Test Equipment Anonymous (TEA) group therapy thread

[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. ***

In the meantime I have been sent the documentation. Many thanks for that of course!

Wilko

[ftg]

So I did not end buying any Anritsu UMTSMasters, even if the price would have been a very reasonable 550eur.
Because instead I bought an R&S FSIQ 7 with a tracking generator.
For a change I have a fully working spectrum analyzer I don't need to repair.

I also had the following bits follow me home:
- Anritsu ML2438A RF Power meter, no probes tho, but I already have one and two probes for it.
- Noise-com WR-15 50 - 75 GHz noise source
- Agilent 83050A 2 - 50 GHz Microwave System Amplifier with two adapters. Verified operation up to 20GHz with the on-site measurement lab.
- IL-Power LPS 2022-IEEE 0 - 100V Autoranging programmable DC power supply.
- R&S Load and Short calibrators, sadly no Open in the same formfactor.
- Handful of decent quality RF adapters, mostly to and from type N.
- A handful of decent quality test cables. Mostly SMA-SMA and N-SMA. Huber-Suhner and Megaphase.
- A mystery Orbis TX SSU box with loads of adapters, RF relays, attenuators and a few amplifiers.

All in all a nice hamfest. Even managed to make time to visit some talks.

[srb1954]

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). 

I would do a visual inspection for leaking capacitors, RIFA capacitors and Schaffner power input modules before powering. Both the RIFA capacitors and Schaffner power input modules are known to let out the magic smoke, and an awful stench.

If you have an insulation resistance tester that might help identify any weak capacitors in the power input module.

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.

This module was an optional extra. I have it on my PM3394 but have never used any of these inputs/outputs.

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.

There is provision on the PCB for the GPIB option chips so you could upgrade the H/W for GPIB but it may not be usable without the corresponding S/W upgrade. I have not seen anything online for S/W upgrades as these were factory options only and required a special uploader program. The service manual refers to "a program running on a Personal Computer with RS232 interface" but states that the scope has to be sent to a service centre for S/W updates.

I have a spare PM3394 service manual that I could part with. It is likely sufficiently close to the updated PM3394A design to still be quite useful, particularly for the calibration procedures.

[dazz1]

I would do a visual inspection for leaking capacitors, RIFA capacitors and Schaffner power input modules before powering. Both the RIFA capacitors and Schaffner power input modules are known to let out the magic smoke, and an awful stench.

I had one of those Schaffner input line filter go off a few days ago on another item of test equipment.  Not nice.  Even after it blew, it still visibly looked OK.  The only external clue was the vent plug blown away.
On the same instrument, I found the cracked RIFA caps before I applied power.

If you have an insulation resistance tester that might help identify any weak capacitors in the power input module.

With SMPS I go around the power supply and apply a few volts across each individual electrolytic to initiate the reforming process, but not enough to kick the circuit into life (5-10VDC).  The aim being to get the electrolytic chemistry started enough so the cap doesn't look like a short circuit when it gets smashed with mains volts. 

On linear supplies, I just ease the voltage up gradually.  I have a power meter on the mains input to look for anomalous power consumption, spikes etc.

I have a spare PM3394 service manual that I could part with. It is likely sufficiently close to the updated PM3394A design to still be quite useful, particularly for the calibration procedures.

Thank you for the offer of a manual.  I have found a few on-line sites with the manuals, but I haven't yet found one easy to download from.  They are big manuals.

[tautech]

I have a spare PM3394 service manual that I could part with. It is likely sufficiently close to the updated PM3394A design to still be quite useful, particularly for the calibration procedures.

Thank you for the offer of a manual.  I have found a few on-line sites with the manuals, but I haven't yet found one easy to download from.  They are big manuals.

https://elektrotanya.com/fluke_pm3370a_pm3380a_pm3382a_pm3384a_pm3390a_pm3392a_pm3394a_sm.pdf/download.html

[Gertjan]

I found my standard attenuator probe for my HP 3200B VHF oscillator!


IMG_6979__HP_3200B_standard_and_doubler_probe-2000pix.jpg

My 3200B did not come with the standard output attenuator, but the optional HP 13515A doubler probe. This is a diode doubler, extending the frequency range of the 3200B from 500 to 1000MHz.

This made the 3200B a lot less useful, so I started looking for a standard output probe. On the local small adds site, I found an older 3200B. Did not look too good, but was cheap and with output probe.

This "new" 3200B has serial prefix 735. Conveniently, the only 3200B manual floating on the web is exactly for prefix 735.
But this oscillator is mistreated by previous non-caring owners. An example:


IMG_6976__HP_3200B_butchered_power_connector-2000pix.jpg

The power connector was butchered, and an Euro mains cable spliced in.....

With the standard output attenuator probe in place, the 3200B can show it's strengths:


HP_3200B_spectrum_&_level-1000pix.png

A very strong output signal, with low harmonics. Green is my existing 3200B, yellow is the new arrival, which is even cleaner.

regards, Gertjan.

[Robert763]

Dunstable Downs rally yesterdaay was OK for getting rid of various bit's and pieces. Didn't sell any more expensive stuff and bench DMMs seem to be totally unwanted at any price. Made one buyers day with an X-Ray cassette of all things. Had very little chance of looking around so didn't buy much. A Texscan 0-60dB 10dB step manual attenuator with N types for 50p, a rebadged ILT 1700 Radiometer for  £5 which is a bargain. Basically a multi-function picoammeter. 0.2pA to 200mA, for light measurement. No sensors but that's not an issue for me. https://internationallight.com/products/ilt1700-research-radiometer And one bit of non-TEA, a slightly tatty Yaesu FT-757GX HF transceiver with matching FC-757AT automatic antenna tuning unit. I've always fancied one of these radios and £150 was a good price even without the ATU. Not tested it yet.

Robert.

[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

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.

Good news!
After poking and bodging my serial adapter board, I got a THM560 all updated!

Of course I messed up Rx and Tx in my design, as is tradition, so I'll do a design revision and provide the corrected files in the other thread in the next few days.

I only tested using MS-DOS so far, so further testing in other versions of Windows is needed (I expect it'll probably break after Win98 or thereabouts).



Next step is to sniff the comms and try to replicate the flash process in python so it will work on any platform with the USB version board I made.

However, the USB version does seem to work for normal serial comms (like taking readings etc) and for performing calibrations.

[sean0118]

IMG_6976__HP_3200B_butchered_power_connector-2000pix.jpg

The power connector was butchered, and an Euro mains cable spliced in.....

They also didn't re-connect the earth right? Chassis would be floating 

[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.

I have decided to keep the Fluke PM3394A and let the Tektronix TDS 350 go.  I opened both of them.  The Fluke looks like what you'd expect to see inside an oscilloscope.  Very nicely laid out.  Clearly well down the transition from defining functions with components to defining functions in code.  A major step up from the PM 3070 that I have.

The TDS 350 was a disappointment.  It looks like it has a thin enclosure wrapped around a collection of spare parts.  The enclosure is flimsy and mostly full of air.  The power supply and the very large fan dominate (to be fair, the Fluke PSU is also large, but doesn't have the oversized fan).    The thing that killed the TDS 350 as an option is the puddle shallow memory.  Only 1k deep. 


Now I just need to get them both running.  One to sell. One to keep.

I know there are better scopes available than the PM3394 but I didn't hand over any money to get either scope.  That makes them both really good, excellent even.  I don't need better scopes.  I just need good enough.  The Fluke 3394A meets that requirement.    So does the Philips 3070. 

[AVGresponding]

The reason the TDS350 is mostly air inside is that it comes from an era when options were actual physical cards that had to be installed, and not just software unlocks.

The Philips combiscope is nice, but the Fluke badge doesn't change the quality of the plastics; be careful, they get fragile with age.

[Robert763]

I had a look at the FT-757GX. It has a couple of issues but one I thought was worth a mention. While doing some initial testing the 757 switched off and would not come back on. Basic circuit looks simple. A relay with 13.8V in series with thr on-off switch on one side of the coil and a NPN transistor (Q10) collector with grounded emitter on the other. Base of Q10 is connected to the 13.8V from the on-off switch with series 10k resistor.

Grounding the collector of Q10 turns the radio on. Check of the switch showed poor contact with a couple of hundered ohms. A drop of switch cleaner sorted that, though it probably wasn't the primary fault.
I pulled the PA board, which has the power circuit and relay on it, out for better access and confirmed the fault with just the power lead connected and shorting J04, the power switch connector and confirming no click fron the relay. Q10 base voltage was 0V without J04 shorted and 0.7V with the short (switch on). So that looked OK. Pulled the transistor and put it on a basic transistor tester. It looked OK, reported as NPN with Hfe 138. But what is the specification? It's a 2SD892R. That is a darlington so the Vbe and Hfe are clearly wrong even without consulting the data sheet. So I put it on my Peak DCA75 Pro semiconductor tester This confirmed the low Vbe & HFE and did not identify it as a darlington.  That looks like the input transistor of the darlington pair has a base emitter short. So I replaced it. The 2SD892x are pretty rare but like most darlington circuits it's not critical. I replaced it with a ZTX600. I chose this as it is a favorite of mine for driving coils and I had stock. So checked the PA board and got a relay click. 
So I put it back in the radio connected everthing up and... the radio won't turn on 
Only 0.7V on the base. Now there is another bit of circuitry around the base of Q10. A diode (D8) and 470 ohm resistor from the normally open contact (13.8V with radio on) Which seems to be there to keep the transistor hard on once the relay closes. More puzzlingly, there another diode (D9) and 100 ohm resistor to a a circuit connection "PTT". What does this do? it clearly reduces the voltage on the base of the transistor Q10 when the PTT is active. But you would not want to turn the radio off when you press the PTT...  A bit of analysis and thought indicates that this is likely to prevent turning the radio on with the PTT active. 
I could not find any mention of this feature in any of the manuals.
Some measurements indicated the PTT line was low, then I noticed the MOX button was depressed. Released that and power swich works as expected :-)  MOX is a manual, latching, PTT switch on the front panel. I must have pressed it whle taking the radio apart.
I had very nearly torn the set apart again....

Robert G8RPI.   

[dazz1]

The reason the TDS350 is mostly air inside is that it comes from an era when options were actual physical cards that had to be installed, and not just software unlocks.

Hi
I'm curious.  What upgrade cards were available for the Tektronix TDS350?  I don't see any facility to mount extra cards, or connectors to connect them too.  The most obvious expansion option to offer would be an increase in the memory depth.  Was that ever offered?

To be fair, the only way to upgrade a Fluke 3394A is to sell it and buy a Fluke 3394B.  Regrettably not an option for me.

[AVGresponding]

The reason the TDS350 is mostly air inside is that it comes from an era when options were actual physical cards that had to be installed, and not just software unlocks.

Hi
I'm curious.  What upgrade cards were available for the Tektronix TDS350?  I don't see any facility to mount extra cards, or connectors to connect them too.  The most obvious expansion option to offer would be an increase in the memory depth.  Was that ever offered?

To be fair, the only way to upgrade a Fluke 3394A is to sell it and buy a Fluke 3394B.  Regrettably not an option for me.

Doing a search it looks like the only option was the GPIB/Printer card. Bizarre on a machine, which as you said, only has a 1kpts memory as standard. There's certainly enough space to accommodate more...

I suspect the reason for the "empty" case might actually be simply because the basic chassis is shared with the TDS400 series? The external dimensions are identical, implying that to be so. My 420A is stuffed full, and includes the 1M option for 120kpts, not much by modern standards, but better than 1kpts!

I've not yet been lucky enough to find a PM3394 at a price I'm willing to pay, but I live on in hope!

[TERRA Operative]

Some of the TDS300 series had a built in printer, they were given a P at the end of the model number.

[AVGresponding]

Yeah the options list mentions thermal printing, but the wording is quite confusing.

[dazz1]

Hi
A thermal printer on a scope!  I suppose it must have seemed to be a good idea at the time.  They probably thought if you have a printer, you won't need a scope camera. 
I know Tektronix make really good test gear, but based on what I have seen, the TDS350 isn't an example of that. 

I have owned various models of Philips scopes for over 40 years.  I currently have a Philips PM3070 and that is a nice scope.  If the Fluke PM3394A works and holds in the magic smoke, it will take the place of the PM3070. 

[tautech]

Hi
A thermal printer on a scope!

Yup quite a few had them.

If the Fluke PM3394A works and holds in the magic smoke, it will take the place of the PM3070.

Not sorted yet Dazz ?
Have you had a distraction ?

[dazz1]

If the Fluke PM3394A works and holds in the magic smoke, it will take the place of the PM3070.

Not sorted yet Dazz ?
Have you had a distraction ?

The PM3394A has been in dry storage for 10 years along with a bunch of other test equipment. I have spent the day reforming the caps on the power supply.  It's switch mode, so I can't use a variac.  If I just hit it with 240VAC, I am confident there would be the release of the magic scope.    I have been applying about 10Vdc, current limited to 10mA, to each individual electrolytic cap. for about 15 minutes.  Just enough to at least partially restore the electrolytic film without waking up the electronics.  So when it gets slammed with 240Vac it will be primed for the hit. That's the theory.  First power tomorrow.  I am hoping I won't have to start a new blog  in the repair forum.

[tautech]

If the Fluke PM3394A works and holds in the magic smoke, it will take the place of the PM3070.

Not sorted yet Dazz ?
Have you had a distraction ?

The PM3394A has been in dry storage for 10 years along with a bunch of other test equipment. I have spent the day reforming the caps on the power supply.  It's switch mode, so I can't use a variac.  If I just hit it with 240VAC, I am confident there would be the release of the magic scope.    I have been applying about 10Vdc, current limited to 10mA, to each individual electrolytic cap. for about 15 minutes.  Just enough to at least partially restore the electrolytic film without waking up the electronics.  So when it gets slammed with 240Vac it will be primed for the hit. That's the theory.  First power tomorrow.  I am hoping I won't have to start a new blog  in the repair forum.

Fingers crossed for ya. 

[factory]

Hi
A thermal printer on a scope!  I suppose it must have seemed to be a good idea at the time.  They probably thought if you have a printer, you won't need a scope camera. 
I know Tektronix make really good test gear, but based on what I have seen, the TDS350 isn't an example of that. 

I have owned various models of Philips scopes for over 40 years.  I currently have a Philips PM3070 and that is a nice scope.  If the Fluke PM3394A works and holds in the magic smoke, it will take the place of the PM3070.

Of course they were a good idea at the time, before cheap digital cameras were everywhere, but a thermal printer would have been limited to a DSO.
Many things at work had a printout from the Yokogawa included in the repair report and scans of them included in manuals/procedures, the scope had a FDD too.

And compared with a Polaroid based scope camera, probably a lot cheaper per print, even including buying the OEM paper roll (which seems to be a standard size). Also a lot less of a pain to setup & use, see the CuriousMarc videos on using ancient Polaroid based scope cameras. As the correct size film is no longer made for the HP scope cameras, in a later video he uses a modern Instax camera with an custom made adaptor for the scope camera.



I'm sure I've seen a thermal printout attachment that fits on the back of some later TDS3000? scopes, Gould had a built in printer option, but I'm not sure if it was pen based or thermal, as I never used one.

David

Edit: edited to made it clear the obsolete film is for the scope camera only and not general photography, some sizes/types are still made for some Polaroid cameras.

[wkb]

Actually, the aptly named Impossible Project led to this

https://en.wikipedia.org/wiki/Polaroid_B.V.

[McBryce]

Hi
A thermal printer on a scope!  I suppose it must have seemed to be a good idea at the time.  They probably thought if you have a printer, you won't need a scope camera. 
I know Tektronix make really good test gear, but based on what I have seen, the TDS350 isn't an example of that. 

I have owned various models of Philips scopes for over 40 years.  I currently have a Philips PM3070 and that is a nice scope.  If the Fluke PM3394A works and holds in the magic smoke, it will take the place of the PM3070.

Gould Oscilloscopes had a built in Thermal printer on the top as an option. I think all 700 and 900 Series offered this.

McBryce.

[factory]

Actually, the aptly named Impossible Project led to this

https://en.wikipedia.org/wiki/Polaroid_B.V.

Have you watched the videos? Marc mentions the size/type used by the scope camera is only available as old stock, the currently available films are not the correct size/type, the wiki mentions some sizes are not made due to the machinery being scrapped along with the factories, when the original Polaroid when bust.

The HP scope cameras are something I've never bothered to try buying, due to the price usually being aimed at camera collectors, rather that old TE collectors.

David

[Gertjan]

[...], Gould had a built in printer option, but I'm not sure if it was pen based or thermal, as I never used one.

I had a Gould 1604. It had a pen based printer on top. I never found the pens for this printer...

This scope was a bit drifty, depending on temperature. So I removed the useless printer, and replaced it with a slowly rotating 12cm fan:


IMG_4647-Gould_1604_met_fan-2000pix.jpg

This cured almost all of the drift.
Also, now I could reduce the speed of the original fan in the back. This made the scope almost silent.

regards, Gertjan.