Test Equipment Anonymous (TEA) group therapy thread

[dazz1]

CuriousMarc often uses it.
new revision of the ROM on his site.

https://www.curiousmarc.com/instruments/hp-4957a-protocol-analyzer

Yes, I have seen Curious Marc's website.
To get this HP 4957A working and updated I need to:

• replace the IEC connector with one that fits in the existing hole,
• figure out which partially failing component is causing the CRT picture distortion,
• buy a programmer and adapter,
• buy a OTP or Flash memory device,
• flush out the rest of the latent faults I haven't found yet.

That adds up to quite a few  $$$ to get  a  working HP 4957A.

[sean0118]

The HP 721A is faulty...   power cord cut off. BWD 141 unknown condition...   

You might need this:
https://www.kevinchant.com/uploads/7/1/0/8/7108231/141_sine_-_sqaure_wave_gen..pdf

Thanks 

• figure out which partially failing component is causing the CRT picture distortion,

Does your model have CRT adjustment trimpots?
https://www.way2.net/hp-4951c-part-2-2-2-2-2/

[dazz1]

• figure out which partially failing component is causing the CRT picture distortion,

Does your model have CRT adjustment trimpots?
https://www.way2.net/hp-4951c-part-2-2-2-2-2/

Your link points to a page I haven't seen before.
I don't recall seeing trimpots.  I have put everything back together so I can't look.
Unless I replace the power connector, any problem with the CRT is irrelevant.
There is a significant risk of additional latent defects. 

[dazz1]

Hi
Oh WOW, the power connector exploded on this HP 4957A as well.  Just like the one I have.
A couple of days ago my 4957A arrived from Frances. It worked for a few minutes until the Schaffer line filter exploded quite impressively.

[wkb]

The Anritsu you bought is a fun device.... Mine was a bit more expensive at €100  but still a steal. Anritsu have accompanying software on their website, albeit that you need licences loaded on the instrument itself to use the more fancy modulation. But you probably do not have an urgent need for, say, WCDMA.

Wilko

[tverbeure]

I deleted the original post, but here's the unit again:

The Anritsu you bought is a fun device.... Mine was a bit more expensive at €100  but still a steal. Anritsu have accompanying software on their website, albeit that you need licences loaded on the instrument itself to use the more fancy modulation. But you probably do not have an urgent need for, say, WCDMA.

About the licenses... Uhm...

https://www.eevblog.com/forum/testgear/looking-for-a-valid-anritsu-mg3700a-iqproducer-waveform-data-license-file/msg6261624/#msg6261624

This kind of power should obviously not be abused...

[Cyclotron]

Tektronix THM565.  I got it from a thrift shop in Beaverton, Oregon, the home of Tektronix.
I find it strange that it has "Not for sale" on the back and the symbols for compliance have been marked out.

Maybe someone took one home?  It has firmware 0.56 on it.  I think the latest is 2.0

[TERRA Operative]

Oh, I have designs for a programmer/updater/calibrator thingo for these. It's essentially an isolated RS232 adapter which allows you to calibrate and firmware update these (you only get 10 calibrations before you need to reload firmware to reset the counter, because reasons..?)

I can provide gerbers, or throw a blank PCB in an envelope if you want.
(I have an RS232 serial type, and also USB type that works except for the firmware update as the original flashing software only works with the true serial comms, it's a pending project to make a python script to replace it).

https://w140.com/tekwiki/wiki/THM500

https://www.eevblog.com/forum/testgear/tektronix-thm56x-portable-scope-hackteardowndiscussion/msg5847789/#msg5847789


Also, BEFORE you power it up, you'll need to replace the SMD capacitors inside (and twi through-hole types on the LCD panel). They ALWAYS leak and will kill the expensive (!) vreg chips quick smart...
For the faded backlight, don't try to remove the old EL panel, just slip a new piece of appropriately sized EL panel in over the top of the old one or you risk damaging the display.

[Robert763]

Busy packing the car for Dunstable Downs Rally tomorrow. Having a clearout. Lets hope the weather is OK.

[Hydron]

Forecast seems reasonable. Need to decide whether it's worth 2 hours each way (and £25 in train ticket) though to visit.

[Cyclotron]

Oh, I have designs for a programmer/updater/calibrator thingo for these. It's essentially an isolated RS232 adapter which allows you to calibrate and firmware update these (you only get 10 calibrations before you need to reload firmware to reset the counter, because reasons..?)

I can provide gerbers, or throw a blank PCB in an envelope if you want.
(I have an RS232 serial type, and also USB type that works except for the firmware update as the original flashing software only works with the true serial comms, it's a pending project to make a python script to replace it).

https://w140.com/tekwiki/wiki/THM500

https://www.eevblog.com/forum/testgear/tektronix-thm56x-portable-scope-hackteardowndiscussion/msg5847789/#msg5847789


Also, BEFORE you power it up, you'll need to replace the SMD capacitors inside (and twi through-hole types on the LCD panel). They ALWAYS leak and will kill the expensive (!) vreg chips quick smart...
For the faded backlight, don't try to remove the old EL panel, just slip a new piece of appropriately sized EL panel in over the top of the old one or you risk damaging the display.

Whoa, nice work!! I was about to start exploring options for updating the firmware. I would love to get a serial adapter up and running. I need to order some other boards so I can throw these on the stack. I can have some here in the US in case anyone needs one.

Too late on the CAPs, I powered it up, and it seems fine. I've taken it apart now, and there's luckily no leakage.  The caps are Nichicon and don't look like the ones in the other photos I've seen. Maybe they've been replaced?  I'll get them replaced either way.

Huge thank you for the advice and links!  This is a cool meter/scope, and I look forward to getting it prepped for use.  Multimeters are one of my biggest TEA weaknesses.

[factory]

The leakage might not be obvious until you remove the caps, this was the case with a few in my THM565 and similar failure with the through-hole caps in the THS710 here too. The corroded battery holder saved the expensive regulators ICs from EOLing in my THM.



More pictures from mine here, turns out it has firmware 2.00 too, the IC is marked for 1.02, wonder if the older versions are archived anywhere?
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg4987024/#msg4987024

Something I've noticed is it powers off before the batteries are fully depleted, not sure if this is normal for these as I've only owned/used this one. I need to revisit it at some point as I forgot about the two Elna caps on the display board.

David

[wkb]

Tektronix THM565.  I got it from a thrift shop in Beaverton, Oregon, the home of Tektronix.
I find it strange that it has "Not for sale" on the back and the symbols for compliance have been marked out.

Maybe someone took one home?  It has firmware 0.56 on it.  I think the latest is 2.0

Likely a pre-production evaluation unit or something like that. Likely to not  have been subjected to full safety, EMI etc qual and hence "should never have left the premises".

[wkb]

Ham sale yesterday evening made a Marconi 4101A 15-200 kHz frequency standard receiver follow me home  Originally designed and built by a French company called Adret, at some point in time bought bij Marconi,

Interesting piece of kit that you can tune to DCF77 at 77.5 kHz and which will discipline a. 5 MHz OCXO to produce a "house standard frequency reference".

It uses a motor-driven potentiomete to, I assume, drive the EFC on the OCXO.

All 74 series TTL, no CPU or whatnot in sight. Judging from the date codes of the chips late 1980s build,





*** If anyone has docs on this unit please let me know. Sofar only found a French language spec sheet. ***

[Cyclotron]

The leakage might not be obvious until you remove the caps, this was the case with a few in my THM565 and similar failure with the through-hole caps in the THS710 here too. The corroded battery holder saved the expensive regulators ICs from EOLing in my THM.



More pictures from mine here, turns out it has firmware 2.00 too, the IC is marked for 1.02, wonder if the older versions are archived anywhere?
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg4987024/#msg4987024

Something I've noticed is it powers off before the batteries are fully depleted, not sure if this is normal for these as I've only owned/used this one. I need to revisit it at some point as I forgot about the two Elna caps on the display board.

David

You folks nailed. The caps were leaking. You could see the oxidized solder. But I don't think I have any other damage. I've removed a couple of chips and nearby components just to be thorough, then refitted them after cleaning. I'll order some new caps.

I've put a pic of the camps I had on mine here:

[Ahax]

Greetings

Just got my hands on a lecroy WaveSurfer 104MXs-A, and a fluke 289. Combined they were 1300eur. Even tho I said I would not buy a new oscilloscope right now, I couldn't pass up the opertunity. The oscilloscope also came with 3 probes.

[BILLPOD]

Holy Cow, Ahax, you got one sweet deal.   I wouldn't pass up a deal like that either.  Congratulations

[TERRA Operative]

I've uploaded the gerbers etc of the RS232 serial port version of the THM programmer to the THM thread:

https://www.eevblog.com/forum/testgear/tektronix-thm56x-portable-scope-hackteardowndiscussion/msg6263352/#msg6263352

[Cyclotron]

I've uploaded the gerbers etc of the RS232 serial port version of the THM programmer to the THM thread:

https://www.eevblog.com/forum/testgear/tektronix-thm56x-portable-scope-hackteardowndiscussion/msg6263352/#msg6263352

This is the kind of support that makes these groups great. TERRA Operative, I can't thank you enough. This will help me speed this THM to upgrades. 

Does anyone think it is worth the risk and effort to pull the memory and take a copy of the old 0.56 firmware it has?  I can't imagine it being of interest, given there are no locked features.

[TERRA Operative]

The only reason to take the image would be juuusssttt in case your hardware has something different if it is a dev version.

v2.0 includes optimisations that apparently speed up the UI etc. so the update is a good one to do.

https://w140.com/tekwiki/images/b/b5/THM500_FW2.0_Changelog.pdf



I wonder if the firmware software can pull the old firmware down, or if a python script can be made to do it?

[dazz1]

Hi
I now have a:

• Fluke PM3394A 200MHz, 4ch, 200Ms/s auto ranging combi-scope with a cool blue screen, lots of buttons, advanced features (for the time) and
• a Tektronix TDS 350, 200MHz, 2ch, 1Gs/s with a large screen.

Which one should I keep?    I already have two scopes on my bench. A Philips PM3070 and a HP 54645D with logic analyser probes and GPIB/Maths module.   I don't really have room for another two scopes.

[srb1954]

I would keep the PM3394A.

I have a PM3394 combiscope and it has been my daily driver for more than 30 years. I mostly use it in analog mode and only occasionally do I need to switch to digital mode to capture a waveform. It is an easy-to-use scope compared to many more modern digital scopes as it has individual controls for practically every regularly used function and you don't have to navigate through menus every time you want to adjust a setting.

The advantages that the PM3394A possesses over the TDS350 are:

• Analog option which is nice for examining fine detail in waveforms and is generally more responsive to use
• 4 channels
• More digital capture memory (especially if you have the extended memory version)
• More flexible triggering options
• Easy to use controls

The disadvantages of the PM3394A are:

• ADC bandwidth is shared across 4 channels so you only get 50Ms/s with simultaneous single shot captures of all 4 channels
• Some of the math functions are only available with the MathPlus option, which only comes as factory installed
• Age - may be due for some capacitor replacements

 
I don't have experience using the TDS350 but its advantages would seem to be:

• Higher digital sampling rate which could be useful when making single-shot captures of very fast transients

The disadvantages of the TDS30 would seem to be:

• Very small capture memory. The memory depth of only 1000 points would seem to be a severe limitation
• Only 2 channels

[dazz1]

I would keep the PM3394A.

I have a PM3394 combiscope and it has been my daily driver for more than 30 years. I mostly use it in analog mode and only occasionally do I need to switch to digital mode to capture a waveform. It is an easy-to-use scope compared to many more modern digital scopes as it has individual controls for practically every regularly used function and you don't have to navigate through menus every time you want to adjust a setting.

The advantages that the PM3394A possesses over the TDS350 are:

• Analog option which is nice for examining fine detail in waveforms and is generally more responsive to use
• 4 channels
• More digital capture memory (especially if you have the extended memory version)
• More flexible triggering options
• Easy to use controls

The disadvantages of the PM3394A are:

• ADC bandwidth is shared across 4 channels so you only get 50Ms/s with simultaneous single shot captures of all 4 channels
• Some of the math functions are only available with the MathPlus option, which only comes as factory installed
• Age - may be due for some capacitor replacements

 
I don't have experience using the TDS350 but its advantages would seem to be:

• Higher digital sampling rate which could be useful when making single-shot captures of very fast transients

The disadvantages of the TDS30 would seem to be:

• Very small capture memory. The memory depth of only 1000 points would seem to be a severe limitation
• Only 2 channels

Hi
There was a time, not very long ago (this morning in fact) when I would have sold my neighbours children for lab experiments to have the chance to own a PM 3394.  Today is the first time I have seen a PM3394 or a TDS350 in the flesh.  Although I have not studied the PM3394 at all, I have certain expectations based on my experience with PM3070s.   

I haven't really had much to do with anything Tektronix, so no defined expectations.  First impressions were what a drab boring colour scheme and it doesn't have enough knobs, LEDs and switches to be a proper serious oscilloscope.  

These two scopes have been inactive for quite a while, so I dare not apply power without going through my process.  I built a test load specifically for the PM3070 PSU testing.  I feel it is likely I can modify that for use with the PM3394 given their shared heritage (both Made in Holland). 

As I expand my test equipment inventory, I try and fill capability gaps and eliminate (sell) redundancy.  So after asking what should I keep, I ask myself, what should I sell.

One of the disadvantages of the PM3394 compared to the PM3070 is that the later includes the little PCB module that interfaces the rear BNC connectors (see attached image) to the main PCB.  I transplanted this from the brown PM3070 because the white one looked so much better.  I sold the brown one.  (All that sounds really racist, but I am referring to oscilloscopes.)  I am already wondering if I can transplant the little pcb again.  I have never used any of the BNC ports on the back but that isn't the point. 

The PM3394 doesn't have the GPIB option and the TDS350 does..  It would be nice if GPIB could be retrofitted.
The backup battery compartment is empty and looks like never used, so that is good.

So at this time I have chosen not to make choice.

[tautech]

There's every chance Dazz when you take the covers off the Fluke it will still show its Phillips heritage.

Sell all 4 and I'll drop something in much better when down your ways in a few weeks. 

[dazz1]

There's every chance Dazz when you take the covers off the Fluke it will still show its Phillips heritage.

Sell all 4 and I'll drop something in much better when down your ways in a few weeks. 

As I expand my test equipment inventory, I try and fill capability gaps and eliminate (sell) redundancy.  So after asking what should I keep, I ask myself, what should I sell.

The current gap in my capability is a spectrum analyser.