[HAM] Source for B3 Service Manuals and other info.

[Karlo Lovric]

----- Original Message ----- 
From: "Scott Hawthorn" <organfreak at donobi.net>
To: "The Hammond Forum" <hammond at zeni.net>
Sent: Sunday, March 30, 2008 11:01 PM
Subject: Re: [HAM] Source for B3 Service Manuals and other info.


> At 12:55 PM 3/30/2008, jshanks wrote:
>>jshanks wrote:
>>I'm looking for a source for service and repair manuals for a B3.  I've
>>found quite a bit of helpful info on the Internet, but nothing like an
>>online troubleshooting guide and a service manual with standard procedures
>>and schematics would really be helpful.
>
> I'm not sure where you can get the manual these days, but I can assure you
> that it contains very little in the way of troubleshooting guides.
> Schematics are readily available though, at <www.captain-foldback.com>
>
>>I've gotten the old B3 up and running.  It sounds good, but has a bit of a
>>strange problem.  When the vibrato is turned on, on either register, the
>>volume output is very low.  The vibrato scanner seems to be working just
>>fine, the very quiet sound from the organ does have a distinct vibrato.
>>I've swapped around the tubes thinking that maybe one was bad on the
>>vibrato channel.  Didn't help.
>>Now, and please tell me if I'm wrong, I believe that their is either
>>something wrong with the output signal to the vibrato scanner or I have a
>>blown component in the preamp clipping the signal.  Without the schematics
>>and troubleshooting guide, this is tough.  Anyone have any ideas?  A
>>complete theory of operation for the preamp would really help.
>
> You were smart to realize that there are two separate channels, and to 
> swap
> the tubes. How did you figure out which tubes without a schematic? It's
> quite common, not "a strange problem" at all, to have trouble in one of 
> the
> channels. You may have failed resistors in the vibrato channel, or the
> infamous "zinc hair growth" (which is the source of many frustrating
> short-circuits) in the vibrato switches themselves, solved by so-called
> flashing, where a voltage is applied to the offending circuits in order to
> burn the hairs away. The safest route for that is to use three 9V 
> batteries
> snapped together. Grab the schematic, look it over, and come back with
> questions.
> >


why three batteries? I did it with only cca 3V from the analog ohmmeter.
Have I had different problem, or just not that bad?

Karlo.