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Old 3rd August 2012, 01:35 PM   #11
diyAudio Member
Join Date: Nov 2011
i measured the red wires 360volts! the etiquette on the transform says red should be 260...

where do those 100volts come from?

for input i choose the blue wire with has to be for 230 input.

the orange are 6.4volts this should of course be 6.3.

link to transformer information

Last edited by mrneedle; 3rd August 2012 at 01:44 PM.
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Old 3rd August 2012, 04:32 PM   #12
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Location: Near Dallas Texas USA
Are you measuring between the two red wires, or measuring each to ground? Measuring them to ground may not give an accurate reading (depending on your meter) becasue of the bridge rectifier.
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Old 4th August 2012, 10:54 AM   #13
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Ok i measured again, 283volts. So I now used the brown wire for 240volt input and the. Measured again. It then gave me 261volts. The orange wires only gave 6.1volts.

Then I looked over the layout again. I noticed the gray wire, from 1uf cap to The volume potmeter. It is the ground to the chassis. The input jack is grounded to the chassis, so then I directly solderded a wire from the input ground to the 1uF cap. And the whole thing came to life... Seems the ground to the chassis is not ok. It still has a bit of a 50hz hum but this is ok for now.

Still I wonder, why did I get sound when switching of the amp?
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Old 4th August 2012, 07:27 PM   #14
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The generally accepted tolerance for heater voltage is +/- 10% so you are ok.

Single ended amps always have a little bit of hum. Hard to say why you got sound when the amp was switched off.
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Old 4th August 2012, 07:54 PM   #15
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Ok thats good to know but ive spend some more time playing guitar and the hum is to much. And gets louder when turning up the volume?

Ive added a second bridge rectifier for the 6.3 volts orange wires but doesnt change anything..

Also i did get a reply from the website owner provider of the diagram he said i should replace the first 1k resistor with a 3watt resistor, i only had one 5 watt resistor so i added the 1k 5 watt resistor but it stll get to hot to touch!
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