Test Equipment Anonymous (TEA) group therapy thread

[vk6zgo]

It looks like it might be an issue with leaky caps. Upon further visual inspection it seems like some caps have leaked.

The supply is interesting - there are two transformers, one for isolation and one for actually generating the voltage. The fan supplied with the power supply does not spin when power is applied. I verified that the fan works with a bench power supply, so the issue is definitely further upstream. A replacement power supply seems to cost 200 bucks, which is way too much.

I already verified that the input filter works and the fuse on there is fine.

Here are some more pictures of it.

The inside of the power supply was very dusty. Not fun!

Edit: I looked again and it seems like the fan is running off an auxillary power supply, which seems to power the rest of the power supply. The problem is most likely within this subsection of the power supply, which is nice because it should be the simplest portion.

Check any high value resistors at the input side. A lot of these supplies use a simple resisitive dropper to generate enough voltage to kick start the switching circuit.

Robert.

That was the "bog-standard" fault with Sanyo TV SMPS.
The good thing was that they kept the same design for years, & all you needed was a bunch of 1 watt 220k resistors & you were good to go!

Sony, on the other hand seemed to love "reinventing the wheel" with power supplies.
My theory was that whenever a new EE joined the company, all "bright eyed & bushy tailed", they were sent off to design a power supply, just to keep him/her out of everybody's hair!

[EggertEnjoyer123]

I replaced two 22uF capacitors which have started leaking. Thankfully the traces still were good (though there was some corrosion). I sprayed rubbing alcohol over everything and soldered some replacement capacitors and now it works.

I'm not out of the woods yet though. There is an issue in the fractional N part of channel A. Channel A only locks onto multiples of 1 MHz right now, and there are a lot of spurs. Channel B has no issues. It's probably time to take apart the scary RF section.

(I was going to make fun of Rigol for having a messed up PLL too, but it seems like they got their act together after the DP832 and the scope fail)

Also it seems like this thing has been left on for 14.4 years before failing. Quite impressive...

Edit: Dave tore down a similar unit in this video: https://youtu.be/Gmryy5KWm_g
I'd bet on it being a leaky cap since it seems like the fractional N synthesizer is just a SP8400 IC

[TERRA Operative]

Anyone want a THS720P with DMM probes, serial cable and a (dead but rebuildable) battery?
https://page.auctions.yahoo.co.jp/jp/auction/d1105269853

15000 yen, buy it now. A steal at that price!


I'd buy it myself, but I already got one with all accessories minus the scope probes. (and 3 other THS scopes...)

[AVGresponding]

EDIT: There is a less complete one on this auction https://www.ppauctions.com/lot/182543/lot-133?

Dang - their payment requirements prevent me from bidding. If anyone takes part, I would be in for this with 120pounds plus costs/fees/taxes.

P.S.: You already know that all red isolators are 75 Ohms, right?

I beg to differ.

[tggzzz]

My theory was that whenever a new EE joined the company, all "bright eyed & bushy tailed", they were sent off to design a power supply, just to keep him/her out of everybody's hair!

That was the standard joke. Or was it a joke?

Given the number of problems with PSUs, it might be that too many such designs escaped into production

[AVGresponding]

My theory was that whenever a new EE joined the company, all "bright eyed & bushy tailed", they were sent off to design a power supply, just to keep him/her out of everybody's hair!

That was the standard joke. Or was it a joke?

Given the number of problems with PSUs, it might be that too many such designs escaped into production

 

[AVGresponding]

Might be worth looking at the Sperry displays data and trying to test the display board separately, think I read somewhere they can be reluctant to light sometimes if not used for a few decades.
https://www.waynekirkwood.com/images/pdf/Sperry_Information_Displays_Catalog_1973.pdf

David

No, they pretty much light or they don't. I'm going off a sample size of 3-digits of NOS. If you're giving them 180VDC through a 390k (470k for the DP) they will strike. If they don't, even 300VDC won't help, they're just DOA.

The only effect you do get, is some will light unevenly, and running them for a while seems to help somewhat, but the strike voltage remains the same and raising the run current seems to make no difference, it's just a good bit of on time that helps them recover somewhat.

I have an ESI 251 with a panaplex display. Last time I turned it on, the display did not come on for several minutes. It did turn on eventually, though. I might just have marginal power supply voltages or a weak joint. I did not take any measurements, so this is not a very useful anecdote.

I've a few days off work, so I'll give this a try with the DOA ones. I'll give them a couple of hours each, at least.

[W6EL]

Anyone want a THS720P with DMM probes, serial cable and a (dead but rebuildable) battery?
https://page.auctions.yahoo.co.jp/jp/auction/d1105269853

15000 yen, buy it now. A steal at that price!


I'd buy it myself, but I already got one with all accessories minus the scope probes. (and 3 other THS scopes...)

But maybe a cracked screen, bad ADC, or inoperable CPU? The fact that they didn't plug it in for a powered-on shot is kind of suspect.

These are very nice units though. They feel tough and they are quite handy. A much better scope than those $200 ones on amazon from Owon.

[TERRA Operative]

A lot of sellers here just don't turn them on, probably can't be bothered finding a power supply.

I've got a lot of good stuff for cheap this way.

[W6EL]

A lot of sellers here just don't turn them on, probably can't be bothered finding a power supply.

I've got a lot of good stuff for cheap this way.

Well, you make a good point, especially as there isn't a PSU included in the auction. I too have had good success with "junk from Japan" ebay auctions. But I do require a working display before I bother with it. Especially for my ham radios which seem to often have custom (unobtainable) displays.

[factory]

Probably another 20+ scans to do the rest of the manual, dependant on available free time. Will see how easy it is to learn how to do a PDF without using MS programs, since redating the PC a few years ago, I got rid of MS office and added Libre Office.

It couldn't be easier. Just paste your scanned images into the word processor in Libreoffice, then go to the File menu and select the option " Export as PDF" .... 

Thanks Vince, that seems the same process as the MS office, except I think it was "print to pdf" as the final step.

There has been a slight delay to scanning the manual, as Mr Lexmark scanner/printer thingy is dead, even two of the caps inside agree.  Mr Peak ESR says they are OK though.  Mr Sorensen 60V 9A can sort that dispute out. 



There has been an irreversible teardown termination oz2cpu style.  Not worth the time to try & fix this cheap crap. The Skynet name on the PSU module seems familiar.

The cheapest supermarket Cannon has been ordered to replace it, the Lexfail was the cheap supermarket option in 2005, think I got my moneys worth out of it.

David

[factory]

Two similar devices. Adret 103a and Takeda Riken TR6120.

Thanks for posting, I've never seen those calibrators before, nice to see something different.

David

[factory]

Today's guess what it is challenge...

David

[duckduck]

Today's guess what it is challenge...

David

Is that Tek blue? Those are selenium rectifiers. No display(?), and a bunch of inductors? BNC outputs on the front? Some kind of signal generator? It's from late 50's-early 60's I think.

[vk6zgo]

It looks Brit or maybe Oz, & apparently small quantity production, from the plethora of single slot screws,
Could possibly be from TMC of Canada, or maybe Henry Radio in the USA, though.

I will hazard a guess, though-----Bardic Systems in Southampton UK, in or around the time period duckduck suggested.

[EggertEnjoyer123]

It seems like the screws on the RF section are pretty hard to get loose.
I've already broken two torx bits and more than half of the screws are still there. The bit ended up getting twisted out of shape because some of these screws are really stuck. They require ridiculous amounts of torque to remove, even with WD-40. It looks like they are tapping screws, which may be why.

If anyone has an easier way to remove the screws that would be nice. Pretty sure I just need a better torx screwdriver

[TERRA Operative]

With a good torx bit in the screw, give a few quick sharp taps with a hammer to 'crack the seal', pending any delicates inside of course...

[Neomys Sapiens]

With a good torx bit in the screw, give a few quick sharp taps with a hammer to 'crack the seal', pending any delicates inside of course...

The real tool of choice for this situation is a Handschlagschrauber (percussive screwdriver). I've yet to encounter a screw it could not handle.
You pre-tension it by turning the handle in the direction you want to turn the screw. Then, making sure of a good seat of the bit in the screw, you hit it with an hammer of at least 500g. Inside is a mechanism made of a ball and an inclined plane which converts the blow into an equally sudden rotational impulse.

[Neomys Sapiens]

EDIT: There is a less complete one on this auction https://www.ppauctions.com/lot/182543/lot-133?

Dang - their payment requirements prevent me from bidding. If anyone takes part, I would be in for this with 120pounds plus costs/fees/taxes.

P.S.: You already know that all red isolators are 75 Ohms, right?

I beg to differ.

[AVGresponding]

With a good torx bit in the screw, give a few quick sharp taps with a hammer to 'crack the seal', pending any delicates inside of course...

The real tool of choice for this situation is a Handschlagschrauber (percussive screwdriver). I've yet to encounter a screw it could not handle.
You pre-tension it by turning the handle in the direction you want to turn the screw. Then, making sure of a good seat of the bit in the screw, you hit it with an hammer of at least 500g. Inside is a mechanism made of a ball and an inclined plane which converts the blow into an equally sudden rotational impulse.

I prefer a battery impact driver, like one of these:



That is in fact the model I have.

The reason I prefer them, is that there is no axial percussion, there are only rotational impacts, and the force and frequency of these can be controlled quite precisely by judicious use of the analogue trigger.

I do have a traditional impact driver, but only for use on my car, and even then, mostly I just use one of my battery ones (I have a 1/2" drive one for stripping wheel nut threads too) these days.

[m k]

The machine is now left on over night but I think there is something else.

The machine has been on since.
Current has been between 160mA and half of it.
(PSU meter)
No glow, but it has had its own pulsing 180V.
Next steady HV and steady connection.

[m k]

If anyone has an easier way to remove the screws that would be nice. Pretty sure I just need a better torx screwdriver

Freeze the screw and tap the tool to tightening side.

Idea for tightening side is that the tight point is pulled out a bit and so can go in a bit.

[m k]

Today's guess what it is challenge...

David

I have hard time understanding what I see.
Seems that red things are rotating but then not.

So 1st pic is from bottom of left and 2nd top of right of last pic.
Top right of 3rd pic has many wires, that seems to be missing from others.

Right of 2nd pic seems to be a mono banana jack but what is the side add-on.

Bottom right of 3rd pic has a trimmer, is bottom left coil adjustable.

Bottom center of last picture seems to have through the plate high power diodes.
But selenium ones used to be mains rectifier stuff.

Between reds is a selector's angle gear.
So last pic seems to be correctly up/down oriented.

What has switched positions, BNC outputs and extra pulse input.
Though high current diodes and BNC output doesn't add up.

[TERRA Operative]

I prefer a battery impact driver, like one of these:



That is in fact the model I have.

The reason I prefer them, is that there is no axial percussion, there are only rotational impacts, and the force and frequency of these can be controlled quite precisely by judicious use of the analogue trigger.

I do have a traditional impact driver, but only for use on my car, and even then, mostly I just use one of my battery ones (I have a 1/2" drive one for stripping wheel nut threads too) these days.

I have an earlier version of the same one. I made a video way back when I gave it an overhaul. I love mine too.

[AVGresponding]

If anyone has an easier way to remove the screws that would be nice. Pretty sure I just need a better torx screwdriver

Freeze the screw and tap the tool to tightening side.

Idea for tightening side is that the tight point is pulled out a bit and so can go in a bit.

This^

To quote AvE, or maybe Uncle Tony, everything is springs. When you tighten a fastener, you compress the spring, and when you release it, it springs back. So, when you tighten a seized screw, you break the seal on the back face of the screw threads, which is where the most friction is when you try to loosen it.