hammond h-100 loud roar on power up

[baldwin 46c]

i just finished putting back together an h-100 . when i power it up none of the keys produce sound , all i hear is a loud roaring sound ! all the tubes test good , all connections i checked and re checked and all seems ok , i even replaced several small electrolytic caps and resistors in the power amp , the film coupling caps in the amp i checked each one and they are all good .
this organ worked ! then i took it apart in order to be able to take it home.
i put it all back together very carefully , i also have a service manual but the problem i am having is not mentioned in the manual .
has any body any suggestions or tips as to what is going on ! HELP !

[enor]

Most likely you've either miswired something, or forgotten to hook something up. When you say "roar"... what exactly does that mean? Post a little video clip of the problem.

[baldwin 46c]

HI ! you could be right but i cannot find where there might be a disconnection or break or god knows what ! i triple checked and re checked , as for the roar ! when i power it up the roar sound comes from the speakers and as its roaring i try playing some keys but none of them respond .
the roar or loud hum sound is very loud and the foot pedal volume has no effect on it when i try to lower the volume that way .
to avoid further damage i am forced to shut the power off .
P.S the hammond service manual SUCKS ! even though its an original one which was acquired by the previous owner at some point . it lacks proper assembly instructions and lacks a parts list and no photos of where boards should be located in the console .
and worst still the wiring schematics show the destination points but it fails to say what that board is and also connections on the stop tabs are there but the stop tabs are not labeled as to what they are .

[Jaim]

It would be helpful to isolate the main amp from the rest of the organ. Does the volume soft have any effect? At this point in the signal chain there is a channel A & B. At the soft tab, try grounding the shielded cables. Any effect?

Jim

[Jaim]

One other thought - is the reverb connected correctly? You could try putting a RCA shorting plug on the reverb input jack.

Jim

[baldwin 46c]

yes the reverb is connected correctly , i also tried with and without the reverb in the system but no change .

[Jyvoipabo]

You replaced some parts on the amp.
Voltage check : Usually when we do that, then we check all the voltages on the amp. This will be done on the bench table. Did you do this ?

Hum hunting : You can also remove the tube one by one except the penthodes that must be removed by pair till the hum disapear.

JP

[baldwin 46c]

no the amp is not the problem , i removed the amp and its power supply and hooked up test speakers and fed a signal from a cd player and all 3 channels worked and sounded good and no hum of any kind .
so the problem has to be up stream somewhere . i checked and re checked all connections and still am not able to isolate what is causing the problem .. on power up after warm up all i hear is a very loud hum and none of the keys respond when pressed .
i am now at my witts end
the service manual that i have is of little or no help , it does not even have a parts list .
i know how to read schematics , but this factory issue manual i am sure it is not complete or accurate , lots of the wiring connections go to unmarked terminals or stop tabs that are not named or labeled in the diagram and a lot of guess work is involved .
and worst still some connections shown are in reverse of what they actually are in the organ .

[Jaim]

The Non vibrato and vibrato signal paths use different preamp boards. If the vib and non vib result is the same, I would have to believe either the voltages going to the bds are suspect or the signal flow through the tab switches is interrupted.
I had an H manual, but relied on a schematic to trace signal flow.
The hum is probably due to a floating input to the main amp. Have you tried grounding the preamp output?

Jim

[Jyvoipabo]

the roar or loud hum sound is very loud and the foot pedal volume has no effect on it when i try to lower the volume that way .....
...and the amp is not the problem
.

Yet the problem can only be between the pedal and the speaker.
Else the pedal would have an action on the hum.
JP