Re: Help! I bricked a perfectly functioning 2467B!
RAM is read/write random access memory.? Power goes off, contents vanish.? EPROM is erasable programmable read only memory.? Power goes off, data stays.
RAM is the arduino's ram memory, EPROM is two varieties in an arduino, and is either the EEPROM, or the FLASH memory program storage.
Chuck Harris is to be found on the Tekscopes2 forum.
Harvey
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On 4/5/2024 5:48 PM, Don via groups.io wrote: Hi Mark,
Thank you for your response. What you have suggested is interesting and may well work, but it is way over my head. I have no computer programming experience (other than a bit of dabbling with Arduino stuff). Not sure if what you are referring to as the EPROM is the same as the RAM chip (which in my scope is an NEC D4464C-15L chip).
It would be terrific if I can find a way to write the cal data via the screen. I recall reading in one of the posts from Chuck Harris on this Forum where he appeared to imply that it was possible to do so, but no details were forthcoming. I am hoping that Chuck will respond and clarify the issue.
Don
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Re: Slightly off topic, but I'm getting desperate. Looking for the Adjustment Program for the HP/Agilent 4263B
Hi Jared,
Silly question, but is your unit actually out of specification?
If you follow the Performance Check procedure in the User manual, what fails?
Regards,
- Guy
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Re: Help! I bricked a perfectly functioning 2467B!
Hi Jon,
I have searched the Forums and did not find any guides or directions to write cal data via the screen of the scope. Could you tell me where you saw the method to rewrite data in a low SN A5 with discrete RAM and a separate battery?
Don
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Re: Help! I bricked a perfectly functioning 2467B!
Hi Mark,
Thank you for your response. What you have suggested is interesting and may well work, but it is way over my head. I have no computer programming experience (other than a bit of dabbling with Arduino stuff). Not sure if what you are referring to as the EPROM is the same as the RAM chip (which in my scope is an NEC D4464C-15L chip).
It would be terrific if I can find a way to write the cal data via the screen. I recall reading in one of the posts from Chuck Harris on this Forum where he appeared to imply that it was possible to do so, but no details were forthcoming. I am hoping that Chuck will respond and clarify the issue.
Don
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Re: Help! I bricked a perfectly functioning 2467B!
The Cal data is stored on an NEC D4464C-15L chip. The battery is separate from this chip (unlike in the DALLAS NVRAM chip)
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Re: trigger problem with 7B70
On Fri, Apr 5, 2024 at 11:14 AM, Mark Vincent wrote: The high speed transistors could be replaced with KSP10BU. The pinout is BEC. I need a PNP transistor, though. Pretty sure KSP10BU is NPN, as I have some and checked everything in my limited stash as a potential replacement. Finding a PNP over 500 MHz looks unlikely, especially in the 2 GHz range of the 151-0271. thanks, Adam
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Re: trigger problem with 7B70
Adam,
The high speed transistors could be replaced with KSP10BU. The pinout is BEC. The voltage ratings are a bit higher. It is a TO-92 case. I have, as well as others here, have used these as replacements. If you find 0367s that are leaky, the replacement is what I used to replace the original leaky one. The 0367 transistor is used in many plug-ins and some scopes. Only the 7D15 has a different p/n yet is the same transistor. From my experience, the KSP type fixed problems the leaky 0367s had in the pieces I have.
Mark
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Re: Help! I bricked a perfectly functioning 2467B!
Bonsoir cher monsieur
You did NOT "BRICK" the scope. Loss,of NV ram cal is easy to fix.
see the many threads here and especially tekscopes2 for NVRAM and CAL data, also eevblog "2465B 0" teardown
if you have the low SN A5 discret with RAM.and separate battery see the method to rewrite the data to default, or a saved copy.
the reference to prom programming is for the later SN with SMD A5 and Dallas NVRAM with internal battery.
Finally Menacham at Condor Audio in Isreal and Qservice in Greece will respond to email questions a,de are very helpful, selling Tektronix spares, recap kits, ICS, etc.
bon courage
Jon
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Re: Help! I bricked a perfectly functioning 2467B!
Hi Don,
I have the same question: "Do you have an EPROM programmer?", but for a different purpose.
One way is to write a small 6802 assembly program with the calibration data embedded in it, and have it copy that back to the NVRAM. You could burn this small program to an EPROM, plug it into the scope in place of your regular EPROM, and turn on the scope to perform the copy. Then, put your original EPROM back.
I was working on such a program, but never quite got it completed. If you are game for trying, I can work with you to finish it. You would need to get an extra EPROM or two for your scope, and you also need to have an EPROM eraser.
I am still hoping to find a way to write cal data via the screen, similar to reading it via EXER 02, but I have not found any clues that a hidden utility like that exists.
-mark
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Re: Help! I bricked a perfectly functioning 2467B!
I'm pretty sure you're supposed to use an eprom programmer. What kind of chip does your scope use to store the cal data?
Make sure the programmer supports the chip.
I could be wrong though.
Benjamin
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Re: TDS744A tick tick tick when power on (and something smelling)
Hello,
Thanks for all comments.
Did find a troubleshooting diagram for the psu and some nominal voltages.
Also started checking the video by Jared.
The weekend is saved!
Regards,
Staffan
Ps. Wish I had a thermal imager¡
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It may have a springy metal plate inside that earths the case to the ¡®scope chassis. Tim P Sent from Mail ( ) for Windows *From:* v_12eng@... *Sent:* 05 April 2024 00:34 *To:* [email protected]*Subject:* [TekScopes] 468 case removal Hi, I just picked up a 468 and am trying to slide the case off, it has some minor damage but it doesn't appear to interfere with the insides. It binds up "sticks" a little past half way off. Do you have to remove the handle on this model I didn't have to on the other ones I have 466, 475? Is there anything with the digital section in the back that interferer's with the case? Jim O
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Re: TDS744A tick tick tick when power on (and something smelling)
To check whether its the standby's fault or if its a shutdown due to a shorted cap somewhere I would try to inject the voltages from a regulated supply and see if current is reasonable.
Its helpful to have the nominal current available, but not mandatory. A shorted cap will lead to currents in excess of 1 amp even on very low voltage that won't hurt anything. In case you have a thermal imager you can then see where the current leads to :-)
cheers
Martin
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Re: TDS744A tick tick tick when power on (and something smelling)
For troubleshooting of standby power supply part you do not need load, but for power supply as such external loads are needed. Please check Jared¡¯s video I mentioned before, there are all details.
Vladimir
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On 5. 4. 2024, at 6:59, Sigur?ur ?sgeirsson via groups.io <siggi@...> wrote:
??ann f?s., 5. apr. 2024 kl. 00:19 skrifa?i Staffan <testjarfalla63@...
: In order to troubleshoot, it would be good to disconnect different parts
and see when the psu fails, but will this work here or does the psu need a
certain load to function properly?
The PSU from my TDS684A didn¡¯t run without a nominal load on the main 5V
rail. I don¡¯t remember how much I loaded it, but it couldn¡¯t have been much
- probably inside an amp.
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Re: trigger problem with 7B70
On Apr 3, 2024, at 22:05 , Adam R. Maxwell via groups.io <amaxwell@...> wrote:
He suggested replacing Q309/Q317 in the trigger pulse generator with the pair from my working 7B70, and that did the trick: stable waveform with sine/triangle/square, and controls work as expected.
I had previously tried replacing them individually with a 2N3906 (one of the few PNP transistors I have on hand), with no luck. Replacing both Q309 and Q317 with 2N3906s actually shows a waveform instead of a blank screen, but it stutters so I've ordered some 151-0220-00 replacements. Messing around with this a bit more tonight, I tested both of the 151-0220-00 transistors from the bad 7B70 in my cheapo tester (BSIDE ESR02 Pro). It recognizes both as PNP transistors, one with B=187, Uf=682 mV and the other with B=150, Uf=676 mV. The 7B70 manual (S/N <205000) specifies 151-0220-00 for Q309/Q317, and the Common Design catalog says a 2N3906 is close (fT is 400 MHz for the 151-0220-00, 2N3906 is 250 MHz). I tried stealing a pair of 151-0220-00 transistors from elsewhere on the trigger board (assuming they were fine) for the Q309/Q317 sockets (replacing the donors with 2N3906s), and the bad 7B70 still did not work. I finally realized my good 7B70 has a >205000 serial number, and the manual for that specifies a 151-0271-00 (which explains why the ones that work in both plugins are marked 151271). That transistor has a minimum fT of 2 GHz, and is an AST4261 or 2N4261 in a TO-92 case, so I might be SOL if the bad 7B70 needs those. I assume the (much!) slower transistor worked at some point in the low serial number unit, but Tek must have had a reason for that change. I've grown a bit less optimistic that NOS 151-0220-00 transistors will be the silver bullet, though. Further bulletins as events warrant, etc. Adam
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Re: TDS744A tick tick tick when power on (and something smelling)
?ann f?s., 5. apr. 2024 kl. 00:19 skrifa?i Staffan <testjarfalla63@... : In order to troubleshoot, it would be good to disconnect different parts
and see when the psu fails, but will this work here or does the psu need a
certain load to function properly? The PSU from my TDS684A didn¡¯t run without a nominal load on the main 5V rail. I don¡¯t remember how much I loaded it, but it couldn¡¯t have been much - probably inside an amp.
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Re: TDS744A tick tick tick when power on (and something smelling)
Many switching supplies need a minimum load, typically on the 5.0 volt rail (could be different).? Is there anything in the documentation for the scope?
Harvey
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On 4/5/2024 12:19 AM, Staffan wrote: Many thanks for all the pointers!
In order to troubleshoot, it would be good to disconnect different parts and see when the psu fails, but will this work here or does the psu need a certain load to function properly?
Regards,
Staffan
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Re: TDS744A tick tick tick when power on (and something smelling)
Many thanks for all the pointers!
In order to troubleshoot, it would be good to disconnect different parts and see when the psu fails, but will this work here or does the psu need a certain load to function properly?
Regards,
Staffan
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Re: trigger problem with 7B70
Hi Barry, Adam,
Thank you for the nice words. Your detailed data taking and coming up with good questions were key to fixing the issues and it was fun to spend time on these puzzles.
Ozan
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On Thu, Apr 4, 2024 at 06:43 AM, n4buq wrote:
I'll second Ozan's helpfulness with this sort of thing. He has helped me a
few times isolate a problem like that whcih I'm pretty sure I would not have
found on my own. Glad you have something going and hope the correct
transistors will fix the rest of the issues with this.
Barry - N4BUQ
Thanks to Ozan for helping off-list with some additional measurement advice and
insight on expected values. I continue to be amazed at what some of you can
understand from a schematic.
He suggested replacing Q309/Q317 in the trigger pulse generator with the pair
from my working 7B70, and that did the trick: stable waveform with
sine/triangle/square, and controls work as expected.
I had previously tried replacing them individually with a 2N3906 (one of the few
PNP transistors I have on hand), with no luck. Replacing both Q309 and Q317
with 2N3906s actually shows a waveform instead of a blank screen, but it
stutters so I've ordered some 151-0220-00 replacements.
Adam
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Also a bit off topic - capacitor issues
Hi - this relates to strange power supply behaviour of a Mac - iMac 24". It may be relevant to other issues people are encountering.
This computer just had its power supply replaced.
Now - provided the mains supply to the computer has been turned off - it will start - and stay on for a time that seems directly
related to the amount of time it has been disconnected from the mains. Weird.
So, as it's a switching supply - is it possible that we are seeing a strange sort of electrolytic capacitor failure - becoming slowly open
circuit with voltage applied, and recovering with no voltage?
Has anyone encountered anything like this?
Thanks
Hugh
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Jean-Paul
Benjamin Badrakh
Martin