Need advice on Lost Channel On Prototype Reduction Unit with Integration

[JDeiner]

I have built a number of Bottlehead Kits and love them. I needed a phono preamp fast and took the easy route by purchasing the prototype Reduction Unit from Bottlehead. I have used it sparingly over the last year or so (it sounds great however!!!). Recently I lost a channel. I switched tubes and phono inputs but the problem remains in the left channel. I have the manual but the prototype is wired differently and I don't want to dive right into it.

Any advice on trouble shooting the unit? Some logic or starting points would be greatly appreciated.

Thanks!

Jim

 

[Grainger49]

I would still take the resistance readings.  Post any out of spec by more than 15%.  The same for voltages.

Bottlehead will sort out the differences.  But having that information here to begin with will give them a foot up.

 

[JDeiner]

Thanks,

I will do that. One thing I should have mentioned is that the channel went from weak to distorted to nothing. I was thinking it may be a bad cap, but they are new.

 

[Doc B]

Check the heater voltages at each socket and make sure the tubes all glow.

 

[JDeiner]

One is glowing noticeably brighter than the other. Will check voltages.

 

[JDeiner]

And now both channels work after switching the tubes back and forth a couple time while swearing. I am going to leave well enough alone. Thanks for the help.