Test Equipment Anonymous (TEA) group therapy thread

[factory]

HP 8920A Radio test set PSU repair update.
On the mains side we have literally blown up IRF 840 main switch MOSFET, ZXT650 driver bipolar, 0.1R 1W, 4.7R 1/4W resistors and 47nF RIFA. Not obvious is 9.1V 1.3W zener short circuit. Replacing those got it running but output voltages ar a bit off and a couple of output electrolytics getting warm 
Most of the output electrolytics were starting to leak physically and electrically. So replaced all those too. Just having a cup of coffee before a final check and putting the PSU back together and plugging in...

Robert.

Having read your repair, I'm glad I replaced the RIFA madness snubber cap, in the HP 54615B* scope when I acquired it, seems to also use a Computer Products PSU, but not the same one.

Are you going to name & shame the peeing capacitors?

*Seems Scottrade has a basket case 54615B, described as missing the power socket, nope missing the whole PSU more like.    eBay auction: #325678748332

David

The Failed parts. Not much left of the ZTX650. he fuse just did it's job.
(Attachment Link)

Thanks, will have to take a closer look at the PSU next time I work on it, seems to mostly have Nippon Chemi Con LXF, with some Rubycon, but lots of glue hiding the details.



David

[Neomys Sapiens]

It is power supply season, isn't it?
I had another look at the Analogic 2030 sythesizer/function generator and the culprit seems to be the PSU for the analogue board. More on this soon..

[Robert763]

HP 8920A Radio test set PSU repair update.
On the mains side we have literally blown up IRF 840 main switch MOSFET, ZXT650 driver bipolar, 0.1R 1W, 4.7R 1/4W resistors and 47nF RIFA. Not obvious is 9.1V 1.3W zener short circuit. Replacing those got it running but output voltages ar a bit off and a couple of output electrolytics getting warm 
Most of the output electrolytics were starting to leak physically and electrically. So replaced all those too. Just having a cup of coffee before a final check and putting the PSU back together and plugging in...

Robert.

Having read your repair, I'm glad I replaced the RIFA madness snubber cap, in the HP 54615B* scope when I acquired it, seems to also use a Computer Products PSU, but not the same one.

Are you going to name & shame the peeing capacitors?

*Seems Scottrade has a basket case 54615B, described as missing the power socket, nope missing the whole PSU more like.    eBay auction: #325678748332

David

The Failed parts. Not much left of the ZTX650. he fuse just did it's job.
(Attachment Link)

Thanks, will have to take a closer look at the PSU next time I work on it, seems to mostly have Nippon Chemi Con LXF, with some Rubycon, but lots of glue hiding the details.



David

Well I'm not a fan of "shotgun" capacitor replacement but this one could have caught me out. There was no sign of any issues with them. When removed it was obvious they were leaking. Even worse a couple were starting to burn the PCB. I didn't replace the main high voltage filter capacitors as they checked out fine when removed.
[ Specified attachment is not available ]

The Advance manual arrived yesterday thank you very much. I've not looked at it yet. Been busy. New rule to keep workhop tidier, no starting new projects until the current one is finished or put away in a Really Useful Box.

Robert.

[Robert763]

The 8920A is fixed and passes all tests.
£75 and some parts I had in stock  I claim the Jammy Git.
[ Specified attachment is not available ]

[m k]

will have to take a closer look at the PSU next time I work on it, seems to mostly have Nippon Chemi Con LXF, with some Rubycon, but lots of glue hiding the details.

Glue under big reservoir capacitor also, not snap in then?
At least easier to remove, if that finally is a positive thing.

Is bottom right also glued between mains choke and the bridge?
Is there some other glue inside a heatsink?

Seems that they really tried to put everything possible in for the machine soldering.
Some coils seem to be without any glue, maybe the glue is just hiding.

[Neomys Sapiens]

The Analogic 2030 has two identical power supplies - one for the digital (left) and one for the analogue part (right). both are fed by the primary transformer and jumper-configured for the position they are used in. The one on the digital side shows outputs of one to three Volts instead of +/-5 and +/-15V. The transformer checks out ok.
Now I have to remove the power supply. Unfortunately, the mechanical part in the service manual is missing, so there is some guesswork involved (like it was to get the thing open).

[Robert763]

Digital (left) PSU looks like some screws through the sideframe and it will just unplug.

[Robert763]

I bought a digital theodolite with distance measurement "Total Station" at a ham radio car boot sale a couple of weeks ago. It was missing the contol panel but was very cheap. What the seller didn't tell me was that it had been taken to pieces 
How do I know it had been taken to pieces? it's a youtube star
Trouble is he took the sensors apart so the calibration is ruined. Note the main body has a list of the sensor serial numbers.
Oh well it was cheap enough for breaking. The sliprings might be useful for mounting sensors on a tripod and tribrach and there is a 30X telescope.

[Vince]

This Niksee DMM puppy just popped up here :

https://www.leboncoin.fr/equipements_industriels/2360408317.htm

Not interested myself but thought it might interest someone here, as it's in good nick, cheap at 20 Euros, and comes with the original manual so you can know the specs and fix it if need be.

[factory]

That looks familiar, was reading an old magazine from 1969 the other day, it has an advert for that very nice DMM. https://worldradiohistory.com/Archive-Electronic-Design/1969/Electronic-Design-V17-N24-1969-1122.pdf



David

[Vince]

What a small world ! 

[EggertEnjoyer123]

Here's a HP 6675A I got from the garbage a month ago. I finally got around to testing it.

Powers on and works nicely. The equipment uses 220V, so I'm using two phases on a 110V outlet. Are there any potential safety issues with this setup? I made an "adapter" where the live and neutral of the power supply go to the two live connections of the sockets.

[TERRA Operative]

A few things happening here in Japanland recently.

Finally got delivery of the custom foam inserts for the soft cases for my THS720 scopes.
I have two of the Tek soft cases and both had the typically rotten foam inserts, so I used 'mycasebuilder' to design a new insert with a couple tweaks for better use of the space.
They came up really nice. 

I have also mostly recreated the deluxe lead set using the original Mueller parts (details added to the THS720 tekwiki page) so I'm well on the way to having ALL the accessories.

Then I recapped my TDS540 scope and installed a brand new Dallas NVRAM sourced from Digikey (date coded this year!), but found that while almost all caps had barely leaked at all, the two on the little piggyback Voltage Controlled Oscillator board on the Acquisition board had leaked good and proper, destroying this PCB, but luckily not making it to the Acquisition board.
So, I designed a new VCO PCB in Diptrace which I'll order soon.
I think I'll have to clean up the existing transistors and varicap diode unless I can find equivalents as the original part numbers seem to be obsolete...

And finally, I'm well on the way to finishing my recreation of the 11683A HP Power Meter Calibrator, to get my HP 437B Power Meter all adjusted nice.
Lots of multiturn trimpots to get each range really dialled in accurately so the power meter will be adjusted as spot-on as possible.

[vk6zgo]

Here's a HP 6675A I got from the garbage a month ago. I finally got around to testing it.

Powers on and works nicely. The equipment uses 220V, so I'm using two phases on a 110V outlet. Are there any potential safety issues with this setup? I made an "adapter" where the live and neutral of the power supply go to the two live connections of the sockets.

Quite a number of US hams, who want to get full legal power out of their linear amplifiers run them at 240v in a similar manner, but it is a bit "frowned on" & they are often urged on QRZ.com & suchlike forums to get a proper dedicated 240v power outlet fitted.

[AVGresponding]

Here's a HP 6675A I got from the garbage a month ago. I finally got around to testing it.

Powers on and works nicely. The equipment uses 220V, so I'm using two phases on a 110V outlet. Are there any potential safety issues with this setup? I made an "adapter" where the live and neutral of the power supply go to the two live connections of the sockets.

The main safety issue is you can't do that with GFCI protected circuits, so make sure you use a plug-in GFCI (240V!) between the power outlet and the TE.

[Robert763]

Make sure your ground is 100%. Some instruments have less attention to isolation beteen neutral and chassis than line. I have seen some PSUs that diddn't like having neutral at 110V below ground.

[srb1954]

A few things happening here in Japanland recently.

Finally got delivery of the custom foam inserts for the soft cases for my THS720 scopes.
I have two of the Tek soft cases and both had the typically rotten foam inserts, so I used 'mycasebuilder' to design a new insert with a couple tweaks for better use of the space.
They came up really nice. 

And finally, I'm well on the way to finishing my recreation of the 11683A HP Power Meter Calibrator, to get my HP 437B Power Meter all adjusted nice.
Lots of multiturn trimpots to get each range really dialled in accurately so the power meter will be adjusted as spot-on as possible.

This is looking good. I hope you will publish the circuit when completed.

[TERRA Operative]

And finally, I'm well on the way to finishing my recreation of the 11683A HP Power Meter Calibrator, to get my HP 437B Power Meter all adjusted nice.
Lots of multiturn trimpots to get each range really dialled in accurately so the power meter will be adjusted as spot-on as possible.

This is looking good. I hope you will publish the circuit when completed.

Yep, will have the usual youtube video with all files and gerbers and stuff released for anyone to freely use.

[duckduck]

A few things happening here in Japanland recently.

Finally got delivery of the custom foam inserts for the soft cases for my THS720 scopes.
I have two of the Tek soft cases and both had the typically rotten foam inserts, so I used 'mycasebuilder' to design a new insert with a couple tweaks for better use of the space.
They came up really nice. 



<SNIP>

And finally, I'm well on the way to finishing my recreation of the 11683A HP Power Meter Calibrator, to get my HP 437B Power Meter all adjusted nice.
Lots of multiturn trimpots to get each range really dialled in accurately so the power meter will be adjusted as spot-on as possible.

Yes, the foam insert is nice indeed. Good to know that's an option.

The TERRA Operative Power Meter Calibrator (henceforth referred to as the TOPMC) looks sharp. How did you make the printed case end? Did you have it cut and printed by the PCB maker?

[TERRA Operative]

Yeah, the end panels are just white PCB's with black silkscreen, nothing too special.
I usually draw the outline in my 3D CAD software (Rhinoceros 3D) using the enclosure drawings from the manufacturer and import it as a .DXF into the PCB software (I use Diptrace).
For the locations of the holes, it's a slight juggling act with the whole design including the relevant components located in their places in the 3D software, and I then make the locations of holes as needed and import those to the PCB software along with the outline.
I then take measurements of the locations of the components in the 3D software and align the footprint in the PCB software to suit. A bit of back and forth and I usually have it all matching by the 3rd or 10th time.

Attached pictures show the 3D model and the resulting panel design (text is always a bit funny, so it looks too big, but it imports to the correct size in the PCB software)


It makes for a really easy way to get nice panels and is pretty cheap. I usually make the rear of the panel (bottom layer of the PCB) a full ground plane, with the screw holes as through-hole pads so it provides some shielding to the metal enclosure.

[Ice-Tea]

Looks like maybe my stuff won't be for sale on eBay anymore starting July? There are new directives that come into effect, ElektroG, essentially for waste disposal? It doesn't really seem to cater to the second hand market, but eBay seems to think i need to comply.

I haven't found a solution yet, but if it's anywhere near the numbers I've seen floating around then that's a total non-starter for me. Truth be told, I don't see how this could work for 90% of eBay offerings. Am I missing something? Or is German ebay going to be empty in a month?

Anyone any insights?

[Vince]

Google found me this...

https://elektrogesetz.com/

Looks like it's  a German only thing, and you are in Belgium so it's irrelevant but... that document also says that this ElektroG thing is merely the German transcription of an old European directive which therefore is bound to apply sooner or later to every country on board. So maybe Ebay is making their life easier by imposing these rules Europe-wide, even if maybe not all countries will be applying this directive at the exact same year/month. I don't know.....

[Ice-Tea]

Sorry, the "German" part was in my head but clearly not in the post 

Yes, it's only for Germany but applies also if you want to ship stuff there. I was refered here for a "solution":

https://epr.interzero.de/germany/weee/calculator

it doesn't fit at all to what I'm doing and if it could be made to work for what I need, there's no way I'm paying those kinds of prices. I just don't get it... Unless I'm misunderstanding, eBay will be a wasteland in Germany after this?

[Vince]

So you mean you would have to increase your prices by XXX Euros to transfer the cost of this directive onto your customers ? And this calculator is tellign you that a 500 instrument, you will now have to sell for a grand ?.... maybe not that bad hopefully...

But, that said... this directive will apply to everybody so it will be a level playing field. Other sellers will have deal with that new expense as well....

It's like VAT... it sucks, but every seller has to transfer it onto their customers, so all sellers are equal in this respect...

Keep us posted once you know what's gonna happen to you...

[tggzzz]

Looks like maybe my stuff won't be for sale on eBay anymore starting July? There are new directives that come into effect, ElektroG, essentially for waste disposal? It doesn't really seem to cater to the second hand market, but eBay seems to think i need to comply.

I haven't found a solution yet, but if it's anywhere near the numbers I've seen floating around then that's a total non-starter for me. Truth be told, I don't see how this could work for 90% of eBay offerings. Am I missing something? Or is German ebay going to be empty in a month?

Anyone any insights?

This is relevant to more than the denizens of this topic. I suggest creating a separate thread just for this.

This will have interesting unintended consequences:

If the equipment to be put on the market can't exclusively be used by business clients [B2B] only, but also by consumers [B2C,] a "guarantee for the event of insolvency", together with a trusteeship, is needed. This financial reserve should ensure that the state doesn't have to pay for the recovery of the remaining WEEE of a bankrupt producer.

Maybe Keysight is right not to sell to individuals.