Test Equipment Anonymous (TEA) group therapy thread

[med6753]

The Heath AG-9A Audio Generator up and running.  Needed minimal work. 2 capacitors, 2 resistors, new line cord, and replace burnt out meter lamp.

It does need an alignment and I have the full assembly manual. The output is set to 50kHz but it's sitting at about 51.5kHz. So it does need some tweaking. But the sine wave is extremely clean thru out it's ranges which is most important. 




Going to let it cook for a while before aligning it.

[bd139]

Wow, Leo's pulse gen is very clean.

And it is fast. Leo has measured mine with a rise time of 34.9ps and a fall time of 35.1ps

Might just buy one of them. I’ve got his GPSDO and it’s an excellent piece of engineering.

Will reply to other bits later.  This thread is hard to catch up with 

[tggzzz]

Do try it, even if it is only a "bucket list" activity.

Definitely on that list, but hopefully I don't have to wait too long.

I waited too long.

Check local height/weight/medical limits.

Unfortunately in the US there are only a very few places that do nice cheap fast winch launches (and no bungy launches!). That means you will be towed sedately behind another aircraft, whereas in a winch launch it is 0-50 in 5s, then climb with your feet higher than your head.

I haven't seen winch launches around, just tow planes.

But you can still make your own roller coaster in the sky. Gliders are aerobatic, some manoeuvres are "normal" and taught before going solo, others can be very extreme.

Even on everyday flights it isn't unusual to pull +3G in a tight thermal. I once did that for a couple of 1-2minutes continuously, rising at >1000ft/min. There was another glider doing the same, at the same altitude, so we looked upwards and saw the top of the other pilot's hat (bank angle 70 degrees ).

Wow, dancing in the sky.

More than you can possibly imagine - until you've seen it and experienced it.



In a competition:

Or, if you prefer, you can float in intense relaxed concentration, looking for the next thermal - often signposted by summer "ice cream" Cu clouds or go and join some circling rator(s).

  Both scenarios sound great to me.

Just do it. Things like this...

[med6753]

bd139.....tomorrow I'm tackling the PSU capacitors in the 465B. They look like they are going to be a royal PITA to get unsoldered from the board. Have you done those caps on a 465/475 and if so, any tips or tricks you can pass on? 

[bd139]

I've done them once only. I've been lucky. Tips:

1. Actually take the timebase board out. It's 10x more difficult if you don't.
2. Buy capacitor adapters (!). Don't try and jump the things or end up with weird towers of capacitors held together with tape. Remember the can is actually part of the circuit. Something like these are good: https://www.ebay.co.uk/itm/272740191627 ... I have my own design but it's not great.
3. You have to hit them hard with a soldering iron. I had trouble doing it with a 50W Weller TCP. Had to work on them slowly and let the board cool regularly. Used nearly half a roll of wick getting them off. The pads lift if you fart near them so be careful.
4. Don't put one in the wrong way round (yes I did that ... fortunately it just hissed like an angry snake)
5. Only buy decent capacitors. I usually go for Panasonic or Rubycon 105oC jobbies next capacitance up and next voltage rating up.

[med6753]

Interesting.....there is no capability to adjust the frequency ranges on the Heath AG-9A. Only the attenuator and the meter. Which are OK. The frequency ranges are set by 2% tolerance tubular capacitors which I did not change. I figured they would be OK since they are precision types. And they are. The specified frequency accuracy is 5%. So at 50kHz that's +/- 2.5 kHz. It's reading 51.563 kHz so it's in spec. So this one is a wrap too but going to continue to let it burn in for a few hours. 

[med6753]

I've done them once only. I've been lucky. Tips:

1. Actually take the timebase board out. It's 10x more difficult if you don't.
2. Buy capacitor adapters (!). Don't try and jump the things or end up with weird towers of capacitors held together with tape. Remember the can is actually part of the circuit. Something like these are good: https://www.ebay.co.uk/itm/272740191627 ... I have my own design but it's not great.
3. You have to hit them hard with a soldering iron. I had trouble doing it with a 50W Weller TCP. Had to work on them slowly and let the board cool regularly. Used nearly half a roll of wick getting them off. The pads lift if you fart near them so be careful.
4. Don't put one in the wrong way round (yes I did that ... fortunately it just hissed like an angry snake)
5. Only buy decent capacitors. I usually go for Panasonic or Rubycon 105oC jobbies next capacitance up and next voltage rating up.

Yes, I realize the capacitor cans are part of the circuit. But can't you just install the new cap....which doesn't have outside can...and then on the bottom of the board jumper together all those pads so you have a complete circuit? 

[bd139]

You can do that if you really want. I can't sleeping knowing that stuff is hiding 

[med6753]

You can do that if you really want. I can't sleeping knowing that stuff is hiding 

Well, I don't have those capacitor adapters and I'm not waiting to order any so that's what I'm going to do. And sleep like a baby. 

[mnementh]

Don't be a dumb/cheap-ass; Spend the 2 quid.    eBay auction: #273254508468   eBay auction: #272740191627  eBay auction: #272799971348  www.voltair.us

mnem

[bd139]

Yeah spend it. Otherwise you end up with shit like this:



Edit: add spiderman meme:

[mnementh]

Oh sweet cheese & crackers...

mnem

[mnementh]

   Woops... here's the kit he makes just for the 465 ($10): eBay auction: #273254508468

mnem
 

[med6753]

   Woops... here's the kit he makes just for the 465 ($10): eBay auction: #273254508468

mnem
 

I bought it. Are you FUCKING happy now??? 

So I will wait to do the recap.

[bd139]

Yes you are now forgiven 

[Mr. Scram]

Nah, just bodge it. I'll bet the next chap to rummage around in that oscilloscope loves the added challenge.

[bd139]

Yeah we love a turd



I try to live my life as if the next person to get what I have touched is an axe murderer

[med6753]

Nah, just bodge it. I'll bet the next chap to rummage around in that oscilloscope loves the added challenge.

Nope, only allowed one bodge/lifetime and I went for broke. 

[tautech]

Wellies? Looked it up. It figures.     Wellies.com

Typical English in formal shirt/tie/hat and walking stick ambling across the soggy country side in knee high rubber boots and drinking brandy.

How fucking quaint. 

Yep, wellies  called gumboots here !

[tautech]

   Woops... here's the kit he makes just for the 465 ($10): eBay auction: #273254508468

mnem
 

I bought it. Are you FUCKING happy now??? 

So I will wait to do the recap.

You guys crack me up. 
Goodonya med, yep make a nice job if you dive deep inside something as often ya just don't wanna go back in ! 

[worsthorse]

Yeah we love a turd



I try to live my life as if the next person to get what I have touched is an axe murderer

        

These are surely words to live by...

[mnementh]

   Woops... here's the kit he makes just for the 465 ($10): eBay auction: #273254508468

mnem
 

I bought it. Are you FUCKING happy now??? 

So I will wait to do the recap.

Yes. Very.    




Here's your reward: You get to be Gene this time. 


mnem
No electrons were harmed in the dissemination of this post. A great many were terribly inconvenienced, however.

[mnementh]

Yeah we love a turd       I try to live my life as if the next person to get what I have touched is an axe murderer...

...who knows where I live.  

mnem

[0culus]

Did you measure the thermistors (paragraph 67 in the 478A manual)? If they're within the "healthy" range, you might be able to recompensate them instead of having Keysight repair it. Hopefully, it's a bit less expensive to just get a new compensation chart made for it.

I haven't yet, as I don't have all the parts needed to build the test jig with me yet. Mind showing a picture of yours?

I didn't yet do the comparative test with bias power. I just checked that the resistance through them was around 3kΩ. First, measure how much current your DMM in Ohms mode uses to measure a 1kΩ resistor. Manually set the range to ensure it's well under 10mA. Mine was around 0.1mA, so no worries about frying the thermistors. Then, measure between pins 1 & 2. Should be around 3K. Then, 3 & 4 should be similar.

I suppose I could make a more careful measurement to see how dissimilar the thermistors' resistances are, but the more complex setup with power supplies is the proper way to compare them. It makes me nervous, though. You really, really have to be sure the rig is correct or you may not get a second chance.

The thing that's confusing me is the thermistor mount works perfectly with the 432A.

I know what you mean. Mine pegs to the lower end on the 432A, but on some ranges of the 431B it sits nicely on zero, yet won't null. So, more troubleshooting is required.

OK, I did this test and mine are both slightly above 3K, matched the same.  My 427A has very low (microamps) short circuit current in ohmmeter mode.

I need to bite the bullet and buy another thermistor...even an unknown one for cheap. That way perhaps I can learn how to fix them on one that I didn't spend a mint on.

[beanflying]

TGINF Le Tour is exhausting just watching, just one final push to the line to go.... Finish time 2am local