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Bottlehead Kits => Crack => Topic started by: koendersav on November 29, 2021, 12:24:55 PM

Title: Crack Voltage reading final step very high
Post by: koendersav on November 29, 2021, 12:24:55 PM

Hello there!

I'm curious if anyone can verify if the voltages are correct. I have arrived at the last step. measuring the voltages on the terminals. The tubes light up nicely, the LEDs light up. I am in the Netherlands and the power supply is set to ''Voltage greater than 235V AC and less than 245V AC'' .
At the start of the build I measured 6.5v at terminal 7 and 9.
At terminal 11 & 12 this was 185v

Now at the last step, these are the voltages I measure. Is this correct ?

1 - 183v
2 - 402v
3 - 0v
4 - 402v
5 - 184v

6 - 0v
7 - 243v
8 - 0v
9 - 249v
10 - 0v

Title: Re: Crack Voltage reading final step very high
Post by: Paul Birkeland on November 29, 2021, 03:34:40 PM

This is an issue that I would expect to see if one of the solder joints along the trail of black wires is not well soldered.  In particular the joint on the headphone jack where the black wires meet seems to be a tough solder joint to get right, as one wire will often not be captured by solder.

Definitely don't use the amp till you get this sorted out, but also don't be too alarmed at the voltages you're seeing as they are being thrown off by the above issue.

Title: Re: Crack Voltage reading final step very high
Post by: koendersav on November 30, 2021, 12:47:59 AM

I think it was late last night..
I had set my multimeter wrong. Instead of measuring DC the meter was on AC.. just measured again but good,

1 - 85v
2 - 184v
3 - 0v
4 - 184v
5 - 85v

6 - 0v
7 - 111v
8 - 0v
9 - 113v
10 - 0v

Do i need to bring down the input on my power transformer ?
if i step down to ''greater than 225v and less than 235v
then i read between terminal :

7-9     = 6.0v
11-12 = 170v

Or is it better to have a higher voltage in this story? as i have it now

Greetings

Title: Re: Crack Voltage reading final step very high
Post by: Paul Birkeland on November 30, 2021, 04:52:31 AM

Either way is going to work fine. 

Title: Re: Crack Voltage reading final step very high
Post by: ajm3s on December 22, 2021, 07:31:06 AM

Instructions allow for 20% variation for initial voltage check.

7-9     = 7.44v  [6.5 VAC]
11-12 = 204v [175 VAC]

The resistance check was as expected.

Final voltage check

1 - 81v
2 - 210v
3 - 0v
4 - 210v
5 - 81v

6 - 0v
7 - 119v
8 - 0v
9 - 119v
10 - 0v


Should I be concerned since the final voltage check states a 10% variation in voltage output from  stated DC listed?

No audible issues, sounds excellent.
FYI 122 VAC @ wall outlet

Al

Title: Re: Crack Voltage reading final step very high
Post by: Paul Birkeland on December 22, 2021, 07:56:07 AM

That's OK.  You have a 12AU7 that's probably around 75% and a 6080 with high emission.