Speedball OB Voltage 170V [resolved]

[hodg68]

Hello all,

I'm currently building the crack + speedball kits and have run into a snag. I completed the crack system last night and it sounded great! Today I started on the speedball and ran into no issues until conducting the final voltage check. When the large board is connected to the terminal rails my voltages are as follows:

Large Board:
OA = 103.6
OB = 170V
B+ = 172.2
G = 0V
OB= 72.3V

Small Board:
OA = 171.6V
IA = 173.7V
B-A/B = 0V
IB = 173.7V
OB 72.3V

Additionally, the two LEDs that are closest to OA do not light up.

Before I connected the large board all my voltages and resistance values were within spec. Any suggestions would be really appreciated!

Best,
J.D.

[Paul Birkeland]

If you pull the 6080 and run the amp with just the 12AU7, does that resolve the voltage issue on the small board up front?

[hodg68]

Hey Paul,

Thanks so much for your quick reply. Just removed the 6080 and the voltages on the small board are now (I think in spec):

OA = 74.5V
IA = 223V
IB = 223V
OB = 70.8V

Also, all of the LEDs on the small board are now lighting up.

Thanks

[hodg68]

Let me know if sending pictures of the build would help troubleshoot. I'm stumped. The 6080 tube worked great last night so I wouldn't think that the tube is bad.

[Paul Birkeland]

It would be a good idea to post some build photos.

[hodg68]

Attached are some picture of the build.

[Paul Birkeland]

Everything that's not an LED on the big PC board needs substantially more heat from your soldering iron to be properly soldered.

[Doc B.]

[hodg68]

Thank you Paul and Doc B! After going through and reheating both the large board and the small board on the speedball it works perfectly! My final voltages are:

Large Board:
OA = 107.9V
OB = 110.7V
B+ = 184.1V
G = 0V

Small Board:
OA = 75.3V
1A = 184.4V
B-A/B = 0V
1B = 184.4V
OB = 72.2V

The OA and OB on the Large Board are a little high but I read on some other posts that these numbers can come down after wearing in the tubes. Here are some completed pictures! It sounds amazing through my Yamaha MusicCast WXC-50 and Sennheiser 800S.

Thanks again for your help!

[Doc B.]

Well done!

[Karl5150]

Nice finish all around, glad you got it sorted.
Karl