggests they corrected the labels on both types of HV boards, which is good.

As for this 4054A, it's always been running with the odd bug here and there --- there's another forum member who's still working out hardware issues. For me, after about 5-10 hours of continuous operation, the 8x300 CPU on the Option 31 card works its way out of its socket and needs to be pressed back down; this is the only recurring issue at the moment.

Back to calibration: I was pretty sure the computer had to be on; my question is more about how you are supposed to do the storage board part of the display calibration procedure after that. Are you supposed to PAGE the screen first or not? Do you set OP LEVEL temporarily or permanently at a level where you can always see the flood gun pattern?

I found that the 4054 service schematics has a "short form calibration procedure" (chapter 2). Here, the OP LEVEL adjustment procedure is:

Adjust the OP LEVEL (R295) so that the crt target has a granular appearance. Reduce the voltage about 10 Volts. The voltage should read about the same as the voltage listed on the crt tag. Generally the voltage will be within 10 V of the tag voltage.

This is a lot clearer, although I'm not sure what a "granular appearance" should be. I suppose I'll try it and find out!

I'm also still not sure if I'm supposed to reset the HV board jumpers to their original settings once calibration is complete. It would be nice to know what they do: I wound up changing the "Input Impedance 73/93/50" jumper (was 75, now 93) and the two J511 and J512 "Remote/Local" jumpers.

This reminds me of another (likely) error in the technical manual: page 5-6 (PDF page 104) talks about a "middle position" for the "90/100 CRT Deflection" jumper (which doesn't really apply here as there are only two positions for this jumper), and it also directs you to "93 position (outer position)" for the 73/93/50 jumper, even though the PCB markings suggest that this position is the middle position.

I'll point out further seeming errors if I find any...

 

[nikola-wan]

I scanned the updated pages - but couldn't get Acrobat to insert them in the posted scans so I did a print to PDF of the scans and posted them on my repository:

https://github.com/mmcgraw74/Tektronix-4051-4052-4054-Program-Files/blob/master/070-2840-03_Oct_1983_4052-4054%264052A-4054A_Technical_Data_updated_pages.pdf

I don't think you should page the screen for the storage calibration - so calibration will be done while the flood guns are active and visible, since you just powered on the 4054A.

I would think you move the jumper back to their original positions after that section of tests are complete.