Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 1824937 times)

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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32825 on: June 08, 2019, 06:42:16 pm »
Heads up for any UK peeps. There's £1 listing again. Check your ebay messages inbox.

That means good buying as well as good selling  :-DD

Edit: note this starts sunday and runs until end of monday
« Last Edit: June 08, 2019, 06:51:07 pm by bd139 »
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32826 on: June 08, 2019, 06:44:49 pm »
Bless me Father for I have sinned, and it has been some time since my last confession  ;D

After getting an ESR meter adapter PCB from EEVBlog user Jay_Diddy_B I find that it has a 27 mV offset on the output. This is designed to be zeroed out using the 'relative' function on a multimeter but neither my handheld or bench multimeter have this function. Tonight I placed an order for two new meters, one for the bench and one for my toolkit so I can use the ESR adapter properly  :-[

Should you find yourself in a chronically leaking boat, energy devoted to changing vessels is likely to be more productive than energy devoted to patching leaks.

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32827 on: June 08, 2019, 07:04:26 pm »
Neat little noise maker, bd! I like all these "quick, I built some test gear" projects you do. :-+

Agree, neat little project.  :-+
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32828 on: June 08, 2019, 07:12:19 pm »
In different news, a fresh ebay score - an HP E3616A bench power supply for a very reasonable £85. I normally hold out until I can snaffle something like this for a song but I really need another quiet linear bench supply so I bit the bullet and opted to just pay a good price rather than an excellent one.

There was one thing about the listing that made me a little suspicious but I'm sure it will all turn out fine. The vendor claims to be in the north of England, but the ham hand in this picture of the item in question looked a little familiar.



Have I uncovered another of BD139's aliases?
« Last Edit: June 08, 2019, 07:14:14 pm by Cerebus »
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32829 on: June 08, 2019, 07:19:39 pm »
Not one of mine! Too much finger nail and you'll rarely see me north of Watford.  That's not a bad price. I actually did a buy it now on one of them about 6 months ago for £10. Unfortunately the seller had missed a zero and cancelled it  :-DD
« Last Edit: June 08, 2019, 07:21:44 pm by bd139 »
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32830 on: June 08, 2019, 08:58:18 pm »
Rebuilt the HV supply on the RCA WO-505A scope. Result: the HV went from -1059V to -1233V vs spec -1300V. So it's perfect!  :-+ Apparently some of those epoxy caps were going leaky.

Here's the rebuilt supply.



And the results. Not as good as I had hoped. The trace is only marginally brighter but acceptable. The focus is good. But the gain both vertical and horizontal still changes with the intensity. So we have a somewhat tired CRT. I'm not going to pursue a replacement as long as it doesn't get worse in the short term. When I calibrate the vertical the assumption will be full intensity.



Here's the vanquished.



Left to do: Replace the caps on the vertical and horizontal boards. Then calibrate and check compensation. Will do that tomorrow. After that this project is a wrap.   :-+ :-+
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32831 on: June 08, 2019, 09:14:03 pm »
I've had my 220 down and 20 up for about 5 years now, unlimited and the down has been pretty consistent but the up can change a bit, between 14 to about 30. I'd love to see upload match the download speed. I'm the last house in my street who can access fibre because the rest of the street is surfaced with bricks and the cable companies refuse to dig that up so those poor souls have to live whatever their copper can provide. Also there are many areas that Virgin has not cabled or will not cable as they took over a company that did the install and provide the services, Telewest, many years ago and believe that they have not done any new cabling since then so I consider myself lucky to be able to get such speeds as the next best speed on general release is I believe 60mbs.

Nothing wrong with 60mbps. That's what I pay for but generally get over 80mbps.


We got gigabit fiber here three years ago. I was the first consumer for our area's install. It took almost six months for Centurylink to work the bugs out but it has been rock solid since. Over the mesh network, connected to the router, I get plenty good enough speeds for everyday use:

https://www.speedtest.net/result/8321703137

[/URL]

And my cabled connection, into my test bench, gets about fifteen times that 50Mb/s number. I considered dropping down to a 150Mb/sec service but it cost almost. Now I am thinking about soaking up all that extra bandwidth by subletting my connection. I bet Centurylink will love that.
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32832 on: June 08, 2019, 09:14:34 pm »
@med: Not sure you'll get much better than that with the intensity vs trace size new tube or not. Some of the older ones were hopeless in that department. I remember we had some old tube ones in secondary school that were like that (may have been telequipment).

Tripped over this earlier. Hamfest bingo  :-DD .... http://n5dux.com/bingo/hamfest/ (refresh it for different things)

Edit: Looks in mirror: Over-caffeinated QRP zealot  :-DD
« Last Edit: June 08, 2019, 09:21:35 pm by bd139 »
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32833 on: June 08, 2019, 09:24:04 pm »
@med: Not sure you'll get much better than that with the intensity vs trace size new tube or not. Some of the older ones were hopeless in that department. I remember we had some old tube ones in secondary school that were like that (may have been telequipment).

Tripped over this earlier. Hamfest bingo  :-DD .... http://n5dux.com/bingo/hamfest/ (refresh it for different things)

Edit: Looks in mirror: Over-caffeinated QRP zealot  :-DD

*sigh* me, too. I remain grateful (as does the long suffering SWMBO) that I could be used to check off any of the other boxes.

* wch considers the kilt option...
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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32834 on: June 08, 2019, 09:30:13 pm »
@med: Not sure you'll get much better than that with the intensity vs trace size new tube or not. Some of the older ones were hopeless in that department. I remember we had some old tube ones in secondary school that were like that (may have been telequipment).


Yea, I think you're right and I've been spoiled by Tek scopes. It's been a VERY long time since I used a hobby scope. Like perhaps 1974 or so.  :-DD I'm letting the RCA cook for a while and the more I look at it the more satisfied I am that it's working as designed.  :-+   
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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32835 on: June 08, 2019, 09:35:15 pm »
@Med, that HV supply rebuild looks really neat, looks as if it has just come out of the factory, brilliant job  :-+
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Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32836 on: June 08, 2019, 09:38:36 pm »
Some good news and a couple of buggers.

The (old) bad news was that I got a modulation domain analyser that will be going to the tip.

The (new) good news was that I was able to rescue the hp10811 10MHz OCXO (and some BNC sockets!), and that I've now built that into a box, which works nicely.

The (new) bad news is that I've looked at that source on my newish hp8562b spectrum analyser, as previously noted: https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2446014/#msg2446014

I and others had wondered what was the cause of the spurs seen in the +-32kHz spurs around the other oscillator's frequency. Well, since the OCXO outut shows exactly the same spurs (including the 2nd harmonic of the spurs), I can be pretty sure the spurs are generated inside the spectrum analyser. Bugger.



Now those spurs are 70dBc down, so I ought not to be too worried about them, but I wonder if I ought to recap the 8562 and tighten up internal connections that may have jiggled loose over the decades. I was hoping not to have to, since the cal stickers are intact even though it is out of cal date.

Neither the spurs nor the "skirt" are visible on my tek492 spectrum analyser, which was recapped by the previous owner. I would show some pictures of that, except I don't want to leave it on long dince the fan has stopped working. Bugger. Naturally it is a Tek special fan, not a sensible HP plain-old-fan.
« Last Edit: June 08, 2019, 09:40:43 pm by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32837 on: June 08, 2019, 09:51:09 pm »
@Med, that HV supply rebuild looks really neat, looks as if it has just come out of the factory, brilliant job  :-+

Thanks!  :-+ On a related note the CRT for the Heath scope is now in Kearny, NJ so it's moving. Typically if something is in Kearny I get within a day. That project is turning into a mini money pit and while I had the expectation that I'd have to change out the CRT I was hoping to get away with it. So I'm anxious to get it installed and finish up that project before I go broke.  :-DD
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32838 on: June 08, 2019, 09:53:15 pm »
@tggzzz: I keep nearly pulling the trigger on an SA from HP from that era. I would like to thank you for putting me off and saving me a lot of money  :-DD

Still considering building my own. I have build the first LO already. I have no way to evaluate if it's a piece of shit or not though because you need a spectrum analyser!
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32839 on: June 08, 2019, 10:19:18 pm »
My $22 ebay TDR 1502 showed up today. As expected, it won't power up.  Unexpected: other than a small stress crack in one side of the case, it is in pristine condition and the original battery pack is in place. Even more surprising, the battery pack is in excellent physical condition.

I don't know a lot about NiCad batteries. The 1502 is designed to (a) require a battery pack in place and (b) for that pack to be putting out at least 9.95VDC to power up, even from the mains. The battery no load voltage reading is 6.1VDC.

Do I have a snowball's chance in hell of getting these batteries to charge?

Has any of my fellow TDR owners rebuilt one of these battery packs?

I could put 12VDC into the TDR, as I did with the 1503, but I'd have to crack the case to do it, which I am not quite ready to do.

I am assuming, of course, that the charging circuit in the TDR is working...
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32840 on: June 08, 2019, 10:55:10 pm »
DG1022Z head injury followed by identity crisis confirmed:





Productive evening!  :-DD

Notes: https://www.eevblog.com/forum/testgear/need-help-hacking-dp832-for-multicolour-option/msg2471817/#msg2471817
« Last Edit: June 08, 2019, 11:01:26 pm by bd139 »
 

Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32841 on: June 08, 2019, 11:31:25 pm »
My $22 ebay TDR 1502 showed up today. As expected, it won't power up.  Unexpected: other than a small stress crack in one side of the case,

Methylene chloride will sort that out: it "melts" the plastic and has superb creep. But it is a carcinogen, so be careful.

Quote
it is in pristine condition and the original battery pack is in place. Even more surprising, the battery pack is in excellent physical condition.

I don't know a lot about NiCad batteries. The 1502 is designed to (a) require a battery pack in place and (b) for that pack to be putting out at least 9.95VDC to power up, even from the mains. The battery no load voltage reading is 6.1VDC.

That will prevent the 1502's charger charging the battery.

Quote
Do I have a snowball's chance in hell of getting these batteries to charge?

Not sure. You can stuff 0.1C current into them indefinitely, but I would start much lower. A current limited power supply is sufficient; say 15V/40mA.

EDIT: see https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2472483/#msg2472483

Quote
Has any of my fellow TDR owners rebuilt one of these battery packs?

Yes. :) Get tagged cub-C NiCd cells, and solder short wires to the tags to join them together. Heatshrink is your friend.

Quote
I could put 12VDC into the TDR, as I did with the 1503, but I'd have to crack the case to do it, which I am not quite ready to do.

No, you don't have to crack the case. Use 4mm banana socket on wires from a bench PSU, and stuff them up the orifice left when you remove the battery pack. Make sure you get the polarity right. Set the bench PSU to 12V, and 250mA.

Whe you do decide to crack the case, realise that the ears will protect the front panel controls (cf Tek scopes), so position it vertically on its face and unscrew the four bolts on the rear. When unscrewed, you may need to twist a screwdriver to separate the case from the front panel.

When you replace the case, realise that pressing on the rear screws can spoil your day. The screws mate with bolts in the chassis that are peened into the chassis. Pressing the bolt can push the peened nut out of the chassis. So, unlike a normal scope, don't rest the case on the rear bolts, but do use the bolts to pull the case onto the chassis.

Once you've cracked the case, don't submerge it in 12" of water until you have followed all the instructions w.r.t. sealing the equipment. If you know where to look, there's 2kV right at your fingertips.

Quote
I am assuming, of course, that the charging circuit in the TDR is working...

It probably is, but you will go slowly mad trying to understand it. It woks iff there is a functional battery (or simulation thereof).

Stuff 12V up the battery compartment, and look at the C6341/C6246 spewing acid over the PCB tracks, then go from there.
« Last Edit: June 09, 2019, 08:00:50 am by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
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Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32842 on: June 08, 2019, 11:35:51 pm »
@tggzzz: I keep nearly pulling the trigger on an SA from HP from that era. I would like to thank you for putting me off and saving me a lot of money  :-DD

Before writing off that class of SA, look at how well it is still working. I'm looking for problems; it would be surprising if I didn't find them.

Quote
Still considering building my own. I have build the first LO already. I have no way to evaluate if it's a piece of shit or not though because you need a spectrum analyser!

It will be a POS. Once you've lifted a "portable" real SA, or looked inside a "real" SA, you will begin to understand why.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32843 on: June 08, 2019, 11:43:19 pm »
My $22 ebay TDR 1502 showed up today. As expected, it won't power up.  Unexpected: other than a small stress crack in one side of the case,

Methylene chloride will sort that out: it "melts" the plastic and has superb creep. But it is a carcinogen, so be careful.


It probably is, but you will go slowly mad trying to understand it. It woks iff there is a functional battery (or simulation thereof).

Stuff 12V up the battery compartment, and look at the C6341/C6246 spewing acid over the PCB tracks, then go from there.

Somehow, I knew someone would have the answers here.  ;D

Thanks!  The only challenge is fitting my big hand in the relatively small compartment normally inhabited by the battery. On the 1503, I opened the case, so getting 12VDC to the posts was easy. I am going to put the NiCad pack on my bench supply and see if they'll take a charge. If I can get them up to 10V, that will give me enough time to see if the CRT lights up.

And, of course, encourage some of those bastard tantalum caps to erupt.   :-DD
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32844 on: June 08, 2019, 11:47:01 pm »
@tggzzz: I keep nearly pulling the trigger on an SA from HP from that era. I would like to thank you for putting me off and saving me a lot of money  :-DD

Before writing off that class of SA, look at how well it is still working. I'm looking for problems; it would be surprising if I didn't find them.

Quote
Still considering building my own. I have build the first LO already. I have no way to evaluate if it's a piece of shit or not though because you need a spectrum analyser!

It will be a POS. Once you've lifted a "portable" real SA, or looked inside a "real" SA, you will begin to understand why.

As much as I love building RF gear and working with decades-old TE, I am very very happy that I bit the bullet and bought the Siglent SA rather than try and figure out how to keep an old spectrum analyzer running or build one myself (and I spent a lot of hours studying W7ZOI's SA design, including working with one someone else built). I use it about as often as anything else on my bench.
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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32845 on: June 08, 2019, 11:48:52 pm »

Thanks!  The only challenge is fitting my big hand in the relatively small compartment normally inhabited by the battery.
That's where long nose pliers become your friend as well as heat shrink  :-DD
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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32846 on: June 09, 2019, 12:00:15 am »
DG1022Z head injury followed by identity crisis confirmed:





Productive evening!  :-DD

Notes: https://www.eevblog.com/forum/testgear/need-help-hacking-dp832-for-multicolour-option/msg2471817/#msg2471817
You been hacking again? Thats some improvement over the standard 25MHz.
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Offline bsfeechannel

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32847 on: June 09, 2019, 12:00:49 am »
And the results. Not as good as I had hoped. The trace is only marginally brighter but acceptable. The focus is good. But the gain both vertical and horizontal still changes with the intensity. So we have a somewhat tired CRT. I'm not going to pursue a replacement as long as it doesn't get worse in the short term. When I calibrate the vertical the assumption will be full intensity.

What CRT is that?

Quote
Left to do: Replace the caps on the vertical and horizontal boards. Then calibrate and check compensation. Will do that tomorrow. After that this project is a wrap.   :-+ :-+

I have no experience in repairing these, but I have a NOS El-Menco 5DEP1 and a used Toshiba 130BHB31, around which, if I do not procrastinate any more, I intend to design and build an old-school scope. For the time being I've been studying circuits and analog scope technology.

Could it be something related to the caps you haven't replaced yet? The circuits I've analyzed up to now show the HV supply to be independent from the amp supply, but in some scopes current flows from the amp supply to the HV supply via the astig plate and the cathode. I was wondering if changing the intensity places a heavier load to the amp supply making it to sag.
« Last Edit: June 09, 2019, 12:03:29 am by bsfeechannel »
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32848 on: June 09, 2019, 12:19:04 am »
And the results. Not as good as I had hoped. The trace is only marginally brighter but acceptable. The focus is good. But the gain both vertical and horizontal still changes with the intensity. So we have a somewhat tired CRT. I'm not going to pursue a replacement as long as it doesn't get worse in the short term. When I calibrate the vertical the assumption will be full intensity.

What CRT is that?

Quote
Left to do: Replace the caps on the vertical and horizontal boards. Then calibrate and check compensation. Will do that tomorrow. After that this project is a wrap.   :-+ :-+

I have no experience in repairing these, but I have a NOS El-Menco 5DEP1 and a used Toshiba 130BHB31, around which, if I do not procrastinate any more, I intend to design and build an old-school scope. For the time being I've been studying circuits and analog scope technology.

Could it be something related to the caps you haven't replaced yet? The circuits I've analyzed up to now show the HV supply to be independent from the amp supply, but in some scopes current flows from the amp supply to the HV supply via the astig plate and the cathode. I was wondering if changing the intensity places a heavier load to the amp supply making it to sag.
Check threads from GK as he’s built a couple.
https://www.eevblog.com/forum/projects/oscilloscope-under-construction/
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