Hammond T-212 multi trigger percussion help

**T-200** · 07-05-2012, 03:42 PM

Are the vibrato and non-vibrato sounds otherwise OK? Just a thump when switching? If you have checked all the wires and connections and cleaned the switch, there must be bad components/soldering on the vibrato board. Check the backside of the vibrato pcb to see that the soldering and everything else is fine. Then you can use our famous "tap and wiggle" method to find the faulty components

. You can tap the transistors, caps and resistors with your finger one at a time with power on (low voltages, very safe). If you hear any strange noises tapping one, it's broken and needs to be replaced. I found over a dozen bad caps like that. Anyway it's good to replace all the electrolytic caps in your T, they may be dead already.

If this doesn't help, I don't know what would...

Jussi

**Teachveech** · 07-05-2012, 04:12 PM

I poked around a bit and I. I Noticed that when I unplugged the green wire on the intermediate amp (pin 7) that ends up at the vibrato switch, that this boom dies down in volume however I loose functionality of the lower manual and the vibrato distorts (I did the mod that gets rid of distortion). I also noticed that pin 7 is located directly above a resistor (4.7k) that I added during the intermediate amp mod (the resistor isn't burned out or anything). Also the percussion mod with circuit yielded the same results (huge volume loss, no decay) exept it returns to normal volume when I turn on the reiteration and the single trigger works only when the reiteration is on.

**T-200** · 07-05-2012, 04:34 PM

I'm sorry but I'm a little confused now... It would be good to know what mods have you made in what order, what problems did those mods make, what mods did you reverse and did the "unmodding" return everything as it was. You had some distortion first, then it was gone. You had the vib switch boom, then it was gone, then it came back. You lost the percussion decay, did it come back when you reversed your mod? Etc.

Carsten's instructions are very good but you have to be very careful to change the right components in right places the right way. I managed after three trials...

Jussi

**Teachveech** · 07-05-2012, 05:08 PM

First I removed all the filter caps from the bus amps then I tried the quick fix percussion mod which didn't work so I reverersed it. Then I successfully changed the percussion voicing. After that I attempted the intermediate amp mod where I screwed up putting the components in (I forgot to use a heat sink and I almost burned the board) which caused lots of distortion to occur so I went back and repaired the damaged parts which got rid of the distortion, that's when the vibrato boom started to happen. Then I replaced a resistor in the vibrato amp to get rid of distortion which worked. And lastly I built and installed the single percussion circuit in the organ and got the volume drop and endless organ like sustain as long as the keys were held (no decay) I have not reversed the percussion mod.

**wagonman76** · 07-05-2012, 05:10 PM

Pin 7 is a good start. So the boom quits when pulling pin 7.

Put back pin 7 and try pulling pin 8. Does the boom return? Try it with the vibrato switch both on and off.

Same thing, try it with individually pulling pin 5. Then with pin 6. Then with pin 4. Then with pin 9.

Let us know what you find. Hopefully we can narrow this down to one part of the preamp, or some other part of the organ.

**Teachveech** · 07-05-2012, 05:42 PM

I got a boom when I tried all of those except when I pulled pin 4 the volume of the boom died down

**wagonman76** · 07-05-2012, 11:24 PM

Assuming you pulled each pin individually and not with others, you say pulling pin 7 or pin 4 made the boom die down. Since it didn't die down when you pulled pin 8, it's not the lower busamp. And no change with 5 or 6 means it's not the upper busamp or that part of the intermediate amp. And the boom dying down when you pulled pin 7 means it's not the percussion causing the boom. And no change when you pulled pin 9 means it's not the vibrato board causing the boom.

So it looks like the boom might be caused by one of the components on the right side of the intermediate amp circuit board, below and between pins 7 and 8. I'd check them real close. And make sure all connections are good, and no solder is bridged where it shouldn't be. Also double check to make sure any components you moved or replaced are in the correct holes. The way Hammond made these boards with all the extra holes makes it real easy to screw up if you're not extra careful.

I had a problem recently with one of the resistors in the same area of the intermediate amp gone bad and causing a horrible hiss and crackle.

As for the percussion, I'm not sure right now except to put it back how it was and let's go from there.

You pull pin 4 or 7 and you say the vibrato distorts and you only have the upper manual. With no pins pulled, and you play these same notes on the upper manual with the same vibrato and drawbar settings and all else, do they still distort? If they do, then you might need a higher value resistor on pin 6.

Also, since adding the resistors on pin 6 (upper manual) and pin 8 (lower manual), are the same notes louder with vibrato on than off? You might need to adjust the vibrato balance pot on the vibrato board so it is the same volume with vibrato on or off.

And once you get the percussion straightened around, you may also need to turn down the percussion volume pot on the percussion board (don't remember which one of the 4 pots it is right now). That will put the percussion volume back similar to how it was before adding the resistors on pin 6 and 8. It should also reduce or eliminate the percussion distortion.

**Teachveech** · 07-06-2012, 02:30 AM

without any pins pulled there is no distortion even when the vibrato is on. The volume of the organ noticeably decreases when the vibrato is switched on. My percussion mod still doesn't work for some reason I soldered the wires and components according to the diagram.

**wagonman76** · 07-06-2012, 03:46 AM

You can turn up the pot on the vibrato board so the volumes will be the same with and without vibrato.

I haven't done the percussion mods so I'm not really that familiar with it. I think I should clean the busbars first. A few of my keys already lock out other notes as long as they are held. I don't use percussion a lot, but I don't think I'm going to change the voices. I like them all except guitar and banjo, and even they may have a use eventually.

Just one bad component and the mod might not work. And it might not even be anything you did. These organs are old. The resistor that went bad on mine looked fine but tested about 30% too high. But you just keep getting more familiar every time you tear into it. These organs are quite the learning experience, and I'm still learning a lot, and it is quite rewarding. I'm not that great with electronics either. One thing that really helped is download the T series schematics at the captain foldback site. I printed the big ones on a large roll of plotter paper at my work.