LD91 signature power transformer wires Help? - diyAudio
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Old 18th March 2013, 06:51 PM   #1
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Default LD91 signature power transformer wires Help?

I recently bought a second hand pair of factory assembled LD91 signature monoblocks. I am really happy with the way they sound, best sounding amps I have owned. I think they are about 5 years old (tent labs module). On power up I am occasionally getting a spark from either one of the 274b rectifiers which I fitted a few weeks ago (new) they did not spark at first. I have looked at fitting a thermistor. But I wondered and it was also suggested that there might be another issue causing this sparking. It would appear the wiring to the power transformer seems to be set for 220v (both red and white wires used) and not 240v. The manual says that the power transformer has two primary windings, each one with 110v + 10v section. (the wires are not labelled).

For 220 volt mains- white of one wire connects to red of second winding. Power switch connections are made to remaining red and white wires. Brown wires are not used and should be insulated and tied off unconnected.

For 240 volt mains- Brown of one wining connects to red of second winding. Power switch connections are made to remaining red and brown wires. Whites are not used and should be insulated and tied off unconnected.

Red and white wire are being used currently so the amp seems configured for 220volts. Sounds easy enough I thought, substitute the white wires for brown . So I opened up the amps bundle of tied off wires, no brown wires! The bundle of insulated and tied off wires are as follows...

A long pair of twisted together yellow wires.

A pair of short loose/not twisted together purple wires.

A long pair of twisted together orange wires with a short orange wire just loose.

I am not keen on taking of the transformer cover as it looks to be quite a task and even so it is not going to tell me much. I have looked on the net, it would appear the white, orange and yellow wires are all on one side of the transformer and the purple and red are on the other. I cannot see if there is any brown wires or not. Can anyone please help with this wiring colour dilemma.
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Old 19th March 2013, 06:46 PM   #2
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Does no one know what I can do to sort this transformer wiring out?

I have contacted diyhifisupply but have not heard back from them yet.
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Old 20th March 2013, 07:15 PM   #3
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I have taken off the transformer cover (took a while), to see if the brown wires were tucked up in side. No joy, no brown wires. The Purple and the red wires are on one side of the transformer. The orange and the yellow wires are on the other. So I am kind of stuck as I don't want to be running 220v configured amps on 240v. I could use a APC line R and change the output of that to 220v but it kind of masks the problem.
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Old 20th March 2013, 08:31 PM   #4
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Location: Charlotte
You should post here:
DIY HiFi Supply - diyAudio
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Old 20th March 2013, 09:15 PM   #5
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Thank you so much for pointing me in the right dirrection. Very kind of you.
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