Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

its always something!

was noodling away in the basement using my pulse generator and hp54502a to tdr some coax cables.  was getting good results and was as happy as a bag of mostly salty water can be on a saturday night.

then the scope died and the basement filled with the smell of something that had zorched.

damn.

despite having my cooking criticized and being called a low life module swapper on this thread, I am not one to be daunted in public  (is hemingway still required reading anywhere?).  so I pulled the power supply from my hp 54504a and sat it beside the dead smelly one.  took about 3 minutes of comparison between the golden unit and the dead one to be 99% sure that one of 4 parallel 8amp 35 volt diodes in the 5.2v section had shorted.  (80sq035).   will pull the diodes tomorrow and see which one blew.  my plan is to then hook the 3 good ones back up and see if the damn thing works.

or maybe since they are in parallel it would be better to wait for new ones from amazon and replace them all? 

https://www.amazon.com/5PCS-80SQ035-DIODE-SCHOTTKY-DO-204AR/dp/B019EB8K7A


in any case..... this feels like vindication for my "have two of everything and don't be afraid to compare them" theory. 







 

 

Nothing wrong in doubling up gear, if you have space to do so, especially on the older items. I myself have about 6 Fluke 25s, 2 Fluke 27, 2 HP3466A, 2 TTi TF930, 2 Bside DMMs and 2 T12 soldering stations.

Also as you discovered they are a good reference point when 1 fails.

[Specmaster]

Regarding that numpty ebay seller, I sent him another message explaining more about why the photo was important and that his response gave me negative vibes. His response to that was to send me a rant back saying he was not a liar etc. So I found a couple of photos that showed the normal boot up screen showing the self test results and then normal starting screen once the test had completed and them told him that his responses had alarm bells ringing loudly in my head and that I was no longer interested in his scope.

When I looked at what photos he has posted on a proper computer, it was also clear that it was in a really filthy state so we'll so I'm well shot of it now.

Never make decisions when you only have a phone to work from is my rule from now on.

[nixiefreqq]

Comparative analysis is a valid troubleshooting technique; one I've been guilty of more than a few times. As long as substitution doesn't become your only repair method, there's no shame in using it as a diagnostic tool.

Just because I'm capable of component-level repair doesn't make me feel obligated to do it that way every time; my time IS worth something, after all. If I can buy a working XYZ board on fleabay for $20, how much diag time can I afford to spend on the original? Sure... figuring out the fault to repair and stow the original board for a spare is a good idea... if you have discretionary time; but I have a bin full of such boards from the Plasma Screen years that are little more than donors for heat sink material and Tesla coil projects now.

I'd definitely replace all 4 at once to be sure your rectifier array all have similar forward voltage drop. Or better yet, replace all 4 with a modern high-current rectifier in a TO-3PJ package.

But first, look for the flaky cap that probably caused the failure.

Here's a thread on this power supply; it links to a hand-drawn schematic which I've attached below.

Hope that helps.


mnem
*tzzzt*

thanks!   that schematic looks great. (hand drawn or not).

your point about the caps is well taken.  none look swollen or leaky...…...but they are gettin' old.  8 of the bastards in parallel behind 4 parallel diodes sure does not make it easy to find the bad one.  oh well, need to go looking for that spare roll of solder wick.

[bd139]

There we go and it's done. I'm attached to that TDS210 now. Even though it's crap it's so nice to use. Everything is two pokes away rather than seven pokes three encoder menus and stuff.

[Specmaster]

There we go and it's done. I'm attached to that TDS210 now. Even though it's crap it's so nice to use. Everything is two pokes away rather than seven pokes three encoder menus and stuff.

So your pleased with it then, knew you would be. What are your thoughts on Hantek DSO5102P, there is a hack for it that takes it upto 200Mhz BW?

[bd139]

I wouldn't go there myself. I did notice they ripped off the TDS 2xx series with that Hantek which is quite funny.

[tggzzz]

Today's hamfest wasn't as interesting as before; the only "interesting" items were some tasty switches - that I don't need.

Now, what should I do with them?

[bd139]

Nice switches. Must be a use for them.

Was that down in Kington Langley? Was considering taking a day out for that and heading back via a drive across the South Coast but I didn't wake up until after it had started. Oops.

Going to do the one in Wimborne on 12th, then drive down to Portland and see if I can find somewhere to set up an antenna and play with my new baby (FT-818) if it arrives before then 

[Specmaster]

I wouldn't go there myself. I did notice they ripped off the TDS 2xx series with that Hantek which is quite funny.

How do you mean go there, with the brand (there does seem to be a lot of happy users around) or the hack?

[bd139]

I wouldn't go there myself. I did notice they ripped off the TDS 2xx series with that Hantek which is quite funny.

How do you mean go there, with the brand (there does seem to be a lot of happy users around) or the hack?

The brand. There's a collection of people who have bought Hanteks (PC connected and standalone) as they were the cheapest DSO around at my local ARC and they are consistently complaining about them. One thing which is quite funny is they seem to be devoid of any working EM immunity as they seem to crash if you key up a 50W TX next to them.

[Specmaster]

I wouldn't go there myself. I did notice they ripped off the TDS 2xx series with that Hantek which is quite funny.

How do you mean go there, with the brand (there does seem to be a lot of happy users around) or the hack?

The brand. There's a collection of people who have bought Hanteks (PC connected and standalone) as they were the cheapest DSO around at my local ARC and they are consistently complaining about them. One thing which is quite funny is they seem to be devoid of any working EM immunity as they seem to crash if you key up a 50W TX next to them.

Interesting, there's plenty of happy users on YouTube and other forums, even ours and I don't think if I went for one that I'm ever likely to be firing up any TX close by let alone a 50 Watt one.

Its just that I could actually get a new one for not too much to replace the Hitachi (freeing up some space) and I'd get the benefit of a warranty in the UK and Amazon have them on prime.

[tggzzz]

Nice switches. Must be a use for them.

Was that down in Kington Langley? Was considering taking a day out for that and heading back via a drive across the South Coast but I didn't wake up until after it had started. Oops.

Going to do the one in Wimborne on 12th, then drive down to Portland and see if I can find somewhere to set up an antenna and play with my new baby (FT-818) if it arrives before then 

I saw someone exiting with what might have been a Philips EE "toy" set from the 1960s. I still have the manual, some of the springs, and a few transistors (AF116 etc).

The contact resistance is <1mOhm, which is right on the limit of any of my instruments and measurement technique.

[bd139]

Interesting, there's plenty of happy users on YouTube and other forums, even ours and I don't think if I went for one that I'm ever likely to be firing up any TX close by let alone a 50 Watt one.

Its just that I could actually get a new one for not too much to replace the Hitachi (freeing up some space) and I'd get the benefit of a warranty in the UK and Amazon have them on prime.

It's worth saving up a little more and getting a DS1054Z if you're going to do that IMHO.

Also don't forget that Amazon's Prime warranty is virtually non existent if it is just "fulfilled by amazon"

I saw someone exiting with what might have been a Philips EE "toy" set from the 1960s. I still have the manual, some of the springs, and a few transistors (AF116 etc).

The contact resistance is <1mOhm, which is right on the limit of any of my instruments and measurement technique.

Those EE sets were pretty good. AF116 is probably dead now. Damn tin whiskers ate a lot of them.

[tggzzz]

Interesting, there's plenty of happy users on YouTube and other forums, even ours and I don't think if I went for one that I'm ever likely to be firing up any TX close by let alone a 50 Watt one.

Its just that I could actually get a new one for not too much to replace the Hitachi (freeing up some space) and I'd get the benefit of a warranty in the UK and Amazon have them on prime.

It's worth saving up a little more and getting a DS1054Z if you're going to do that IMHO.

Also don't forget that Amazon's Prime warranty is virtually non existent if it is just "fulfilled by amazon"

I saw someone exiting with what might have been a Philips EE "toy" set from the 1960s. I still have the manual, some of the springs, and a few transistors (AF116 etc).

The contact resistance is <1mOhm, which is right on the limit of any of my instruments and measurement technique.

Those EE sets were pretty good. AF116 is probably dead now. Damn tin whiskers ate a lot of them.

Mine was an EE20, like the one below (20=number of circuits)

[bd139]

Nice. I always wanted the Philips ones. They had more meat to them. Alas by the late 70s, Tandy had the mindshare so I got a 160-in-1 shitebox instead.

[nixiefreqq]

Comparative analysis is a valid troubleshooting technique; one I've been guilty of more than a few times. As long as substitution doesn't become your only repair method, there's no shame in using it as a diagnostic tool.

Just because I'm capable of component-level repair doesn't make me feel obligated to do it that way every time; my time IS worth something, after all. If I can buy a working XYZ board on fleabay for $20, how much diag time can I afford to spend on the original? Sure... figuring out the fault to repair and stow the original board for a spare is a good idea... if you have discretionary time; but I have a bin full of such boards from the Plasma Screen years that are little more than donors for heat sink material and Tesla coil projects now.

I'd definitely replace all 4 at once to be sure your rectifier array all have similar forward voltage drop. Or better yet, replace all 4 with a modern high-current rectifier in a TO-3PJ package.

But first, look for the flaky cap that probably caused the failure.

Here's a thread on this power supply; it links to a hand-drawn schematic which I've attached below.

Hope that helps.


mnem
*tzzzt*

the diodes all checked out ok.

started pulling the caps and the 4 out front looked ok and measured ok.

pulled the 4 in the back and oooooops!  now that there is the problem.

the black goo eating away at the traces cleaned up with isopropyl and the short went away. 

surprised me that the leakers still tested ok with a one button chinese component tester.  guess they did not need as much electrolyte as was originally in 'em?

new caps are on order.

thanks nmem! 

without your push i'da been tempted to say "well if the easy ones to get out are ok, the harder ones to reach must be ok too."

[mnementh]

Today's hamfest wasn't as interesting as before; the only "interesting" items were some tasty switches - that I don't need.

Now, what should I do with them?

QUITE tasty.

Capacitor substitution boxes. One for electrolytics, one for ceramic disc and one for MLCCs. Make 'em all in shielded enclosure/enclosures.

Interesting, there's plenty of happy users on YouTube and other forums, even ours and I don't think if I went for one that I'm ever likely to be firing up any TX close by let alone a 50 Watt one.

Its just that I could actually get a new one for not too much to replace the Hitachi (freeing up some space) and I'd get the benefit of a warranty in the UK and Amazon have them on prime.

It's worth saving up a little more and getting a DS1054Z if you're going to do that IMHO.

Also don't forget that Amazon's Prime warranty is virtually non existent if it is just "fulfilled by amazon"

I saw someone exiting with what might have been a Philips EE "toy" set from the 1960s. I still have the manual, some of the springs, and a few transistors (AF116 etc).

The contact resistance is <1mOhm, which is right on the limit of any of my instruments and measurement technique.

Those EE sets were pretty good. AF116 is probably dead now. Damn tin whiskers ate a lot of them.

That is exactly what I learned when I went reasearching cheap DSOs a couple years ago; that while these were all cheap-ass 'scopes, there were distinct levels of "cheap-ass" and the DS1054Z was about as low as you could go and still be a usable tool for anything more than AF. At that level, it is considerably more bang for the buck than the Hantek offerings; hands-down.




I grew up with the 160-in-1; I was 12-ish or so and my mother and I saved up together for it (this was my childhood in McKeesport; we were very poor, and it was for reals a big "discretionary expenditure"); I remember building the "crystal" radio (okay, ge AM detector and crystal earphone) and all I could receive was evangelist radio and Howard Stern between ball games. Even at that tender age, I knew he was a putz. 

But I learned a lot from that box; like how easy it was to kill LEDs and transistors, and that resistors are our friends.    I later found a 75-in-1 (not a lot of difference between the two, really) at a neighbor's yard sale; spent two whole week's allowance on it and happily ignored the Px with its penny candy aisle for most of the next month replacing the missing bits. I later hacked the crystal earphones from both kits into a stereo set with RCA plugs so I could listen to mom's old 8-track deck in bed...   



Interesting that our conversation should go here at just this time; as I just uncovered a very special box from a protected spot under my motorcycle... *Cue flashiebackie sound effect*

Fast forward 30 years to when my wife was pregnant with our son; I stumbled across 2 of the later "Electronics Learning Lab" kits at a church sale. These were the last kit Forrest Mims had a hand in; and it was obvious that he had a bug up his arse to do something of value with that legacy. It's a much more capable kit in every way; with a proper (if small) breadboard and actual digital logic study work as well.  They have been carefully stored away in a box through 3 moves, and I've "augmented" them with several randomly acquired "grab bags" and "learning kits" from Jameco and Acme. I'm hoping to add my collection of Mims' Engineer Notebooks and several random "Build-It" kits I know are in "the Mountains of JENGA" somewhere...

He is ALMOST old enough... ALMOST.  *wibble*

Comparative analysis is a valid troubleshooting technique; one I've been guilty of more than a few times. As long as substitution doesn't become your only repair method, there's no shame in using it as a diagnostic tool.

Just because I'm capable of component-level repair doesn't make me feel obligated to do it that way every time; my time IS worth something, after all. If I can buy a working XYZ board on fleabay for $20, how much diag time can I afford to spend on the original? Sure... figuring out the fault to repair and stow the original board for a spare is a good idea... if you have discretionary time; but I have a bin full of such boards from the Plasma Screen years that are little more than donors for heat sink material and Tesla coil projects now.

I'd definitely replace all 4 at once to be sure your rectifier array all have similar forward voltage drop. Or better yet, replace all 4 with a modern high-current rectifier in a TO-3PJ package.

But first, look for the flaky cap that probably caused the failure.

Here's a thread on this power supply; it links to a hand-drawn schematic which I've attached below.

Hope that helps.


mnem
*tzzzt*

the diodes all checked out ok.

started pulling the caps and the 4 out front looked ok and measured ok.

pulled the 4 in the back and oooooops!  now that there is the problem.

the black goo eating away at the traces cleaned up with isopropyl and the short went away. 

surprised me that the leakers still tested ok with a one button chinese component tester.  guess they did not need as much electrolyte as was originally in 'em?

new caps are on order.

thanks nmem! 

without your push i'da been tempted to say "well if the easy ones to get out are ok, the harder ones to reach must be ok too."

Glad I could help! Good that it wasn't the diode array at all; means your repair should be relatively painless. Just gonna say... since you have the PSU out replace 'em all, not just the ones that test bad. The ones that test good will follow suit sooner rather than later. 


Years of lurking on the BadCaps forums taught me one thing:

Electrolytic caps are the devil's footsoldiers, and they WILL hide their fallen from you. 10 caps in a row will test good; the last possible one, no 11, will be the one that brought it all crashing down in a hail of sparks and smoke. It's like they're the electronic manifestation of Murphy's Law.     Trust NO CAPACITOR. EVER.


mnem
"Murphy's a bitch; and she has puppies." - grand-dad

[BillB]

I grew up with the 160-in-1;

The 150-in-1 was my first.  Memories. 

Years of lurking on the BadCaps forums taught me one thing:

Electrolytic caps are the devil's footsoldiers...

  Truer words have never been spoken.

[Berni]

I didn't have any of that. All i had was old magazines and old junk to take apart and rip parts out of.

[factory]

Today's hamfest wasn't as interesting as before; the only "interesting" items were some tasty switches - that I don't need.

Now, what should I do with them?

QUITE tasty.

Capacitor substitution boxes. One for electrolytics, one for ceramic disc and one for MLCCs. Make 'em all in shielded enclosure/enclosures.

Not a bad idea, I have a pile of those switches too (single deck versions) they looked far to good to part with, but I sell the lot of ordinary paxolin wafer switches that came with them.

Could they be used for making calibration check boxes for resistance, capacitance or inductance?

David

[tautech]

Mine was an EE20, like the one below (20=number of circuits)

I had that one too for my 7th birthday.
Box long gone but the bits are still stashed away.......dunno what for, must chuck them out.

How many hole did those terminal thingies punch in your fingers ? 
IIRC there's my DNA all over my old kit.

[bd139]

IIRC there's my DNA all over my old kit.

Grim 

[tautech]

IIRC there's my DNA all over my old kit.

Grim 

Another hole in a finger wouldn't worry me in the least these days but I well remember indeed how grim it was for a woosie little 7 year old and that's 50+ years back. 
I remember the old man having to unhook me a time of two until I hardened up enough to manage it on my own.

Ouch !

[mnementh]

Today's hamfest wasn't as interesting as before; the only "interesting" items were some tasty switches - that I don't need.

Now, what should I do with them?

QUITE tasty.

Capacitor substitution boxes. One for electrolytics, one for ceramic disc and one for MLCCs. Make 'em all in shielded enclosure/enclosures.

Not a bad idea, I have a pile of those switches too (single deck versions) they looked far to good to part with, but I sell the lot of ordinary paxolin wafer switches that came with them.

Could they be used for making calibration check boxes for resistance, capacitance or inductance?

David

Certainly; they have quite broad self-cleaning contacts, so should be very low contact resistance. For the smaller values of capacitor and inductor common-mode noise would be a problem, so I'd want to use dual-stacked switches so both sides make/break. Fortunately these appear modular; it shouldn't be too hard to make a dual-stack out of 2 singles.

That 6 gang would nicely do all the common nF, pF and uF sizes; would be easy and tidy with 3 sets of jacks and all 3 would be independent.

I'd do another with the common MLCC (SMD ceramic) caps being used today; those tend to exhibit much lower ESR than common ceramic disc and older generation epoxy encapsulated ceramic caps. Also, they vary much more due to derating; choosing MLCCs correctly for a circuit often requires trial and error confirmation.

That Muirhead 3-gang looks like it is 12-position Double-Throw; it could be used to make R/C pairs or L/C pairs or could also be used to do the same make/break a pair of contacts at a time just like the 6-gang, only not as many selections.


Just a few ideas off the top of my head... 


mnem
*Back to my hole*

[tggzzz]

Today's hamfest wasn't as interesting as before; the only "interesting" items were some tasty switches - that I don't need.

Now, what should I do with them?

QUITE tasty.

Capacitor substitution boxes. One for electrolytics, one for ceramic disc and one for MLCCs. Make 'em all in shielded enclosure/enclosures.

I've never been a fan of capacitor boxes, since I don't do much audio frequency stuff where they might be applicable. Besides, when I foul up my calcuations, I find it easier to swap the associated resistors.

Doesn't seem much point in having boxes for electrolytics since their tolerance is so poor anyway. With MLCCs, again there isn't much point if you can lose 90% of the rated capacitance at the rated voltage. Mica caps seem the most relevant types.

Resistance boxes are, arguably, more useful. But I already have a 7 decade KVD, a 3+2 decade KVD and a 0->121.1ohm 4 decade pot. Maybe a Harmon resistor divider network.