Mainline switches [resolved]

[bergurbrag]

Hi !
 I am a little bit worried when it comes to the voltage check. The Amp works well but to get high enough output I need to turn up the input signal almost to the top.

I have done the biasing and it is 145VDC on both sides. The rest is as follows:

+275vDC on the Power Supply Board    275V      269VDC
+6.3vDC on the Power Supply Board    55-65V   59VDC
 -6.3vDC on the Power Supply Board    50-60V   52VDC
IA on the A side C4S Board                    275V      270VDC
IA on the B side C4S Board                    275V      270VDC
Breg Regulator Board (both sides)    220V      215VDC
-reg Regulator Board (both sides)    0V          0VDC
Kreg Regulator Board (both sides)    8-12V     9VDC

Seem all ok but the input voltages to the PSB are 8,5VAC and 117,6VAC under load. I measured these secondary windings voltages as 135VAC and 9VAC before soldering them to the PSB. I used stranded wires of the same diameter as those solid ones that came with the kit.

Is this problematic ?

With Regards,

Bergur

[Paul Birkeland]

Using stranded wire in a kit is a really, really bad idea.  It's not a problem to have the level controls turned up almost to the maximum; that is relatively normal for certain headphones when paired with the Mainline.

[bergurbrag]

Ok, thank you for your answer. This is the only place I used stranded wire in the whole build.

I have some wire left, one that is not stranded, black and red and a drain wire in a black sheathing. The same that is soldered to to 6,3VDC terminals of the PSB.

Is it ok to use that wire ? I will off course trim off the drain wire.

Is the reading of 117,9 VAC and 8,5VAC ok under load ?
Are the other readings ok ?

Bergur

[bergurbrag]

... and I meant using Pre Out on an another amp. I need to turn the volume of that amp up quite a bit

[bergurbrag]

... I have measured the wire I would like to use and it is a hair larger in diameter both striped. I am talking about the one with a drain wire and a foil shielding.

Please advice me on this matter

[Paul Birkeland]

If the amp is working, I would leave it alone.  If you go in and start replacing wires, you're introducing the possibility that new problems are created.

Yes, the AC transformer voltages will decrease under load.  What is your powerline voltage and which wiring configuration for the power transformer did you use? I would imagine maybe you have something like 225V AC of powerline voltage and your amp is set for 230V nominal, which would be a situation that would predict the loaded AC voltages you see, and there's nothing out of the ordinary about that.

[bergurbrag]

Thank you for your advice. I live in a country with 230VAC mains. I have measured the voltage going in to the transformer and it is 230VAC.

I used a configuration for Greater than 225VAC and Less than 235VAC

I measured the diameter of the stranded one again and it was really bad. I could not leave it....
I went a head and changed the wires to the one I mentioned earlier, the one with a drain wire and foil shield. It improved the voltage read under load a little bit.
Before re-wiring I measured the transformer, with no load, and it was 140,7VAC and 9,5VAC

Thank you again for responding fast and professionally ! I appreciate it very much

[bergurbrag]

... and, yes, the amp still works beautifully