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-   -   Problems with PT325.2i (http://www.diyaudio.com/forums/tubes-valves/220614-problems-pt325-2i.html)

wknight 28th September 2012 09:57 PM

Problems with PT325.2i
 
Hi
I have bought the power transformer Musical Power Supplies PT325.2i
It heats without load.
It takes about 200mA without load.

If somebody use it, please tell me about your experience.

thanks a lot to MuzicalMatt the problem is solved I have got new one.

kevinkr 29th September 2012 12:21 AM

Sounds like this transformer has an internal short, but double check that the short is not external and that the primary voltage is correct for your area. If all checks out OK externally I'd return it as defective.

Tom Bavis 29th September 2012 12:55 AM

Was this transformer designed for 60 Hz? It will draw more on 50 Hz, especially if voltage is on the high side as well. Does current drop drastically when voltage is lowered 20%?

wknight 29th September 2012 08:32 AM

In the datasheet is written "50Hz".
If I connect it in 240V mode it takes 100mA.

DF96 29th September 2012 09:21 AM

If it is taking 200mA on 220V setting, and 100mA on 240V setting, then it is probably suffering from core saturation due to being run unloaded. Some cheaper transformers (and some expensive ones?) run too close to the limit (or just over the edge) when unloaded. Try adding a realistic load, preferably via a lamp limiter.

wknight 29th September 2012 11:50 AM

I have made one more test.
I have use output (325V) coil as primary. It takes only 14mA.
DF96 is right ! It is core saturation.
thanks
temporally I will use it as is but I am going to buy new one

maybe I will buy this one https://www.edcorusa.com/p/590/xpwr002_240

What do you think about ?

kevinkr 30th September 2012 01:05 AM

Edcor makes great stuff, use it all the time.

If the core is saturating I would not use that transformer, it will burn up pretty quickly.

DF96 30th September 2012 01:55 PM

A bit of Googling showed me that this supplier (MPS) has recently opted to get his transformers made in China. They may be cutting corners on the winding, or the core. MPS might not realise this. I would report your findings to MPS (who appear to be away at present according to their ebay shop). See what they say. Bear in mind that with transformers you broadly get what you pay for, and MPS appearsto be one of the cheaper makes.

wknight 30th September 2012 02:25 PM

Quote:

Originally Posted by DF96 (Post 3184806)
A bit of Googling showed me that this supplier (MPS) has recently opted to get his transformers made in China. They may be cutting corners on the winding, or the core. MPS might not realise this. I would report your findings to MPS (who appear to be away at present according to their ebay shop). See what they say. Bear in mind that with transformers you broadly get what you pay for, and MPS appearsto be one of the cheaper makes.


PT325.2i - 44$
XPWR002-240 - 57.33$

PT325.2i ~62W
XPW002-240 ~140W

Accordingly to this the price per watt of PT325.2i is higher ;)

Am I right ?

DF96 30th September 2012 03:31 PM

Transformer prices don't necessarily scale $/W.

Anyway, there is clearly something not quite right. It could be a shorted turn, but I think saturation is more likely. Maybe the factory got confused and built it with an core airgap. Or maybe they just used too few turns (quicker so cheaper to build). Maybe they sent you a 120V primary by mistake.


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