Hammond M-103 Tube Organ

[RicharD]

Seems like one of our fine members has experience servicing Hammond organs.  I just picked up an old M-103 today for a whole $40.00.  I lit it up just long enough to see if it works and it does mostly.  I do know better than to run these w/o oil and I seriously doubt this puppy has had a drink in decades.  I'd love to get some tutorials on the basics of servicing these.

Thanks!
-Richard

Mods:
Feel free to move this to a different forum if you feel it's inappropriate here.

[Ritchie200]

Calling GroundhogKen!!!

Jim

[DummyLoad]

an m-100 with french provincial cabinet in cherry. 

[Rev D]

 The M100 series are great, and so affordable. The oiling system is a trough with wicks going to the bearings on the tone wheel generator assembly. Use ONLY hammond oil for it and it can take sometimes a month or more if they're frozen up.

 Anway here's the scoop, log onto www.organforum.com and they'll have oodles of info in the search area as well as some of the premiere organists and repair people around (kinda like Hoffman for Organs!). I promise you if you can't find it there, it probably isn't worth knowing. Good luck on a nice score!

Regards,

RD

[Tiny_Daddy]

I have ignored the hype and used 10W-30 oil for many years with good results. Comments anyone?

[LooseChange]

I have ignored the hype and used 10W-30 oil for many years with good results. Comments anyone?

DIY'ers are the best!

[John]

I have ignored the hype and used 10W-30 oil for many years with good results. Comments anyone?

Hey, if it's good enough for a V8, it oughta be good enough for an organ!

[RicharD]

Organforum daht com appears to be down this morning.  I joined a Hammond Yahoo group but they need to approve each of my posts + from browsing it appears to be much more cosmetic in nature and not technical.  On top of that Yahoo's layout is positively annoying.

The oil was my first question.  I know not all oils are created = but I was suspecting something more along the lines of 3in1 or sewing machine oil and not 10W30 motor oil.  I seem to recall when I was a kid, we used Singer sewing machine oil.  How's about Hunter ceiling fan oil?  Olive oil.  :P


>Calling GroundhogKen!!!

Yes, do come out and look for your shadow.

So I only ran the organ for less than 5 minutes.  Hammonds are built like tanks and i've driven a Chevy longer w/o oil.  I hurriedly checked out all the butts etc.  Upper and lower manuals work.  Pedals do not.  Main amp  (AO-29) works but hums and crackles.  That's to be expected.  I already planned on a cap job, grounded cord, and fusing.  The reverb amp (AO-44) appears to be not working or maybe not getting signal.  The AO-44 schematic is well worth a read for guitar amp builders.  It's a little push pull amp using 6GW8's.  The other tubes are a 12AX7 and a EZ81.  I think that's the poopular chassis to hijack into a geetar amp.  Vibrato is not working and neither is the percussion block so it's got a hand full of issues.  

I think it's gonna be a fun restoration project.  My wife isn't too happy about a big ol organ in the living room.  It's either gonna hafta go upstairs or find a new home.  Unfortunately nobody wants a Hammond unless it's a B3.  I think this particular organ is more restorable than a boat anchor, although it does weigh enough.

[GroundhogKen]

M's are great sounding organs--brighter than B3s, C3s, and A-100s.

Jon Lord played the Hush solo and the Deep Purple In Rock album on an M.

I'm pretty sure Green Onions was an M.

If the generator turns, down worry about the oil.  Over-oiling is worse than under-oiling.  You can buy some oil when you get the chance.

Replace the filter caps.  Install a grounded cord. 

You can fix the crackle by cleaning the tube pins and sockets.  Just spray some contact cleaner on a Q-tip and swab the tube pins.  Work the tubes in and out of the sockets and swab again.  Don't spray cleaner directly on the tubes.

Here's some recommended reading:
http://www.dairiki.org/HammondWiki/HammondMaintainanceAndTroubleshooting

Try to get your wife interested in the restoration aspects--bringing a piece of furniture back to its former glory.  (I know it's a long shot.)


Ken

[RicharD]

Ken,

Thanks for the info.  I didn't realize over oiling could be a problem.  The general consensus at the Yahoo group is to use only Hammond oil.  I found a place up the road in Houston that sells it so I'll get a bottle headed this way.  The generator does spin and the organ does play so I'm in good shape.  Tuning up the amps is the least of my worries at this stage.  I've got some serious cleaning to do first.  I'm gonna spend more on caps than I did on the organ.  That's nothing new here.      The hum and crackles came as no surprise.  I think the biggest surprise was the fact that it lit right up w/o an earth shattering kaboom.  Cosmetically it's got it's share of scratches, the front legs are cracked, and there's no bench.  first thangs first though.... time to read the suggested reading.

Thanks!
-Richard

[Dave]

I have bought and sold lots of them. Haven't found a dead one yet. Even the M-2's which are older seem to still be kicking around just fine.
I have heard of people using Type F automatic transmission fluid. And in a pinch I even used it myself one time. Works fine, but don't use it if the organ resides on a carpet. Yikes!
Cool find. I would buy all I could get my hands on at 40 bucks a pop.

Dave

[DummyLoad]

pics? 

[RicharD]

pics? 

please stand by

[RicharD]

It's gonna cost $100.00 for caps if I go with multi-cans.  I may cheap out and build a cap board or 2.  I broke out my wire markers and labeled the harness before I pulled the chassis.  Seemed like a wise thing to do.  There's an ocean of wires in there.  Somebody over-oiled this thang once upon a time whereas the main amp chassis is coated.  This might have paid off in the long run whereas the generator still spins freely.  There's a funny note in the link Ken posted where they guy says there's no mention of this over-oil indicator in the service manual.     Nowhere nearly as much dirt as I expected.  the AO-44 is a cool little chassis.  There is not a 12AX7 in there, I was mistaken.  There is however a 2N306 germanium NPN transistor.  Looks like the closest sub is a NTE103A, which is an $8.00 transistor.     I found NOS real McCoy 2N306's for less.  A unique circuit is a pair of #12 lamps in series between the source and the tank input.  Audio signal limiters.... simple & genius.

[Ritchie200]

Jon Lord played the Hush solo and the Deep Purple In Rock album on an M.


Ken

Now all you need is a line-out for the Marshall...
Jim

[Rev D]

 Can't recall the mod, but its easily done. Many use the line out to go to effects, other amps and in some cases Leslies they can't get adapters for. They made about a million different leslies. Other mod's are the Foldback mod which isn't difficult looking, just awkward getting the iron in there to do it and the thin resistance wire I'm told. The poorman foldback mod is as such:

&feature=related

 What the heck is it? On the upper manuals on organs other than B3's, C3's, A100's drop out a harmonic on the top manual at a certain point. Why is this a problem? Well its not unless you want the screaming high note the jazz/rock players play with the Leslie wailing. The mod restores the harmonic and its essentially wiring the top 18 wires or so to the keys instead of them going to I believe ground. Its just tedious, but for a amp builder wouldn't be hard at all. For the casual player it might not even be necessary but I know how we all like to tinker... 
 
 As mentioned, they're hardy beasts that refuse to die and the only thing that gets them down for the most part is caps and dirt and dust in the tone generator slider controls (can't recall they're real name getting old sucks...). Other things is the keystops on the bottom and top of keys but parts are readily available. Organ forum will be up, its kinda up and down and I believe it might be out of the UK I'm not sure, many of the guys there are and the response can be long enough at times where I wonder where its located. Oh well, thats about all I got, I researched them a bit as I really wanted one, but in my APT I just couldn't deal with a real tone wheel organ right now, so I use the laptop, midi controller and a software that gets close to tonewheel sound at least for a keyboard hack like me... 

Regards,

RD

[LooseChange]

Looks like tha M100 I've got on my bench. Did a cap job and the PT is bad.

[PRR]

> There is however a 2N306 germanium NPN transistor.  Looks like the closest sub

Is it busted?

Probably not, if nobody has been sticking strong signals in the hole.

If the collector is not sitting 5V-10V, then use "any NPN". The bias is hardly affected by transistor parameters, the gain is stabilized, current and voltage are quite low. A 10/$1 2N5088 may not have vintage hiss, but will work dandy.

[RicharD]

>Is it busted?

Dunno... haven't dug into it that far.  Something is keeping the reverb from working.  It could be most anything, I suspect either a dirty switch or a bad RCA cable.  My comment on the transistor was really more of an observation.  I like your pennies on the dollar solution should it be a bad piece of germanium.  That's good info to store for another service project that keeps coming back.  This guy is using an old tape recorder as a distortion unit.  It has a germanium transistor hanging right off it's input.  I've told him to be careful what he plugs into it.  It's headed back for a 3rd time.  Last time I put a coupling cap in front of it.

[RicharD]

>Is it busted?

Nope.  It actually has a LOT of gain.  I didn't bother to measure it but I did notice that at -40dB on my function generator drove the reverb amp pretty much full blast.  I cheaped out on the recap and used radial leaded Nichicons in lieu of can caps.  Price was a big issue but safety was another concern.  The 50/50 cap in the main chassis has the negative sitting at -22V according to the schematic.  Not exactly lethal but...........  I went ahead and added fuses to both chassis and of course a grounded power cord.  It has gotten too late to test the main chassis tonight, but I did light up the reverb chassis earlier and that amp is all good and very very quiet.  So quiet I didn't think it was working at first.  I need to do a little more research with regards to all the terminals on the main chassis before I light it up stand alone w/ speaker.  At a glance I think it's OK.  Looks like 5 groups, 120V power, pedals, vibrato, inputs, & percussion.  Fun project thus far.  Lotta contact cleaner.

[RicharD]

I reassembled the organ this evening.  The organ came back up with far fewer problems.  The reverb worked as do the pedals & percussion, but the vibrato was still not doing it's thang.  I found a bad 6AU6 and a miswire (my mistake) in the harness.  That got my vibrato working but now there was motor boating.  At first I thought I was in for a scanner rebuild (doesn't look like fun), but once I got behind the organ I realized it was only the reverb that was motor boating.  I swapped out the 6GW8's and motor boating ceased.  Alright!  98% good.  It's a really nice sounding organ.  The top manual with the percussion on is just so.... Hammond sounding.  The vibrato is rich and the reverb is 3 dimensional since the reverb speaker is 100% wet signal and a smaller driver.  2 issues left to resolve.  The start motor doesn't always want to engage.  I think lubrication and exercise will resolve that.  The sticky issue is I have 3 keys on both manuals that are not voicing the 1st drawbar.  Most likely it's broken wires and fortunately there's a cool "clickable" chart that shows me where to look.  It is however possible that when I moved it, I slammed a pickup into a tone wheel.  That might be bad news.  Looks like the trick is to scope the pickups.  I'll probably use a geetar amp as a stethoscope.  That's tomorrow's fun.

[GroundhogKen]

You're awesome Richard.

This thread warms my heart.

Identify whether the missing 1st drawbar notes are related to the specific keys or specific tones.  You can usually tell by trying to activate the tone using a different key and with a different drawbar.  If you can make the missing tone play with a different key and drawbar, then the problem is a key contact issue.  If the tone is missing everywhere, then its a tone generator issue which is usually no too difficult to fix.


Ken

[Dave]

If the keys that are not working the way you think they should are the uppermost keys on the right side of the manuals, then its probably normal. Read up on Hammond organ "foldback" and you will probably find the answer you are looking for.

My knowledge on the subject is not perfect but I'll give you an idea....
In the uppermost range of the keys, certain frequency ranges were ommitted (I think this was an attempt to make the percussion more apparent on those keys). This can be fixed by opening it up and resoldering some wires, but it is quite a task and the tone generator is very cumbersome to work with.

Dave

[RicharD]

Ken you are awesome.  That suggested reading link you posted has driven this restoration project.  So far, every question I've had has a pointer.  I've gotten more assistance from your link than anywhere else.  That's the nature of the Hoffman forum.

It's hard to believe people throw these things away.  OK sure, they're extremely heavy, they do only 1 thang albeit very well, and they are somewhat cumbersome to work on, but man they sure do sound great.  Of course my house is the island of misfit electronics so this thang fits right in.

The missing tones:
It's the same 3 keys on both manuals which are A2, D2, and E2.  The tone is only missing from the 1st drawbar on the lower manual and the 1st & 8th drawbar on the top manual.  According to the clickable chart, it looks like: 

(note, contact, contact)
A2 = 34  &  77
D2 = 39  &  82
E2 = 41  &  84

It looks as if these contacts are used by other keys so that leads me to believe it's wire related which apparently is more common than a stuck tone wheel.  Looks a bit like searching for a needle in a haystack.  "Fortunately I keep my feathers numbered for just such an occasion."

[DummyLoad]

 :glasses9: can't wait to hear it!

[RicharD]

I did not realize that with the percussion on, the 8th drawbar does nothing.  I rechecked the voices this afternoon and started out disappointed because I thought I had a dead drawbar.  About 1/2 way through, I realized the errors of my way.  Sure it's cool to dig on the percussion, but maybe not during testing.  This meant I only had 3 voices out, 34, 39, & 41.  That tone generator map is the bomb.  I followed it to voice 39, chopstick, viola, broken wire.  Exact same deal for 34 and 41.  I'm glad it's push back cloth wire because getting strippers in there woulda been a drag + the angle of the capacitor layout is not user friendly to a south paw solderer.  A little oil on the starter motor fixed that problem.  Cranks up first time every time now.

So...... It's working 100%.  That was almost too easy.  Now.... time for mods.  The first one is a no brainer/must have mod, a line output.


The 2nd is gonna be a bit more complicated and that adding bass to the lower manual.  It's probably the biggest shortcoming of this organ.  It has 1 octave of bass pedals, but I'm about like a 1 legged man at an ass kicking contest when I try to play them.  This is no easy task.

"The main problem to be surmounted is that the ToneGenerator in a spinet is missing some of the needed tones. To extend the range of the lower manual down one octave, one needs to add tones 6 through 17. The pedal tonewheels (1 through 12 (or 13, depending on model) are not readily useable for the lower manual. (The pedal tonewheels are "complex shaped" to produce tones rich in higher harmonics --- furthermore their pickups are wired in series, to support pedal sustain.) Tones 13 (or 14) through 17 are simply not present in the ToneGenerator."

[RicharD]

Well.... I think I'm gonna hack the Hammond up.  It's been fixed for ages and I never play it.  Nobody I know wants it.  If it was an A3, B3, or C3, it'd be a different story.  The missing octave and a half between the bass pedals and the keyboards is nothing short of annoying.  I smell 2 good guitar amps in my near future as well as some spare parts.  The keyboards may get used as a tube based synth ala Metasonix.

[DummyLoad]

Well.... I think I'm gonna hack the Hammond up.  It's been fixed for ages and I never play it.  Nobody I know wants it.  If it was an A3, B3, or C3, it'd be a different story.  The missing octave and a half between the bass pedals and the keyboards is nothing short of annoying.  I smell 2 good guitar amps in my near future as well as some spare parts.  The keyboards may get used as a tube based synth ala Metasonix.

dibs if'n yer gonna sell any of it. 

[RicharD]

I'll sell you the whole enchilada but you gotta take the whole thang.  Name yer price.

[DummyLoad]

I'll sell you the whole enchilada but you gotta take the whole thang.  Name yer price.

i'll call you this afternoon.