Test Equipment Anonymous (TEA) group therapy thread

[med6753]

Recent purchase off local Craig's List. Keithley 175 DMM. My first Keithley. I have plenty of units from the other "big 3" in the US (Tek, Fluke, hp) so this will round out my collection.

As purchased. In VG condition and works in all functions.



Internal view.



Performed my usual exorcism of all electrolytics and tants.



Internal after re-cap.



Performed calibration of DCV and Ohms and it was within spec on all ranges. No adjustments required. I don't have precision ACV sources other than 1.00V so that's all that was checked.

 

[wkb]

More stuff to go fix: two E4418B RF power meters managed to sneak into my ham shack. One HP branded, the other Agilent branded.

Something to work on now the autumn is closing in..

These have a lithium backup battery that should be replaced.

Be careful though! Extract or take notes of all the revision details before removing the battery, as it will be lost.
It's no big deal though as it is simple to reprogram, as per this Keysight guide, as long as you took notes or photos of the data.

https://docs.keysight.com/kkbopen/how-can-the-e4416a-e4417a-e4418a-epm441a-e4418b-e4419a-epm442a-e4419b-memory-be-erased-for-security-purposes-588277960.html

I also have a 437B, and my 8481A sensor and cable are cross compatible with my E4418B.
Not sure if my E8482A sensor is compatible with the 437B though..

Well, both were sort-a in bits and some previous owner had removed both batteries 

The Agilent powered up once I installed a replacement Li cell. The HP was a bit more temperamental: it powered up, or not, without a real pattern. In the mean time both have decided to consistently *not* powerup. 

I need to go sit down and check out this stuff. These models have a bit of a reputation for power up issues.

Oh, and to add insult to injury: both ran successful self tests initiated from the front panel. That is, when they still powered up 

[nfmax]

I did an investigation into this issue when it happened to my instrument: https://www.eevblog.com/forum/repair/(mended)-ep4418b-power-meter-doesnt-turn-on/msg3991700/#msg3991700

I believe the industrious Chinese have made replacement keypad PCBs available. But it looks like a tricky job to fit

[wkb]

Took a close look at the sensor connector/flex wire assembly of the Agilent one. Looked like a war zone, essentially all pin soldering was loose/horrible/disgusting  . No wonder that while it did powerup/run it displayed "No sensor connected" 

Pictures are clear I suppose.

[TERRA Operative]

More stuff to go fix: two E4418B RF power meters managed to sneak into my ham shack. One HP branded, the other Agilent branded.

Something to work on now the autumn is closing in..

These have a lithium backup battery that should be replaced.

Be careful though! Extract or take notes of all the revision details before removing the battery, as it will be lost.
It's no big deal though as it is simple to reprogram, as per this Keysight guide, as long as you took notes or photos of the data.

https://docs.keysight.com/kkbopen/how-can-the-e4416a-e4417a-e4418a-epm441a-e4418b-e4419a-epm442a-e4419b-memory-be-erased-for-security-purposes-588277960.html

I also have a 437B, and my 8481A sensor and cable are cross compatible with my E4418B.
Not sure if my E8482A sensor is compatible with the 437B though..

Well, both were sort-a in bits and some previous owner had removed both batteries 

The Agilent powered up once I installed a replacement Li cell. The HP was a bit more temperamental: it powered up, or not, without a real pattern. In the mean time both have decided to consistently *not* powerup. 

I need to go sit down and check out this stuff. These models have a bit of a reputation for power up issues.

Oh, and to add insult to injury: both ran successful self tests initiated from the front panel. That is, when they still powered up 

Theese do have issues with the front panel button mylar wearing out, especially the power button that causes the unit to not turn on.
Take a look at the schematics available online and you can see the connector to the front panel where you can jumper two pins to manually turn it on to check the rest of the unit works.
The mylar in mine needed replacement, but they are available cheap from ebay so no big deal.

There is a trick to dissassembling the front panel so hit me up when you are ready and I'll run you through the process.

[m k]

I guess name change doesn't help much with those solderings.

[wkb]

Well, yes and no.

The HP-branded unit appears to have a different connector style but the same flex wire.

The HP version is a 'solder cup' style, whereas the Agilent has pins as shown on the previous picture. The holes in the flex are in my personal opinion too wide compared to the pin diameter. This makes for less than optimal soldering (at best).

That said, I assume (hope...) that the soldering shown is not HP factory standard soldering but some ill-fated repair attempt. Meanwhile I removed the mess, cleaned the flex and resoldered everything using proper leaded solder. Not that RoHS unleaded rubbish 

[wkb]

Like this.

nb: The unsoldered pin does not appear to have had a trace attached, so no worries

[wkb]

More stuff to go fix: two E4418B RF power meters managed to sneak into my ham shack. One HP branded, the other Agilent branded.

Something to work on now the autumn is closing in..

These have a lithium backup battery that should be replaced.

Be careful though! Extract or take notes of all the revision details before removing the battery, as it will be lost.
It's no big deal though as it is simple to reprogram, as per this Keysight guide, as long as you took notes or photos of the data.

https://docs.keysight.com/kkbopen/how-can-the-e4416a-e4417a-e4418a-epm441a-e4418b-e4419a-epm442a-e4419b-memory-be-erased-for-security-purposes-588277960.html

I also have a 437B, and my 8481A sensor and cable are cross compatible with my E4418B.
Not sure if my E8482A sensor is compatible with the 437B though..

Well, both were sort-a in bits and some previous owner had removed both batteries 

The Agilent powered up once I installed a replacement Li cell. The HP was a bit more temperamental: it powered up, or not, without a real pattern. In the mean time both have decided to consistently *not* powerup. 

I need to go sit down and check out this stuff. These models have a bit of a reputation for power up issues.

Oh, and to add insult to injury: both ran successful self tests initiated from the front panel. That is, when they still powered up 

Theese do have issues with the front panel button mylar wearing out, especially the power button that causes the unit to not turn on.
Take a look at the schematics available online and you can see the connector to the front panel where you can jumper two pins to manually turn it on to check the rest of the unit works.
The mylar in mine needed replacement, but they are available cheap from ebay so no big deal.

There is a trick to dissassembling the front panel so hit me up when you are ready and I'll run you through the process.

Thanks for the offer.  I do not currently think it is the keypad, as it worked flawlessly, very responsive to gentle pushes etc. Smells like "something else", the question of course being "but WHAT."

[salvagedcircuitry]

Upgrading the cooling in my TTI tga1244 / wavetek 195 / Fluke 284-U. replaced the cmos batt while I was in there for good measure. Stock configuration uses a sunon 80mm 2.4w ball bearing 41cfm fan. There's enough room to squeeze a 92mm fan in there so I grabbed my hand punch and made some holes. Look ma, no metal filings I'm installing a sleeve / maglev fan as a replacement. Now I should be able to use it while filming. Yay.

[wkb]

Well, yes and no.

The HP-branded unit appears to have a different connector style but the same flex wire.

The HP version is a 'solder cup' style, whereas the Agilent has pins as shown on the previous picture. The holes in the flex are in my personal opinion too wide compared to the pin diameter. This makes for less than optimal soldering (at best).

That said, I assume (hope...) that the soldering shown is not HP factory standard soldering but some ill-fated repair attempt. Meanwhile I removed the mess, cleaned the flex and resoldered everything using proper leaded solder. Not that RoHS unleaded rubbish 

The HP looks different, the soldering looked OK. Of course I could not resist removing old solder/resoldering.

[onsokumaru]

Ok, next one in the pack was this Tek 11401. What blew my mind is how good the touch CRT works!
It has three modules mounted, and they look like high end stuff for the time. I couldn't put any proper signal on the scope yet, but looks promising.

[Vince]

Wow that's quite a rare sight even on here !  Welcome to the club, have a 11401 as well. Different plug-ins : two dual input amps + an advanced triggering plug-in that includes TV trigger options.
Scope works perfectly but whenever it decides to start misbehaving, it will be the end for him... this beast is so complicated (with no proper service manual to boot) that I just wouldn't be able to fix it. So I enjoy it while it works, crossing fingers it will stay working for as long as possible....

The CRT touch-screen works really well because.. well it's not really a "touch" screen. There is a grid/matrix of infra-red LEDs in front of the CRT.
You don't actually need to even touch the CRT to activate it, try it : approach your finger super slowly.. you will see the screen activate before your finger even contacts the CRT...

[Ice-Tea]

Guess who got burned?

[tautech]

Guess who got burned?

The guy that didn't take the time to download the datasheet and check what packages were available.

Don't ask....   

[m k]

How many times you've forgotten something from an order, in a row.

This 8860A Multimeter from the loot is also working

What kind of a bottom MCU it has?

You see it when you remove the inner cover plate.

I may have a solution if somebody has that MCU problems, if I can have the faulty one, possibly more if it includes a piggypack ROM.

[wkb]

Followup to the Agilent E4418B saga:

Apart from the half-baked soldering on the sensor connector I reported earlier it seems to have more issues which I am addressing one by one:

I had a broken 74HC14 hex inverter in there which is part of the power on/off circuit. Essentially it had turned into a non-inverting inverter.    Never had that before. The power switch circuitry IMHO is far more complicated than it needs to be but ok.. Apart from the fubared inverter chip I had to modify the circuit a bit following the approach I found here on an EEVblog posting.

Result sofar: it now reliably powers on, passes all self tests, detects a sensor.  But it sofar refuses to Zero a known-good sensor.

I need to re-enter hardware rev and option info too.

More debugging to do..

[44kgk1lkf6u]

What is a non-inverting inverter?  Is it an ordinary buffer?  Or is it what engineers call the Signetics don't gate?

[Zoli]

What is a non-inverting inverter?
...

It's a defective IC.

[wkb]

What is a non-inverting inverter?  Is it an ordinary buffer?  Or is it what engineers call the Signetics don't gate?

It is from the Illogical IC family of which for example the Exclusive Maybe Gate and the Never Gate are also members.

In other words "Its dead Jim".

[McBryce]

What is a non-inverting inverter?  Is it an ordinary buffer?  Or is it what engineers call the Signetics don't gate?

Something similar to the bidirectional diodes I have maybe?

McBryce.

[dl6lr]

I can supply a TTL compatible zener-capacitor for your amusement. It measures absolutely fine on most capacitor and ESR testers (up to 5V). Borrowed from a non-working horizontal deflection circuit in my Tek logic analyser.

[EggertEnjoyer123]

I swapped the hard drive with one of those SD to IDE adapters on my Lecroy 7200A and the scope now gets further during boot.

Unfortunately it seems like I need a computer from the 90s to be able to create bootable floppies for the scope.

[Robert763]

You might also need the right version of DOS.
I keep a small collection of old PC's just for this type of thing. Did a bit of R&S kit a couple of years ago. While I had the installation software it installed a bootloader and would only run if the HDD was formatted and booted from MS-DOS 6.2. Not windoze FreeDos or anything else. Fortunatly I also have a collecton of old operating systems..... 

[dazz1]

Hi
In 1985 I was at University and learned a method for tuning and characterising control loops using noise and statistical analysis.  I didn't know that a specific item of test equipment was available to do that method, and more.  A correlator is really good and dragging known signals from below the noise floor, and doing statistical analysis in the time and frequency domains.

Roll forward almost 40 years and some how I saw the HP 3721A Correlator on an auction site.  The seller was located only 6km from my home with a low reserve price.  At first I didn't realise what it did until I Google showed me a little information about it, including the operator manual.  Then I realised what it could do.  The manuals are dated May 1971, and for its time, it is a very capable and quite amazing item of test equipment. 

I was the only bidder.

In 1976 the HP catalogue had the price of the HP 3721A  listed at $USD10,125.
To get the most out of the HP 3721A also required the HP 3722A Pseudo-random noise generator priced at $USD3,600 and,
the HP 3720A Spectrum Analyser Display priced at $USD7,265.

In 1971 import duty was about 130% plus the excessive cost of shipping and fees.  This trio of matching test equipment was priced at about the same as a nice house.  Although a government department made the purchase, it seems it could only afford the HP 3721A.  This was an expensive item of test equipment.  I suspect it has only survived for so many years because it cost too much to throw away.

It powers up and the CRT is crisp.  The only concerning thing is that the service manual has the parts section book marked.  The manuals are dated 1971 but other documents show the HP 3721A was shipped to Australia to be calibrated in 1983.  That would have been very expensive. 

The fan mod is ugly but well executed. 

This instrument is capable of a lot of things and learning to get the most from it will be a steep learning curve.

The HP 3721A was sold as faulty.  I need to run through the 22 page performance check to see if it does have a fault.
The performance check and the calibration procedure specify the HP 3722A Noise Generator is required.  I don't foresee any danger of obtaining an HP 3722A under any reasonable circumstances, so I will need to make an equivalent with modern parts.