Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mresistor on December 19, 2020, 01:35:40 pm

Title: Hammond S6 organ transformers identification help
Post by: mresistor on December 19, 2020, 01:35:40 pm

Good day all.  I dismantled an old Hammon S6 organ some time ago and forgot to label a couple of the little transformers that were used as input and output transformes paired to two 6BA6 pentodes in the solo control section. Which one is the input and which is the output for the 6BA6 tubes?
I have taken ohm readings for them.  The transformers are labeled AO-26361-0 annd AO-26363-1.  Schematic link is below.  Solo control is in the upper right side.


AO-26361-0   input 446 ohms
                    output  ct to one side 998 ohms
                                ct to other side 1119 ohms
                                once side to other side 2.2 ohms


AO-26363-1   input  447 ohms   
                     output  ct to one side 5 meg ohms  ( funky readings on the output side )
                                 ct to other side  5 meg ohms
                                 one side to other side  262.5 ohms   


 https://web.archive.org/web/20060504081905/http://users.rcn.com/clonk/ChordOrgan/Schematics/Figure6.gif (https://web.archive.org/web/20060504081905/http://users.rcn.com/clonk/ChordOrgan/Schematics/Figure6.gif)


here is a snippet 

Title: Re: Hammond S6 organ transformers identification help
Post by: mresistor on December 19, 2020, 01:50:32 pm

I think I may have figured it out..  Generally I have seen that the wires from output transformers that connect to the plates of tubes are color coded red-blue-black(or another color) and these wires are usually larger guage wires.


The AO-26361-0 has red-blue on one side and I think they were connected to the plates of the preceding 12AU7 preamplifier with the three output wires of smaller guage connected to the grids of the 6BA6 tubes.


The AO-26363-1 has three larger guage red-blue-brown on one side and I think those wires were connected to the plates of the 6BA6 tubes while the smaller output wires were wired to ground and the other to a cap and then the grid of V20 preamplifier,   

Title: Re: Hammond S6 organ transformers identification help
Post by: thetragichero on December 19, 2020, 07:48:36 pm

can't find much information on these but if you're able to put a small ac voltage on the plate wires of the primary (say 10vac?) you can calculate the turns ratio and from that primary impedance

Title: Re: Hammond S6 organ transformers identification help
Post by: PRR on December 20, 2020, 12:14:37 pm

> funky readings

Auto-range DMM? Short another winding while you measure a winding. The high inductance confuses the auto-range; a short on any winding makes all windings far less inducty.

But what are you going to do with these parts? It's not a power amp, not a sensible preamp.

Title: Re: Hammond S6 organ transformers identification help
Post by: mresistor on December 20, 2020, 04:50:59 pm

Hi PRR - just want to know which one was the output transformer ..      alas  true  I might never do anything with it ..