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Tektronix 2247A problem. Keep or return?
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Hi folks. I recently purchased a Tek 2247A scope and upon testing it for the first time, it locked up when testing the B sweep with a msg that said
'INVALID INTERRUPT FROM 0993:F082' When I rebooted, the screen has an indecipherable error message that appears to read something along the lines of 'Part Number 100-xxxx-00' with a bunch of exclamation marks. I couldn't clearly read what the part number as it was out of focus and could get it to focus well enough to read the numbers. The 'Auto Level' and 'Auto' LEDs were flashing which indicates both a RAM and ROM problem according to the service manual. The SGL SEQ LED was also flashing but there's nothing in the service manual that mentions that LED, or at least nothing that I've found. I let the scope sit for 10 minutes and it booted back up in service mode and gave a failed battery warning, and ran through self calibration. I left the unit on and it locked up after about 10 minutes with the same error as before. After the reboot I went into the service menu and ran the self test 'until fail' and the test ran for 30 minutes without issue. I also ran through the self calibration once more. It's now been powered on for a few hours without any problems or locking up and all functions 'seem' to be working as expected. Thoughts? Would something like this be caused by a battery issue? That seems like an easy fix but if it's something deeper, I'm not sure if I'd want to chance it. Thanks! Jay |
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Jay,
I have two 2465's here, and they're known for quite a few gremlins, including NVRAM battery issues, among other problems. In my case, I have two good ones, and I can have an excellent one by parting them together and renovating. I'll cast off the remaining wreck. You can do the same with yours. It's quite an old scope, repairable, with good manuals, but far outside any warranty support. Why did you buy it then? It isn't reasonable to expect these to be without major flaws needing to be addressed. If you're ready to do that work, dive in. If you're not willing to do all that work, you should return it and buy a new overseas model with warranty. Rigol, Instek, Owon, etc. It's something like owning an older car. Much more repairable, but needing much more time into it. |
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On Fri, Mar 28, 2025 at 09:12 PM, VE6WMR wrote:
Thanks for the reply and perspective. I fully understand these are old scopes and have no problem putting in a little work to get a scope working as it should. I just get a little spooked when I can't reproduce a problem. Earlier, I turned the scope off for about an hour and started it up again and as of now the scope has been running for about 7 hours without any issues. All of the functions I've tested have been working as expected. All channels work, the display is sharp, measurements seem accurate, triggers are working well, etc. So far the only issues I encountered were the first few startups after unpacking. I have a little bit of time to decide what to do and whether to send it back or keep it. I'll play around with it for the next week or so and see if the gremlins misbehave. |
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It’s not unreasonable to expect that the power supply is in need of a
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recap, and a marginal power supply could cause random problems. In your shoes I’d pull the case and measure the power supplies for voltage and ripple. There’s typically a table with allowable values in the service manual. ?ann f?s., 28. mar. 2025 kl. 23:27 skrifa?i Jay Czaja via groups.io <jmczaja@...>: On Fri, Mar 28, 2025 at 09:12 PM, VE6WMR wrote:including |
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On Fri, Mar 28, 2025 at 06:12 PM, VE6WMR wrote:
Jay,Comparing a 2465 to a 2247A is a bit like apples and oranges, but understood the well meaning intention to be helpful in the sense that both are old. But for one luckily the 2247A does not rely on NVRAM to store cal constants. As suggested check all voltages and ripple to make sure they are within spec. Also while you are in there, check power supply diodes, and any with ZM or ZS markings needs to be replaced as they are known to get leaky over time and cause problems. There are 17 of these diodes on the 224x (and 2252 same series) scopes power supply. Use fast diodes like MUR160 (600V 1A) or similar. Do not use common 1N400x. Also replace the 3V Lithium battery, its only meant to hold the setting of the last session, no calibration at risk. I have both 2465B and 2247A scopes, but the 47A is usually my go-to scope 95%. |
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Thanks again guys! The 2247A has been running overnight with signals in each channel and everything has been humming along ok, no lockups.
I'll put it on the bench sometime today or tomorrow and check the DC voltages per the service manual and check for ripple. I'll have a look at the diodes and check their marking and see what's what.. If any electrolytics require replacing, will this throw off the calibration? I don't have any of the fancy gear to do a proper calibrations (PG506A, marker generator, etc). I have a really nice 2245A and enjoy using it and always wanted a 2247A. This particular one seems to be clean and in very good condition overall. The trigger section on the 2247A seems better than my 2245A as well. The 2400 series scopes look nice but the 224x's are probably more scope than I'll ever need. I also have a nice 2232 that I like using for the DSO section. I mess around with building synthesizers and the 2232 is nice for catching really slow events. Thanks again! |
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On Sat, Mar 29, 2025 at 12:57?PM Jay Czaja via groups.io <jmczaja=
[email protected]> wrote: Thanks again guys! The 2247A has been running overnight with signals inSounds like a keeper to me! If the scope has been in storage for a while, it's possible that the power supplies stabilize as the caps reform or warm up or some such. You may still want/need to recap it, and I've never heard of a case where the calibration is thrown off by improving the power supplies. I've never worked on a 2247A, though, so YMMV. |
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I just cracked it open and checked the DC voltages and ripple. Everything was well within spec. The inside also looks very clean!
I didn't notice the tag earlier but it appears to have been taken from a hospital environment. It was a bit of a pain to pull the chassis from the case. Of course, the only tiny dent on the top of case was putting enough pressure on the side rails to make it difficult for the chassis to slide out without resistance. I'm guessing you might be right and maybe the caps needed to reform or something along those lines. At this point I had the scope running for hours. Left if unplugged for a few hours and had it running for a few more hours and everything seems to be ok. I'll probably recap it in the near future as I plan for this to be my everyday scope w/ my 2232 for 'slower' stuff. The 'green screen of death' had me a little worried but feel relieved that it's been stable since those initial issues. All functions I've tested so far have worked perfectly. I'll need to play around with the menu and measurements system a bit more but the few quick measurements I've made were good. I need to read about the menu/measurement section as it has more features than the 2245A which I've been using. I appreciate all the responses. I'm sure I'll have more questions! |
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On Sat, Mar 29, 2025 at 09:57 AM, Jay Czaja wrote:
Thanks again guys! The 2247A has been running overnight with signals in eachJust replace the 3V battery to get rid of the annoying power up error message and the recalibration routine running every time. You need to lift the main processor board that is on top, and the battery is at one end of the board. To lift the board there are some flat ribbon type conductors and connectors to deal with, but if you are careful and methodical its pretty straight forward procedure. Last time I recall the battery swap can be done by just partially lifting the board, which limits the amount of ribbon cables to deal with. I have a really nice 2245A and enjoy using it and always wanted a 2247A.The 47A is a 45A with additional digital functions (and push buttons), otherwise they are identical scopes. Make sure to check those suspect diodes on the power supply board in both your 45A and 47A scopes. A quick glace should tell you if you need to replace them. The power supply board is in the middle of the lower side, kind of a pain to get it out and even more pain to get it back in due to the connecting pins. But you should be able to read the labels on a couple of diodes without removing the board to make sure you don't have any time bombs sitting in there. If you find voltages and ripple specs are ok I would not even bother recapping unless you see a capacitor that is obviously leaking or bulged up, which I doubt. These 224x scopes if I recall used high quality Mallory or Sprage caps, and I've never bothered to replace any in my 47A, but most definitively had to in my 2465B. Those old caps sometimes even end up measuring better specs than modern equivalent caps (value/ESR). |
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On Sat, Mar 29, 2025 at 01:42 PM, Jay Czaja wrote:
Just check the power supply diodes for either ZM or ZS markings and replace. And the 3V battery. Should then be done and ready to enjoy. |
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Thanks again. I'll pull the processor board and have a look at the power supply and replace any diodes marked ZM or ZS.
I'll definitely replace the battery, I think Digikey has the correct one. I'll leave the electrolytics as-is unless I see anything that looks suspect. Had the scope off all night and cold started it in the morning without issues. I'll do this over the next fews days for good measure but thing are looking good at this point. |
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