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Old 18th Jun 2018, 11:36 am   #1
TowerRadio
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Default Farnell E30/2 PSU transformer burn-up

Can anyone see a problem with replacing a burnt-up original transformer in my E30/2 with 2 toroidals of suitable output which will fit in the void left? The toroids would be flat, one on top of the other, secured to the back panel by a large nut and bolt, flat washer, rubber washer and whatever else it takes to secure them. Les.
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Old 18th Jun 2018, 11:47 am   #2
Sinewave
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Default Re: Farnell E30/2 PSU transformer burn-up

The only immediate issue is isolation.
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Old 18th Jun 2018, 1:18 pm   #3
MrBungle
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Default Re: Farnell E30/2 PSU transformer burn-up

Cost might be an issue. If you don’t alresdy have them, two toroids might cost more than a new E30/2 at current prices!
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Old 18th Jun 2018, 1:59 pm   #4
TowerRadio
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Default Re: Farnell E30/2 PSU transformer burn-up

I have two suitable already, bought at what I thought to be a bargain price. So long as I insulate each from the other and both from the case (at the same time allowing for some degree of air circulation) are there any other things that can cause me trouble? The transformer that came with the PSU was burnt up when I got it but I think there was a short to one of the 2N3055 connections at the back. A degree of caution and in-line fuses will be used when I first power on.

Les
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Old 18th Jun 2018, 2:25 pm   #5
MrBungle
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Default Re: Farnell E30/2 PSU transformer burn-up

Should be fine then. One thing to note is the E30 benefits from addition of a diode across the terminals and the pass transistor otherwise the load tends to blow the driver transistor if there’s a power failure or overload.

I rather like those little power supplies myself.
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Old 18th Jun 2018, 7:20 pm   #6
duncanlowe
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Default Re: Farnell E30/2 PSU transformer burn-up

I'm sure you know, but just in case, make sure that one end of the bolt is isolated from the case (and will remain so if something gets put on top of the case etc) otherwise you have a nice low resistance single turn secondary.
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Old 18th Jun 2018, 7:29 pm   #7
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Default Re: Farnell E30/2 PSU transformer burn-up

Depending on MCB rating and Type and where you catch the turn on cycle you can get enough surge to trip some MCB's with toriods. The ratings for this PSU's toriods might not put you in this region but if you do get a turn on trip then slow turn on might be required.

Pete
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Old 18th Jun 2018, 10:23 pm   #8
TowerRadio
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Default Re: Farnell E30/2 PSU transformer burn-up

Thanks for everyones advice. When I get round to doing the repairs I will post again. Les.
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