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Test Equipment Anonymous (TEA) group therapy thread
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Specmaster:

--- Quote from: factory on July 11, 2022, 07:56:28 pm ---
--- Quote from: m k on July 11, 2022, 01:00:14 pm ---
--- Quote from: factory on July 10, 2022, 07:44:35 pm ---Well the intermittent display fault has returned to my HP 54615B, trouble is after the second power up, the Hsync/Cal signals don't stay borked for long enough, to see if they are failing at the same time as the display, the signals are correct before the CRT fully warms up and the picture appears.  |O

Hsync & cal signals measured, before they quickly corrected themselves to 19.72kHz (Hsync) & 1.2kHz (probe cal).


I can't find the "any" key.  :-//


David

--- End quote ---

Is there warmer than usual?

Our freezer has removable shelves.
Pretty optimal for cooling bigger things.

80Mhz clock and 1/4 slower sync.
How is this clock generated?

A far fetched.
Sort of direct lines out of the machine, says xDevs 54600A schematics.
Pages 22-23/125 there have +5VF_Core, its buddy +5VF_Pad is clipped but component numbers are still present.
Can you show your version of them some cold spray?

--- End quote ---

I guess it was a little bit warmer when I acquired it (Jan 2021), it hasn't been used much due to this fault, when last used in December, it required about an hour warm up time, before the horizontal display would lock.

Temperature was around 18°C to 23° (depending which crap thermometer I look at) in the workshop when I checked over the weekend. I've no freeze spray ATM and our freezer sleeves are the plumbing, i.e non removable unless you want to destroy it.

Both the HP 54600A & 54654N use a custom IC (Foxy for 54600A & Jackal for 54654N) to provide the H & V Sync signals and the probe cal signal is divided down from the H-Sync by a 74393, the custom IC has a 40MHz clock input, could check this in the future.





I have to thank whoever posted the 54654N CLIP, as the part # of the Jackal IC is the same one used in my 54615B, around it is the 40MHz oscillator & 74393 IC.



David

--- End quote ---
David,

I've found it for you, see below.  :-DD

med6753:
Slow but steady progress on the 465B re-cap.

All the old cans removed. Started installation of new caps. There is definitely a shortage of high value capacitors which makes cobbling together lower values in parallel required. For example....the 2 caps in foreground are 560uf/100V to be put in parallel for unavailable 1200uf/100V. In the right rear is a 4700uf/35V and 330uf/35V in parallel for an unavailable 5000uf/35V.

 
bd139:
I wouldn’t worry about precision there. They are usually specified to -20% +100%. A 5600uF is fine for the 5000uF
med6753:

--- Quote from: bd139 on July 12, 2022, 05:21:58 pm ---I wouldn’t worry about precision there. They are usually specified to -20% +100%. A 5600uF is fine for the 5000uF

--- End quote ---

Of course and I realize that. But anal me insists we be as close as possible.  |O :P :-DD
bd139:

--- Quote from: med6753 on July 12, 2022, 05:24:01 pm ---
--- Quote from: bd139 on July 12, 2022, 05:21:58 pm ---I wouldn’t worry about precision there. They are usually specified to -20% +100%. A 5600uF is fine for the 5000uF

--- End quote ---

Of course and I realize that. But anal me insists we be as close as possible.  |O :P :-DD

--- End quote ---

Been there. I’ve untrained myself from that way as it was getting expensive  :-DD
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