The reason why they want you to use the 10 Amp range when calibrating even though the current is only 1.5 amps is because you will have a lower burden voltage (due to the lower value shunt resistor used for the multimeters 10 amp range). The closer the measured current nears the limit of the meters selected current range the higher the burden voltage.
Hi, I love your videos and your even tempered, laid back approach to trouble shooting. I only have one minor critical comment and it is probably myself being pedantic. However you refer to your HP (Hewlett Packard) 34401 DMM as an Agilent. I prefer HP be called HP not Agilent/Keysight... and think it was a mistake for them to let the measurement division get away. In any event I own several pieces of HP test equipment and I love it, as do many others I know. You should be proud of your HP gear, it is some of the best ever made. Keep up the excellent quality videos and building your lab from ebay finds.
Nice video. I think it was very risky to calibrate this unit. If it was broken you could have bricked it easly. On the other hand quite strange deffect - it must have lost part of stored calibration constants. I think it is almost impossibe. It may have been caused by memory failure but in this case the deffect may appear again. I don't know what type of memory does it have, Tek. used to use Dallas memory with battery (i.e. DS1225) - the battery was rated for 10 years but it is well known that they work much longer and maybe it is dying now? . Or just maybe sb. has tried to calibrate it before and stored some strange data? About the 10 amps ampmeter during adjustment procedure I belive that they wanted to avoid meters with high resistance of current shunt and high burden voltage.
+Jacek Pawłowski I would guess that someone tried to calibrate the thing with those connectors disconnected. And, yes, it has a Dallas chip with a built-in battery. Maybe it was risky to calibrate, but it worked.
Nice skillful job, I like most of your videos! I am a little scared when I see such complicated digital PSU, many things can go wrong/strange with it after some years of age and the troubleshooting and fixing might be close to impossible at some point. I usually stick to simple testgear where complexity cannot make it more useful.
Congratulations for this successeful repair. I have one unit like yours that recently stop working after being stored for a few months ( it was working before storage), now when it is switched on all displays blink and nothing else happens. I suspect that the battery of the Maxim Dallas NVRAM (DS1220Y-200) chip that holds the calibration parameters has finally died and the power supply is not able to start up. Any idea or comment about what could be wrong?
So it's common to calibrate with short circuiting lab power supplies? No load needed? When I think about it a load of any kind will make measurements not accurate, but isn't there risk to damage the meter?
If the intention is to check the current limit accuracy, shorting with an amp meter should do just fine. The supply can only go as high as 3A, which my meters should handle fine. And they have fuses just in case something goes bad.
Thank you for your reply. I would also recommend enabling output with a button on power supply. Else these may be a spark when you connect DMM to PSU set at 15V or more. This is because some PSU has 1000uf or larger output cap. And connecting DMM in current mode short circuits the CAP.
Wish I could find such good deals on ebay. I'm thinking about using a super cap and some diodes as a fix for the dallas chips internal battery problem. what you think?
I don`t think it`s going to work because the internal battery of the dallas chip is probably shorted out or with a low resistance and that would discharge de capacitor very fast... if it isn`t then it might work hahaha
I've been watching piles of your videos. They're all excellent and informative. Thanks for taking all the time you do to make them!
Thank you for the videos, I love the repair videos and I'm watching each of them, giving blue thumbs up each time.
Great repairs !
Nice job! Your repair methodology is very insightful.
Very skillful repair, great job! Just bought a PS2520G from ebay. Good to have your video in the back pocket, just in case something is wrong!
My hat off to you for figuring this one out...cheers.
The reason why they want you to use the 10 Amp range when calibrating even though the current is only 1.5 amps is because you will have a lower burden voltage (due to the lower value shunt resistor used for the multimeters 10 amp range).
The closer the measured current nears the limit of the meters selected current range the higher the burden voltage.
Glad I found the channel, subscribed
Hi, I love your videos and your even tempered, laid back approach to trouble shooting. I only have one minor critical comment and it is probably myself being pedantic. However you refer to your HP (Hewlett Packard) 34401 DMM as an Agilent. I prefer HP be called HP not Agilent/Keysight... and think it was a mistake for them to let the measurement division get away. In any event I own several pieces of HP test equipment and I love it, as do many others I know. You should be proud of your HP gear, it is some of the best ever made. Keep up the excellent quality videos and building your lab from ebay finds.
Realy interesting video, thanks a lot, keep up the good work.
Greatings from Denmark
Thanks, I was having issues finding how to recalibrate this unit after getting it from a surplus sale for a bargain!
excellent video on test and repair. There are lots of these for sale on ebay
A very good PSU from Tek. Nice done job!
Nice video.
I think it was very risky to calibrate this unit. If it was broken you could have bricked it easly. On the other hand quite strange deffect - it must have lost part of stored calibration constants. I think it is almost impossibe. It may have been caused by memory failure but in this case the deffect may appear again. I don't know what type of memory does it have, Tek. used to use Dallas memory with battery (i.e. DS1225) - the battery was rated for 10 years but it is well known that they work much longer and maybe it is dying now? . Or just maybe sb. has tried to calibrate it before and stored some strange data?
About the 10 amps ampmeter during adjustment procedure I belive that they wanted to avoid meters with high resistance of current shunt and high burden voltage.
+Jacek Pawłowski
I would guess that someone tried to calibrate the thing with those connectors disconnected. And, yes, it has a Dallas chip with a built-in battery. Maybe it was risky to calibrate, but it worked.
Nice video. Good troubleshooting. Tek makes such great hardware. Subscribed. Thanks.
It's not Tek it is GW Instek. It is rebranded by Tek ;-P
NICE JOB !!!!
Nice skillful job, I like most of your videos! I am a little scared when I see such complicated digital PSU, many things can go wrong/strange with it after some years of age and the troubleshooting and fixing might be close to impossible at some point. I usually stick to simple testgear where complexity cannot make it more useful.
parabéns pelo belo trabalho !
Nice !!! Congratulations !!!
Wonderful job.
Congratulations for this successeful repair.
I have one unit like yours that recently stop working after being stored for a few months ( it was working before storage), now when it is switched on all displays blink and nothing else happens. I suspect that the battery of the Maxim Dallas NVRAM (DS1220Y-200) chip that holds the calibration parameters has finally died and the power supply is not able to start up.
Any idea or comment about what could be wrong?
No idea, sorry.
That was a good one because it had a few problems.
Is there anything you can't fix? Superb job yet again!
So it's common to calibrate with short circuiting lab power supplies? No load needed?
When I think about it a load of any kind will make measurements not accurate, but isn't there risk to damage the meter?
If the intention is to check the current limit accuracy, shorting with an amp meter should do just fine. The supply can only go as high as 3A, which my meters should handle fine. And they have fuses just in case something goes bad.
Thank you for your reply. I would also recommend enabling output with a button on power supply. Else these may be a spark when you connect DMM to PSU set at 15V or more. This is because some PSU has 1000uf or larger output cap. And connecting DMM in current mode short circuits the CAP.
well done
Very nice video.
Блин, классные у тебя ролики, прямо таки затягивают.
Wish I could find such good deals on ebay.
I'm thinking about using a super cap and some diodes as a fix for the dallas chips internal battery problem. what you think?
What Dallas chip is there? Can't you get a replacement for a reasonable price?
I don`t think it`s going to work because the internal battery of the dallas chip is probably shorted out or with a low resistance and that would discharge de capacitor very fast... if it isn`t then it might work hahaha
Now if you could Fix my Tektronix 465B Oscilloscope with Traces that are too Short!
What did you pay for this thing?
around $150 as far as I remember