Date   
Re: TDS744 not 'A' has a problem , help needed

Bob Koller
 

Well done!

Re: Clock error on TDS3034

 

Thanks David K. for your info. The company that you linked to seems to have 1 (!) clock/ram module left.
You may have read in my recent post that I have successfully dug out the empty battery and connected another one so my quest is over.

Raymond

Re: TDS744 not 'A' has a problem , help needed

Brian
 

Hi Bob , thank you . That was only the second one of those scopes I've had anything to do with , I am mostly 500 series + 661 and 564 along with 7000 series and 24XX .  My first one was a TDS420A with a dead PSU , changing the caps revived it , nothing else was wrong with it . The TDS744 was also one that did not start up , after sorting out the PSU the other faults showed themselves , it was the first time fixing a component level fault on an acquisition pcb . I now have to do something about the Dallas chips they are dated '93!!

On Thursday, 30 May 2019, 15:26:46 BST, Bob Koller via Groups.Io <testtech=yahoo.com@groups.io> wrote:

Well done!

Re: TDS744 not 'A' has a problem , help needed

Stephen Hanselman
 

Brian,

Changing out these chips is not really a problem. While they do keep some scope specific info I’ve operated 540A’s without the chip. If you have a vanilla model, no options I’m not sure it’s worth the effort. EBay, yes I know, has some replacements, when you look at the offerings look for one that has a “+” in the part number. So it seems like these are newer ones. The Tek forum has a thread that gives the cross wiring needed to program the Dallas chip in a more common NVRAM environment.

On the other hand if your scope remembers the date and time the chip is probably ok, for a while.

My technique is to add fresh solder to each pin and then heat the pin, not the board, and suck it out. I then insert a socket. So far I have not had an issue with losing data in the chip.

As it stands I have good images for the 540, 540A, and 540B.

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.

On May 30, 2019, at 07:53, Brian via Groups.Io <brianas1948=yahoo.co.uk@groups.io> wrote:

Hi Bob , thank you . That was only the second one of those scopes I've had anything to do with , I am mostly 500 series + 661 and 564 along with 7000 series and 24XX . My first one was a TDS420A with a dead PSU , changing the caps revived it , nothing else was wrong with it . The TDS744 was also one that did not start up , after sorting out the PSU the other faults showed themselves , it was the first time fixing a component level fault on an acquisition pcb . I now have to do something about the Dallas chips they are dated '93!!

On Thursday, 30 May 2019, 15:26:46 BST, Bob Koller via Groups.Io <testtech=yahoo.com@groups.io> wrote:

Well done!




Re: Corona Electric FT-100A

Tim Phillips
 

from Tim P (UK)
There is a drawing (only) of the front panel on TekWiki, under 500 plug-ins.
or do you have that and need actual photos?
Tim

On Thu, 30 May 2019 at 15:14, Kurt Rosenfeld <kurt.harlem@...> wrote:

The Corona Electric FT-100A is a 500-series plug-in for plotting Ft of
transistors. Does anyone have photos of this unit that they can share?

thanks, -Kurt



Re: TDS744 not 'A' has a problem , help needed

Brian
 

Hi Stephen , fortunately the scope remembers the date and the clock is running fine . I have NVRAM back-up s/w from EEBLOG so hopefully it will keep a record of the contents assuming it works on the much older scopes but I cant see why it shouldnt . I do have some GPIB experience and enough gear to connect to the scope .The scope does have nice options for me 13,1f,2f,2m so I dont really want to loose any of themThe Dallas chips are DS1650Y and DS1486 , I understand that one of them holds calibration data - I dont know that even with the gear I have a complete recalibration would be possible so I need to keep that info as intact as possible for as long as I can . Any calibration equipment that I dont currently have will take time to get hold of as I am retired and only a hobbyist/collector .

On Thursday, 30 May 2019, 16:03:41 BST, Stephen Hanselman <kc4sw.io@...> wrote:

Brian,

Changing out these chips is not really a problem. While they do keep some scope specific info I’ve operated 540A’s without the chip.  If you have a vanilla model, no options I’m not sure it’s worth the effort.  EBay, yes I know, has some replacements, when you look at the offerings look for one that has a “+” in the part number. So it seems like these are newer ones. The Tek forum has a thread that gives the cross wiring needed to program the Dallas chip in a more common NVRAM environment.

On the other hand if your scope remembers the date and time the chip is probably ok, for a while.

My technique is to add fresh solder to each pin and then heat the pin, not the board, and suck it out.  I then insert a socket.  So far I have not had an issue with losing data in the chip.

As it stands I have good images for the 540, 540A, and 540B.

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.
On May 30, 2019, at 07:53, Brian via Groups.Io <brianas1948=yahoo.co.uk@groups.io> wrote:

Hi Bob , thank you . That was only the second one of those scopes I've had anything to do with , I am mostly 500 series + 661 and 564 along with 7000 series and 24XX .  My first one was a TDS420A with a dead PSU , changing the caps revived it , nothing else was wrong with it . The TDS744 was also one that did not start up , after sorting out the PSU the other faults showed themselves , it was the first time fixing a component level fault on an acquisition pcb . I now have to do something about the Dallas chips they are dated '93!!

    On Thursday, 30 May 2019, 15:26:46 BST, Bob Koller via Groups.Io <testtech=yahoo.com@groups.io> wrote:

Well done!




Re: TDS744 not 'A' has a problem , help needed

Bob Koller
 

An option for the problematic Dallas parts are offered on eBay item 302913384290, seller is kellyjo_13. I bought a pair last year for my TDS784D, works fine, but are too tall if you have the Option 5 TV board. I had to remove mine, not needed anyway.

Re: Latest firmware for TDS210 and TDS2CM?

Mark Jordan
 

I tried to upgrade my TDS220 serial B031665 with the latest firmware V1.19 but the scope doesn't boot.
    Changed the original 27C040 for a AT49F040, removed R306 and shorted R307.
    Any ideas?

    Thanks,
    Mark Jordan

On 24-May-19 19:37, zenith5106 wrote:
On Fri, May 24, 2019 at 04:57 PM, Jared Cabot wrote:

it had the earthing recall fix already done too, so it was post recall as well.
That was done on TDS210 below B049400 and TDS220 below B041060.
If your S/N is lower than that and has the P/S MOD sticker the main board has been replaced to the newer version.
This was not a recall but it was done on extended warranty if one or more BNC connector had become loose.

/Håkan


Re: TDS744 not 'A' has a problem , help needed

Brian
 

Hi Bob , yes I have seen those and keep them in my watch list . i dont have the TV trigger option pcb , 1990 to 2003 I was working in the tv equipment industry but with everything going digital then the need for that sort of thing was on the way out - unless of course it was a very digital trigger option , now I'm retired I have no need for that and would likely take it out if it was there .I cant think why they went for those chips when the 420A gets away with ordibary CMOS rams and nice high capacity Lithium batteries connected via plugs and sockets - it works for me and doesnt go obsolete .

On Thursday, 30 May 2019, 16:21:06 BST, Bob Koller via Groups.Io <testtech=yahoo.com@groups.io> wrote:

An option for the problematic Dallas parts are offered on eBay item 302913384290, seller is kellyjo_13. I bought a pair last year for my TDS784D, works fine, but are too tall if you have the Option 5 TV board. I had to remove mine, not needed anyway.

Re: 2215 problem

tekscopegroup@...
 

About 10+ years ago I fixed my first scope, it was a 2213A given to me "on loan" and of course the main problem as in many of these 22xx was it would not power up, just a flash of the power Led about once a second. At the time one could only find online for gratis download the 2213 service manual that does not fully match the A version, specially in regards to the PS section so troubleshooting was tougher from the start. I remember trying to make the preregulator section work, that is what generates the 43V for the actual power supply switcher, and it was frustrating, to say the least, specially if you make simple mistakes you very easily end up burning or blowing up something in that section that was good (Mosfet, resistors, the TIP3x or TIP4x (I think it was) TO-220 transistors, Regulator IC, etc). And as I can remember the preregulator will refuse to start even if perfectly ok without the load provided by the second stage of the power supply. So I used an external power supply to feed the +43V and the scope would still not power up, just the same flicker of the power led. So then I checked all the power supply outputs, rectifier diodes, capacitors, etc. Nothing. Finally since the problem seemed to start pointing towards some other part on the board for which I did not have a replacement, someone in this group (while still at Yahoo) send me a whole 2213A main board for the cost of shipping, it was partially gutted but it still had most key parts I needed. Turns out in the end the problem was the main switching transformer T948 that apparently had developed a short in one of the secondaries and was causing the whole power supply to shut down at startup.

So before you mess around any further with the preregulator section chasing windmills and possibly causing more damage, I would suggest that your very first step should be to test the second switcher section of the power supply by feeding it around +43V and see if the scope powers up. If it does then you will know for sure the problem is not in the preregulator but somewhere else, and leave it alone until you can get the scope to power up with the external DC supply. Another possibility is that one of the power supply outputs are looking into a short or higher than expected current draw, it could be just a dried out capacitor, leaky or shorted (fast) rectifier diode, or could be it something downstream in the circuits being powered. I recall there are some jumpers that can be removed to insulate one or more of the power supply outputs at a time from their respective loads, but you need to at least keep a proper load on one of the outputs (I think it is the +8.6V) with a adequate size/value resistor, otherwise things will not be stable and the test will lead you nowhere else but into yet another wrong rabbit hole.

Again, it is amazing how sensitive and temperamental the preregulator is to very simple mistakes specially with all the high power parts, even when you think you just removed or replaced a part only to quickly check if there might be any changes and you are sure it should be perfectly safe there is no way something will go wrong, bum! it will usually blow up that part and/or something else and/or let out the magic smoke. Welcome to switching power supply troubleshooting.

BTW, first thing should be to get an accurate service manual for your version of the scope. That makes a huge difference. And good luck, the 2215 is a nice basic scope well worth fixing.

Re: Corona Electric FT-100A

Colin Herbert
 

That drawing is rather difficult to locate; it isn't in the directory of series-500 plug-ins. I found it by searching for "FT-100A".
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Tim Phillips
Sent: 30 May 2019 16:06
To: TekScopes@groups.io
Subject: Re: [TekScopes] Corona Electric FT-100A

from Tim P (UK)
There is a drawing (only) of the front panel on TekWiki, under 500 plug-ins.
or do you have that and need actual photos?
Tim


On Thu, 30 May 2019 at 15:14, Kurt Rosenfeld <kurt.harlem@...> wrote:

The Corona Electric FT-100A is a 500-series plug-in for plotting Ft of
transistors. Does anyone have photos of this unit that they can share?

thanks, -Kurt



Re: Corona Electric FT-100A

Kurt Rosenfeld
 

Yes, I am looking for actual photos of the instrument.

Re: 2215 problem

Bob Albert
 

Thanks for your comments on repairing the unit.  I need to keep a clear head on this.  I have some spare IRF820s now but before I install I will see about supplying 43 Volts.  I have a little 0-50V 500 mA supply I can use for that once I see where to connect it.  Any help on that?
I have far too many projects, several units laying around apart and no room to work.  But I do have lots of working gear so there is still a rather complete setup available.  Even the microwave oven in the kitchen needs some attention.  I just replaced the stove top and the garbage disposer and did some yard cleanup and snaked out a couple of drains.
Life is a lot of fun and if I didn't have these repair jobs I would wonder why I have all this gear.  At this point I would like to get at least one unit working again to free up workspace.
Bob

On Thursday, May 30, 2019, 9:19:01 AM PDT, <tekscopegroup@...> wrote:

About 10+ years ago I fixed my first scope, it was a 2213A given to me "on loan" and of course the main problem as in many of these 22xx was it would not power up, just a flash of the power Led about once a second. At the time one could only find online for gratis download the 2213 service manual that does not fully match the A version, specially in regards to the PS section so troubleshooting was tougher from the start. I remember trying to make the preregulator section work, that is what generates the 43V for the actual power supply switcher, and it was frustrating, to say the least, specially if you make simple mistakes you very easily end up burning or blowing up something in that section that was good (Mosfet, resistors, the TIP3x or TIP4x (I think it was) TO-220 transistors, Regulator IC, etc). And as I can remember the preregulator will refuse to start even if perfectly ok without the load provided by the second stage of the power supply. So I used an external power supply to feed the +43V and the scope would still not power up, just the same flicker of the power led. So then I checked all the power supply outputs, rectifier diodes, capacitors, etc. Nothing. Finally since the problem seemed to start pointing towards some other part on the board for which I did not have a replacement, someone in this group (while still at Yahoo) send me a whole 2213A main board  for the cost of shipping, it was partially gutted but it still had most key parts I needed. Turns out in the end the problem was the main switching transformer T948 that apparently had developed a short in one of the secondaries and was causing the whole power supply to shut down at startup.

So before you mess around any further with the preregulator section chasing windmills and possibly causing more damage, I would suggest that your very first step should be to test the second switcher section of the power supply by feeding it around +43V and see if the scope powers up. If it does then you will know for sure the problem is not in the preregulator but somewhere else, and leave it alone until you can get the scope to power up with the external DC supply. Another possibility is that one of the power supply outputs are looking into a short or higher than expected current draw, it could be just a dried out capacitor, leaky or shorted (fast) rectifier diode, or could be it something downstream in the circuits being powered. I recall there are some jumpers that can be removed to insulate  one or more of the power supply outputs at a time from their respective loads, but you need to at least keep a proper load on one of the outputs (I think it is the +8.6V) with a adequate size/value resistor, otherwise things will not be stable and the test will lead you nowhere else but into yet another wrong rabbit hole.

Again, it is amazing how sensitive and temperamental the preregulator is to very simple mistakes specially with all the high power parts, even when you think you just removed or replaced a part only to quickly check if there might be any changes and you are sure it should be perfectly safe there is no way something will go wrong, bum! it will usually blow up that part and/or something else and/or let out the magic smoke. Welcome to switching power supply troubleshooting.

BTW, first thing should be to get an accurate service manual for your version of the scope. That makes a huge difference. And good luck, the 2215 is a nice basic scope well worth fixing.

Re: 7B92A time-base plug-in odd behaviour

Colin Herbert
 

Has no-one any ideas about this? Surely it can't be that unusual a problem?
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Colin Herbert via Groups.Io
Sent: 24 May 2019 16:49
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7B92A time-base plug-in odd behaviour

Not totally the case, Albert. As I said, the instability can be present after warm-up and can be stopped or induced by "wiggling" the Time/Div knob. Specifically, if the delaying or delayed time-base is showing (i.e. the Time/Div knob is "IN") and the Time/Div knob is pushed in a little more firmly, the time-base stops and a vertical line or dot (depending on the Y input) at the left-hand side is shown.

Yes, It is the model with the "Alt Off" position on the Trace Sep knob; the S/N is B096566.

Colin.

Re: 7B92A time-base plug-in odd behaviour

Albert Otten
 

Hi Colin,

When the sweep stops I would expect a blanked screen. You still see the signal at the start position of the sweep. This could perhaps mean that the sweep is running but that the sweep output to the horizontal amplifier is interrupted.
Is the screen blanked when you don't trigger the sweep(s)?
Perhaps you should choose the lowest possible sweep rate. If you then wiggle the time/knob and the sweep reappears, does it start then at the left side or does it start "random" at some horizontal position, as if the sweep was running normally but with sweep output interrupted? Maybe you can also recognize a still normally running sweep from the trigger light blinking.
(Just an idea. I have not encountered this problem.)

Albert

On Thu, May 30, 2019 at 07:01 PM, Colin Herbert wrote:


Has no-one any ideas about this? Surely it can't be that unusual a problem?
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Colin
Herbert via Groups.Io
Sent: 24 May 2019 16:49
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7B92A time-base plug-in odd behaviour

Not totally the case, Albert. As I said, the instability can be present after
warm-up and can be stopped or induced by "wiggling" the Time/Div knob.
Specifically, if the delaying or delayed time-base is showing (i.e. the
Time/Div knob is "IN") and the Time/Div knob is pushed in a little more
firmly, the time-base stops and a vertical line or dot (depending on the Y
input) at the left-hand side is shown.

Yes, It is the model with the "Alt Off" position on the Trace Sep knob; the
S/N is B096566.

Colin.


Re: TDS744 not 'A' has a problem , help needed

Stephen Hanselman
 

I've heard the talk flow both ways but to my knowledge the calibration data is held in NVRAM on the Acquisition pca not in the Proc. I've looked in several of the Dallas Chips and mostly what you see is empty space. I suspect, but have no proof, that these things are used to store trace data. I have taken non-working (fails SPC etc) and swapped in working calibrated Acq and had it remember it's calibration data.

Calibration requirements are actually fairly lax. You need a good, accurate DC source, DMM, and after that almost any reasonable sig gen would work. I have SG503 and SG504 the scope tells you if the particular signal you are looking at from the "SG's" is correct and then goes off and calibrates itself. The initial DC calibrations are critical however. The las thing is a HPIB based controller to run the test suite. I tried several incarnations and finally bought a Tek Data Manager. Given no experience and all manual TE I would plan on a full day for the cal, and be prepared to become extremely bored.

If you look at your diagnostics screen where it shows SPC, Voltage ref, Frequency...... there are 4 states Initialized (after cold start), running, passed, failing. I found out the hard way that even when you pass the CVR testing voltage ref may say "running" although not next in the sequence you have to run probe comp to get it to read "passing" there are a few other gotchas in the software similar to this.

If you were close by I'd tell you to bring it in as an afterschool project, but...

Hope this helps you a bit. Like they say though, your mileage may vary

steve

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Brian via Groups.Io
Sent: Thursday, May 30, 2019 8:19 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] TDS744 not 'A' has a problem , help needed

Hi Stephen , fortunately the scope remembers the date and the clock is running fine . I have NVRAM back-up s/w from EEBLOG so hopefully it will keep a record of the contents assuming it works on the much older scopes but I cant see why it shouldnt . I do have some GPIB experience and enough gear to connect to the scope .The scope does have nice options for me 13,1f,2f,2m so I dont really want to loose any of themThe Dallas chips are DS1650Y and DS1486 , I understand that one of them holds calibration data - I dont know that even with the gear I have a complete recalibration would be possible so I need to keep that info as intact as possible for as long as I can . Any calibration equipment that I dont currently have will take time to get hold of as I am retired and only a hobbyist/collector .

On Thursday, 30 May 2019, 16:03:41 BST, Stephen Hanselman <kc4sw.io@...> wrote:

Brian,

Changing out these chips is not really a problem. While they do keep some scope specific info I’ve operated 540A’s without the chip. If you have a vanilla model, no options I’m not sure it’s worth the effort. EBay, yes I know, has some replacements, when you look at the offerings look for one that has a “+” in the part number. So it seems like these are newer ones. The Tek forum has a thread that gives the cross wiring needed to program the Dallas chip in a more common NVRAM environment.

On the other hand if your scope remembers the date and time the chip is probably ok, for a while.

My technique is to add fresh solder to each pin and then heat the pin, not the board, and suck it out. I then insert a socket. So far I have not had an issue with losing data in the chip.

As it stands I have good images for the 540, 540A, and 540B.

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.
On May 30, 2019, at 07:53, Brian via Groups.Io <brianas1948=yahoo.co.uk@groups.io> wrote:

Hi Bob , thank you . That was only the second one of those scopes I've had anything to do with , I am mostly 500 series + 661 and 564 along with 7000 series and 24XX . My first one was a TDS420A with a dead PSU , changing the caps revived it , nothing else was wrong with it . The TDS744 was also one that did not start up , after sorting out the PSU the other faults showed themselves , it was the first time fixing a component level fault on an acquisition pcb . I now have to do something about the Dallas chips they are dated '93!!

On Thursday, 30 May 2019, 15:26:46 BST, Bob Koller via Groups.Io <testtech=yahoo.com@groups.io> wrote:

Well done!




497P power supply aluminum spacers???

radioconnection@...
 

Just started recapping my 497P power supply... I found two sets of about 1/4" aluminum spacers after removing the board. One pair are close to 6-32, the other pair are close to 4-40 hole size. I can see where one pair is used, but I am baffled as to where the other pair was used.

Pete

Re: TDS744 not 'A' has a problem , help needed

Brian
 

Hi Steve , thank you for that . I have heard several ideas about the NVRAM contents , one is said to hold just saved waveforms and setups and the other holding cal data and installed options , cant remember which is said to do what so I'll need to search EEblog again . I have heard it said also that there are a couple of NVRAM chips underneath the acquisition pcb , little 8 pin chips , that hold factory cal data but that it is only a copy of one of the Dallas chips and is there for emergency's for use at a cal center , those 2 chips are there even on my non A version . The same source if I remember correctly said that the system does not actually use this data it relies on the Dallas chip .
I have a Fluke DC calibrator and 6.5,7.5 and 8.5 digit DVM's. Signal generators , I have synthesized gen's up to 18GHz but their output is too low , but I do have a couple of small  1MHz - 5GHz amps with output up to 20dBm that might make it possible . the final output will not be levelled directly but the input will be , to make certain I do have HP438A power meter and sensors , I also have a RACAL true RMS voltmeter that is good to 2GHz .Unlike some here I do have several old PC's with windows 95/98 could even run windows 3.11 , I have also the NI PC2A GPIB cards and drivers and a copy of the cal s/w

I am in the UK if you hadnt guessed so I think we are more than just a few miles apart or I would be happy to join you for that after school project
Brian

On Thursday, 30 May 2019, 20:32:31 BST, Stephen Hanselman <kc4sw.io@...> wrote:

I've heard the talk flow both ways but to my knowledge the calibration data is held in NVRAM on the Acquisition pca not in the Proc.  I've looked in several of the Dallas Chips and mostly what you see is empty space.  I suspect, but have no proof, that these things are used to store trace data.  I have taken non-working (fails SPC etc) and swapped in working calibrated Acq and had it remember it's calibration data.

Calibration requirements are actually fairly lax.  You need a good, accurate DC source, DMM, and after that almost any reasonable sig gen would work.  I have SG503 and SG504 the scope tells you if the particular signal you are looking at from the "SG's" is correct and then goes off and calibrates itself.  The initial DC calibrations are critical  however.  The las thing is a HPIB based controller to run the test suite.  I tried several incarnations and finally bought a Tek Data Manager.  Given no experience and all manual TE I would plan on a full day for the cal, and be prepared to become extremely bored.

If you look at your diagnostics screen where it shows SPC, Voltage ref, Frequency...... there are 4 states Initialized (after cold start), running, passed, failing.  I found out the hard way that even when you pass the CVR testing voltage ref may say "running"  although not next in the sequence you have to run probe comp to get it to read "passing"  there are a few other gotchas in the software similar to this.

If you were close by I'd tell you to bring it in as an afterschool project, but...

Hope this helps you a bit.  Like they say though, your mileage may vary

steve

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Brian via Groups.Io
Sent: Thursday, May 30, 2019 8:19 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] TDS744 not 'A' has a problem , help needed

Hi Stephen , fortunately the scope remembers the date and the clock is running fine . I have NVRAM back-up s/w from EEBLOG so hopefully it will keep a record of the contents assuming it works on the much older scopes but I cant see why it shouldnt . I do have some GPIB experience and enough gear to connect to the scope .The scope does have nice options for me 13,1f,2f,2m so I dont really want to loose any of themThe Dallas chips are DS1650Y and DS1486 , I understand that one of them holds calibration data - I dont know that even with the gear I have a complete recalibration would be possible so I need to keep that info as intact as possible for as long as I can . Any calibration equipment that I dont currently have will take time to get hold of as I am retired and only a hobbyist/collector .

    On Thursday, 30 May 2019, 16:03:41 BST, Stephen Hanselman <kc4sw.io@...> wrote:

Brian,

Changing out these chips is not really a problem. While they do keep some scope specific info I’ve operated 540A’s without the chip.  If you have a vanilla model, no options I’m not sure it’s worth the effort.  EBay, yes I know, has some replacements, when you look at the offerings look for one that has a “+” in the part number. So it seems like these are newer ones. The Tek forum has a thread that gives the cross wiring needed to program the Dallas chip in a more common NVRAM environment.

On the other hand if your scope remembers the date and time the chip is probably ok, for a while.

My technique is to add fresh solder to each pin and then heat the pin, not the board, and suck it out.  I then insert a socket.  So far I have not had an issue with losing data in the chip.

As it stands I have good images for the 540, 540A, and 540B.

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
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On May 30, 2019, at 07:53, Brian via Groups.Io <brianas1948=yahoo.co.uk@groups.io> wrote:

Hi Bob , thank you . That was only the second one of those scopes I've had anything to do with , I am mostly 500 series + 661 and 564 along with 7000 series and 24XX .  My first one was a TDS420A with a dead PSU , changing the caps revived it , nothing else was wrong with it . The TDS744 was also one that did not start up , after sorting out the PSU the other faults showed themselves , it was the first time fixing a component level fault on an acquisition pcb . I now have to do something about the Dallas chips they are dated '93!!

    On Thursday, 30 May 2019, 15:26:46 BST, Bob Koller via Groups.Io <testtech=yahoo.com@groups.io> wrote:

Well done!




Re: 497P power supply aluminum spacers???

Chuck Harris
 

They either keep the PC boards separated, or keep the
aluminum cover from being crushed. They should show up
in the parts blowup... if you can find them.

I recall that they are under the circuit board, and hold
it off of the inner chassis.

-Chuck Harris

radioconnection@... wrote:

Just started recapping my 497P power supply... I found two sets of about 1/4" aluminum spacers after removing the board. One pair are close to 6-32, the other pair are close to 4-40 hole size. I can see where one pair is used, but I am baffled as to where the other pair was used.

Pete



Re: Weird(?) behaviour in tek 492BP power distribution - Please help

 

Hi folks, thank you for the replies.
I am using a Fluke 87V to make the measurements and it has been reliable up to now.
The voltages returned to the expected values when the HV supply board and the Deflection Amplifier board (A64; PN:671-0372- ) are removed from the instrument.
It is connected to the +300V power rail, but I could not find any connection to the +100V power rail.
I will check the semiconductors on this board while I am waiting for the HV power supply to arrive.
Maybe the +100V returns to normal if I find what is causing the +300V to go low.
It took me a looong time to figure out to use the 494 manuals to find information on boards similar to the ones installed in my instrument ( S/N: B030799).
I got the idea after reading another thread on this forum about the "evolution" of the 49x SA line.
Is there a common failure on the deflection board that I should check first?
Regards,
Roger