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Test Equipment Anonymous (TEA) group therapy thread

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bd139:

--- Quote from: factory on June 26, 2022, 07:51:11 pm ---
--- Quote from: bd139 on June 26, 2022, 07:35:59 pm ---
--- Quote from: factory on June 26, 2022, 07:13:45 pm ---
--- Quote from: bd139 on June 26, 2022, 03:14:23 pm ---Ok Newbury megapost. It has been 3 years since the last one. Bloody COVID.

So what did I bag?


Next we have the HP 3311A function generator. Again it works absolutely fine. Paid £20 for it too. One of the feet fell to bits in the car but this is sort of expected.



Very nice



Will work out a new foot solution to this...




--- End quote ---

Didn't you 3DP one of those feet sometime ago?
Don't know why, but that rear foot always seems to crumble, on that type of case, the front one for the tilting bail, must be made from a different plastic.

David

--- End quote ---

I probably did. Can't remember that far back. I blocked my escapades in 3d printing out of my mind so I don't go down that rabbit hole again. Then again, never know what might happen  :popcorn:

--- End quote ---

Beanflying & VK5RC have done 3DP replacements, they are listed in the 3DP parts thread under 5300A, 5300B & 34702A.
https://www.eevblog.com/forum/testgear/replacement-knobs-feet-and-fittings-for-test-equipment/msg2255136/#msg2255136
https://www.eevblog.com/forum/testgear/replacement-knobs-feet-and-fittings-for-test-equipment/msg2472369/#msg2472369

David

--- End quote ---

Excellent. Many thanks. Bookmarked.

May buy another 3DP when I've moved. Got an excuse now.

mnementh:

--- Quote from: Vince on June 26, 2022, 03:20:50 pm ---
--- Quote from: mnementh on June 26, 2022, 02:41:29 pm ---
--- Quote from: Vince on June 26, 2022, 11:30:10 am ---...So yeah, I HATE those trimmers too ! :-DD   
--- End quote ---

Looks like a job for 3DP to me. Setting aside the plastic rot you describe (yuckyputz!  :P), I quite like the beefy ceramic substrate I'm seeing there. I'd try to find a way to fix them.

mnem


--- End quote ---

I think it might be easier (and more durable/reliable) to just cut the missing/broken shaft in a skinny metal rod, drill a tiny hole in the center of the knob and press fit the rob into the knob.  ;D

But the problem remains that the original design is flawed, in that there is nothing that keeps the shaft/knob from lifting out of the bore in the trimmer/ceramic base. Shaft does not "clip" into the trimmer. It's just a smooth skinny cylindrical shape. It holds into the bore merely thanks to interference. There is nothing to ensure "clamping" force onto the knob to make sure the wiper is making a good reliable contact with the track on the ceramic base. So if one could implement such a mechanism, that would be a nice improvement.

Obviously in practice it's not worth the trouble, so long as modern replacements are available, and at a reasonable cost.

But I guess as an exercise, just for the fun of it, yes you could try to make something with your 3D printer(ssss)...
--- End quote ---

My thought was more along the lines of dealing with the whole knob being crumbly. First thought was to print a new knob with a hole that could accept a m2 screw installed from the back of the ceramic base. Make it without stops so you just hold the screw with pliers and spin the knob on til it's snug.

But if it's easily replaced with 0.100" spaced 10-turn trimpot as Terra suggests, that's probably the simplest solution.

mnem
 :-/O

mnementh:

--- Quote from: Cerebus on June 26, 2022, 03:35:39 pm ---
--- Quote from: BU508A on June 26, 2022, 08:49:40 am ---What a nice hack for cleaning soldering pads on a pcb:

https://youtu.be/KDVu06WySjg?t=397

--- End quote ---

Agreed, neat trick.

(Too long; can't be bothered to watch): Cut a wedge out of high temperature resisting silicone rubber, put it into a [improvised] holder, and use the edge of the wedge to squeegee/wipe solder off pads after heating them to above melting point.
--- End quote ---

Not the first time I've seen this trick; there was a Hakko soldering video where the author demonstrated using the edge of the silicone rubber "oven mitt" to squeegee solder away in similar fashion. Easily a decade ago.  :-//

mnem
*tssssst*

factory:

--- Quote from: bd139 on June 26, 2022, 07:42:10 pm ---
--- Quote from: factory on June 26, 2022, 07:36:27 pm ---
--- Quote from: bd139 on June 26, 2022, 06:17:56 pm ---I will make amends. My purchase rate of TE is higher than ever  :-DD

I got rid of the 7L12 because quite frankly it scared me. It could literally turn into a brick at any moment with no hope of repair. There are literally no parts mules for it or anything.

--- End quote ---

Looking at the pile of SA crap I got at the last PP auction, the HP 8557/8/9 SA plug-ins aren't any better, the same mechanical parts, switch wafers & knobs are broken/missing on most of them.
Clearly the mixer, Yig oscillator and attenuator are trouble too, judging by them either being missing or labelled as futzed, though I suspect some of that might have been the operators fault.  :-BROKE

David

--- End quote ---

Yes same with the SA's that were floating around today. I enquired about a couple. I was being pushed a 20GHz one for £60 and told what a good deal it was. But it came with a printed manual in a tesco carrier bag and a little zip lock bag taped on the front with some HP leaf contacts in it. He said he'd tried to repair it but not got around to finishing it. My daughter who was with me today actually laughed slightly too loudly at that. I passed on it.

--- End quote ---

Yes probably best avoided (unless in perfect condition & fully working), I should have mentioned turning one of the controls and there was the sound of one dropping off.  :-DD
The 400ish page PDFs put me off doing anything with the most complete one, shame they didn't come with any manuals, the joblot of 141 series SA plug-ins (in similar condition) did at least come with some. Oh that & the corrosion of the gold plated traces, some of which are used for those rotary switches.
Much prefer the older 141 series SA.

David

bd139:

--- Quote from: factory on June 26, 2022, 08:15:57 pm ---
--- Quote from: bd139 on June 26, 2022, 07:42:10 pm ---
--- Quote from: factory on June 26, 2022, 07:36:27 pm ---
--- Quote from: bd139 on June 26, 2022, 06:17:56 pm ---I will make amends. My purchase rate of TE is higher than ever  :-DD

I got rid of the 7L12 because quite frankly it scared me. It could literally turn into a brick at any moment with no hope of repair. There are literally no parts mules for it or anything.

--- End quote ---

Looking at the pile of SA crap I got at the last PP auction, the HP 8557/8/9 SA plug-ins aren't any better, the same mechanical parts, switch wafers & knobs are broken/missing on most of them.
Clearly the mixer, Yig oscillator and attenuator are trouble too, judging by them either being missing or labelled as futzed, though I suspect some of that might have been the operators fault.  :-BROKE

David

--- End quote ---

Yes same with the SA's that were floating around today. I enquired about a couple. I was being pushed a 20GHz one for £60 and told what a good deal it was. But it came with a printed manual in a tesco carrier bag and a little zip lock bag taped on the front with some HP leaf contacts in it. He said he'd tried to repair it but not got around to finishing it. My daughter who was with me today actually laughed slightly too loudly at that. I passed on it.

--- End quote ---

Yes probably best avoided (unless in perfect condition & fully working), I should have mentioned turning one of the controls and there was the sound of one dropping off.  :-DD
The 400ish page PDFs put me off doing anything with the most complete one, shame they didn't come with any manuals, the joblot of 141 series SA plug-ins (in similar condition) did at least come with some. Oh that & the corrosion of the gold plated traces, some of which are used for those rotary switches.
Much prefer the older 141 series SA.

David

--- End quote ---

Yes the 141T was more "Apollo Era Engineering" as I call it. If I was to grab an SA it'd be a bang up to date one (that doesn't go rusty like one vendor) or a 141T. So probably the 141T and a hernia it is.

They keep turning up for affordable amounts and I quite fancy having a go at one.

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