Bottlehead Forum

Bottlehead Kits => BeePre => Topic started by: ericoto on January 24, 2015, 04:07:55 PM

Title: Help with new BeePre [solved]
Post by: ericoto on January 24, 2015, 04:07:55 PM

Just finished BeePre 2 days ago, when I started out 300b do not light and LED's on B c4s board do not light, both channels. I looked over construction, remelted some connections, I did find that I had not placed a jumper between neg out and - reg, rechecked and soldered rectifiers diodes to terminals 6&7 of transformers, but none of these changes had any effect. Resistance checked out fine, I have moderate kit building experience. Current voltages are
terminal   expected   measured
1                  5                 0
2                  90-110        166.1
3                  0                 0
4                  9.85            10.63
5                   0                 0
6                   146             168.2
7                   0                 0
8                   0                 0
9                   0                 0
10                 186             193 
11                 146             180.3
12                  0                  0
13                  0                 0
14                  0                 0
15                  186             192.8
16                  5                  0
17                  90-110        178.8
18                  0                   0
19                  9.85             10.64
20                   0                  0
Any help appreciated. Thanks

Title: Re: Help with new BeePre
Post by: Paul Birkeland on January 25, 2015, 07:24:37 AM

I would wonder if the fat pins on one of the 300B sockets aren't oriented properly?  It looks like you have voltage to heat the 300B, but it's not making it through the tube itself.

-PB

(PS - thanks for your thorough post)

Title: Re: Help with new BeePre
Post by: ericoto on January 25, 2015, 08:29:40 AM

Thanks for response, I realized I was testing without 300b in place, replaced and now all voltages spot on. both sides, all leds light up. Still one channel not yet in, suspect poor solder in switches, about to reinspected and resolder.

Title: Re: Help with new BeePre
Post by: ericoto on January 25, 2015, 08:57:51 AM

Still having issues with left channel, still no sound only a strange "submarine, underwater " low frequency rumble" type sound that doesn't change with volume control. Can occasionally hear distant music on some input selector settings. Solder junctions at input, balance volume and output all look good.

Title: Re: Help with new BeePre
Post by: Paul Birkeland on January 25, 2015, 10:45:27 AM

So the voltages are all spot on?  The low frequency rumble would suggest that you may have gotten the hot and the ground backwards on your output wiring (going from T-strips back to the output jacks).

-PB

Title: Re: Help with new BeePre
Post by: ericoto on January 26, 2015, 01:31:43 PM

Thanks again, last night could not finish, but just found ground wiring error and preamp now works and sounds great! Low frequency rumble I heard was microphonics from 300B. Playing through Bob Latino M125 monoblocks I made last year. Sound is clear and dimensional. Overall very pleased, kit was easy to construct, although challenging. Thanks again for help and now I need another project, perhaps the attenuator.  ;D