Test Equipment Anonymous (TEA) group therapy thread

[WastelandTek]

So the only probes I have lying around are cheap P6100 ones at the moment and they are quite frankly shit. Even putting your hands near them causes problems and adequate compensation is pretty difficult. They overshoot like mad and generally suck balls. Now I have a scope worth investing in it looks like I need to buy some decent probes.

So first stop was to find some suitable Tek probes. Turns out a broken piece of shit still goes for £50 or so which is not something I'm paying for a risky dodgy probe purchase.

Next stop was China to see what they had on the market and you can get a 300MHz probe which has a dubious rise time on it. Reviews I have seen suggest the specifications are exaggerated.

Then to Probemaster who do ones with the correct indicator pins. Good job. So a kit of 3 probes including carriage and duty and VAT is going to set me back £200. Nope.

Now to TME who sell Testec 300MHz probes with apparently a good reputation and decent 1.2ns rise time. That's £105 for two, which is better and probably worth it if they perform ok.

Does anyone have any other options?

Edit: found some Testec ones at 250MHz 1.4ns rise time but they are switchable ones (spit yuck) but two for £50: https://uk.farnell.com/testec/tt-mf312-2-6-11020-2-6/probe-oscilloscope-double-mid/dp/4308104

Shipping and VAT are a bummer, but I am a big advocate of the Probemaster products.  Well built, and they sell replacement parts so you can fix them.

[bd139]

Fine if you only play with LV stuff otherwise I like some CAT rated probe to hang onto. 

yeah talking 15V max here

[BU508A]

2 off 10X probes not switchable. 10-50pf. autosense would be nice but not important. Main thing is something that actually adheres to the specification.

Currently looking at these: https://www.reichelt.com/gb/en/modular-probe-250-mhz-x10-testec-mf-212-p32418.html

I'd recommend the Hameg HZ350 ones:

https://www.ebay.co.uk/itm/274125155674   <--- NOS, ca. 69.- Euro / piece

Made by Rohde & Schwarz (after they'd bought Hameg)

HZ350 HAMEG Tastteiler

10:1  350MHz  mit automatischer Tatkopferkennung

Anstiegszeit <1ns
Eingangsimpedanz 10MOhm II 12pF
Max. Spannung 400V (DC+Spitze AC)
Länge 1,2m
automatische Teilungsfaktor-Kennung
Mess-Kategorie CAT I

[Neomys Sapiens]

As we enter the 1980's lets pause and remember Big Hair and the Decade Fashion Failures 

Huh. You are into the turtle/shoebox hybrids too now?

[mnementh]

So the only probes I have lying around are cheap P6100 ones at the moment and they are quite frankly shit. Even putting your hands near them causes problems and adequate compensation is pretty difficult. They overshoot like mad and generally suck balls. Now I have a scope worth investing in it looks like I need to buy some decent probes.

So first stop was to find some suitable Tek probes. Turns out a broken piece of shit still goes for £50 or so which is not something I'm paying for a risky dodgy probe purchase.

Next stop was China to see what they had on the market and you can get a 300MHz probe which has a dubious rise time on it. Reviews I have seen suggest the specifications are exaggerated.

Then to Probemaster who do ones with the correct indicator pins. Good job. So a kit of 3 probes including carriage and duty and VAT is going to set me back £200. Nope.

Now to TME who sell Testec 300MHz probes with apparently a good reputation and decent 1.2ns rise time. That's £105 for two, which is better and probably worth it if they perform ok.

Does anyone have any other options?

Edit: found some Testec ones at 250MHz 1.4ns rise time but they are switchable ones (spit yuck) but two for £50: https://uk.farnell.com/testec/tt-mf312-2-6-11020-2-6/probe-oscilloscope-double-mid/dp/4308104

Hong Kong Texas makes a number of probes in the range you're talking about; good enough quality that HPAK has used them for OEM. http://www.hktexas.hk/en/pro_passive_probe.html

The fun part is finding a distributor; they seem to be like the best kept secret, etc.

mnem
*desperately seeking pizza*

[Neomys Sapiens]

Other news: the 'dodo' multimeter (YEW Model 2441) is in. Will post about it soon. With the controls not visible in the pictures, the operation becomes a bit clearer. I spent at least 2h searching for information about it...nada. Maybe someone could find something on a .jp site, but in the part of the world using the latin alphabet there seems to be nothing.

[Specmaster]

That's fine. Doesn't involve greasy fingers touching the screen.

I actually made a light pen for my BBC micro back in the day. One of my first electronic projects. Used a transistor, a photodiode and plugged in the joystick hole. I managed to squeeze it all in a Berol pen. Used it, err, once. That was a bus to maplin job. Back when they were actually worth going to. And not shut

Argh yes, I remember those days fondly, and they always had a clearance section of overstocked items or items being dropped from their catalogue, always worth a look there. They used to have a quite a big store at lakeside retail park.

[Specmaster]

So the only probes I have lying around are cheap P6100 ones at the moment and they are quite frankly shit. Even putting your hands near them causes problems and adequate compensation is pretty difficult. They overshoot like mad and generally suck balls. Now I have a scope worth investing in it looks like I need to buy some decent probes.

So first stop was to find some suitable Tek probes. Turns out a broken piece of shit still goes for £50 or so which is not something I'm paying for a risky dodgy probe purchase.

Next stop was China to see what they had on the market and you can get a 300MHz probe which has a dubious rise time on it. Reviews I have seen suggest the specifications are exaggerated.

Then to Probemaster who do ones with the correct indicator pins. Good job. So a kit of 3 probes including carriage and duty and VAT is going to set me back £200. Nope.

Now to TME who sell Testec 300MHz probes with apparently a good reputation and decent 1.2ns rise time. That's £105 for two, which is better and probably worth it if they perform ok.

Does anyone have any other options?

Edit: found some Testec ones at 250MHz 1.4ns rise time but they are switchable ones (spit yuck) but two for £50: https://uk.farnell.com/testec/tt-mf312-2-6-11020-2-6/probe-oscilloscope-double-mid/dp/4308104

Those probes of yours, the problems sounds more like an issue with either a dodgy connection and or poor screening, I've never noticed any such effects when using my probes, and I don't have any of the really good ones at all, just generic probes in the main.

[worsthorse]

the dog is home and doing okay given the circumstances. it looks like we'll have a couple of weeks to a couple of months more with her, for which i am grateful. thanks for all the kind words and shared stories.

[rcrook]

Hmmmm My second piece of test gear in a month...

Heathkit IO-12 Laboratory Oscilloscope. No idea about it's electrical health but its aesthetic health is a bit on the crusty side. Now Im thinking I need a variac and an isolation transformer. I'm not sure I can afford either after my spending spree this month.

Looking forward to actually getting this working.

[Zucca]

It's always like this.

Got a Agilent Agilent 66309D for about 350€, I was happy. For European market it was cheap...
Yesterday I won a Keithley 2306 for 68€... damm it. Now the 66309D needs to go...

Another brick in the wall to sell...

 

[Zucca]

Hmmmm My second piece of test gear in a month...

Heathkit IO-12 Laboratory Oscilloscope. No idea about it's electrical health but its aesthetic health is a bit on the crusty side. Now Im thinking I need a variac and an isolation transformer. I'm not sure I can afford either after my spending spree this month.

Looking forward to actually getting this working.

Good one!, a little bit of passion, brush and soap and let it fly again.

[capt bullshot]

2 off 10X probes not switchable. 10-50pf. autosense would be nice but not important. Main thing is something that actually adheres to the specification.

Currently looking at these: https://www.reichelt.com/gb/en/modular-probe-250-mhz-x10-testec-mf-212-p32418.html

My favourites: PMK PML211 (fixed 10:1, 200MHz spec)
https://www.batronix.com/shop/measurement/probes/PMK/PML211.html
Not excactly cheap, but they come with a gold plated spring loaded tip and a stainless steel one, are rather slim (not as bulky as the Testec ones), and some neat accessories (like the probe stand for placing them on testpoints etc).

Edit: I have them @ work, so I didn't have to pay for them myself, an I keep them well hidden from the others ...

[med6753]

Hmmmm My second piece of test gear in a month...

Heathkit IO-12 Laboratory Oscilloscope. No idea about it's electrical health but its aesthetic health is a bit on the crusty side. Now Im thinking I need a variac and an isolation transformer. I'm not sure I can afford either after my spending spree this month.

Looking forward to actually getting this working.

My first oscilloscope was my Father's O-10 in the 1960's. Your IO-12 is essentially the same just updated a bit.

A very open layout and easy to work on. But note it's vacuum tube so high B+ voltages are involved so be careful. Paul Carlson did a restoration video on one. Don't have the link off hand but should be easy to find.



The vertical amplifier is AC coupled only so you can't measure DC voltages or offset. It's band pass on a good day is 5MHz. And it's a recurrent sweep scope rather than modern triggered sweep so you have to play with the frequency vernier and the sync amplitude to get a trace lock....that after 2 minutes will start drifting.     

Edit...here's the link...

[bd139]

Thanks for all the probe tips everyone. I have been adding them to a large spreadsheet so will review and purchase based on that.

In the meantime I have been futzing with the power supply for the JW pulse generator. I am loathed to spend £6 on an LT1073. I also wasn't happy with my naive boost converter as it was a hack job and required a function generator driving it and was inefficient, unstable and audible! Too much to deal with! So I designed a self-oscillating flyback converter using some old Ferrox cores I had lying around and a BJT. This gives 168-172 DC volts out which is pretty good. I'll add a feedback loop into it later with a TL431 and trimmer and use that to shut down the oscillator when it reaches desired voltage. Should be able to adjust it between around 50-160V then which is good for testing different transistors for avalanche behaviour including the 2n3904 which requires 120V+ to ping.



BTW LTspice is total shit for designing these things on. Better to go straight to prototype.

[med6753]

I smell smoke. 

[bd139]

Hahaha no explosions on this one so far. Not much to blow up. The last one scared the shit out of me as it was an IRF510 and was running very very hot. That could have gone bang pretty sharpish.

TBH I mostly like building DC converters and would spend all day doing that. Anyone hiring? 

[beanflying]

Hmmmm My second piece of test gear in a month...

Heathkit IO-12 Laboratory Oscilloscope. No idea about it's electrical health but its aesthetic health is a bit on the crusty side. Now Im thinking I need a variac and an isolation transformer. I'm not sure I can afford either after my spending spree this month.

Looking forward to actually getting this working.

I have seen worse fixer uppers. I am sitting on a Philips Scope that contains bird feathers and poo in my to do stack  If you only want 100 or 110V to run gear then skip the variac and get a CHEAPER and SAFER stepdown transformer off evilbay. My voltage sits at 250 or a touch over and I had a mix of Japanese and US gear to run so I want with the 100V nominal Japanese option eBay auction: #112082824397 Not sure if it was this seller but it is this transformer. Working well on two bits of test gear.

[Cerebus]

the dog is home and doing okay given the circumstances. it looks like we'll have a couple of weeks to a couple of months more with her, for which i am grateful. thanks for all the kind words and shared stories.

Good to hear that they are home. Judging from what you say it sounds like you're dealing with chronic renal failure, something that we've had a lot of experience with in this household albeit with cats not dogs. Our vet had us giving the beasts subcutaneous fluids which, by providing some much needed electrolytes, made them much more comfortable and greatly extended the time that they had good quality of life. Bugsie (aka bugblatter, aka Pythagorus, aka π) lived for another year after his diagnosis thanks to this. If your vet hasn't already suggested this and you're comfortable with IV bags and sticking needles in your pooch then perhaps it's something to discuss with them. Good luck.

[med6753]

On the recently completed 485 I mentioned that I was unable to adjust out some peaking on fast rise time pulses. Decided to see if I could determine why. The pulses were fine until the last IC before the vertical output and that's where the issue was. Closer examination of that area revealed some prior gorilla has been in here. The IC was clearly changed out. And I suspect some damage to traces might have occurred which has screwed up impedance matching. So....investigated how difficult would it be to swap over the vertical board from the parts mule.

Here's that peaking.



First off...the service manual gives absolutely no instructions on how to remove the vertical board. So I was on my own. Turns out it's not too bad. Most of the board is modular except for 2 solder connections for the delay line. But the biggest issue was the vertical output IC is stud mounted to the chassis crammed next to the CRT.

Here's that stud on the right. Right in between the very delicate wires to the CRT vertical deflection plates. I was able to get a ¼ inch wrench (spanner) in there and VERY carefully remove the nut. Once that was done the board lifted and guided the deflection plate wires through the holes.



Here's where the board resided in the scope.



And here's the vertical board itself. The vertical output IC is the large round silver can on the right.



And the underside of the board showing the stud mount and the deflection plate wires. The mount did have some heat sink grease on it. Guess what I'm out of and need to order? Yep, some heat sink grease. When I get it I'll swap this board in and see what happens.

[nixiefreqq]

On the recently completed 485 I mentioned that I was unable to adjust out some peaking on fast rise time pulses. Decided to see if I could determine why. The pulses were fine until the last IC before the vertical output and that's where the issue was. Closer examination of that area revealed some prior gorilla has been in here. The IC was clearly changed out. And I suspect some damage to traces might have occurred which has screwed up impedance matching. So....investigated how difficult would it be to swap over the vertical board from the parts mule.

Here's that peaking.


First off...the service manual gives absolutely no instructions on how to remove the vertical board. So I was on my own. Turns out it's not too bad. Most of the board is modular except for 2 solder connections for the delay line. But the biggest issue was the vertical output IC is stud mounted to the chassis crammed next to the CRT.

Here's that stud on the right. Right in between the very delicate wires to the CRT vertical deflection plates. I was able to get a ¼ inch wrench (spanner) in there and VERY carefully remove the nut. Once that was done the board lifted and guided the deflection plate wires through the holes.


Here's where the board resided in the scope.


And here's the vertical board itself. The vertical output IC is the large round silver can on the right.


And the underside of the board showing the stud mount and the deflection plate wires. The mount did have some heat sink grease on it. Guess what I'm out of and need to order? Yep, some heat sink grease. When I get it I'll swap this board in and see what happens.

dammit med. 

built up a lot of tension as the pictures progressed........and then....."tune in next".

keep some grease on hand ya' blue bastard!

will be anxiously awaiting a happy ending.


edit  reread my posting above and maybe it could have been worded more carefully.  (NO....that is NOT what i was talking about!)

[med6753]

Keep your shirt on, the heatsink compound will be here Monday. 

[tggzzz]

dammit med. 

built up a lot of tension as the pictures progressed........and then....."tune in next".

keep some grease on hand ya' blue bastard!

will be anxiously awaiting a happy ending.

edit  reread my posting above and maybe it could have been worded more carefully.  (NO....that is NOT what i was talking about!)

Care to explain to the rest of us 

[mnementh]

It's always like this.   Got a Agilent Agilent 66309D for about 350€, I was happy. For European market it was cheap...   Yesterday I won a Keithley 2306 for 68€... damm it. Now the 66309D needs to go...

Another brick in the wall to sell...

 

...Or another shelf on the wall to build.

On the recently completed 485 I mentioned that I was unable to adjust out some peaking on fast rise time pulses. Decided to see if I could determine why. The pulses were fine until the last IC before the vertical output and that's where the issue was. Closer examination of that area revealed some prior gorilla has been in here. The IC was clearly changed out. And I suspect some damage to traces might have occurred which has screwed up impedance matching. So....investigated how difficult would it be to swap over the vertical board from the parts mule.   ...First off...the service manual gives absolutely no instructions on how to remove the vertical board. So I was on my own. Turns out it's not too bad. Most of the board is modular except for 2 solder connections for the delay line.

   But the biggest issue was the vertical output IC is stud mounted to the chassis crammed next to the CRT...   

Wow... from a engineering and balanced-capacitance/noise-isolation standpoint that design is very clever... but from a serviceability standpoint it's a dicksore. If they'd moved that IC a cm or three in almost any direction it would've been safer in terms of getting a wrench/fingers in there by that fragile CRT and plate leads. 

dammit med.   built up a lot of tension as the pictures progressed........and then....."tune in next".   keep some grease on hand ya' blue bastard!

will be anxiously awaiting a happy ending.   edit  reread my posting above and maybe it could have been worded more carefully.  (NO....that is NOT what i was talking about!)   

Yeah; you can put the grease on a foot if you're young and limber, but it does generally work better on your hand.   

mnem
Just put a dropcloth over the 'scope until you're finished, okay...?

[BU508A]

edit  reread my posting above and maybe it could have been worded more carefully.  (NO....that is NOT what i was talking about!)

--
"free range primate"

I think, you are in a good tradition here.