Test Equipment Anonymous (TEA) group therapy thread

[factory]

A handle with screws would have made it easier to clean the top cover.
My 427A is a German built one, with the rechargeable battery option, mains transformer is 230V only though for this one. Never seen a Japanese made one before, would be interesting to see pictures of the boards if they are different (before the re-capicide).

The 204B oscillator was also made in Japan, I saw one for sale on ePay USA a few years ago.

David

[TERRA Operative]

Ooh, rechargeable? I wonder how involved building that option from scratch for my meter would be?.....
Maybe even 18650 lithium or something fancy....


I'll take photos of mine when I take it apart, it looks  relatively boring and normal though.

[factory]

The rechargable battery option is not covered in the manual, BD139 did reverse engineer the circuit in his 427A, he removed the battery as it was expired and converted it the mains only with an extra regulator board (transformer voltage was much higher without the battery fitted);
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg4197496/?topicseen#msg4197496
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg4331551/?topicseen#msg4331551

I've added some more pictures of my 427A to the previous post, I had some trouble with the negative battery connection, it was intermittently touching the internal chassis, thanks to whoever worked on it before. 



To get to those hidden connections wasn't easy. 



Back together, the ring terminals are not visible, it took a while before I found the cause of that fault.





David

[TERRA Operative]

Ah, so the rechargeable version has a different mains transformer? That's a pain if so.

Although, the standard version will work down below 18V somewhere, so the lithium battery with well filtered boost converter is still viable.

[factory]

Yes a different transformer, to allow for charging and it's only got one primary winding for 230V, something to note if exporting one of these from UK.

As it wasn't already on the web, I've scanned the later manual for the HP 427A Voltmeter, part no. 00427-90008 that was originally printed in June 1983, it's been sent to Bama, KO4BB and added to the files section on the HP groups.io.
Most pages were scanned at 300dpi, except those with circuit diagrams which were scanned at 600dpi, it looks a bit worse after turning into a pdf file, I added the blank pages and if you set the cover page to separate, using two page mode in your pdf reader, it should read as the actual book.

Hopefully it will help with the production changes, as the German & Japanese serial numbers won't match the US ones in the change notes.

David

[TERRA Operative]

If you can upload the original files somewhere, I can pump them through Photoshop to crunch them down to a small size at almost original quality if you want.


[EDIT] Here you go, I optimised and bookmarked the PDF file, reduced the file size from 71Mb down to 16Mb with same resolution and imperceptibly less colour space.
https://groups.io/g/HP-Agilent-Keysight-equipment/files/All%20HP,%20Agilent%20and%20Keysight%20instruments%20in%20folders%20by%20part%20numbers/000%20to%20999/427A%20Multimeter

[TERRA Operative]

oooerrrr, shopping spree time tonight...... ouch, muh wallet..

Just won a HP 8648C with the high stability timebase and high output level options. So I'll mix and match with the one I am already working on that @factory helped me get parts for and keep the best one with all the options and sell off the other. Will be good alongside my power meter for calibrating my 1+GHz TDS700 series scopes.

Also scored some 16048C kelvin clip test leads for my 4263B LCR meter, will be handy for testing stuff that doesn't easily fit in my other fixtures.

And finally I got a P6249 box with all accessories minus the actual probe. I bought it because it has a heap of probe attachments and stuff that are otherwise expensive and hard to get.
I'll keep an eye out for the actual probe to fill the box in future auctions.


(All pictures from the auctions).

[TERRA Operative]

Aannnnddd, I just finished the reproduction gauge scale for my HP 427A

I'm pretty happy with where it sits now, so here it is.
Two files, one to print on plastic printable sticker paper, the other is the cutlines for the outline and mirror window, for cutting out on a sticker cutter etc.
(The small holes I didn't bother with, they can be cut out with a scalpel after the sticker is applied to the gauge face for perfect fitment.)

[Vince]

oooerrrr, shopping spree time tonight...... ouch, muh wallet..

Just won a HP 8648C with the high stability timebase and high output level options. So I'll mix and match with the one I am already working on that @factory helped me get parts for and keep the best one with all the options and sell off the other. Will be good alongside my power meter for calibrating my 1+GHz TDS700 series scopes.

How timely your post !

A couple hours ago I contacted a seller over here that's selling a mint, fully working HP 8648A for 500 Euros.
I always wnated one of these style/generation of HP RF gen, so a working one, local, for only 500 Euros looked like a good deal to me, though I know nothing about these instruments and their market to be honest... I only had a quick Google and they seemed to sell for much more than that.

But... it's an 'A' and goes "only" to 1GHz and starts at 100kHz.... I didn't know there was this 'C' revision with much better specs, 3+ GHz (perfect to test my 3GHz TDS694C), and starts as low as 9kHz.

So... looks like you just saved me 500 Euros, thanks Terra ! 

I will now be searching for a 'C'... not too fussed about time bases though, as I would just feed it with an external one which would also feed all the other TE in the lab.
So if I can get one cheaper with a less accurate time-base, the better...

[TERRA Operative]

There is also a D version that goes to 4GHz A bit more rare and expensive though....

I wonder how much it would cost to ship one of mine to you once they are all working.....? hahaha

[Vince]

There is also a D version that goes to 4GHz A bit more rare and expensive though....

OH !! 

I think in my particular case it's therefore wiser to stick to the C version then... less rare means easier to find and cheaper, and at 3.3GHz it's just perfect to test the 3GHz B/W of my Tek scope, +10% extra, just perfect. I think that's the ideal model for me then ! 

I wonder how much it would cost to ship one of mine to you once they are all working.....? hahaha

We shall find out hopefully in a year so, hopefully... keep one warm for me please ! 

[marcumr]

Hi everyone.
A warm one for me too. Thank you.

[m k]

Any idea why many Japanese sellers are using free shipping?
(have I already asked it)

Must be a cultural thing.
And I've still got some of those through HK post.

[TERRA Operative]

International? Not many Yahoo Auction sellers even ship international let alone for free. As for inside Japan, maybe 1/3 to a half have free shipping I guess?

[m k]

Must be an ePay thing then.

I'm many times too far from Japan, or something like that.

[Kosmic]

Must be an ePay thing then.

I'm many times too far from Japan, or something like that.

I always thought it was some kind of error. But I also saw a lot of listings with free shipping from Japan. I Never tried to buy one though.

[m k]

My latest.
I accepted a partial refund.

BTW,
it was before I dropped to 1/4 visdom.

[factory]

Ouch, guess they used a box that was too small?  Did the display survive?

David

[m k]

Yes and yes.
Those half rack mounting thingies probably saved some.

I think it will be fine when bumpers are added.
The corner is smashed so that when big parts are glued there is an irregular space, perfect for epoxy.
Only question is if and how the handle connection part should be supported more, wire stitching is one possibility, back side of it has also some space for epoxy.

[shakalnokturn]

Packing idiots...

One of my favourites for smashed plastic is PVC glue but in this case if the parts won't align correctly I'd also go with epoxy. If there's sufficient room on the inside reinforcing with fiberglass mesh such as "Fibatape" coated in epoxy has been found to be rather efficient.

Some more meters to join my pack, (I got hit by a case of "Neosapyism") the DMM's need at least some cleaning. The harder problem is the solder burn on the Norma.

[factory]

Finally got round to looking at the HP 34401A, that the AC & frequency measurement had stopping working on. A while ago I found a bad tantalum capacitor and a burnt Zener.
Parts were ordered from Mouser to replace all the tantalum caps, I choose higher voltage rated parts where possible, from the Kemet low leakage range.

All the tantalum capacitors on the mainboard have now been replaced, as I had to remove the 32 year old electrolytics to access a couple, those also got replaced. There are two more tants on the display board, I haven't changed them yet, as they are underneath the display itself, don't really want to disturb it unless I have to. The dead Zener was also replaced.

I'm glad I didn't clean the PCB & fully reassemble the unit, as it was still dead on AC & frequency mode, errors were 621 & 622, looking those up in the manual didn't tell me anything I didn't already know. 
Measuring the voltages across the tantalum capacitors, revealed only 2V on one of them, it should be 15V, you've guessed it another dead Zener, thankfully none of the failed parts had burnt the PCB.

It now passes the self tests and is working on AC & frequency once more. 

Before


The old parts, minus the second Zener which disappeared.


After


David

[Vince]

Does anyone know if Brother Neomys is still around ?

Anyone knows him personally and can contact him ?

I mean I am getting worried... I sent him a PM 2 or 3 weeks ago about something kinda important to him, to some degree, yet got no response and didn't see him posting here either.... I hope he is well wherever he is.... 

[factory]

Last active Feb 12th, around the time I escaped Stoke hospital, https://www.eevblog.com/forum/profile/?u=136804

I Hope he's OK. 

David

[Vince]

2 months.... that's not looking good then 

[tautech]

Does anyone know if Brother Neomys is still around ?

Yep.
A reasonably regular on Discord TEA.
Last seen a week or 2 back.