Test Equipment Anonymous (TEA) group therapy thread

[med6753]

More HP Counter goodness. This time a 5326B. It's off by about 6Hz. I guess it will need a tweak but I gotta RTFM. Another time. I just wanted to verify that it works.





I hear that missing feet is an HP thing. Certainly seems so. But I fixed that issue with shelf adhesive felt feet. Will do the job. 

[mnementh]

I see NUSSINK!!!

mnem
*toddles off to ded*

[Ice-Tea]

why our politicians think that electric cars do not pose problems for the grid ...

sorry, German only.
https://www.gunboard.de/uploads/monthly_2020_07/IMG_4346.MP4.4481e17956c060cc4b266af1bd559dc6.MP4

60V telephone wiring @ 50mA (which doesn't work, by the way) gives 1kW?

Is this a parody?

EDIT: still watching. PLease tell me this is a parody??

[dazz1]

Hi
I scored a Wavetek 2520 Sig Gen  0.2MHz to 2.2MHz in remarkably good condition considering it's considerable age.
It passes its self check and the LCD display and keys all look like they are working perfectly.
I opened the top and it looks good inside.  The warranty void stickers are still in place.
I haven't connected it to my SpecAn yet.

This used to be owned by what was the government telco. It was purchased about the time that cellular phones were starting to be installed.  It may have also been used for UHF point to point links.  I noticed two of the buttons have stickers on them.  I don't know if this is factory or done later.

I want to calibrate it and figure out how to use all its features.    I don't know what I am going to use it for but it was too good a price to let pass.

I am now seeking a copy of the manual for user and calibration instructions.  I am hoping someone might be able to provide a scanned copy.

Dazz

[tggzzz]

Do have a look at the Keysight app note and web calculator, its well explained there.

I'm probably being dense because I'm tired, but what Keysight app note?

He is probably referring to
5952-3706 Y-Factor Method for Noise Figure Measurement Accuracy
or
5952-8255 Fundamentals of RF and Microwave Noise Figure Measurements
or
5980-0288 10 Hints for Making Successful Noise Figure Measurements

That web calculator is probably the same as the enclosed excel-sheet. Can't attach it, too large.
Look for NFUC2017* at Keysight.

Thanks.

The original points, now snipped, were not about noise figure. I agree Wolfgang's points are correct when measuring noise figure, but I don't think they are when using a noise source as a poor man's tracking generator. If I'm wrong, I'd like to be enlightened

[Saskia]

why our politicians think that electric cars do not pose problems for the grid ...

sorry, German only.
https://www.gunboard.de/uploads/monthly_2020_07/IMG_4346.MP4.4481e17956c060cc4b266af1bd559dc6.MP4

60V telephone wiring @ 50mA (which doesn't work, by the way) gives 1kW?

Is this a parody?

EDIT: still watching. PLease tell me this is a parody??

It is, but our politicians actually tell us that this is the real deal. The green party being ideologically sound is telling us that the electricity is coming from the grid and they have a ought kobolds to not worry about any battery issues.

[bd139]

Gah if anyone sees this don’t buy it https://www.ebay.co.uk/itm/233653337978

Check the description for why 

Incidentally I’m getting my 8050a today apparently  . My arm is bloody useless for unscrewing stuff though so I may delegate opening it to my eldest. She needs to learn anyway 

[VK5RC]

OK not TE but close, just ordered an Icom IC 705, the portable ham transceiver 5-10W, HF to 400MHz, along the same design lines as the 7300, 7610 and 9700, weight just above 1kg with internal battery. Direct sampling receiver to 30MHz, single downconversion above that.
I think it will displace the ft 817. The display alone is cool.

[bd139]

Enjoy. I was considering one of them myself before I decided to bail out. FT817 needs to die.

[VK5RC]

Thanks, I am a bit of an icom fan, I seem to 'get' their menu structure. I get so lost in yaesu. D'oh. Sign of an ageing brain - rigidity!

[bd139]

Yaesu menus were bloody awful. I wouldn’t blame that on your brain 

[Specmaster]

Gah if anyone sees this don’t buy it https://www.ebay.co.uk/itm/233653337978

Check the description for why 

Incidentally I’m getting my 8050a today apparently  . My arm is bloody useless for unscrewing stuff though so I may delegate opening it to my eldest. She needs to learn anyway 

No, its OK, the transformer has 3 tappings on it for voltage selection, 100V, 120V and 240V according to the manual.

[VK5RC]

Yaesu menus were bloody awful. I wouldn’t blame that on your brain 

Glad to know that it just isn't me!

I remember one of the better transceiver reviews written by an exHP EE, and one of his criteria was whether you could get it out of the box and on the air without reference to the manual for a basic set up.
Ergonomics seems to be a thing of the past for some gear - TV remotes seem to be particularly bad at present.
(And get off my lawn -) end of harrummph!

[bd139]

Gah if anyone sees this don’t buy it https://www.ebay.co.uk/itm/233653337978

Check the description for why 

Incidentally I’m getting my 8050a today apparently  . My arm is bloody useless for unscrewing stuff though so I may delegate opening it to my eldest. She needs to learn anyway 

No, its OK, the transformer has 3 tappings on it for voltage selection, 100V, 120V and 240V according to the manual.

Well it had 3 tappings until some numpty connected it to 240V and it's now for parts only I reckon 

[bd139]

Yaesu menus were bloody awful. I wouldn’t blame that on your brain 

Glad to know that it just isn't me!

I remember one of the better transceiver reviews written by an exHP EE, and one of his criteria was whether you could get it out of the box and on the air without reference to the manual for a basic set up.
Ergonomics seems to be a thing of the past for some gear - TV remotes seem to be particularly bad at present.
(And get off my lawn -) end of harrummph!

Yes completely agree there. I rarely if ever read the manual for something if I'm honest. That came from years of dealing with "enterprise software" where the manual was either defective or incorrect 

[med6753]

Gah if anyone sees this don’t buy it https://www.ebay.co.uk/itm/233653337978

Check the description for why 

Incidentally I’m getting my 8050a today apparently  . My arm is bloody useless for unscrewing stuff though so I may delegate opening it to my eldest. She needs to learn anyway 

No, its OK, the transformer has 3 tappings on it for voltage selection, 100V, 120V and 240V according to the manual.

Correct.

[Joe M]

I have more THD/Audio meters that I will ever need in a life time.

I own:

Audio Precision System 1
HP 8903a
HP 334a
Keithley 2015
QuantAsylum QA401

don't know why I keep all of them 

[nixiefreqq]

hey med

when equipped with just a plain jane crystal those counters shift a little when you take the cover off.  if fitted with an ocxo it is not a problem.

am betting that it will improve if you just put the top back on. 

if you still need to adjust it, the trimmer cap is accessible thru one of the vent holes.  oh.....don't use a screwdriver or you will go crazy as the set point changes when you withdraw the shaft.  hopefully you have a really small diddle stick.


good luck.


ps  ok children.  don't start any nonsense.  we all know what a diddle stick is. 

[bd139]

Gah if anyone sees this don’t buy it https://www.ebay.co.uk/itm/233653337978

Check the description for why 

Incidentally I’m getting my 8050a today apparently  . My arm is bloody useless for unscrewing stuff though so I may delegate opening it to my eldest. She needs to learn anyway 

No, its OK, the transformer has 3 tappings on it for voltage selection, 100V, 120V and 240V according to the manual.

Well it had 3 tappings until some numpty connected it to 240V and it's now for parts only I reckon 

Actually looking at the schematics if it was overvolted it'd put 46v across the opamps and probably blow the ass out of the input FET. Not touching it with a 6 foot long stick that one 

[xrunner]

ps  ok children.  don't start any nonsense.  we all know what a diddle stick is.

[med6753]

hey med

when equipped with just a plain jane crystal those counters shift a little when you take the cover off.  if fitted with an ocxo it is not a problem.

am betting that it will improve if you just put the top back on. 

if you still need to adjust it, the trimmer cap is accessible thru one of the vent holes.  oh.....don't use a screwdriver or you will go crazy as the set point changes when you withdraw the shaft.  hopefully you have a really small diddle stick.


good luck.


ps  ok children.  don't start any nonsense.  we all know what a diddle stick is.

Turns out it was 6Hz off with cover off and on. Surprisingly it made no difference.

I have lots of diddle sticks. 

Edit...I saw that trimmer cap but wasn't sure if it was for the counter or perhaps the DVM so I wanted to check the manual first. I didn't want to monkey around and twiddle with the diddle until I was sure of what I was diddling. 

[capt bullshot]

Some update on the fine Belgian TEA:



It's alive and at least does something but showing the E4 message:

So the normal eevblog member would follow the "don't turn it on, take it apart" workflow. For some particular reasons (basically because I'm curious), I decided to turn it on before I take it apart. Nothing happened, the display was blank, some LEDs were lit at the front panel. Randomly pushing and turning buttons and knobs revealed this:

The A and B inputs apparently worked, since I could turn on and off the trigger LEDs by changing the trigger level. With an input signal applied, these LEDs start blinking, showing the input is working to some extent.

So one might think now, at least some analog supply is alive, operating the inputs, but maybe the digital supply is dead. The next step shall prove this assumption wrong:

Pushing the reset button brought some more life into the unit, the display showed a row of zeros and more buttons operated something else but the button was intended to. E.g. one of the numeric keypad buttons changed the mode. Normally one is intended to change this setting by the arrow up/down buttons.

OK, We've at least power to the digital components, and the processor does something though not what it's supposed to. Maybe there's a faulty EPROM?

Now I've tried to hold the reset button while turning on the unit. This apparently works, the display shows "E4" now. Pressing the reset button again now brings the unit to a somewhat better state - still no counting or measurement working, but all the buttons work as expected, and one can read out e.g. the trigger level settings.

So the power on reset circuitry most probably is toast in some way.
I had to look up "E4" in the manual (didn't read that until now). It's an internal self test, indicating "Measurement Logik Fail". First step in the fault finding flow is to check the int/ext ref source switch (so I did, was OK), next is to swap the "COAC" ASIC. Can't do that, since this chip most probably is unobtanium now. So my next thought was: That darn COAC (counter on a chip) ASIC might be dead, could one replace that by some CPLD or FPGA stuff if neccessary? For sure this would be an interesting task!
Reading the manual revealed some more self testing procedures, this showed "E4" as the only failure. So RAM and EPROM and other stuff is considered OK now.

More playing around shows the counter can display the "Hold Off" setting (time), though the knob doesn't work.

The knob is stuck, one cannot turn or pull, obviously another point to repair. According to the manual, a special internal path to the mighty "COAC" is used to display the "Hold Off" setting. So now, I came to the conclusion, the COAC is OK as it can measure this setting. Phew.

Now, with Hold Off turned on, the counter actually shows plausible frequency measurements up to around 200kHz. Above its garbage.

This is another hint the COAC most probably is fine, but the CEX board might be faulty, as this acts as a prescaler and high resolution extension to the COAC.

See some preliminary teardown pictures here:
http://wunderkis.de/pm6654/teardown/

Started a new thread in the repair area:
https://www.eevblog.com/forum/repair/philips-pm6654/msg3142792/

[FransW]

Congratulated.
We share interests.
Frans, PE1CCN

[bd139]

 

[bd139]

Ok unwrapped. Well this is not a good start. It has the AN/USM-486 sticker on it. Fair enough. US labelled.  Methinks oh fuck it's 120V set up. Well it is indeed!

And I find this inside.





Fingers crossed the fuse went before anything else did. Going to buzz it out quickly and strap it to a 5V supply and see what the deal is. If it survived it, it might give me a bit more confidence on buying that other one 

It's pretty tidy though which is good news.

Edit: transformer is melted