Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

@25 CPS, that look like a nice scopemeter you got there, so jelly right now. You say you got it from a Hock Shop, you mean a shop where someone burrowed money against it and then failed to buy it back again?

[med6753]

Well that was easy. The 8000A needed no adjustments. All parameters in spec.



Next up. 8010A after it settles in for several hours.

[mnementh]

Amazon.ca Heads-Up: 0805 Resistor Sample Book

              

CAD$13.49 at:https://www.amazon.ca/gp/product/B08P8TYQ2S/

For those in the Great White North... this Amazon is worth jumping on while you can. I got two because they promised 170 different values of 1% 805 resistors; I was figuring there had to be some skeevy catch, like a short 10-20ct strip of each or somesuch, so I bought two. But no... what came was 2 books of 1% 0805 resistors, 50 each in standard E24-Series values from 0R0 to 10M0. That's 8500 pieces for 13.49 Canuckistan shekels or US $9 & change each.

So much for double-filling one book to recycle the other for my caps! 

mnem
 

Make sure you measured them before you use them. Some of those kits are distinctly wrong 

The subtle bastard is if some "NP0" caps show a strong C-vs-V dependence

Well, as these are resistors, I don't think we're going to have to worry much aboot the derating curve typically associated with MMLCCs.  And I would hope that at least in this company, that phenomenon would be pretty well-known...

And I agree with bd as far as double-checking the values... while Yageo is an established "Chinese Domain" producer... random lots at curious discounts off Amazon definitely do bear closer scrutiny. Fortunately, I have plenty of time for such on my hobbyist workbench.

mnem

[cyclin_al]

@mnem dwagon   We finally got the electronic toys out for a first bash.  Sometime post-birthday we finally got both dry weather and free time on Canada Day.
Very happy with the toys chosen    SWMBO wants one now too...
   However, I found some extras when I was shaking out the gravel at the end.

That's one of the wheel axles' drive cup and bearing. The screw is held in with LokTite, so heat will be required to get that screw stub out. Also, there is evidently a problem with some of these kits being assembled with CA instead of LokTite, so a fair amount of heat may be required.    As shown in the above diagram, the screw is a M2x8mm flat head.



You won't be easily able to "convert to 2WD" without ruining the wheel axle... they use a CV joint at the wheel end so the shaft is captive. While technically it is possible to disassemble this, it is not meant to be disassembled, so will be difficult to do so without damaging the spring retainer and/or losing parts.



There is a shortcut way to get the diff apart without completely dismantling the frontend. I did it this way myself to grease my diffs. The 12429 comes factory with upgraded metal gears; it needs to be greased with a light plastic safe silicone grease or grease containing PTFE.

I'm using this for the diffs and main spur gear: [url]https://www.amazon.ca/gp/product/B07YLLPN51/[/url]   It's a little thicker than I like, but it sticks well and once it runs in the drag reduces to nearly nil. It still drags a bit more than I like on the main spur gear; next time I have them apart I may try a dry PTFE or graphite lube instead.

 I also apply ChainLube to all the dogbone drive cups and CV joints using a screwdriver as an applicator. It penetrates well, but once the carrier evaporates it stays put, which is what you want.

If you can't salvage what you have, your quickest way up & running is going to be the 12428 parts list from Banggood's USA warehouse:

[url]https://usa.banggood.com/Wltoys-12429-Front-Differential-RC-Car-Parts-p-1636119.html[/url] and have them ship to a US address you can pick up at.

Otherwise, you'll have to order from the China warehouse; use the same link and select a Canada delivery address & it'll automatically adjust the warehouse. Upgrade your shipping to Canada Direct Mail (not Canada Priority Direct) and it should be in your hands in 8-14 days. I dunno if Canada still has the $20 small purchase exemption on Duty; adjusting your order size to accommodate may be something to consider.

You may also want to consider getting the whole differential assembly (watch out for the one for the Feiyue FY01; it is similar but no go), and def scroll through all their 12428/12429 parts list: [url]https://usa.banggood.com/search/12428.html[/url] recommended are the aluminum hub hexes if they have 'em, but the huge aluminum bling sets are not a good idea, as there are really only a handful of bits (mostly the wheel hubs) you can used without trading out flexy parts that bend and creating a car that breaks instead.

   [url]https://usa.banggood.com/Metal-Heat-Sink-5V-Cooling-Fan-For-1-or-10-Car-540-3650-Motor-p-919362.html[/url]

This looks like the motor heat sinks I'm using; it has the 2 screws holding the fan on (it works fine) and it has the channels cut in the underside that allow the fan to drive air down to all the fins. You'll need to mod the underside of the body (the part with the driver) with a hot-air gun in the vicinity of the fire extinguisher to get clearance for the fan.

Don't get this one. I tried and no way in hell it'll fit short of cutting chunks out of the body.

Power for the fan is a bit of a PITA; I tried using the LED power but the fan severely drops the voltage if connected there, indicating to me either a current-limiting resistor in the circuit or possibly overloading a pin on a CPU, as the car does control the lights from the CPU to flash them in cases of OLP or LV. 

The LED circuit is switched open-drain or open-collector output (switched from the (-) side for those playing along at home), and you can tap regulated +5V at the LED harness. Then you need to find a BATT (-), which is where the PITA part comes in, as the Receiver/ESC is potted inside that plastic box.

Simplest solution would be to skin the heat-shrink off the BATT(-) connection, add a small (-) wire, then a piece of heat-shrink big enough (or stretched enough with a pair of needle-nose pliers) to get over the whole Deans' connector. I did it by skinning back insulation on the BATT (-) wire near the ESC and soldering to the wire inside with a wrap of Kapton tape. I do not like it at all; totes janky-looking.

Cheers!

mnem
 

Maybe I was not quite clear enough with my words.  It connects the differential TO the front drive shaft.  It is actually this cup:


I assume that it is impractical to drill out the screw shaft and re-tap the cup.
Otherwise, the tinker-dwagon would have suggested that?
It certainly is a frustratingly small size to work on.

I assumed for 2WD, I would have to go in and remove the loose 12T gear and its bearing.  Then on the other side, remove the front drive shaft so it is not flopping about.
Then again, the problem is not the same as dwagon thought.

EDIT: That video linked is still very useful, it shows I will need to remove the diff in order to get to the 12T gear to remove it and eventually re-assemble it to the cup.

*grumble* The Bang-em-good parts list does not show what I need.  Searching needs to be done; to be honest my earlier post was a quick message and I have not yet given it a fair shot to search on my own.  Let's see what I can find before lunch and afternoon activities take over.

EDIT2:  Closest part I found, which looks perfect from the photos, was this:
https://usa.banggood.com/Differential-RC-Car-Steering-Cup-1280-For-Wltoys-144001-124018-124019-1-or-14-4WD-High-Speed-Racing-Vehicle-Models-Parts-p-1599501.html
However, Q&A on this part indicates it is not what I need.

[mnementh]

   ...a Scopemeter!

This was a hock shop find that was very lightly used, if at all.  The reference lead for the green probe was still in the package and looked like it was still twisted together from the factory.

Okay... so give us the real dirt. How much did you pay...? 

mnem

[mnementh]

Maybe I was not quite clear enough with my words.  It connects the differential TO the front drive shaft.  It is actually this cup:

I assume that it is impractical to drill out the screw shaft and re-tap the cup. Otherwise, the tinker-dwagon would have suggested that?   It certainly is a frustratingly small size to work on.   I assumed for 2WD, I would have to go in and remove the loose 12T gear and its bearing.  Then on the other side, remove the front drive shaft so it is not flopping about.

Sorry; that was in part my fault. The exploded views I'd been looking at show that cup having a D-cut shaft... or maybe I got that mixed up with pics of the rear diff in my head.

Yes, it is impractical to tap/drill; those cups are usually hardened for wear resistance nearly to the point of embrittlement. While in some cases this is case-hardening that doesn't extend to that shaft area, I wouldn't dare count on it. My first line of attack would be to scribe a slot in the end of that screw stub, then apply heat and use a very small flat-bladed screwdriver to try and back it out.



Dang... you are in a bit of a pickle here. On mine, the grub-screws (0128) in the driveshafts right at the spur gear (0015) were tight as hell, and had CA rather than LokTite. Getting them off may require enough heat to damage the spur gear.

My gut reaction is... (contrary to my previous warning aboot dismantling the "CV" joints) that since they sell these parts with that joint disassembled, they've made them to be disassembled/reassembled. If so, the course of action least likely to cause more damage will be to dismantle the "CV" joint above and those in the front wheel axles.



You'll need to remove the radio electronics (they're zip-tied and held down with very sticky double-faced foam tape) and remove the top plate (this means also dismantling the front shocks from the plate to get to the screws that hold it down) from the chassis and unscrew the long screw that goes down through the steering rack slider assembly. It's more work than popping the steering rod loose from the servo or rack, but you want to avoid that as they get loose very quickly if you do pop them, even once. Then remove the spur gear cover.

Then you can take the spur gear and both driveshafts out to work on it. You'll need to work the spring retainer (0127) around the body of the ""CV" joint (0083) like a circlip; try to avoid stretching the spring as that will ruin it. There will be a thin pin (0072) that goes through the joint under that spring; press it through and then you should be able to remove the dogbone shaft (0082).

Watch out when disassembling that joint; there will be a bushing (0079) in the middle of the ball that will try to fall out and roll into the nearest HVAC register (0no0no0mygawdn0), never to be seen again. Once you have the parts all baggied up for later, you can reassemble the center chassis of the car, then remove the front wheels, unscrew all 4 kingpins, then remove the front axles and dismantle those "CV" joints. Leave the front gearbox alone until you have repair parts on hand.

Actually, while you have this area all apart, I recommend you inspect the main chassis plate very carefully with a flashlight around the back of the front gearbox, servo mount and the spur gear housing. The nature of the damage I'm seeing here suggests to me that this car was run head-on at high speed into something very hard and solid like a wall or curb. You may find hidden damage that really necessitates a rebuild on a new chassis plate. 

Cheers!

mnem
 

[25 CPS]

@25 CPS, that look like a nice scopemeter you got there, so jelly right now. You say you got it from a Hock Shop, you mean a shop where someone burrowed money against it and then failed to buy it back again?

That's correct.  A bunch of my test equipment's come from pawn shops where people have sold in/borrowed against test equipment and then not bought it back.  This has worked out well for me because I've been able to negotiate some pretty steep discounts because they invariable "don't know what it is", "can't test it", "it turns on but don't know how to use it".





This Extech power analyzer and the Heathkit semiconductor curve tracer was from a pawn shop in Scarborough that seems to get a lot of test equipment in compared to the others I periodically check out.  I also got an SPL meter from them and a Hewlett Packard 3550B test set which has an oscillator, a attenuator patch panel, and a voltmeter built into a carrying case with a whopping lead acid battery to power it all standalone, and some miscellaneous tools like outlet testers etc.



This Agilent U1115A came from a pawn shop in small farm town Ontario.  I have no idea how or why it ended up there but I took a country drive across the top of Toronto, picked it up, then looped back downtown to work for the afternoon shift.  This one wouldn't even turn on even though there were batteries installed - this turned out to be a fantastic deal because the little insulating piece of plastic was transparent and had never been removed so I got a great deal on it because it wouldn't turn on because it was new and unused!  Unfortunately, all they had was the U1115A.  What I was really hoping was that someone had sold the meter they were using or planning to use with the remote display with it and get a deal on a complete system but unfortunately they only had the display.  This was right at the very start of the pandemic in early 2020 too.  On my way out of the little town, I stopped at the Tim Hortons to get a coffee and I was standing in the parking lot drinking it down a bit before starting the drive and I saw someone roll through the drive thru wearing a full military gas mask complete with filter canister on it.  I sure hope it had a drinking straw built in like the way S-10s do otherwise all that protection was about to be negated as soon as they took it off to drink that coffee.

   ...a Scopemeter!

This was a hock shop find that was very lightly used, if at all.  The reference lead for the green probe was still in the package and looked like it was still twisted together from the factory.

Okay... so give us the real dirt. How much did you pay...? 

mnem

The Scopemeter wasn't the same kind of steal the other stuff was, though.  It was a hard negotiation because of the Fluke name and it's a current product with a big $$$ price new so I ended up spending real money even though I did get them to move a bit down from what they wanted for it despite being untested, and one hell of a lot less than the cost of buying one new.  It was one of those situations where you know it's painful but you end up getting out your credit card because you know it won't be within reach again until it's discontinued and beat up, well used ones start hitting the market years from now.  That said, I'm so glad I'm not going to be dependant on coaxing clapped out, destroyed Tektronix 465s at work to life anymore every time I have to troubleshoot analog ("but we don't do that anymore") problems.

[mnementh]

'nuff sed.

mnem
*currently nuking a battery box for another bicycle*

[AVGresponding]

Discord is activated

[eevcandies]

I bought some of those smd resistor/cap "kit" books...sadly it was summer & they used some cheapo extra gummy labels...By the time  it arrived the labels had all fallen off & were just a sticky clumpy mess in the package & the ink also "peeling off"....with all the approx 170 labels essentially missing, the book isn't so handy!

[duckduck]

Reader's Digest version: High-voltage film capacitors are no longer available in "tall skinny can" format, only big rectangular boxes. How do I attach the replacement capacitor securely when the new cap's footprint is to large to fit on the PCB?

Unabridged version: I just bought an HP 6209B DC power supply (0-320V 0-100mA) off of the estuary of wickedness. It's a late model, and a real beauty - traces were taped by hand and gold-plated. I was looking forward to long, blissful nights with just me, a 12AX7, and a high voltage power supply. Well, it turns out that one of the caps is making noise, the kind that can be detected by ear. The seller was a good sport and, at my suggestion, gave me a partial refund. The user manual is available online ( http://www.nousnexus.com/Manuals/HP_6209B.pdf ) and helpfully contains a schematic and parts list. The cap that failed is C20 - "film 25μf 475Vdc". It's a radial and ~30mm in diameter (see image, attached). I hop on digi-key and all of the 25μF film caps rated for >= 475VDC are boxes with footprints like 42x35mm. How the heck do I fit a large footprint component on a PCB designed for a tall skinny cap can? I was thinking that maybe I could build a little stand out of unclad FR-4 and gobs of silicone, and then plop the cap on top so it's raised off of the PCB (see DaveCAD, attached). Of course I would make something more structurally sound than what I sketched, but you get the idea. Is there a better way to solve this problem? Glue the cap to the side of the enclosure and run wires? Use multiple smaller caps in parallel? Use an electrolytic cap? Build my own capacitor? Give up and take up golf instead?

[med6753]

Mount a 5 lug terminal strip in similar fashion as the one to the right of the fuse. Install cap on terminal strip. Run wires down to the circuit board. Problem solved. 

[med6753]

Another successful calibration completed. This 8010A was pretty much dead nuts.



Next up. Mastech MS8040. I don't have a service manual for this guy so several years ago sent an e-mail to the US distributor asking if one was available. Nope. So decided to send an e-mail directly to Mastech. That e-mail dropped into a Chinese black hole never to be seen again. The DMM has 2 trim pots. I discovered that one of them is for DCV. I've never been able to figure out what the 2nd trim pot does. So the only thing I can set with certainty is DCV. I don't use it for measuring volts anyway but it does have a very useful capacitance range that I use to check new stock capacitors to make sure I don't have a duff replacement when re-capping equipment.

[med6753]

 

[mansaxel]

Reader's Digest version: High-voltage film capacitors are no longer available in "tall skinny can" format, only big rectangular boxes. How do I attach the replacement capacitor securely when the new cap's footprint is to large to fit on the PCB?

Unabridged version: I just bought an HP 6209B DC power supply (0-320V 0-100mA) off of the estuary of wickedness.

<snip>

Oh, a 6209b. I just might have been a watcher on that specimen. Many DC volts. Much fun. I think (who am I fooling, in here?) I'd be done once I have one of those. And maybe a 6203b...

Is there a better way to solve this problem? Glue the cap to the side of the enclosure and run wires? Use multiple smaller caps in parallel? Use an electrolytic cap? Build my own capacitor? Give up and take up golf instead?

I'd look at what med suggested. Sounds about right.

[nixiefreqq]

 

swmbo wanted to hang her union jack out today!

had to point out that king george III no longer has troops quartered in pennsylvania to come protect her tory ass, and that the local patriots would shoot our dog and burn the house down.

the sound of artillery coming from town convinced her.  (although that is the reenactment of our 1863 kerfuffle).



"wars and rumors of wars"

[Specmaster]

 

What a lovely, fine pair of red neck hillbillies 

[factory]

Reader's Digest version: High-voltage film capacitors are no longer available in "tall skinny can" format, only big rectangular boxes. How do I attach the replacement capacitor securely when the new cap's footprint is to large to fit on the PCB?

Unabridged version: I just bought an HP 6209B DC power supply (0-320V 0-100mA) off of the estuary of wickedness. It's a late model, and a real beauty - traces were taped by hand and gold-plated. I was looking forward to long, blissful nights with just me, a 12AX7, and a high voltage power supply. Well, it turns out that one of the caps is making noise, the kind that can be detected by ear. The seller was a good sport and, at my suggestion, gave me a partial refund. The user manual is available online ( http://www.nousnexus.com/Manuals/HP_6209B.pdf ) and helpfully contains a schematic and parts list. The cap that failed is C20 - "film 25μf 475Vdc". It's a radial and ~30mm in diameter (see image, attached). I hop on digi-key and all of the 25μF film caps rated for >= 475VDC are boxes with footprints like 42x35mm. How the heck do I fit a large footprint component on a PCB designed for a tall skinny cap can? I was thinking that maybe I could build a little stand out of unclad FR-4 and gobs of silicone, and then plop the cap on top so it's raised off of the PCB (see DaveCAD, attached). Of course I would make something more structurally sound than what I sketched, but you get the idea. Is there a better way to solve this problem? Glue the cap to the side of the enclosure and run wires? Use multiple smaller caps in parallel? Use an electrolytic cap? Build my own capacitor? Give up and take up golf instead?

I'm not sure the description in the manual is correct, it says film for C20 but when you search the military part sites for 0180-1848 it is then described as an aluminium electrolytic, see here; https://www.parttarget.com/5910-01-311-5312_5910013115312_PFP250YN2A1P2.html/-18280EA8-7F78-47CF-815F-0CF3C4CD45F8

When you look up the Sprague DFP (one of the alternate parts) it is also an aluminium electrolytic, I think the manual is incorrect, this wouldn't be the first error we have seen in old manuals.



David

[kleiner Rainer]

Duckduck,

the schematic you posted shows a polarized cap for C20 - I would simply replace it with a 105 Deg. low ESR electrolytic. Modern ones for switchmode power supplies should work. Maybe they replaced the initially planned cap with a foil one due to too much ESR of the electrolytics available back then?

Ah - page 3.7, chapter 3-50 output capacitance:

"3-51 An internal capacitor (C20}. connected across
the output terminals of the power supply. helps to
supply high-current pulses of short duration during
constant voltage operation. Any capacitance added
externally will improve the pulse current capability,
but will decrease the safety provided by the constant
current circuit. A high-current pulse may
damage load components before the average output
current is large enough to cause the constant current
circuit to operate."

So it looks to me that 10-22uF/485V should do the job. BTW hp provided jumpers to remove that cap, so it seems that it is not highly important for loop stability.

Greetings,

Rainer

[Robert763]

Rainer and Factory beat me to it. That looks like an electrolytic.
What's the part number on the actual capacitor?  I'd stick a modern electrolytic in there and if you are worried about HF noise stick a film cap, maybe 470nF across it too.
   

[Robert763]

A bit of TE constructon this morning. I needed a low level radiated source at around 10GHz so I knocked something up out of bits.
As you can see there is not much  to it, A SMA socket, two bits of tinned copper wire and a SMD diode. I cut the cap and threaded neck off a small cryotube to make a cover.
The center bit of wire is the radiator and the L shape to one side is a choke providing a DC return path.
The diode is  unknown type, it's one half of a dual diode package that was the mixer in a domestic satelite LNB that I found at the side of th road. Don't even know the model number because it had been run over. The lastic casing was missing and part of the feed was ground away  but still a source of parts.

One note is that the SMA is stuck in a hole drilled in a hockey puck this is a great way of holding this sort of part while soldering as it does not sink heat away or melt.

[med6753]

swmbo wanted to hang her union jack out today!

had to point out that king george III no longer has troops quartered in pennsylvania to come protect her tory ass, and that the local patriots would shoot our dog and burn the house down.

the sound of artillery coming from town convinced her.  (although that is the reenactment of our 1863 kerfuffle).



"wars and rumors of wars"

It is ironic that the Battle of Gettysburg was fought July 1 - 3 in 1863. But yes, she would do well to keep that Union Jack in the closet. 

[bd139]

Ignoring the American focus of Traitor Day, managed to get out on the walk I was going to do yesterday. Got couple of cliche photos of the Ouse Valley Viaduct, some quality British engineering the Americans didn't take with 'em and made stuff out of wood instead...

This was opened in 1841 while the Americans were still working things out with each other and is still in active use today. Impressive! Americans still haven't worked out each other yet.





No TE related contribution. As explained on Discord last night I was humming and hawing over a 34401A and lost it 

[mnementh]

We're on the road again, looking at properties.   

Of course, the very first property we looked at last week was awesome; an older house with good space inside & out, and a nice driveway with room for my recently built shed. We never even got to apply; they emailed my wife that it had been taken while we were on our way home.

mnem
life is the journey, not the destination.

[bd139]

We're on the road again, looking at properties.   

Of course, the very first property we looked at last week was awesome; an older house with good space inside & out, and a nice driveway with room for my recently built shed. We never even got to apply; they emailed my wife that it had been taken while we were on our way home.

mnem
life is the journey, not the destination.

Good luck mnem. Fingers crossed for you here. Total shit show having to do that now esp so soon