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View Full Version : SL1200 MK5 US to EU Voltage conversion



neilmacey
04-07-2016, 11:47
Hello to all

I've recently joined AOS after lurking for some years. I've learnt an awful lot from this forum and am very grateful to everyone for sharing their knowledge. I have a specific problem that i wonder if anyone can shed light on

I recently converted a pair of SL1200 MK5 from US 100v to EU 230v using info gleaned from the external PSU thread. I didnt want to go down the external route as these decks travel a lot and its something else to carry / forget.

I used a 24v / 30 VA toroidal transformer from RS in place of the original. The US PSU board had no fuse, although it had the holes in the board for the fuse holder so i cut the tracks on the underside of the board and inserted one. I changed the resistor on the PSU board for a 4.7kohm as there was enough voltage passing across the switch to make the pitch and strobe leds glow when the on/off switch was in the off position.

It all works perfectly fine except there is a rather loud 'clack' audible through the speakers when switching on. It hasn't caused me any problem as yet because i now make sure the volume is down on the amp before switching on but im concerned that one day i might forget and cause damage to my speakers.

This did not happen before when using a step down transformer and it doesnt happen with any friends original EU voltage decks either. I am wondering if it is something to do with the capacitor on the PSU board being too low value for the increased voltage running through it at that point. Also, i have noticed when comparing to a friend's deck that there seems to be a 3rd wire running from the on/off switch to the PSU board which is not present on mine

Any advice would be very welcome
thanks in advance
Neil

337alant
11-07-2016, 17:34
Have you tried an RC contact suppressor across the switch contacts, example.

http://www.maplin.co.uk/c/components/transformers-and-ferrites/ferrites-and-emc

Alan