Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Balticnoiseforge on March 16, 2023, 06:27:31 am
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Hallo iam inside digging in a old Laney VH100R doing several things.
But there is something iam wondering about considering the filament supply.
My laney has a 4 wire heater
Blue: 0
Grey: 3.4
Grey: 0
Blue: 3.4
The blue wires are going to the tube pins while the greys are soldered together into ground, i tried having them ungrounded and got same voltage on the heaters.
But thing is, i want to try elevate the heaters to make the amp less "noisy" as one of the things to try improve it.
But since this is a unusual heater setup could feeding the grey cables soldered together voltage cause any issue? I assume it would be okay, but have not stumbled upon this before.
Laney later made them with just a CT that they also fused with 5a to ground, which would be seen if you are looking at a schematic.
( Picture is not of my amp, but same model - there in right corner you can see the two grey cables going to ground and the blue wires to pins. )
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The center tapped 6.3v filament winding is actually two separate 3.15v windings connected in series to give 6.3V total. Usually a transformer manufacturer will make the series connection internally and only bring out a single wire as the center tap. Other times, the manufacturer will bring out all 4 wires of the two 3.15v windings and in this case the user needs to make the series connection outside the transformer covers. This sounds like what you have. If so, you must leave the two grey wires connected together and connect to your elevated dc source.
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Thanks, it is basically acting as a standard CT then. Thanks for info regarding inner works of transformer.