Zalman ZM750-EBT: synchronous golden platform from Sirtec

Conclusion and evaluation

The Zalman ZM750-EBT did not pass the combined and crossload testing in accordance with the ATX specification, so according to my evaluation methodology, it is not deserving of an evaluation. What I like about this unit is the reasonable ripple suppression, which is on par with other units of this same platform from Sirtec, and while it does sometimes cross into mainstream values, it is still rather an acceptable result. In most of the other areas however it is worse.

The efficiency is slightly lower than what you would expect, which has now been confirmed by two other sources. The same goes for voltage hold-up time, which is incredibly low at just 10 ms, but to actually stay within spec because of voltage spikes, the real in-spec hold up time is just under 7 ms. This is by far the worst result we have seen yet. Another serious problem is that this unit’s over power protection seems to be non-functional. As a result, we were able to drop the 12V to just slightly above 10 V without it kicking in, which once again is totally unacceptable. And lower than that, the unit did finally shut down, but not because of UVP, but rather from the overheating protection.

Heat is another serious problem as with overloading, and some parts of the unit overheated so much as to cause a very bad smell. The area that overheated is too far away from the temperature sensor because otherwise the unit’s fan would have immediately kicked in to high gear. To compound all these problems, Zalman elected to use low-quality Teapo SC capacitors. I should point out however that they do offer a generous warranty period of 7 years. So even though low-quality capacitors in a high-end is not something I’m keen on, with its reasonable price and long warranty, this unit would have been worth considering – if it was not for all the other problems.

Neprosel

Pros + modular cabling
+ acceptable ripple suppression
+ long warranty
+ OK efficiency
+ OK build quality
Cons mediocre voltage regulation
over power protection not working
under voltage protection not working
local overheating in overload scenario
incredibly short voltage hold-up time to stay in spec
Power Good hold-up time not in compliance with ATX
bad capacitors
Be aware of… /?\ supposed multiple revisions

Thanks

I thank the Zalman company for providing the Zalman ZM750-EBT unit.

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