And now the final part: cooling of the U800.
The consensus seem to be, that the TekTronix made chips are "better" in terms of failing on the long term.
Mine is not getting hot, but it may have to do whem touching the chip is is just doing almost nothing?
Maybe when the scope is running on a very high frequency with a high repetition rate, it may get hot due to more capacitive load??
Anyway, I decided to help this little chip a bit.
What I did was, I removed the nut where the metal tab from under the chip is, and made a brass (for thermal conductivity) bushing the same height as the remaining part of the chip.
So basically, I try to guide the heat through this bushing to the top, and there transfer it to a cooling element.
I also put some thermal conductive grease on top of the chip, although this may be of little effect.
The cooling I found at Mouser's, it is a double to-220 part.
I will start adding pictures to show what I did.
Un saudo,
Satbeginner (Leo)
I thought the Maxim dies were not specific to the U800 but for the other custom chips, U400's maybe
and funny enough, one of the 15 Ohm resistors went up to 4968 Ohm!! without any markings or change of color.
Be careful. The studs that secure U800 are NOT at ground potential. I may be mistaken but I think each stud is at a different potential. So you could easily cause a short. The heatsink modifications I've seen for U800 are glued to the top of the chip away from the studs. So check what you've done very carefully or you might have magic smoke.
Be careful. The studs that secure U800 are NOT at ground potential. I may be mistaken but I think each stud is at a different potential. So you could easily cause a short. The heatsink modifications I've seen for U800 are glued to the top of the chip away from the studs. So check what you've done very carefully or you might have magic smoke.
That studs (or embedded bolts ?) is -5 (negative five) volts.
Posted this at -> post #2 at the beginning of this thread, yep, I measured it with DMM.
And now the final part: cooling of the U800.
The consensus seem to be, that the TekTronix made chips are "better" in terms of failing on the long term.
Mine is not getting hot, but it may have to do whem touching the chip is is just doing almost nothing?
Maybe when the scope is running on a very high frequency with a high repetition rate, it may get hot due to more capacitive load??
Anyway, I decided to help this little chip a bit.
What I did was, I removed the nut where the metal tab from under the chip is, and made a brass (for thermal conductivity) bushing the same height as the remaining part of the chip.
So basically, I try to guide the heat through this bushing to the top, and there transfer it to a cooling element.
I also put some thermal conductive grease on top of the chip, although this may be of little effect.
The cooling I found at Mouser's, it is a double to-220 part.
I will start adding pictures to show what I did.
Un saludo,
Satbeginner (Leo)
Be careful. The studs that secure U800 are NOT at ground potential. I may be mistaken but I think each stud is at a different potential. So you could easily cause a short. The heatsink modifications I've seen for U800 are glued to the top of the chip away from the studs. So check what you've done very carefully or you might have magic smoke.
and funny enough, one of the 15 Ohm resistors went up to 4968 Ohm!! without any markings or change of color.
Leo, which resistor is that ?
No markings ? You still have it ? Photo please.
Must be either R1010 or R1019. Both were bad in one of my 2465B, one was open and the other measured 68K, but both had visible signs although not that easy to see.
Must be either R1010 or R1019. Both were bad in one of my 2465B, one was open and the other measured 68K, but both had visible signs although not that easy to see.
And now the final part: cooling of the U800.
The consensus seem to be, that the TekTronix made chips are "better" in terms of failing on the long term.
Mine is not getting hot, but it may have to do whem touching the chip is is just doing almost nothing?
Maybe when the scope is running on a very high frequency with a high repetition rate, it may get hot due to more capacitive load??
Anyway, I decided to help this little chip a bit.
What I did was, I removed the nut where the metal tab from under the chip is, and made a brass (for thermal conductivity) bushing the same height as the remaining part of the chip.
So basically, I try to guide the heat through this bushing to the top, and there transfer it to a cooling element.
I also put some thermal conductive grease on top of the chip, although this may be of little effect.
The cooling I found at Mouser's, it is a double to-220 part.
I will start adding pictures to show what I did.
Un saludo,
Satbeginner (Leo)
Be careful. The studs that secure U800 are NOT at ground potential. I may be mistaken but I think each stud is at a different potential. So you could easily cause a short. The heatsink modifications I've seen for U800 are glued to the top of the chip away from the studs. So check what you've done very carefully or you might have magic smoke.
Hi,
thanks for your response, in the picture you can see this cooler stays far away from any surrounding part, I also have like 8-9 mm from the case.
Although my U800 stayed cool, I just wanted to help it a little by conducting heat away from the chip.
The spring washers are no good in doing this, but -my thoughts- a solid brass ring might help, and also cooling the chip -although plastic- itself a bit.
I never liked glue and heatsinks, in my book they always end up somewhere loose in the device... ;-)
Un saludo,
satbeginner (Leo)
I have open up mine at last. Some chips are date coded 1997. The battery backed up SRAM is 1995.
I believe this scope was "overhauled" in some way about 10 years ago, by the refurbish company which I bought it from.
Some pics here - the site crashes when I try to upload anything sizeable.
http://peter-ftp.co.uk/screenshots/2017-03-28_225205.jpg
http://peter-ftp.co.uk/screenshots/2017-03-28_225239.jpg
I have open up mine at last. Some chips are date coded 1997. The battery backed up SRAM is 1995.
I believe this scope was "overhauled" in some way about 10 years ago, by the refurbish company which I bought it from.
Some pics here - the site crashes when I try to upload anything sizeable.
http://peter-ftp.co.uk/screenshots/2017-03-28_225205.jpg
http://peter-ftp.co.uk/screenshots/2017-03-28_225239.jpg
Now I need to find out where to check the supply voltages,
...
but can't find the LED DATA signal.
Is the LED clock definitely pin 16 J652?
How do you get to the front panel? I can see some screws on the bottom, but there are many buttons etc to remove. At that point I would rather pay someone who has done this before, a couple of hundred GBP... I am in the UK.