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Test Equipment Anonymous (TEA) group therapy thread
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BU508A:

--- Quote from: TERRA Operative on July 04, 2022, 02:39:21 pm ---Step two on the tube amp.

Tube sockets are mounted, so a mock-up on how things will look (minus the output transformers).
I'll have to find another voltage regulator tube so they match. :P


--- End quote ---

Do you have those anode caps as well?
mnementh:

--- Quote from: tggzzz on July 04, 2022, 01:09:53 pm ---
--- Quote from: nixiefreqq on July 04, 2022, 12:14:17 pm ---y'all got me playing with my 54622d ..... and damn it.   those squishy switches under the crt were back to being a pain in ass.
...
finally tried larger rectangles of AL tape and it so far is 100% good.

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Does anybody have any experience of using conductive repair pads like these?
https://www.ebay.co.uk/itm/254871615598
450pcs Conductive Pads Keypad Repair Kits 2mm-8mm Box For IR Remote Controller
Thickness of pads: various, between approx. 0.5mm

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Actually, now that I think of it... I've never had this problem on over a dozen 546xxx scopes where I've serviced the panel; every one has come back 100%, even this most recent 54600A, which literally had spots eaten out of the PCBs...

Are you guys scrubbing both the PCB and the pads on the membrane with IPA? You have to, both front and back in order to get a reliable read.

I don't use Q-tips; I scrub both the membrane and the PCB with a cotton kitchen towel (fine short nap; terry loops will snag on solder joints and edges of PCB) soaked in IPA.

Trick with the membrane keypad is to hold the body of the button in one hand and scrub each one individually; this allows you to scrub the conductive pad pretty aggressively with the IPA/towel in the other hand.

I also scrub around the solder joints on that intermediary cable with IPA and a toothbrush; that area collects cruft due to the tape stuck over it and will make the scope misread as it scans the buttons. On assembly, just leave those solder joints bare, or if you're anal aboot such things, a fresh strip of Kapton tape over the solder joints. Also, it is important to loop that ribbon cable exactly the same as HP made it; if you fold it over itself you'll have poor read problems.

mnem
 :-BROKE
Cerebus:

--- Quote from: Robert763 on July 04, 2022, 07:44:05 am ---
--- Quote from: Cerebus on July 03, 2022, 10:49:14 pm ---
--- Quote from: Vince on July 03, 2022, 04:46:45 pm ---Now I think or it, one big advantage of punches is that you can make any shape you want, not just round holes... so it opens up an entire new world of possibilities  8)
You could make a hole with a flat, to fit pots and keep them from spinning round and round, or anything... as long as someone somewhere sells the shape that you want...

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They used to be quite common - you could get punches for the classic potentiometer with flat, D connectors, IEC inlets, and so on. Last time I bought some sheet metal punches the ones for anything other than purely round and rectangular holes seemed to have disappeared off the lists of the moderately priced manufacturers and I didn't look at the extortionately priced ones.

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Made obsolete in industry by laser cutting and CNC routing.
I've bought a 2mm laser cut panel with D shaped holes for less than a blank panel by the equipment case OEM

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Yes, but the OEM blank panels usually cause a "You want how much for a small sheet of 2mm anodized aluminium?!?!" reaction, so that isn't an indication of absolute cheapness, just relative inexpensivity.  :) My usual supplier will sell me a sheet of 2mm anodised aluminium cut to size (~100x300) for £3.91 including postage and VAT, a Metcase front panel of the same size with 4 mounting holes off RS is £25.26 + VAT.

Although it's relatively inexpensive nowadays to get a simple sheet part perforated in suitably arcane ways by someone offering CNC laser cutting (or waterjet or milling) there are drawbacks. The waiting, obviously. The producing a proper CAD model instead of what's often quite simple marking out, or even none at all. Modifying an existing bit of kit (e.g. substitute IEC mains socket for various unobtainable historical horrors) isn't going to fly by the CNC route at all, nor any similar modification of in-situ plant. Finally, not everything is a simple sheet of ally, the punches work brilliantly on the ubiquitous die cast aluminium box and I'd be surprised if my latest production in the same, 7 holes on the lid and three on one side would have left me with any change from £100 if I had sent it out to be done - workholding and setup time being the main ticket item there.

So the punches still have their place, even in industry. How many sparkies are going to make a drawing and wait for someone to perforate their boxes for them?
TERRA Operative:

--- Quote from: BU508A on July 04, 2022, 02:43:33 pm ---
--- Quote from: TERRA Operative on July 04, 2022, 02:39:21 pm ---Step two on the tube amp.

Tube sockets are mounted, so a mock-up on how things will look (minus the output transformers).
I'll have to find another voltage regulator tube so they match. :P


--- End quote ---

Do you have those anode caps as well?


--- End quote ---

I have these ones at the moment.
I might still use different HV rectifier tubes without the top-cap though, not 100% sure yet... Depends on how dangerous I feel. :D
GreyWoolfe:
A day late and a dollar short as usual.  My contribution to 5000.  It was a freebie from the ham radio club I used to belong to.  They got it from a silent key estate and couldn't sell it.  I bought a couple of things so I got it as a gift.

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