Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- TekScopes
- Messages
Search
|
Re: TDS3054 Replacement of DALLAS DS1742W (U640), data content in NV-RAM
A DS1742W from China? Chances are really high it's a counterfeit. Here's an eevblog thread that has some pictures of a China fake vs real:
The dimensions are a giveaway, at least on that one. Further in that thread, there's a link to someone who made an adapter board for a DS1744WP, which is still available from reputable sources (Mouser, Digikey, etc). Functionally, it's the same as the DS1742W, but with more SRAM that would never be accessed. The adapter board fits TDS3000 scopes. I ended up doing surgery on my old DS1742W to connect an external battery. I'd recommend not throwing away your old DS1742W, and install a DIP socket. -mark |
|
Re: Tek 7854 intermittent issues
On Mon, Aug 31, 2020 at 01:12 AM, Nick Corvid wrote:
And in response to Albert, you are correct that it's missingHi Nick, the dot pattern is not what I expected. It seems that still linear interpolation is done to fill missing horizontal positions. I expected to see no dots at all during some wide horizontal gaps. Anyway, in my opinion it's clear that data are missing. In your new photos there is also a negative outlier and, very strange, a negative trace near the end of the sweep which looks like a inverted portion of the correct waveform. In the correct waveform the rising edges end more or less rounded while the falling edges are sharp. Wrong sign bit? I thought I would see horizontal gaps when I do a too fast single sweep acquisition. But my 7854 simply refuses AQS with a nasty beep. Albert |
|
Re: Strange Tek2440 issue
100nsec per div and faster sounds like the switch from real time sampling to equivalent time interpolation (300Msample/sec real time). You can turn off the equivalent time mode by going to the Acquire menu and setting 'Repet' to Off. If that enables you to get to faster sweep speeds then the problem is clearly in the circuitry that does the equivalent time interpolation but I would need a thorough read of the manual to go into any detail!
Regards, Roger |
|
Re: Tek 7854 intermittent issues
Q141, sheet <11> coordinates E2. The other transistor in the clamp is Q41,
toggle quoted message
Show quoted text
coordinates E5. Dave Casey On Sun, Aug 30, 2020 at 6:12 PM Nick Corvid <awsomedrack@...> wrote:
Thank you for the suggestion Dave, I'll have a look at where the power |
|
Re: Tek 7854 intermittent issues
Thank you for the suggestion Dave, I'll have a look at where the power supply points are located in the manual and see if anything seems out of spec when I'm next able. And in response to Albert, you are correct that it's missing chunks of the horizontal in dots mode, or were until I had set up my camera to take pictures and the behavior changed again.(this thing is making me crazy!) Leading to these pictures:
Vector mode: /g/TekScopes/photo/252782/1?p=Created,,,20,2,0,0 Dots mode: /g/TekScopes/photo/252782/0?p=Created,,,20,2,0,0 Some of the issues can be found in analog modes, but usually only very intermittently, for example the trace jittering horizontally even with a solid trigger (and the intensity for the A time-base but I'm pretty sure that is just a dirty pot). Also this may be unrelated as I don't know exactly what operating as intended is but one of the transistors on what I am fairly certain is the horizontal amp board can get very hot to the touch while the others stay cool when the machine has been running for over 10 minutes. This is the transistor in question: /g/TekScopes/photo/252782/2?p=Created,,,20,2,0,0 . Haven't had the time to find where it lives on the circuit diagram |
|
Re: Strange Tek2440 issue
Szabolcs, from here (TekScopes) posted a method of accessing the internal battery of the Dallas NVRAM modules using a heat gun and a scraper. The difference in these modules was that there were two batteries that were visible. Anyway I scraped down to pin 7 of the DS1210 and soldered a wire to it on each module. I ran those to a small circuit board where I had a battery holder and two diodes on it. The diodes fed the voltage to each of the modules.
toggle quoted message
Show quoted text
When I put it back together it didn't work. Then I noticed I forgot to plug in one of the ribbon cables! Anyway, the subject for the post I mentioned above is: Easy method for NVRAM battery replacement Vince. On 08/30/2020 05:53 PM, Bob Albert via groups.io wrote:
Not your current problem but I replaced the NVRAM chips in my 2440 and the scope doesn't work. I switched one of them back and still no joy. I will try the other one. --
K8ZW |
|
Re: Strange Tek2440 issue
Bob Albert
Not your current problem but I replaced the NVRAM chips in my 2440 and the scope doesn't work.? I switched one of them back and still no joy.? I will try the other one.
toggle quoted message
Show quoted text
I probably got some counterfeit modules from China.? I am hoping it will be fixed when I put the old one back.? ?How did you fix yours? Bob On Sunday, August 30, 2020, 02:37:52 PM PDT, Vince Vielhaber <vev@...> wrote:
I picked up a 2440 on ebay that had the dead nvram battery problem.? Got that fixed up with an external battery.? Ran thru the self cal and ext cal and all seems fine, except when the sweep rate is turned above 100 or 200 ns. In trying to research this a bit, the only thing I could find was on one of the Tek forums back in 2017 but there were zero responses.? Here is how the other person described the problem: --------------------------------------------------------------------- The 5 volt regulated rail is getting crowbared when the scope Sec/Div is set to 100ns or faster. If save is pressed at a slower setting the Sec/Div can then be set to any value without the 5 Volt rail getting pulled down. It appears the issue only occurs during an active acquisition cycle at 100ns Sec/Div or faster. ---------------------------------------------------------------------- While I didn't measure the 5v rail, the screen shrinks a couple of times as the waveform changes, the inputs get switched to GND and the display goes blank.? Sometimes, if I'm quick enough, I can turn the sweep back down (1us or slower) and it'll recover, but I still have to go to the input coupling and switch the inputs off of GND. Anyone seen this or have any ideas what's going on? Thanks! Vince. -- ? K8ZW? ? |
|
Strange Tek2440 issue
I picked up a 2440 on ebay that had the dead nvram battery problem. Got that fixed up with an external battery. Ran thru the self cal and ext cal and all seems fine, except when the sweep rate is turned above 100 or 200 ns.
In trying to research this a bit, the only thing I could find was on one of the Tek forums back in 2017 but there were zero responses. Here is how the other person described the problem: --------------------------------------------------------------------- The 5 volt regulated rail is getting crowbared when the scope Sec/Div is set to 100ns or faster. If save is pressed at a slower setting the Sec/Div can then be set to any value without the 5 Volt rail getting pulled down. It appears the issue only occurs during an active acquisition cycle at 100ns Sec/Div or faster. ---------------------------------------------------------------------- While I didn't measure the 5v rail, the screen shrinks a couple of times as the waveform changes, the inputs get switched to GND and the display goes blank. Sometimes, if I'm quick enough, I can turn the sweep back down (1us or slower) and it'll recover, but I still have to go to the input coupling and switch the inputs off of GND. Anyone seen this or have any ideas what's going on? Thanks! Vince. -- K8ZW |
|
Re: Tek 4654M; No Trace, No +5V, No +95V; Help
Slight correction. From the manual, it appears TP60 (et. al.) has a 28uS period making that about 38kHz instead of 30kHz.
toggle quoted message
Show quoted text
Thanks, Barry - N4BUQ ----- Original Message -----
From: "Barry" <n4buq@...> |
|
Re: TDS3054 Replacement of DALLAS DS1742W (U640), data content in NV-RAM
you can just throw in a completely blank chip in there, no problem
reading the old chip and writing in the new one doesn't do much and doesn't do any harm either as I have learned...specially now that the # of hours is messed up the number of hours are stored in minutes (in HEX) at 07E0-07E3 and also at 07E8-07EB (the same number repeated) that's probably the only thing you need |
|
Re: Free 6 pin lemo cable and THS720 question
As far as I know, there is no menu accessible way to see the battery condition on the THS720. I think that got added to the THS730, but that may be wishful recollection on my part.
One usability issue on the THS720 that is worth keeping in mind is that the two input channels do not share a ground. For low speed stuff with other scopes, I commonly just ground an unused input channel to the board under test and then wrap the ground lead of the probe that I am using arount the probe cable to keep it out ot the way. That does not work on the THS720! Each input channel must have it's own ground connection. The THS720 is a really handy little scope! I like mine a lot. Thanks for the article on building the battery packs! BobH |
|
TDS3054 Replacement of DALLAS DS1742W (U640), data content in NV-RAM
Hello all,
a TDS3054 (built in year 2001) shows the following symptoms when connected to power: - 'A system error has occured', Error Count =11, 'display error', goes away after short power off/on - Unrealistic high 'total operation time' (16350105 hours) - Impossible time setting (e.g. '11:80:21') Topic #157465 also deals with this issue, the problem is data corruption inside U640 DALLAS DS1742W, exhausted lithium battery, date code on the package is '0029'. I ordered replacement DS1742W via Amazon in China (the chips I received seem fully functional when tested on a programmer), date code on the package is '0945'. How should I prepare the new DS1742W I am going to install in the scope? Simply read out the (most probably) rubbish of the old DS1742W and copy it to the new one? Is a memory map available somewhere which shows the addresses of the relevant memory locations and their expected content in a working scope? (the address locations 0x7F8...0x7FF are described in the DS1742W data sheet) I cannot believe that appr. 2k of memory are fully used to store internal scope status data. Thanks for any help! Best regards -Roland |
|
Re: Tek 4654M; No Trace, No +5V, No +95V; Help
Harrison,
toggle quoted message
Show quoted text
If you suspect the multiplier is bad, you can disconnect its input by unsoldering the wire to the transformer. You can see that in the the picture of the HV board that I added just now here: /g/TekScopes/album?id=252850 If I remember correctly, you have to be somewhat careful that the wire is not close enough to arc back to the transformer. I remember that happening and had to move it a bit further away so that I could have the rest of the HV circuit operating but not engage the multiplier. If you have a meter that can measure the output of the transformer (I forget the output value but it would theoretically be 1/3 of the anode voltage and it's at around 30kHz as I recall), then you might could establish that everything else works up to that point. Thanks, Barry - N4BUQ ----- Original Message -----
From: "n4buq" <n4buq@...> |
|
Re: DEC PDP11/05 on a 202D cart - did one survive?
From Tim P (UK)
I don't know if you have seen the P7001 section on TekWiki - it's under 7000 series, as it uses the 7704A. Lots of pictures of the 'guts' of the P7001 and some stuff on the interfacing. I would be interested in how many were sold, and who bought them. (Chuck, do you know??). Tim On Sun, 30 Aug 2020 at 16:17, Holger L¨¹bben <tekscopesinput@...> wrote: Hi! |
|
Re: Tek 4654M; No Trace, No +5V, No +95V; Help
Hi Harrison,
toggle quoted message
Show quoted text
Yes, the 3x multiplier is U550. For mine, even after I replaced it, I did some testing on it and, at lower voltages, it would triple the input voltage; however, it appeared that at operating voltage, it would arc internally thus blowing the fuse. If I'm not mistaken, this is a common failure for that module after all these years. There's a thread on/around October 7, 2017, where the messages for that can be found. Thanks, Barry - N4BUQ ----- Original Message -----
From: "Harrison" <buma7@...> |
|
DEC PDP11/05 on a 202D cart - did one survive?
Hi!
I've added an old picture of a Tektronix DPO/DEC PDP 11/05 combination on a 202D cart to the photo section: /g/TekScopes/photo/252847/0 Has one of these machines survived? I'm looking for some detailed pictures of this combination. Holger |
to navigate to use esc to dismiss