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3.5kV power supply teardown

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rolycat:

--- Quote from: ve7xen on May 28, 2014, 10:10:03 pm ---I believe Schaffner inlet filters from the 90s have a history of doing this, it plagues test equipment too. If you replace it, don't use NOS, is the general advice.

--- End quote ---
Yes, I contacted Schaffner and they recommend the current model FN9226-3-02 as a replacement. It's missing the plastic flanges around the screwholes, but should fit OK. It was pricey though, so in the event I used another brand of filter which happened to fit pretty well.


--- Quote ---Dave did a teardown of another electrophoresis supply a while ago, if you haven't seen it:


--- End quote ---
I did watch that, thanks. An interesting teardown as always, but I wasn't very impressed with the EC250-90 - the general design and regulation seemed more primitive than the Pharmacia models I've seen.

HighVoltage:
Interesting to see those blue 47nF capacitors in the voltage multiplier section. ( I think they are also made in Sweden but I forgot the name)
And then see the German made WIMA at the output stage.
I remember the days, when we opened anything of quality and it was full with red and yellow WIMA capacitors.
These days, you really have to look for them.

Also the high voltage diodes look like they are of high quality, may be Vishay or so.

It would be really nice to look at a schematics for this instrument.
May be the layout is so nice, because it was for medical applications and money did not matter too much.
Any Idea how much this unit was, when it was brand new?
Thanks for these nice tear down pictures, I really enjoyed looking at them.

rolycat:

--- Quote from: tom66 on May 28, 2014, 08:48:03 pm ---How does it sense output voltage and load current?

--- End quote ---
Good question. The only tap I can see from the output stage is two high voltage 10M resistors in series lurking under the output terminals. They connect to the positive output at one end and two of the non-inverting inputs of a TL074 quad op-amp at the other.

rolycat:

--- Quote from: HighVoltage on May 29, 2014, 01:59:16 pm ---Interesting to see those blue 47nF capacitors in the voltage multiplier section. ( I think they are also made in Sweden but I forgot the name)

--- End quote ---
Rifa:

Since swallowed by the Kemet Corporation. The large blue 470n X2 capacitors and the white 2n2 Y2 caps in the mains input stage were also made by Rifa.

The transformers are also Swedish - the control section supply transformer was made by Transformator-Teknik AB of Åmål, Sweden.
(Incidentally the town is famous; there's an eponymous film with a very controversial title.)


--- Quote ---It would be really nice to look at a schematics for this instrument.

May be the layout is so nice, because it was for medical applications and money did not matter too much.
Any Idea how much this unit was, when it was brand new?

--- End quote ---
It's still a current model, cosmetically tweaked as the EPS 3501 XL. These are quoted by GE Healthcare, (who bought Amersham Lifesciences, who bought Pharmacia), at $4,971.


--- Quote ---Thanks for these nice tear down pictures, I really enjoyed looking at them.

--- End quote ---
My pleasure.

HighVoltage:
Yes, RIFA, that was the name...  ... we used them in the 1980th a lot in projects in Sweden.

I was so much intrigued by your teardown, I found a EPS 3501 XL in like new condition and just bought it. It should be here in a week or so. Then I will open it up and see, if there are any visible differences. Thanks for your inspiration.

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