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Test Equipment Anonymous (TEA) group therapy thread

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factory:

--- Quote from: bd139 on July 02, 2022, 01:48:05 pm ---
--- Quote from: factory on July 02, 2022, 01:44:59 pm ---
--- Quote from: bd139 on July 02, 2022, 01:31:15 pm ---Couple of Y RIFAs and a large hand grenade inline filter on the back panel  :scared:

Cool I will dig them out. Let me know if you need any other bits. Some of the rails are cracked and brittle so not sure how good they are.

--- End quote ---

Thanks, will check the manual tonight, it is a lot newer than what I normally add to my collection, so not sure what else might be useful to me.

I'm guessing the little transformer? on one of the boards, is something to do with the telecomms input/output for isolation and not PSU related.

David

--- End quote ---

Yeah probably balanced to unbalanced or isolation. Whole thing is 600 ohms oriented.

This was 1988 -> 1995 approx. I think this one is around 1994.

I was mostly after the displays, precision resistors/capacitors and some of the JFETs in it. The rest is just bunce :)

--- End quote ---

OK I forgot last night, spent too much time looking at Agilent scope diagrams.  |O

You mentioned missing boards yesterday, it seems the two missing boards (A5 & A8) are part of option 001 (A4 is replaced with A204 too), the numbers are coded into the board levers & guides.
There are some TC Zeners on some boards, seeing the prices of them you probably what to save those, don't know if any of the analogue IC s interest you.

Also far too many PROMs to cause nightmares in that, wonder if they just did board swapping on these, instead of fault finding using the 700+ page manual.  :-DD

David

Neper:

--- Quote from: Vince on July 02, 2022, 07:24:10 pm ---
I am quite interested in what looks like an old A3 format HP Plotter...
--- End quote ---

Speaking of which, there used to be a company making HP-compatible plotters and selling them by the boat load. Had one to plot films for making PCBs.

I can't for the life of me remember the name of this company. Any help?

Neper:

--- Quote from: Brumby on July 03, 2022, 02:11:55 am ---Nevertheless, ANY vehicle with a white hat on the rear parcel shelf will be travelling at a speed that would allow someone to walk in front, waving a red lantern.
--- End quote ---

For a time, we had a variation on this theme, over here, in the shape of a loo roll with a crocheted cover. The nodding dog was optional.

m k:

--- Quote from: mnementh on July 03, 2022, 01:34:23 am ---WELCOME TO 5000!           

--- Quote from: factory on July 02, 2022, 07:48:19 pm ---From the Agilent 54654N diagrams, that were linked to recently.
The monitor cable has three connections for +15V and ground, six total.
Three connections for the intensity pot.
Last four connections are half bright, full bright, HS (Hsync?) and VS (Vsync?).
Interesting the HS goes through a 74393 to provide the probe compensation signal.
HS & VS come from the big Jackal custom IC and the half bright, full bright from a PAL IC.

Other relevant pages have been cropped, rotated & added below.

This forum post suggest the Hsync is 19.72kHz and the Vsync is 60Hz.
https://www-elektronik-si.translate.goog/phpBB2/viewtopic.php?t=30373&postdays=0&postorder=asc&start=30&sid=c8ec2c01726d6cc1ee123fe5ebbe8c3d&_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp

Guess I need to locate those on my 54615B, to try & narrow down where my intermittent horizontal roll problem is, but it's not the same board.

David

--- End quote ---

Okay, I've traced out the 54621D and the VCC, GND are in the same locations, plus Pin 10 dssig_grd is also tied directly to GND. However the BRIGHTNESS pot is not brought out to this header on the 54621D.

   
                        VSync                                                    HSync 
   
My guess is that 13/14 are still the sync signals, and they have repurposed 7, 8, 9, 11, 12 for their greyscale scheme. 54645A agrees; trace 1 is the 54621D, trace 2 is the 54600A.


   

However, pin 8 is a different story; all I'm getting from the 54600A is noise.   :wtf:

Then the light dawns; the pot isn't connected to the monitor PCB, duh. Then it occurs to me the voltages usually present on a brightness pot, so I connect the cable back in the 54600A and probe the pot. Yup... (-58V) sent out pin 9 to the pot. Without knowing how the 54621D does its greyscale, I'm not too sanguine about connecting that (-58V) back to its mainboard.

I think this is probably a good point to call it a night. ;)

mnem
 :-BROKE

--- End quote ---

So you were not short of machines, all clear then.
Better also that incoming voltage is not 125V.

Maybe one final thing, 31 of Toshiba E9054B31-CDHT is green.

Neper:

--- Quote from: Cerebus on July 03, 2022, 02:35:56 am ---Talking of hats in the back of cars: A bloke I used to know used to say that you can make a car invisible to the police by leaving a homburg hat in the rear window.  :)

I don't know if the following still works simply because I don't know if the police still use them, but one trick was to leave a hardbacked log book that looked like the  log books police were required to fill out on taking a car out on the dashboard - strategically placed so that the front and spine were invisible outside the car.  Acted as a near perfect traffic warden repellant. (Anybody remember actual traffic wardens rather than the council parking goons we have nowadays?)

--- End quote ---

Here, it used to be a sticker of the police union in the windscreen.

They're even selling them on ebay.

https://www.ebay.de/itm/133505122703

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