Electronics > Repair
DSO-X 3024A Power Supply defect
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enz:
Hi All,

bad luck today.

When I plugged in my DSO-X 3024A the circuit breaker tripped and I saw a light flash cominf out of the backside of the oscilloscope.
After opening the device and inspecting the power supply I noticed a burned part, see picture below:

I think the broken part was a varistor, but I am not 100% sure. Could also be a capacitor.
Can anyone identify the part?

Otherwise I would leave the part unpopulated.

Best regards,
Martin

JFJ:
The part might be a NTC thermister, like this:

https://www.yoycart.com/Product/571067033190/
soesante:
Believe its NTC Thermistor...

Sent from my SM-J730G using Tapatalk

ArthurDent:
The blown part is obviously a NTC thermistor as others have pointed out but the question is why did it blow? It is possible that it was just that part, it happens, but there may have been something more serious that caused it to blow. In the lower left there is F1 a 6.3A fuse, is that blown?

You say the problem caused a breaker to trip. That sounds more like a direct short from one of the A.C. input leads to ground (earth) or a line-to-line short. If it was just a problem within the power supply the 6.3A fuse would blow but not the breaker. What is the breaker capacity? It is probably several amps higher. There are 2 toroidal inductors on the left side of the power supply, probably one on each leg of the A.C.. If there was an arc-over in that area, that may have caused the problem.

It would be a good idea to carefully check the power supply out and not just replace that part and plug it back in to power.

Edit: I said fuse was 0.3A and it is actually 6.3A.  Thanks to PA0PBZ for pointing out my error.
PA0PBZ:

--- Quote from: ArthurDent on September 20, 2018, 05:04:08 pm ---In the lower left there is F1 a 0.3A fuse, is that blown?

--- End quote ---

I think it says 6.3A so it could well be that the breaker was faster. When something like this happens the diodes are the first suspects. If you find one shorted replace them all!
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