Test Equipment Anonymous (TEA) group therapy thread

[tggzzz]

150 Euros for a 500MHz probe isn't that bad imho.

https://www.reichelt.de/rf-probe-500-mhz-10-mohm-testec-12070-p217578.html?

Agreed, but I don't have much use for a probe with a 31ohm input impedance (10pF@500MHz), especially when you include the inductance of a ground lead.

At those frequencies I prefer a 500ohm 1pF resistive divider probe. Bonus: you can make those yourself by soldering a 450ohm resistor to the board and 50ohm cable

[BU508A]

I hate plastic shrouds. I do not trust them and imo they wear out really fast.
And when you are in the middle of the guts of a thing somwhere in the outback of nowhere
and find out, that this strange signal behaviour is coming from a bad BNC connection
and you have wasted half an hour of time, then ... well then it is time to go home and
have a cold beer or something.      

Even the probes for my Tek THS720A have metal shrouds and they are the original ones.

[FransW]

PM 2423 Manual

[BU508A]

Agreed, but I don't have much use for a probe with a 31ohm input impedance (10pF@500MHz), especially when you include the inductance of a ground lead.

At those frequencies I prefer a 500ohm 1pF resistive divider probe. Bonus: you can make those yourself by soldering a 450ohm resistor to the board and 50ohm cable

Next time I'll consult the datasheet first. 

You are right, 10pf is way too much for a 500MHz probe. No idea what they are smoking at Testec ...

[tggzzz]

Agreed, but I don't have much use for a probe with a 31ohm input impedance (10pF@500MHz), especially when you include the inductance of a ground lead.

At those frequencies I prefer a 500ohm 1pF resistive divider probe. Bonus: you can make those yourself by soldering a 450ohm resistor to the board and 50ohm cable

Next time I'll consult the datasheet first. 

You are right, 10pf is way too much for a 500MHz probe. No idea what they are smoking at Testec ...

Even good passive "high" impedance probes are 6.5pF, and only for scopes with a 6-9pF input!

There are many probes like that Testec, from many manufacturers They have some utility when connected to the circuit directly, typically using bent paper clips:

[bd139]

The trick I use in such circumstances is to think "how can I avoid making that measurement"

[Wolfgang]

Agreed, but I don't have much use for a probe with a 31ohm input impedance (10pF@500MHz), especially when you include the inductance of a ground lead.

At those frequencies I prefer a 500ohm 1pF resistive divider probe. Bonus: you can make those yourself by soldering a 450ohm resistor to the board and 50ohm cable

Next time I'll consult the datasheet first. 

You are right, 10pf is way too much for a 500MHz probe. No idea what they are smoking at Testec ...

Even good passive "high" impedance probes are 6.5pF, and only for scopes with a 6-9pF input!

There are many probes like that Testec, from many manufacturers They have some utility when connected to the circuit directly, typically using bent paper clips:

Ugly stuff Why not use a DIY FET probe ? You can have 1pF input capacitance with those.
https://electronicprojectsforfun.wordpress.com/rf-measurement-techniques/high-frequency-probes/

[PA0PBZ]

Not sure why you even want to do that in the 2nd picture with the long green and red wires hanging from the pads.

[med6753]

Lots of action here at my complex. The septic system needed work to install new piping between the septic tank and the leach field. Problem is the leach field is on the other side of the through road owned by the county. Obviously the county isn't going to allow you to block traffic and dig up the road. Solution: A “Ditch Witch” which bores a large diameter hole under objects, such as road. I've never seen one in operation before. It is a cool device. At the same time land lord had the trenching equipment to hook up the electrical in the garage that I rent. Nice to finally have power out there.

The following is a dumb ass test. This is the washing machine in our laundry room. Notice the water hook ups. Given that arrangement what can you NOT get on your wash cycle. If you know the correct answer there's no prize other than you are not a dumb ass. If you don't know the answer don't guess. Because then I'll have to conclude you're a dumb ass. Seems they are every where. And they breed too.

[tggzzz]

Ugly stuff Why not use a DIY FET probe ? You can have 1pF input capacitance with those.
https://electronicprojectsforfun.wordpress.com/rf-measurement-techniques/high-frequency-probes/

I don't disagree! (And I've bookmarked that reference)

The passive probes are pleasantly robust and high voltage, though.

[med6753]

Seems in every family or group you have that “problem child”. For me it's this 465B/DM44. It's the same scope that gave me fits for months with the channel 2 attenuator switch deck. Now it's got 2 other issues. First, every once in a while both traces have a small amount of 120Hz ripple. And also both channels are displaying some high frequency round off.

So today deep dive into the power supply. The voltages are all in spec but here's some ripple measurements on it's cousin 475A. That's the +5V. Spec is 2mV or less. It's right at the limit. The -8V is showing same. Right at the limit. The +15V, +55V reference, and +110V are comfortably under their limit. So it looks like it's time to change the filter capacitors in the supply.

As far as the high frequency issues are concerned going to hold off until the capacitors are changed. And if it still has that issue I have a spare vertical pre-amp board I can change out rather quickly.

[bd139]

This is why I'm done with the infernal things 

I wish you luck however 

[med6753]

This is why I'm done with the infernal things 

I wish you luck however 

Yea, I hear you. The way I look at it is these guys are getting OLD. And they're gonna have problems. But it keeps me on my toes and there's the satisfaction of getting it fixed.

Case in point...the recent 7904 outage. Truth be told I never thought I'd ever get that one fixed and I had thoughts of throwing it into the parts bin. 

[mnementh]

↑Chuckit/Fuckit/Bucket.

As promised, here's a few pictures of the PM6603's innards.

And it sure isn't a Philips machine. They did not use Philips headed screws. The housing is dominated by a big (and heavy!) silvery box: (SNIP ALL SORTS OF TEA pr0n GOODNESS just for sanity's sake) 

   This is much nicer than I'd thought.

Now we know where ELECRAFT got their chassis design inspiration from... Damn; that thing is built like a brick shithouse!     Jeebus... is that a ferrite core XFMR being used on 50/60 cycle line voltage?

PITA today. I bought some Wittig probes to go with the HM203. Nearly paid as much for the probes as the scope. But the damn BNC holes are slightly recessed on the scope and the probes have plastic shrouds around the BNC. Going to have to trim ~3mm off the end so they will actually go in the scope 

If that's the worst that happens to you in a day, it's been a damned fine day my friend.  

Lots of action here at my complex. The septic system needed work to install new piping between the septic tank and the leach field. Problem is the leach field is on the other side of the through road owned by the county. Obviously the county isn't going to allow you to block traffic and dig up the road. Solution: A “Ditch Witch” which bores a large diameter hole under objects, such as road. I've never seen one in operation before. It is a cool device. At the same time land lord had the trenching equipment to hook up the electrical in the garage that I rent. Nice to finally have power out there.

The following is a dumb ass test. This is the washing machine in our laundry room. Notice the water hook ups. Given that arrangement what can you NOT get on your wash cycle. If you know the correct answer there's no prize other than you are not a dumb ass. If you don't know the answer don't guess. Because then I'll have to conclude you're a dumb ass. Seems they are every where. And they breed too.

Not so dumb as you think. The hot water is obviously borked, note missing handle and shaft. This means it's turned off at the other end. Now if you left that connected, anytime somebody set the washer to a "WARM" cycle, it would backflow and spray all over hell & creation through the hole where the valve shaft on the hot water bibb used to be.

This at least gets the washer functional until you can get somebody out with the crimpers to repair that fucking demonic PEXX piping.

Fuckitol.... I guess those years spent working in the Ding & Dent Appliance warehouse DID teach me a thing or two of value... 

   

When people in the biz say "A Ditch Witch" they usually mean a trencher like the ones above. The same company has also pioneered  directional drills and hydro-tunneling systems seen below. Which did they use on your site?

      

mnem


mnem
moo.

[bd139]

This is why I'm done with the infernal things 

I wish you luck however 

Yea, I hear you. The way I look at it is these guys are getting OLD. And they're gonna have problems. But it keeps me on my toes and there's the satisfaction of getting it fixed.

Case in point...the recent 7904 outage. Truth be told I never thought I'd ever get that one fixed and I had thoughts of throwing it into the parts bin. 

Very true. On a positive note I have a crap load of tek parts to sell now from my failures

PITA today. I bought some Wittig probes to go with the HM203. Nearly paid as much for the probes as the scope. But the damn BNC holes are slightly recessed on the scope and the probes have plastic shrouds around the BNC. Going to have to trim ~3mm off the end so they will actually go in the scope 

If that's the worst that happens to you in a day, it's been a damned fine day my friend.  

That’s ok top of the 33oC here today (91.4oF) and the 38oC (100.4oF) tomorrow. Highest recorded temp here ever was 38.5oC 

Tends to reduce the average age of the population this weather 

[med6753]

Not so dumb as you think. The hot water is obviously borked, note missing handle and shaft. This means it's turned off at the other end. Now if you left that connected, anytime somebody set the washer to a "WARM" cycle, it would backflow and spray all over through the hole where the valve shaft on the hot water bibb used to be.

This at least gets the washer functional until you can get somebody out with the crimpers to repair that fucking demonic PEXX piping.

Fuckitol.... I guess those years spent working in the Ding & Dent Appliance warehouse DID teach me a thing or two of value... 

mnem
moo.

No, it's NOT borked. It was done intentionally. About 5 years ago when fuel oil prices spiked in order to save fuel and keep the price of using the washing machine in check the land lord disconnected the hot water. So the machine is cold water only. But he never told anyone that he did that I guess because he assumed that people would see very clearly that it's cold only. Now you know what happens when you assume. Obviously I saw it immediately and made adjustments to do my laundry in cold water. Not so the other dumb asses who live here. Do you know how many times I go to use the machine and it's set to warm or hot?  More than I can count.     

[med6753]

That’s ok top of the 33oC here today (91.4oF) and the 38oC (100.4oF) tomorrow. Highest recorded temp here ever was 38.5oC 

Tends to reduce the average age of the population this weather 

The highest temp that was recorded here was 104 F (40 C) I think in 1933.

[med6753]

They used this ditch witch.

[mnementh]

Not so dumb as you think. The hot water is obviously borked, note missing handle and shaft. This means it's turned off at the other end. Now if you left that connected, anytime somebody set the washer to a "WARM" cycle, it would backflow and spray all over through the hole where the valve shaft on the hot water bibb used to be.

This at least gets the washer functional until you can get somebody out with the crimpers to repair that fucking demonic PEXX piping.

Fuckitol.... I guess those years spent working in the Ding & Dent Appliance warehouse DID teach me a thing or two of value... 

mnem
moo.

No, it's NOT borked. It was done intentionally. About 5 years ago when fuel oil prices spiked in order to save fuel and keep the price of using the washing machine in check the land lord disconnected the hot water. So the machine is cold water only. But he never told anyone that he did that I guess because he assumed that people would see very clearly that it's cold only. Now you know what happens when you assume. Obviously I saw it immediately and made adjustments to do my laundry in cold water. Not so the other dumb asses who live here. Do you know how many times I go to use the machine and it's set to warm or hot?  More than I can count.     

Or maybe, like most landlords, he's too busy/lazy/cheap to fix it or pay the guy who has the tools to fix that fucking demonic PEXX piping. I know from experience it is usually the hot water that springs a leak on that shit. I always look for the "lazy" excuse as the likeliest.

mnem
I fought the lawn and the lawn... LOST! HAH!

[med6753]

Not so dumb as you think. The hot water is obviously borked, note missing handle and shaft. This means it's turned off at the other end. Now if you left that connected, anytime somebody set the washer to a "WARM" cycle, it would backflow and spray all over through the hole where the valve shaft on the hot water bibb used to be.

This at least gets the washer functional until you can get somebody out with the crimpers to repair that fucking demonic PEXX piping.

Fuckitol.... I guess those years spent working in the Ding & Dent Appliance warehouse DID teach me a thing or two of value... 

mnem
moo.

No, it's NOT borked. It was done intentionally. About 5 years ago when fuel oil prices spiked in order to save fuel and keep the price of using the washing machine in check the land lord disconnected the hot water. So the machine is cold water only. But he never told anyone that he did that I guess because he assumed that people would see very clearly that it's cold only. Now you know what happens when you assume. Obviously I saw it immediately and made adjustments to do my laundry in cold water. Not so the other dumb asses who live here. Do you know how many times I go to use the machine and it's set to warm or hot?  More than I can count.     

Or maybe, like most landlords, he's too busy/lazy/cheap to fix it or pay the guy who has the tools to fix that fucking demonic PEXX piping. I know from experience it is usually the hot water that springs a leak on that shit. I always look for the "lazy" excuse as the likeliest.

mnem
I fought the lawn and the lawn... LOST! HAH!

It doesn't leak, He's not lazy, and his Father is a plumber.  And yes...PEXX is the devil if not installed properly...or even if done properly. 

[mnementh]

   They used this ditch witch.

Neat. Those things pack a lot of ergs into a small machine. You get close enough to its transit and you can feel the damn thing grinding away in the pit of your stomach. 

mnem
*grrrrrrrrr...*

[mnementh]

It doesn't leak, He's not lazy, and his Father is a plumber.  And yes...PEXX is the devil if not installed properly...or even if done properly. 

LOL...Well then, he knows enough to make it LOOK like the hot water was recently borked and it's "just a temporary fix until he can get around to doing it right."

That, my friend, is the landlord's stock in trade. 

mnem
"Wilbur, you ever fixed one of these German 5-speeds?"
I watched a guy fix a Jap-a-NEEZE trans-mish-ee-on once..."
"Close enough... SHE'ZZ YOURZZZ!!!"

[med6753]

   They used this ditch witch.

Neat. Those things pack a lot of ergs into a small machine. You get close enough to its transit and you can feel the damn thing grinding away in the pit of your stomach. 

mnem
*grrrrrrrrr...*

Yep, you could feel the ground vibrating as it was drilling.

[Ero-Shan]

PM 2423 Manual

Thanks, even if I don't have that DMM. It may be of Japanese origin, but the schematics are absolutely genuine Philips! Did they redraw them?

[Ero-Shan]

↑Chuckit/Fuckit/Bucket.

As promised, here's a few pictures of the PM6603's innards.

And it sure isn't a Philips machine. They did not use Philips headed screws. The housing is dominated by a big (and heavy!) silvery box: (SNIP ALL SORTS OF TEA pr0n GOODNESS just for sanity's sake) 

   This is much nicer than I'd thought.

Now we know where ELECRAFT got their chassis design inspiration from... Damn; that thing is built like a brick shithouse!     Jeebus... is that a ferrite core XFMR being used on 50/60 cycle line voltage?

It's a 'tape wound core' (had to look that up) transformer. I'm really happy with that acquisition, even if it has only 5 digits. It has a certain right feeling to it.