Author Topic: HP 16700 PSU in 230V region woes  (Read 37 times)

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Offline FrodeMTopic starter

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HP 16700 PSU in 230V region woes
« on: Yesterday at 11:45:06 pm »
Have anyone here experienced problems with the power-supply of the HP 16700 logic analyzer blowing up when running in 230V regions? I am in particular thinking of the Celestica 7000 variety, which does claim to handle 230V just fine but I have had two blow on me so far.

The first time it was the switcher for the standby power source. An all-in-one TOP227Y switch mode regulator in a single TO-220 package. This blew quite violently, taking out a whole trace on the PCB, some resistors in its path, as well as D7.

For the second one , it was a small 8-pin chip, probably part of the main regulator. Fortunately, not as violently and this far I only found D7 as the only other part that has blown.

Is it just me, or does this PSU have really slim margins?

Some notes on the design. I plan to fix the second one with parts from the first one, and I'm in the process of drawing up a schematics as a consequence. I now see that the main board of the PSU uses a charge-pump type of design, instead of switching a transformer. That explains why D7 is very prone to damage: it's the main boost converter diode. All current driving the unit passes through it, and with 230V mains it is natural that the flyback suges it needs to pass will peak harder.

Does anyone else have similar experience with these supplies?
 


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