Smoke und fire after switching on old electronics TEK DSA 602
Physikfan, Tue Aug 01 2017, 11:51AMHello friends of electronics
A dealer for used electronics supplied me two Tektronix 11000 oscilloscope frames, DSA 602 and DSA 602A.
I was of the opinion that the devices were checked at least once before delivery.
I switched on the devices in a large exhibition hall to test the frames and some 11000`s like 11A72 etc.
That was not very smart.
After approximately 5 to 10 minutes after switching on, one of the devices worked electrically initially faultlessly, biting smoke came out from both devices, which greatly influenced the air quality in the exhibition hall.
Even one of these devices started to burn inside.
After extinguishing the fire, the dealer agreed not to have checked the equipment before loading.
However, every experienced electronics engineer should know that one should deal very carefully with a very long time of unused HP and Tektronix devices.
You should first connect these devices to a variable mains supply and the full mains voltage should applied step by step only after 2-5 minutes, in order to re-form various capacitors and to avoid potential explosions etc.
I would be interested in whether someone has already had similar experiences with smoke and fire when switching on old electronics.
The only positive thing followed this action was a corresponding price reduction.
You will get some pictures of the burned parts soon.
I hope I get from you also some hints how to repair these devices.
The documentation of the Tek devices is unfortunately not sufficient in the 11000 series, in contrast to the 7000 series.
Best regards
Physikfan
Re: Smoke und fire after switching on old electronics TEK DSA 602
Sulaiman, Tue Aug 01 2017, 12:16PM
Variacs are excellent tools but I prefer putting a high wattage mains voltage filament lamp in series, (especially for smps, which does not apply here)
I expect to see a brief flash from the lamp at power-on due to caps charging etc.
then a dull or no glow for normal operation, and fully bright if things go wrong.
The current limiting provided by the lamp usually protects from fire etc.
A switch contact across the lamp allows full power operation once you feel comfortable.
When we see what was damaged other ideas may come.
Sulaiman, Tue Aug 01 2017, 12:16PM
Variacs are excellent tools but I prefer putting a high wattage mains voltage filament lamp in series, (especially for smps, which does not apply here)
I expect to see a brief flash from the lamp at power-on due to caps charging etc.
then a dull or no glow for normal operation, and fully bright if things go wrong.
The current limiting provided by the lamp usually protects from fire etc.
A switch contact across the lamp allows full power operation once you feel comfortable.
When we see what was damaged other ideas may come.
Re: Smoke und fire after switching on old electronics TEK DSA 602
johnf, Tue Aug 01 2017, 07:05PM
usually it is the electrolytic capacitors depolarising---acting like short circuits this takes out the rectifiers and they go short circuit and now the ac on the DC rail kills at random.
the other failure mechanism is a shorted turn in the mains transformer due to green spot
johnf, Tue Aug 01 2017, 07:05PM
usually it is the electrolytic capacitors depolarising---acting like short circuits this takes out the rectifiers and they go short circuit and now the ac on the DC rail kills at random.
the other failure mechanism is a shorted turn in the mains transformer due to green spot
Re: Smoke und fire after switching on old electronics TEK DSA 602
DerAlbi, Tue Aug 01 2017, 09:40PM
Reforming old capacitors is perfectly possible, but i dont see how this can be done in a working device. Once you supply enough power for the operation of a device there is no way to limit the heat of the capacitor leakage current. So its a well meant thought having a light bulb in series, but it simply does not work like that.It only works if you put in a 50k resistor and dont turn the sucker on. But most poer supplies have some StBy power drainage so there is also no use.
DerAlbi, Tue Aug 01 2017, 09:40PM
Reforming old capacitors is perfectly possible, but i dont see how this can be done in a working device. Once you supply enough power for the operation of a device there is no way to limit the heat of the capacitor leakage current. So its a well meant thought having a light bulb in series, but it simply does not work like that.It only works if you put in a 50k resistor and dont turn the sucker on. But most poer supplies have some StBy power drainage so there is also no use.
Re: Smoke und fire after switching on old electronics TEK DSA 602
Conundrum, Fri Aug 11 2017, 05:18AM
Same here. I think the correct method is to use a variac in series with load.
Conundrum, Fri Aug 11 2017, 05:18AM
Same here. I think the correct method is to use a variac in series with load.
Re: Smoke und fire after switching on old electronics TEK DSA 602
Physikfan, Fri Aug 11 2017, 02:34PM
Pictures of the damaged DSA602:
DSA602
Power supply from the side
Power supply from the rear
Rear of rear cover plate
smoked components
I am looking forward to your comments
Physikfan, Fri Aug 11 2017, 02:34PM
Pictures of the damaged DSA602:
DSA602
Power supply from the side
Power supply from the rear
Rear of rear cover plate
smoked components
I am looking forward to your comments
Re: Smoke und fire after switching on old electronics TEK DSA 602
Hazmatt_(The Underdog), Fri Aug 11 2017, 04:05PM
Yea that's one of those clear WIMA mylar caps. Boy they sure do go up in flames don't they.
I had a couple do that, made a real mess of things. It's just the line input filter though. You can see the surge clamp tube under the char.
Just start rinsing the soot off with IPA, assess any actual damage, and replace the cap with a .01uF 600V PP type WIMA.
The smoke however, has permeated every nook and cranny of the scope though, you will probably need to rinse every part of that guy.
You ought to replace that clear one next to the inductor in the upper right corner as well for good measure (even though it never sees any AC)
I don't envy you having to deal with the smell, but it will eventually dissipate, that scope is going to stink for a while though.
Hazmatt_(The Underdog), Fri Aug 11 2017, 04:05PM
Yea that's one of those clear WIMA mylar caps. Boy they sure do go up in flames don't they.
I had a couple do that, made a real mess of things. It's just the line input filter though. You can see the surge clamp tube under the char.
Just start rinsing the soot off with IPA, assess any actual damage, and replace the cap with a .01uF 600V PP type WIMA.
The smoke however, has permeated every nook and cranny of the scope though, you will probably need to rinse every part of that guy.
You ought to replace that clear one next to the inductor in the upper right corner as well for good measure (even though it never sees any AC)
I don't envy you having to deal with the smell, but it will eventually dissipate, that scope is going to stink for a while though.
Re: Smoke und fire after switching on old electronics TEK DSA 602
Hydron, Fri Aug 11 2017, 06:08PM
If it's the line input filter then wouldn't an X or Y cap (depending on location) be a better idea than just a standard 600V PP cap?
And yes, those damn caps are terrible, have seen bad ones a number of times myself (though nothing with dramatic flames!)
Hydron, Fri Aug 11 2017, 06:08PM
If it's the line input filter then wouldn't an X or Y cap (depending on location) be a better idea than just a standard 600V PP cap?
And yes, those damn caps are terrible, have seen bad ones a number of times myself (though nothing with dramatic flames!)
Re: Smoke und fire after switching on old electronics TEK DSA 602
Physikfan, Fri Aug 11 2017, 07:28PM
Images of parts of the smoking and burning DSA602A:
Power supply board with defective filter X2
Filter X2 in detail, this component burned.
This board looks better than the non-firing board of the DSA402.
I am looking forward to your comments.
Physikfan, Fri Aug 11 2017, 07:28PM
Images of parts of the smoking and burning DSA602A:
Power supply board with defective filter X2
Filter X2 in detail, this component burned.
This board looks better than the non-firing board of the DSA402.
I am looking forward to your comments.
Re: Smoke und fire after switching on old electronics TEK DSA 602
Hazmatt_(The Underdog), Sat Aug 12 2017, 04:45AM
Can you make out the value on the top of the cap?
Keep up the good work.. you should be able to salvage this one.
Hazmatt_(The Underdog), Sat Aug 12 2017, 04:45AM
Can you make out the value on the top of the cap?
Keep up the good work.. you should be able to salvage this one.
Re: Smoke und fire after switching on old electronics TEK DSA 602
johnf, Sat Aug 12 2017, 04:47AM
self healing paper capacitor -yeah right
replace with PP X2 or Polyester X2
johnf, Sat Aug 12 2017, 04:47AM
self healing paper capacitor -yeah right
replace with PP X2 or Polyester X2
Re: Smoke und fire after switching on old electronics TEK DSA 602
Physikfan, Sun Aug 13 2017, 02:00PM
Hi Hazmatt_(The Underdog)
Here are images of parts of the DSA602:
Defective component, 0.6 uF X, is removed.
Second same component still intact.
As you can see the value of the cap of the DSA602 is 0.6uF X.
Small filters
As you can see the value of these caps of the DSA602 is 0.015uF
Images of parts of the DSA602A:
Second same component still intact
As you can see the value of the cap of the DSA602A is 0.6uF X2.
Small filters
As you can see the value of these caps of the DSA602A is 0.015uF
Hello Johnny10
The pictures are showing views of boards from DSA602 (3) and DSA602A (2).
The pictures 1,2 and 3 of my last post show different views of the first power supply board of the DSA602.
The pictures 4 and 5 of my last post show the analog views of the same power supply board of the DSA602A.
For me it is remarkable that the same capacitors RIFA 0.6 uF X and RIFA 0.6 uF X2, both on the upper left of the boards, and also ONLY these, are fumed in these different oscilloscopes DSA 602 and DSA 602A, randomly?
I must also admit that this incident was my first encounter with this type of interference suppression capacitors.
Regards
Physikfan
I am looking forward to your comments
Physikfan, Sun Aug 13 2017, 02:00PM
Hi Hazmatt_(The Underdog)
Here are images of parts of the DSA602:
Defective component, 0.6 uF X, is removed.
Second same component still intact.
As you can see the value of the cap of the DSA602 is 0.6uF X.
Small filters
As you can see the value of these caps of the DSA602 is 0.015uF
Images of parts of the DSA602A:
Second same component still intact
As you can see the value of the cap of the DSA602A is 0.6uF X2.
Small filters
As you can see the value of these caps of the DSA602A is 0.015uF
Hello Johnny10
The pictures are showing views of boards from DSA602 (3) and DSA602A (2).
The pictures 1,2 and 3 of my last post show different views of the first power supply board of the DSA602.
The pictures 4 and 5 of my last post show the analog views of the same power supply board of the DSA602A.
For me it is remarkable that the same capacitors RIFA 0.6 uF X and RIFA 0.6 uF X2, both on the upper left of the boards, and also ONLY these, are fumed in these different oscilloscopes DSA 602 and DSA 602A, randomly?
I must also admit that this incident was my first encounter with this type of interference suppression capacitors.
Regards
Physikfan
I am looking forward to your comments
Re: Smoke und fire after switching on old electronics TEK DSA 602
Hazmatt_(The Underdog), Sun Aug 13 2017, 05:17PM
Yea you now know what the culprit is, just replace them, its an easy task.
Hazmatt_(The Underdog), Sun Aug 13 2017, 05:17PM
Yea you now know what the culprit is, just replace them, its an easy task.
Re: Smoke und fire after switching on old electronics TEK DSA 602
Hydron, Tue Aug 15 2017, 10:45AM
The clear caps are notorious for dying, especially after not being used for some time. It is not random or particularly surprising.
Replace every one with a modern equivalent - will not be difficult or expensive, and they are not likely to have killed anything else except by smoke or fire damage.
Hydron, Tue Aug 15 2017, 10:45AM
The clear caps are notorious for dying, especially after not being used for some time. It is not random or particularly surprising.
Replace every one with a modern equivalent - will not be difficult or expensive, and they are not likely to have killed anything else except by smoke or fire damage.
Re: Smoke und fire after switching on old electronics TEK DSA 602
radiotech, Tue Aug 15 2017, 05:44PM
The storage history of old electronics is important. Also insulation tests, using meggers,
can predict the moisture content of high voltage circuits but require very careful analysis.
If you have set diodes alight, what damage has been done to the transformer winding ?
Also, enameled copper wire has a limited insulation lifetime, from the moment it
was wound on a core. Copper is so reactive, it eventually destroys the integrity of
the insulation. Aluminum wound coils are much better, for obvious reasons.
You might consider using an arcing fault circuit breaker on the test bench.
radiotech, Tue Aug 15 2017, 05:44PM
The storage history of old electronics is important. Also insulation tests, using meggers,
can predict the moisture content of high voltage circuits but require very careful analysis.
If you have set diodes alight, what damage has been done to the transformer winding ?
Also, enameled copper wire has a limited insulation lifetime, from the moment it
was wound on a core. Copper is so reactive, it eventually destroys the integrity of
the insulation. Aluminum wound coils are much better, for obvious reasons.
You might consider using an arcing fault circuit breaker on the test bench.
Re: Smoke und fire after switching on old electronics TEK DSA 602
Conundrum, Wed Aug 16 2017, 06:11AM
Never knew that!
I wonder if this is the reason why old HDDs eventually just fail?
Seen this a few times, the actuator does not move yet nothing obvious is wrong.
Conundrum, Wed Aug 16 2017, 06:11AM
Never knew that!
I wonder if this is the reason why old HDDs eventually just fail?
Seen this a few times, the actuator does not move yet nothing obvious is wrong.
Re: Smoke und fire after switching on old electronics TEK DSA 602
Physikfan, Fri Aug 18 2017, 11:01AM
To all DSA602 and DSA602A owners
Please which DSA602 and DSA602A owner has already had its device open and
can tell me something about the wiring of this board just next to the power supply?
It is about the two-pole white plug, the third from the left bottom, with the two cables red and brown.
In my DSA602A it is present, in my DSA602 it is missing.
I wonder now, due to a lack of circuit diagram, whether it has to do with the power supply of the floppy disk drive in the DSA602A.
The DSA602A has one, the DSA602 has none.
Best regards
Physikfan
Physikfan, Fri Aug 18 2017, 11:01AM
To all DSA602 and DSA602A owners
Please which DSA602 and DSA602A owner has already had its device open and
can tell me something about the wiring of this board just next to the power supply?
It is about the two-pole white plug, the third from the left bottom, with the two cables red and brown.
In my DSA602A it is present, in my DSA602 it is missing.
I wonder now, due to a lack of circuit diagram, whether it has to do with the power supply of the floppy disk drive in the DSA602A.
The DSA602A has one, the DSA602 has none.
Best regards
Physikfan
Re: Smoke und fire after switching on old electronics TEK DSA 602
johnf, Sat Aug 19 2017, 06:48AM
That is why god let us invent multimeters with a continuity function
IE find out where it goes
johnf, Sat Aug 19 2017, 06:48AM
That is why god let us invent multimeters with a continuity function
IE find out where it goes
Re: Smoke und fire after switching on old electronics TEK DSA 602
Physikfan, Thu Aug 24 2017, 08:48AM
My latest information:
Both the DSA602A and the DSA602 should have this cable on this board.
This cable is apparently missing on my DSA602.
Physikfan, Thu Aug 24 2017, 08:48AM
My latest information:
Both the DSA602A and the DSA602 should have this cable on this board.
This cable is apparently missing on my DSA602.
Print this page