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Jazzo 27th November 2007 10:11 AM

Pass X250.5 Voltage Change Confusion
I'm trying to help someone determine if a X250.5 from US has a transformer and board that can change 110V to 220V.

An old thread on this forum addressed this issue, but was incomplete and confusing.

Nelson believed the USA amps made up to 2006 (?) were supplied with multi-use Plitrons. The transformer in question has 6 leads, with 3 soldered in a straight line of 3 holes, and the other 3 soldered similarly.

The other thread described a 110V transformer that had only 3 leads, and the Italian importer said it could not be configured for 220V.

Does six leads mean it can be used for any voltage via a jumper change?

jacco vermeulen 27th November 2007 02:02 PM

Why not just count the number of primary leads ?

Maousse 27th November 2007 03:03 PM

Or post a photo ?;)

Jazzo 27th November 2007 07:37 PM

Well, are not six leads coming out of the transformers all primaries?
Sorry, no photo capability.

Nelson Pass 27th November 2007 08:37 PM

Current X250.5 transformers are shipped voltage-specific. You
will need to email us a serial # for more definitive information
on your particular unit.


vuki 23rd January 2008 10:19 AM

Recently my friend also had a chance to buy used x250.5 from USA and had the same dilemma. The seller even contacted PassLabs and was told that the conversion for that model is not possible. Thinking about it, it seemed to me quite impossible for Plitron to make to different transformers for the same job, so I guessed that new "single primary" versions were just internally bridged same old transformers.
Lucky for me (since my friend bought that amp based on my presumption) it turned out I was right.
In less than an hour, with a little help of multimeter, xacto knife, pliers and soldering unit the US rated X250.5 became EURO. :D
One can even take out all the taps to have 110,120,220,240V connection possibility. And main fuse should be also changed. (Less important when going to a higher voltage).

I think it's a great news for all buyers interested in used PassLabs amps. ;)

Nelson Pass 23rd January 2008 06:16 PM

No, it really is a different transformer.

Voltage conversion for current production units is accomplished
by replacing the transformer.

vuki 23rd January 2008 06:42 PM

I don't know about that. I just told what happened. Anyway... that was the unit with the Plitron transformer for which was told (by PassLabs) that it couldn't be converted to 220V because it is single primary. Procedure included taking off protective band around transformer and cutting through isolation strip. Primaries were briged inside - beneath all that isolation and crimped to the color coded output wires (just three of them). So, indeed, it wasn't supposed to be converted to 220V, but it could be done.
I really doubt that Plitron makes special new transformer for PassLabs 220-240 models, because all their amp PS transformers have multiple primaries and transformer manufacturers prefere to use multiple thinner wires to single fat wire. It's so much easier for them to crimp those taps to output wires inside and there is no real reason to make true single primary. Except if your intention is to prevent transcontinental used PassLabs amp sale. :xeye:

vuki 13th June 2009 04:28 PM

2 Attachment(s)
Surgery picture.

Nelson Pass 13th June 2009 07:41 PM

When I read the January post, I asked Plitron whether that form of
construction was correct in the model we were purchasing. They
informed me that it is not, specifically that the transformers in
question have a single primary, not dual primaries with hidden

I don't recommend that anyone assume that they can successfully
perform that surgery.


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