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Bottlehead Kits => Crack => Topic started by: jeffreyperr on May 02, 2016, 03:58:15 AM

Title: Strange voltages on speedball boards after installing film capacitors
Post by: jeffreyperr on May 02, 2016, 03:58:15 AM

Everything on the amp was working great until I replaced the 100uf electrolytic caps with two 250v 100uf Erse Pulse X film caps. When I did a voltage check on the Speedball boards I got the following voltages. While I was installing it one of the speedball wires did break but I replaced it. Do these voltages mean I wired something wrong or is there something special I'm supposed to do to use film caps? Any help would be great! The voltages are below.

Small Speedball board...
0A:178.3V
1A:185.9V
A/B:113.5V
1B:185.5V
0B:177.7V

The correct voltages would be...
0A:60-90V
1A:170-270V
A/B:0V
1B:170-270V
0B:60-90V



Large Speedball board...
0A:177.5V
0B:177.3V
G:112.1V
B+:185.7V

The correct voltages would be..
0A:75-100V
0B:75-100V
G:0V
B+:170-195V

Title: Re: Strange voltages on speedball boards after installing film capacitors
Post by: Doc B. on May 02, 2016, 04:55:28 AM

Voltages will not change when you change the output caps. Ergo, you have a bad connection somewhere. You may have missed another broken connection.

Title: Re: Strange voltages on speedball boards after installing film capacitors
Post by: jeffreyperr on May 02, 2016, 05:06:37 AM

Could a broken connection cause there to be voltage on the ground terminal?

Title: Re: Strange voltages on speedball boards after installing film capacitors
Post by: Doc B. on May 02, 2016, 02:23:17 PM

Yes, you need to reinspect all of your solder joints.

Title: Re: Strange voltages on speedball boards after installing film capacitors
Post by: Paul Birkeland on May 08, 2016, 08:10:59 AM

I would wonder if your 12AU7 is still glowing?