Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Hi-Q on August 06, 2013, 05:03:59 AM

Title: Low Crack Voltage
Post by: Hi-Q on August 06, 2013, 05:03:59 AM

Hi,
Sorry my english not good.

I measure the voltage PT-3 from output 149VAC. It seems correct, right?
The problem is terminal 13 (B+) measured only 150VDC.

Everything is working correctly.
But why B+ is too low?

Thanks!

Title: Re: Low Crack Voltage
Post by: Paul Joppa on August 06, 2013, 11:29:09 AM

We do not however have transformers with 100v primaries, as used in Japan. If you have 100vAC power, then you need a step-up transformer to generate 120vAC.

Title: Re: Low Crack Voltage
Post by: Hi-Q on August 06, 2013, 04:52:21 PM

Input voltage +-223VAC.

Measured output voltage is 149-150VAC.
The transformer labeled at 150VAC, I think it's already good.

Based on the calculation, I must increase secondary output higher than 160V. It means the transformer has wrong label, right?  ???

So how much secondary AC voltage needed to make 170VDC B+?  :o

Title: Re: Low Crack Voltage
Post by: Paul Birkeland on August 06, 2013, 08:45:50 PM

Please proceed with construction of the kit and report any DC voltage problems present (I do not believe you will encounter any).

-PB

Title: Re: Low Crack Voltage
Post by: Hi-Q on August 07, 2013, 05:45:06 AM

yes,
i already told you, my crack running well. ::)

my question is how much secondary AC voltage needed to make 170VDC B+?

Title: Re: Low Crack Voltage
Post by: Paul Joppa on August 07, 2013, 12:34:37 PM

Sorry, my mistake. 150vAC with 220vAC supplied to the 240v transformer, with the tubes operating, should be about 150vAC on the high-voltage winding. That should make about 155vDC with the Crack power supply, so your voltages are as expected, and within the range for correct operation.

Title: Re: Low Crack Voltage
Post by: netmask254 on September 09, 2013, 03:08:08 AM

Just want a double confirm: The 240V transformer shall work well with 220V input voltage without sound quality problem, is this correct? Thanks a lot!

Title: Re: Low Crack Voltage
Post by: Paul Birkeland on September 09, 2013, 05:30:20 AM

Ah, I somehow missed this.  Yes, 240V on the 220V transformer will work nicely.

-PB