Need Help

[rockpassion]

I need some technical help with my BeePre.  I replaced the 300b sockets which meant I had to take off the C4s boards and detach all the wires from the sockets.  In checking the Resistance and Voltage everything is within the limits given in the construction manual.  The one exception is terminal 17, the Voltage should be 90 - 110 Vdc.  I am getting 0.  I have checked everything a dozen times.  I did find I had miswired the connections to B2 and B3, I had them reversed.  I fixed that mistake.  I checked the Capacitor connected to this terminal and it was within spec.  At this point I do not know what to do next. 

I do not know if this has any bearing on the problem.  One of the reasons I changed the socket was how loose the 300b was in the socket.  However, before I started working on this the 300b on the side I am having problems popped and flashed and I lost sound from that tube.  I turned off the system and turned it back on and everything seemed to be ok.  Although, not all the wires on the heater grid lit up and I also got a purple glow for a while inside the tube. 

Any thoughts.

Thanks in advance for any help.

Richard

 

[kgoss]

An easy first test is to swap the tubes to see if the bad voltage follows the tube.

 

[Paul Birkeland]

You can also swap the big C4S boards between channels.  Often times a problem like this is simply a broken wire (likely the one from "OB"), as a C4S with issues will tend to give the regulated B+ voltage instead of 0V.  Perhaps the wire from OA to IB on that board is broken instead? 

 

[rockpassion]

Paul,

Thank you for the suggestions.  Here's what I have done since your suggestions.  I changed the C4S boards swapping one side to the other, I changed all the wires and resoldered all the terminals that pertain to the C4S boards on both sides.  The good news is that all the Resistance and Voltage are per the spec with two exceptions.  Again, it is the Voltage at terminal 2 and 17.  The terminal at 2 is reading .32 vdc and at terminal 17 it is reading -.17 vdc. 

In removing and replacing the wires on the boards could I have burned out the trace connections in the board.  Or could the capacitors be bad.  Although, I did measure the capacitors and the both measures at 9.66 pf approximately. 

At this point I am stuck, what do you think should be my next step. As a side note I replaced the 10 uF capacitors that came with the kit with russian caps of the same value.  They have been working fine and sound really nice. 

Thanks again for any help you can provide.

Richard

 

[Paul Birkeland]

Can you post some photos of the build? 

The capacitors are not bad.  I really doubt your burned a trace.  (I'm not sure I ever have on any of our masked boards)

 

[rockpassion]

Hey Paul,

Once again thanks for the response.

I will get pictures by Monday or Tuesday.  I hope I just have something miss wired. Maybe your second set of eyes can find it.

Richard

 

[rockpassion]

Hey Paul,

Due to some recent medical issues I am not going to be able pursuiing continuing with the repair of my BeePre.  I have changed the stock bypass caps to a Russian variety.  As a result, because they are not stock I cannot return them to Doc for repair.  The Bottlehead site said you are available to do this.  Is that true?  If so how much do you charge?

Thanks

Richard Vince

 

[Paul Birkeland]

Well, you could put the stock caps back in, then send it in for repair.  I am also available to help with your repair as well. 

-PB