Test Equipment Anonymous (TEA) group therapy thread

[guido]

I've got some matches:

Data Precision 3500, got two. Nice panaplex displays. sloooww autoranging. Beware of leaky caps! Both meters were bad.

Prema 500, got two. 6.5 digit meters. If not stable, replace the chopper amp. I also replaced the electrolythics. Beware of loosing the call data. They use ordinary IC sockets and if the 21C14 RAM looses connection even for a split second, it's gone. I hacked in battery monitoring ICs in mine, hardwiring the supplies and CS on the RAM. Still need to calibrate them again though.

HP3456A, got two (yep, there is a pattern). Can have ROM rot. Thing powers up normally and seems to work. Untill you hit a button that jumps to a memory location that is rotten. Then it hangs. Also most likely you will need to replace the caps on the powersupply. They are usually bad. Still need to have another look at one of mine, the reading is not stable at lower voltages. The other one is fine.

HP3458A, got two. Yeah, right. Keep on dreaming.

Do have a TM504 though, doing nothing at the moment (three TM50(0)3's fit better on the bench).
Besides the stuff listed, there is a lot more...

[GreyWoolfe]

Well I see that you're in the USA and I did a quick Ebay search and there is one on there right now on Buy it Now or best offer, might need a little bit of cleaning etc and the last owner has added his own reference voltage it seems, anyway here is the link http://www.ebay.co.uk/itm/Vintage-Heathkit-Ig-4505-Deluxe-Oscilloscope-Calibrator-/202061628998?epid=1603942225&hash=item2f0bcfc646:g:odgAAOSwQm9Zw~dX

I just got my hands on one for free.  The square wave is for crap but there are bulging caps inside.  I think I am also going to do the BNC connector mod as in the video.  That is a nice mod.

[neo]

If you’re broke, that’s the best time to do it. All the cool things I have made were when I was broke. When I’m not broke I just buy kit and play with it.

If you look inside the scope calibrators they’re not particularly clever little boxes. Not sure why they fetch such a high price.  You can calibrate a scope to a reasonable degree with a 10Mhz crystal oscillator and some divider ICs. Vertical cal can be done with a battery, pot and DMM. Rise time of a 100MHz scope is in the order of 3.5ns so you don’t need a crazy fast edge. I reckon you could build something superior for $5 of stuff from Tayda.

If it that easy i could probably build something better with what i literally have laying around. Could be interesting to see....
Though it arguably a mute point since the only manual i could find does not address calibration

[Specmaster]

If you’re broke, that’s the best time to do it. All the cool things I have made were when I was broke. When I’m not broke I just buy kit and play with it.

If you look inside the scope calibrators they’re not particularly clever little boxes. Not sure why they fetch such a high price.  You can calibrate a scope to a reasonable degree with a 10Mhz crystal oscillator and some divider ICs. Vertical cal can be done with a battery, pot and DMM. Rise time of a 100MHz scope is in the order of 3.5ns so you don’t need a crazy fast edge. I reckon you could build something superior for $5 of stuff from Tayda.

If it that easy i could probably build something better with what i literally have laying around. Could be interesting to see....
Though it arguably a mute point since the only manual i could find does not address calibration

I just did a quick google search for the service manual for your scope and found one in seconds, try this link and you'll have a copy including all calibration instructions. It is split into 6 download sections, you must download all 6 before unpacking it into a PDF file.

http://www.eserviceinfo.com/download.php?fileid=11470

Good luck.

[neo]

Thank you, the only one i was able to find was the operation manual.

[bitseeker]

I must admit that these are not my first devices. When I learned that I might get these, I started looking for manuals and repair advice. That was when I discovered EEVblog and this very thread. I immediately knew I had to sign up.
Before this haul I already owned about a dozen DMMs, 8 oscilloscopes, some analog meters, a frequency counter, and components galore (I collect them as well).

I've never been a RF guy, but suddenly I start yearning for a SA. This thread is no good. Must stay away from it.

Welcome, Ero-Shan! Congrats on that haul. Even if they're all broken, that's quite a score. The bad news is that you already have TEA. "Normal" people wouldn't have brought it all home. The good news is that we think that's totally OK.

[Specmaster]

Fact is that high end test gear, even if it's passed it usefulness in an industrial situation needs to be saved so it can live another day in the hands of the professional / hobbyist in their home labs / workshops.  Who would not normally be able to justify their considerable cost when new, especially with SWMBO.

SWMBO on the other hand always forgets the considerable amount they squander on having their hair done so often, those designer bags. Shoes and boots that don't get worn, not to mention the clothes that in general get worn once (if there lucky) to a function / family do etc. and never see daylight again

[bitseeker]

Who would not normally be able to justify their considerable cost when new, especially with SWMBO.

Plus, a lot of the old "high end" stuff is quieter (electrically) and more robust, repairable, hackable, educational, interesting, aesthetically pleasing, efficient to operate (i.e., knobs and buttons!), etc., than new equipment.

[bd139]

My Tek 475 is misbehaving so I'm disinclined to agree until it and me are friends again 

Got HV arcing somewhere, the trace is shifting at 50ns sweep and the chop mode has just died 

Specmaster: I sympathise. Sounds like you have the same situation as me. SWMBO managed to clock up £3k on a catalogue account without me knowing in only 2 months. Bang went 2016's shares dividend. At least it put a barrier of "you can't complain at me now" in place which is why my bench went from heap of crap to shiny stuff

Talking of which, I need a new laptop 

[Specmaster]

bd139: Sorry to hear about that kick in the wallet, that amount would have brought you some pretty decent shiney stuff indeed onto your bench. Maybe withdrawal of privileges for a while might be in order, you control the tv remote etc 

Speaking of shiney stuff, that could be what's up with your Tek 475, after years of sitting around in that dirty old garage it's got used to the dirt and grime but since you've cleaned it up, it can't cope with it anymore and is paying you back for waking it up from its slumber 

Laptops, I'm not a big fan of although I have 2 of them, hardly ever use them to be honest, prefer a nice under the desk tower system with some serious oomph packed inside and some decent cooling going on and 5.1 sound system, laptops are OK but not as a main computer in my opinion.

My fluke 8505A seems to be there now, the error code on the ohms range is resolved, it was telling me that the connections needed checking, had it set on 4 wire but using 2 leads only. It will take a bit of time to learn how to drive this thing properly though. 

[bd139]

Hahaha tempting

I think you could be right with the Tek. I just spent an hour filling baskets up with parts to replace the HT and CRT bias section components as a load of them have drifted and it appears one of the capacitors has a big crack in it. Cost nearly as much as the damn scope did! I think these are like running classic cars at the end of the day

I'm not too bothered about laptop oomph. Mainly want something smaller this time I can lug around on the road. It's a terminal to something much more powerful in the office really where it can sit in a noisy rack (48 core Xeon E5, 64Gb RAM, 4TiB enterprise SSD sized, although I have to share that with 3 other people!)

Congratulations on the 8505A success. Interested to see how it turns out as they look like rather nice toys

[neo]

Hahaha tempting

I think you could be right with the Tek. I just spent an hour filling baskets up with parts to replace the HT and CRT bias section components as a load of them have drifted and it appears one of the capacitors has a big crack in it. Cost nearly as much as the damn scope did! I think these are like running classic cars at the end of the day

I'm not too bothered about laptop oomph. Mainly want something smaller this time I can lug around on the road. It's a terminal to something much more powerful in the office really where it can sit in a noisy rack (48 core Xeon E5, 64Gb RAM, 4TiB enterprise SSD sized, although I have to share that with 3 other people!)

Congratulations on the 8505A success. Interested to see how it turns out as they look like rather nice toys

As far as laptops go, if you want my opinion, i would go with an IBM thinkpad. I got an old R52 thinkpad and my only complaints with it are remedied with having a power desktop (which i do).
The only thing i use this pc for is datasheets and remote control of my desktop and it does both well, there are other thinkpads though i can only speak for what i got.

[Specmaster]

Here is my latest addition to my bench meters section, it's so big that it will be forced to sit at the bottom of my scope stack I think. Needs a bit of a clean up exterior wise, inside its OK, well put together as you'd expect from a premier brand.

Not fully tested it out yet, much more to it then my other meters even though it lacks diode test, capacitance test, Frequency mode, continuity test etc, but who could resist all these sexy digits and buttons?

Its going to be a big learning curve learning how to use those modifiers, although I expect most of them will more to do with using it remotely via the IEEE interface, which I can't see myself ever using.
All the sections have their own plug in cards with a hinged flap to get access to the test points and trimmers for calibration purposes, which can also be carried via the front buttons if I'm reading the manual correctly.

No calibration stickers on it so I expect that it could be out a bit, although it does pretty much agree with my other meters so its properly good enough for my purposes.

As you can see, it has had a serious knock in its life and I'd like to try and fill those chips with some sort of filler and then paint the bezel. Does anyone know the name of the actual colour that Fluke used on this range of meters at all?

It does have one of the bottom feet broken and also one of the bottom feet is missing as are the 2 flipout tilting bails, anyone know where I could source these from at all?

I'll leave you to look at the test gear porn that is the photos.

[tautech]

I think you could be right with the Tek. I just spent an hour filling baskets up with parts to replace the HT and CRT bias section components as a load of them have drifted and it appears one of the capacitors has a big crack in it. Cost nearly as much as the damn scope did! I think these are like running classic cars at the end of the day

Most likely why it was put away some years back. When rail voltages check out OK and there's a CRO display problem it's the first place I check as those many M Ohm resistors can drift badly or go OC. Give that EHT area a good clean too. 

[Specmaster]

My Tek 475 is misbehaving so I'm disinclined to agree until it and me are friends again 

Got HV arcing somewhere, the trace is shifting at 50ns sweep and the chop mode has just died 

Specmaster: I sympathise. Sounds like you have the same situation as me. SWMBO managed to clock up £3k on a catalogue account without me knowing in only 2 months. Bang went 2016's shares dividend. At least it put a barrier of "you can't complain at me now" in place which is why my bench went from heap of crap to shiny stuff

Talking of which, I need a new laptop 

You and your Tek 475 started something with all the other test gear now, since I got the fluke 8505A up and running OK, the HP 3466A is misbehaving. The only function button that latches now is the resistance range so now I have to tear it down and see what can be done. This a bit like Toy Storey when the toys come to life, thats what our test gear seems to be doing behind our backs 

[Specmaster]

Found the culprit, on the top of the push buttons there is the clear plastic cover and there is a small claw whose job it is to allow the push button to be pushed in but prevent it from being withdrawn as there is a tough in the button assembly that this claw rides in and it hits the claw at the end of its designed travel.

This claw has broken off and the piece can be seen in the second photo, has anyone done a repair like this before at all and if so how did you do it please?

Perhaps there is a way of removing the affected switch by desoldering all the pins and carefully prising the metal tabs that appear to be holding in the assembly and then replacing it with another from a donor of some sort?

[bd139]

Oh I hate those switches. You can probably buy a direct replacement switch easily. I bought one for my Thandar TG210 from bitsbox.co.uk. Look for “latching changeover” switches. Process is simply bending the metal tabs back, desoldering, remove and replace. The only problem is that they are complete dicks to get out.

Typical failure modes we’re all having today!

[Specmaster]

Yes, I agree, its to be expected they are about 30 years old now and may have seen many thousands of operations in that time. I'll have a look at bitsbox and see if they have any. 

[bd139]

Big warning when you’re getting the old one out: getting all the legs cleanly desoldered is a pain. I actually tend to pull the top off the switch, extract the innards, Dremel most of it off, then desolder the legs individually and clean up the holes with chemtronics soder wick. This was after I ruined a board getting one off with a pump years ago.

[Specmaster]

Thanks for the warning, I have a desoldering station so hopefully that will manage the job ok. I don't now for sure but I suspect you were using a manual solder pump? Parts ordered, (1 for a spare) and also postman just been and so I now have all the parts I ordered for the 1740A so I now replace the MPSH81's and also the 2N3134 (I did get 2 of 2N2905A's) as backs if required, so hopefully I'll get her all fired up again and see how she goes later today. 

[bd139]

I was using a manual pump. If you’ve got a proper rework iron you should be fine. Need to get one of them actually. eBay time!

Good luck with the transistors!

[Specmaster]

Just looking at the data sheet for the latching switch, its a single latching switch and I need one that part of a gang thats interlocked! I wonder how difficult it would be just to replace the clear plastic top part or to extract the single locking mechanism on the top?

[bd139]

They’re all single switches. There should be a metal release bar that disengages all the other switches in the group.

[Specmaster]

There is, but the last switch in the group is on/off switch that has its own single latch as does the one from bitsbox, data sheet attached. I think if the top latching bits are removed it should work?

[Specmaster]

Heads up anyone thinking of getting a similar meter to bd139 theres a Kenwood DL-2051 going on Ebay in case you hadn't noticed (listed this morning) and heres the link http://www.ebay.co.uk/itm/Kenwood-DL-2051-Digital-Bench-Multimeter-with-cables-probes/282692846303?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D47230%26meid%3D7d4c9ff4168349139b53bd656a793d24%26pid%3D100678%26rk%3D1%26rkt%3D4%26sd%3D282692846303&_trksid=p2481888.c100678.m3607&_trkparms=pageci%253Ad44b3bfa-b0ec-11e7-9988-74dbd180fa71%257Cparentrq%253A1b4f126015f0a86c4fccb291ffffb04d%257Ciid%253A1