Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

Well, not quite. I took it apart because I had already sprayed it with 3 different kinds of contact cleaner at least 5 or 6 times and still intermittent contact. Worse yet, I didn’t actually find anything wrong... but it worked perfectly after I scrubbed and sprayed it with food grade silicone spray lube.

It wasn’t until a few days later when I was editing pix I took during the work that I found the one pic right after I’d removed the plunger clearly showing a tiny grain of sand which had gotten in there.

Just proof that sometimes, following a known effective procedure consistently is as important as diag and inspection results. 

In this case, it is my opinion that the switch is made this way on purpose such that it can be serviced this way. I see no good reason not to take advantage of the fact to give it a good scrubbing every once in a while. 

mnem
 

As a rule you should NOT use silicone lubricants on contacts. If there is any arcing at the contact Silicon Dioxide (glass) can form ruining the contact. Some contaminants can also cause silicone to form solid insulating layers on contacts. If you get even tiny amounts of silicone near contacts it can cause issues. One case was the UK Post Office Telephone exchanges (Old Strowager type) where thy had problems eventually traced to the floor polish changing to have silicone wax in it.

A good grease lubricant for contacts is petrolum jelly  "Vaseline". Mixing in a little oil based contact cleaner makes it even better.

I disagree where self-cleaning/wiping contacts are concerned; particularly pots & sliders. 3 decades of empirical experience points to the contrary, and petroleum jelly is flammable (in an arc-flash situation it breaks down creating flammable vapors which can ignite/scorch surrounding plastic), where the microscopic residue from a good food-grade silicone spray is not. Its hydrophobic nature also inhibits issues from moisture in the air.

Use what you choose to; I'll stick with my food-grade silicone. If I'm wrong in that, OFW.   

In this case, if you're worried about the silicone spray (or you don't know which of the dozens of such spray concoctions out there is a good choice), just scrub/flood the thing with alcohol as seen in my pictorial and run it dry like it came from HP.   

mnem
 

[mnementh]

PS: One day I would like to know what you think about ECC Ram, I still don't have a clear opinion on that stuff.

Interesting here.

Hoo boy. There's a locked thread just waiting to happen. 

mnem
*currently developing ECC underwear*

[BU508A]

Nice DC Load in the USA (NAWTS):

https://www.ebay.com/itm/224133731707

[Cerebus]

Had a problem using my 3478A yesterday.  Wanted to check a low resistance cable, so wired up for 4 wire and got some curious readings.  Tried 2 wire and it was worse.  Checked my cables and tried again.  Still had stupid numbers.  Rechecked cables and shuffled them around.  Still no joy.


Then I hit the front/rear switch..........   

[McBryce]

Nice DC Load in the USA (NAWTS):

https://www.ebay.com/itm/224133731707

For $100 more than it costs new?? https://www.aliexpress.com/item/32639254948.html

McBryce.

[Cerebus]

Yeah, but are you going to get something from China into the US without paying customs duty? Not in the current climate I fear. Probably works out cheaper than a new one from Aliexpress.

[Specmaster]

Well, not quite. I took it apart because I had already sprayed it with 3 different kinds of contact cleaner at least 5 or 6 times and still intermittent contact. Worse yet, I didn’t actually find anything wrong... but it worked perfectly after I scrubbed and sprayed it with food grade silicone spray lube.

It wasn’t until a few days later when I was editing pix I took during the work that I found the one pic right after I’d removed the plunger clearly showing a tiny grain of sand which had gotten in there.

Just proof that sometimes, following a known effective procedure consistently is as important as diag and inspection results. 

In this case, it is my opinion that the switch is made this way on purpose such that it can be serviced this way. I see no good reason not to take advantage of the fact to give it a good scrubbing every once in a while. 

mnem
 

As a rule you should NOT use silicone lubricants on contacts. If there is any arcing at the contact Silicon Dioxide (glass) can form ruining the contact. Some contaminants can also cause silicone to form solid insulating layers on contacts. If you get even tiny amounts of silicone near contacts it can cause issues. One case was the UK Post Office Telephone exchanges (Old Strowager type) where thy had problems eventually traced to the floor polish changing to have silicone wax in it.

A good grease lubricant for contacts is petrolum jelly  "Vaseline". Mixing in a little oil based contact cleaner makes it even better.

I disagree where self-cleaning/wiping contacts are concerned; particularly pots & sliders. 3 decades of empirical experience points to the contrary, and petroleum jelly is flammable (in an arc-flash situation it breaks down creating flammable vapors which can ignite/scorch surrounding plastic), where the microscopic residue from a good food-grade silicone spray is not. Its hydrophobic nature also inhibits issues from moisture in the air.

Use what you choose to; I'll stick with my food-grade silicone. If I'm wrong in that, OFW.   

In this case, if you're worried about the silicone spray (or you don't know which of the dozens of such spray concoctions out there is a good choice), just scrub/flood the thing with alcohol as seen in my pictorial and run it dry like it came from HP.   

mnem
 

Just be certain to treat IPA with the respect it deserves, use only in a well ventilated room, it too is highly combustible and can be easily ignited by a small spark, so you need to be sure that it has completely evaporated before powering up the circuit.

[Specmaster]

Yeah, but are you going to get something from China into the US without paying customs duty? Not in the current climate I fear. Probably works out cheaper than a new one from Aliexpress.

Here in the UK there is a good chance that you'll get away without paying import duty, its all down to how the seller declares the item on the customs' declaration paperwork.

[mnementh]

(SNIP)

In this case, if you're worried about the silicone spray (or you don't know which of the dozens of such spray concoctions out there is a good choice), just scrub/flood the thing with alcohol as seen in my pictorial and run it dry like it came from HP.   

mnem
 

Just be certain to treat IPA with the respect it deserves, use only in a well ventilated room, it too is highly combustible and can be easily ignited by a small spark, so you need to be sure that it has completely evaporated before powering up the circuit.

https://youtu.be/-0cjCPBiIq4

https://youtu.be/20fbQfsmNKc

Awww... where's the fun in THAT...?!?     

Same is extra-true of silicone spray; even food-grade varieties usually use some form of alcohol as a carrier, sometimes along with toluene or xylene and may even have butane as a propellant! 

Of course, we all know that's right where YOU like to play, ya pyro! 

mnem
Can you say BOOM! boys and girls...?

[Cerebus]

Same is extra-true of silicone spray; even food-grade varieties usually use some form of alcohol as a carrier, sometimes along with toluene or xylene and may even have butane as a propellant! 

I think that's will have butane or some other highly flammable hydrocarbon as a propellant (unless it's really, really old). The only things that don't nowadays are medical inhalers (my asthma inhalers use R134a) and food products - whipped cream in a can uses nitrous oxide, quite what is used in the strange emulsified fat and flavouring cheese simulant known only on the north American subcontinent known as Cheez Whiz I don't know (Tritium? Compressed sewage gas? Some other noxious gaseous waste product?).

Edited: Speeling, or more accurately a complete inability to type straight.

[Cerebus]

Here in the UK there is a good chance that you'll get away without paying import duty, its all down to how the seller declares the item on the customs' declaration paperwork.

It will be a lie, it always is, even when a correct declaration and correct value would attract no VAT or duty. I don't think I've ever had a CN1 from China that had an accurate product description or accurate price, let alone the two together.

[bd139]

Well it's a good day for stuff today.

Firstly big thanks to Specmaster who sent me a replacement analogue board for my exploded F25. I just stuffed it in while eating my lunch and it works perfectly on all ranges now, not just volts, and appears to be spot on cal as well. Many thanks! . This one's a keeper. I really like the fact that I can use it as a melee weapon at extremely short notice 



To do on this one is general clean up. New proper HRC fuse ordered for it as well now and the other two were good from the old one.

More to come as I get some time...

[mnementh]

Yup. You can keep it handy leveling out that one wonky table leg; not like it'll notice. 

mnem
 

[bd139]

Item number two. This was the £30 spectrum analyser gamble which appears to have paid off so far despite being 100% untested.





Very nicely constructed. This is a house clearance item so RIP to the engineer who this came from. It will be looked after and not bounced.

After doing some digging it appears to be a very faithful build of the Radcom 1989 simple spectrum analyser: http://archive.retro.co.za/archive/amateur/SimpleSpectrumAnalyser-Radcom-Nov1989.pdf

I am suspicious about the mains filter so will bring it up on a bench power supply when I get some time and check it out thoroughly.

[BU508A]

Item number two. This was the £30 spectrum analyser gamble which appears to have paid off so far despite being 100% untested.



Very nicely constructed. This is a house clearance item so RIP to the engineer who this came from. It will be looked after and not bounced.

After doing some digging it appears to be a very faithful build of the Radcom 1989 simple spectrum analyser: http://archive.retro.co.za/archive/amateur/SimpleSpectrumAnalyser-Radcom-Nov1989.pdf

I am suspicious about the mains filter so will bring it up on a bench power supply when I get some time and check it out thoroughly.

What is that missing IC7?

[Specmaster]

Here in the UK there is a good chance that you'll get away without paying import duty, its all down to how the seller declares the item on the customs' declaration paperwork.

It will be a lie, it always is, even when a correct declaration and correct value would attract no VAT or duty. I don't think I've ever had a CN1 from China that had an accurate product description or accurate price, let alone the two together.

Thats my point precisely, unless the customs decide to open up the parcel, they will never really know what it contains. 

[Specmaster]

Well it's a good day for stuff today.

Firstly big thanks to Specmaster who sent me a replacement analogue board for my exploded F25. I just stuffed it in while eating my lunch and it works perfectly on all ranges now, not just volts, and appears to be spot on cal as well. Many thanks! . This one's a keeper. I really like the fact that I can use it as a melee weapon at extremely short notice 



To do on this one is general clean up. New proper HRC fuse ordered for it as well now and the other two were good from the old one.

More to come as I get some time...

Glad to have helped out, it keeps another item out of land fill and doubles as a mallet if required so whats not to like 

Edit, Don't forget if you can get hold of a F27 case in good condition, the guts of the F25 will fit it and then you have the added benefit of the REL and the MIN/MAX functions as well.

[bd139]

Item number two. This was the £30 spectrum analyser gamble which appears to have paid off so far despite being 100% untested.



Very nicely constructed. This is a house clearance item so RIP to the engineer who this came from. It will be looked after and not bounced.

After doing some digging it appears to be a very faithful build of the Radcom 1989 simple spectrum analyser: http://archive.retro.co.za/archive/amateur/SimpleSpectrumAnalyser-Radcom-Nov1989.pdf

I am suspicious about the mains filter so will bring it up on a bench power supply when I get some time and check it out thoroughly.

What is that missing IC7?

Inverts the X axis output for scopes which have opposite X axis voltage/deflection. There were quite a few that did this. The thing has a "hameg settings" sticker on the back so I assume that didn't need inverted X.

[bd139]

Glad to have helped out, it keeps another item out of land fill and doubles as a mallet if required so whats not to like 

  

I've got some Ikea stuff arriving tomorrow. I was going to club in the wooden pegs with it  (only joking)

Thanks again

[mnementh]

I'd pay to see that. 

mnem
*rummages in pocket for change*

[mnementh]

   Inverts the X axis output for scopes which have opposite X axis voltage/deflection.

There were quite a few that did this. The thing has a "hameg settings" sticker on the back so I assume that didn't need inverted X.

Shocking to see it's another 741. 

mnem
 

[bd139]

   Inverts the X axis output for scopes which have opposite X axis voltage/deflection.

There were quite a few that did this. The thing has a "hameg settings" sticker on the back so I assume that didn't need inverted X.

Shocking to see it's another 741. 

mnem
 

Does the job here - fancy ramp generator 

Final item. Examining the gouged out, still beating heart of the old Fluke 25. This is the only signal source I have that doesn't require digging in the cupboard for more than a few seconds at the moment.



Need a sit down after all this excitement

[bd139]

Edit, Don't forget if you can get hold of a F27 case in good condition, the guts of the F25 will fit it and then you have the added benefit of the REL and the MIN/MAX functions as well.

Yeah will keep an eye out for that as well  . One each of 25 and 27 would be nice for the bench  

[TERRA Operative]

Speaking of 3478A's, anyone got a 1QF7-0067 hybrid module they are willing to part with?
One of my meters doesn't seem to believe in AC, so I need a new module to get my AC ranges back...

[Specmaster]

Speaking of melee weapons, the same is true of the Brymen 867 / 869 meters and it is interesting to note that they are almost identical in weight, feel, construction and size, the latter of which can be seen by the photo of my BM867 and F27 side by side. I would have perfect confidence in both of them surviving the abuse that the military inflict on their instruments.