Hammond X77 Owners Corner

[indianajo]

Andy keeps telling everybody how essential to the organ experience a Leslie is, especially to the X77, and I wonder. I like the simulated stereo vibrato I get from my H100 just fine. I don't use all that much vibrato, anyway, just as a garnish.
Running all those X77 signals out through the legs to an external power amp, and possibly back again to a reverb tank, runs of 3 to 8', was just asking for hum. I hear they got it.
The H100 is very similar to the X77 but the runs are about 3' to a 3 channel power amp, back up to the reverb switches, and down again to the power amp. That works fine. No hum.
So IMHO copy the H100 wiring. The schematics are on archive.org: the whole service manual. The precious metal plate tab switches are a great feature, it is just al that wiring that was not, IMHO. The cool thing, you can put a digital reverb effect up in the top, not all the way down past the power amp on the low keys end. With a wall transformer driven effects unit, you don't even have to run 120 VAC up in to the high gain area of the tab box. The power amp would fit up in the top, too, with IC amps.
With high performance tubes being a scarce commodity, energy costing $.42 a KWH, and everybody hating the H100 so badly for the sound of the 71 dried up electrolytic capacitors they are never going to change, I'm thinking of putting the whole power amp up on top of the keyboards of my 2nd and 3rd units, shotgun replacing everything original with modern parts. Replacing the whole electronics package after the four 12 pin AMP plugs on the back of the tab box. Also making a few of the same for sale, if all the H100 haven't gone to the landfill already. It is a marvelously expressive organ, all under tab control, no screens or levels of menus or pre-programming required of your song performance.
As far as programmed squences of custom sounds beyond the four available on the drawbar sets, I think I've figured a way to do that without custom displays that will die in 5-10 years, rubber contact buttons that will die in about the same time, and software that will be force updated bi-annually by hardware changes to fill microsoft's or whoever's purse. I just bought 160 pin blocks, to go on program boards, swept by analog switches, to program up to a dozen sounds in sequence like a dozen sets of drawbars, and count through them with a couple of pistons for thumbs or kick pedals, for counting up and down through the sequence. All this should also fit in the open space above the keyboard, with the program boards maybe swinging up to face the player as he programs with $.02 jumpers. Or just flick through a dozen touch switches to access programmed sounds like a dozen sets of drawbars set up already.

[Admin]

I agree that it should be a fairly easy connect, but it is not consistent. I therefore have to conclude that I have some further electronic problems within the X77, and not just switching issues. I know that by-passing a Leslie for a neo-ventilator is just wrong, but having shown the X77L to a seasoned Hammond friend reinforced my attitude that it is a mess. This pairing and the block diagram in the service manual showing the signal routing confirms this was a bad idea, in any world. I wish I had found an easier TWG when I thought about getting back into keyboards. Thank you for your input.

Most all of the problems found X77, intermittent signal, crackling, pops, hum and RF originate in the console due to lack of shielding, bad wire routing practice, bad switch contacts, and crappy push on connectors used for point-to-point wiring connecting the internal circuit boards. All these problems can be overcome with a bit of knowledge and effort. The X77 Leslie is not the weak link in this system.

Often Hammond "afficiandos" are fixated on one model, the B3 and the B3 only. The X77 sounds like Hammond, but not a B3. If you think that the greater variety of sounds that can be produced by the X77 by virtue of channelization and switching is unecessary, and you've not heard the end result, I can understand why you would think it was a bad idea.

[Admin]

I don't use all that much vibrato, anyway, just as a garnish.
Running all those X77 signals out through the legs to an external power amp, and possibly back again to a reverb tank, runs of 3 to 8', was just asking for hum. I hear they got it.

There is no reason that line level multi-channel audio cannot be run far greater distances than 8' without hum. See my previous post as to the source of the problem. It has nothing to with the length of the cable between the organ and X77 Leslie. No, the reverb signal is not routed back to the tank in the console from the Leslie.

[GSDC1100]

Thank you for your input Admin. I was fighting reality looking for a simple fix as I am tired of repairing, and want to be playing. I guess we all do.

A wise member said I should not PM as others may benefit from what I am asking. So here goes.....

The X suffers from intermittent signals, crackling, pops, hum and RF originating in the console due to lack of shielding, bad wire routing practice, bad switch contacts, and crappy push on connectors used for point-to-point wiring connecting the internal circuit boards.

Have other members had experience correcting these faults and how did they turn out. Specifically, which "fixes" worked really well, or as they say, good bang for the buck. I am hoping to not have to do a complete re-build or re-wire, but I am ready for serious efforts.

Thanks to all, (again)

[Admin]

All the problems are fixable. You will need to have the service manuals for the X77 and X77L.

The first thing to realize is that there are four channels coming out of the organ to the Leslie:

• Vibrato
• Non-Vibrato
• Percussion/Reverb
• Bass

When fixing problems, it will be helpful to isolate the problem to one or more of these channels.

Second tip is that you can use the Main and Echo tabs to isolate the problem to either the organ or the Leslie. If the Leslie is plugged into the Main socket and the Main tab is up, no signals will be fed to the Leslie. If this switch has dirty contacts you may have intermittent audio on one or more channel.

So with service manuals in hand the above knowledge, let us know what you want to fix first.

[GSDC1100]

I have the service manual now. I am thinking that I will isolate by disconnecting the push on connectors for the inputs at the pre-amp boards. Am I right in trying to eliminate the other signals as early as I can in the chain (pre-amps)?

So to check out the signal on the vibrato channel, I will disconnect the non-vibrato, percussion and pedal inputs to the associated pre-amps, and see what I get on the vibrato alone. I should probably clean the push on contacts with Deoxit as I am already on that channel. Then I can do the same for each isolated channel and see where the worst problems are.

Make sense?

[indianajo]

Many of the similar push on connectors on my H100 were soldered by dealer service decades ago. Only the low level frequency input ones. The high level power supply connectors have enough current to stay burned off. The ones on the outputs aren't soldered either.
Wirewrap doesn't work either at below TTL current levels. The pins aren't gold plated and the wire is not silver plated, the way JSC required wirewrap connections to be. The power supply pins can work in wirewrap, as long as the current is above 50 ma. Mine do, 3 samples. See the 1970 delta relay catalog about suitable connection metals at different currents.
I second the motion on the poor routing on the x77, as the routing on the H100 does work without hum or crosstalk. Same TG, different harness.

[ShaneByrd]

Hi guys! This is my first post, but I've been lurking for a year or so. I appreciate all of the information that's helped me troubleshoot problems (especially with my M3). Well, I've got an X77GT and X77P that I don't have room for any more. When I got them I didn't receive the bench, pedals, or even the 12 pin cable, so I haven't even been able to test it. It does spin up and run. If any of you are near the Florida panhandle and need a project just PM me.
I'm sorry for not posting this in the classified section, but I'm just giving it away :)

I'm not sure if I can edit an older post, but I wanted to say that this organ has found a home! Thanks Ed!

[ed white]

THANK YOU- my search is over and I can concentrate on PLAYING now-:->

[Guest]

Hey everybody. I have an X77 and would love some feedback on how to get rid of the hum and also how to boost the sound. We have a sanctuary that seats about 450 people on the floor and another 150 on the balcony. Is there a booster kit or amplification module that can be used for this? Thanks.

[Admin]

Let's start with the level. Did you just acquire this organ? If it was in someone's home or a small venue, the levels may have been adjusted down. There are four channels of amplification for this organ: vibrato, non-vibrato, bass, percussion and reverb. Each has an unlabeled level control within the console. You'll need a service manual to locate tI'hem.

It's also possible that the level is affected by dirty switch contacts, bad capacitors, or connectors.

The X77 Leslie is rated at 200 combined watts and can put out some serious sound. If you've eliminated the above suggestions, I'd suggest buying a second Leslie. They come up on eBay all the time for under $500.00

[indianajo]

It's also possible that the level is affected by dirty switch contacts, bad capacitors, or connectors.
The X77 Leslie is rated at 200 combined watts and can put out some serious sound.

I own the predecessor model, the H100, and quadrupled my volume by changing electrolytic capacitors in the power amp and power supply chassis. You'll find some of those functions in the Leslie in the X77. My 48 year old speaker drivers are fine. I did have a couple of oxidized potentiometer wipers that needed moving. I don't imagine Hammond used better quality e-caps two years after mine was built. Some of the e-caps in my 3 organs were changed in 1985 or 1997. Even the high grade e-caos in Allen organs fail after 30 years, dropping power to 1/50 the nominal value. Hint, the 1985 ones were cheap short life ones and needed changing again last year.
200 W should fill a 300 seat auditorium.
As those chassis are probably connected by AMP plugs, you can save money by removing the chassis and taking to the guitar amp repair facility. Versus an expensive on site visit by an organ repairman. Pry the latches back with a little screwdriver and twist another screwdriver under the flat edge. They tend to be stuck at this age. Just tell the guitar amp repairman to replace all the electrolytic caps with new long life ones, and clean the pots, final check wattage out. Take pictures disassembling so that it goes back the same way.
Tone quality can be improved by changing e-caps up in the preamp areas, but these are wirewrapped in and will require a repairman on site. I'd have that done last.
The hum might decrease with new caps, but X77 without the P suffix had some built in by sloppy design. Check your dataplate on the back bottom whether an X77P or not.

[bnelson218]

I've spent a lot of time thinking about the X77 and all its inherent noise and hiss. In my first rebuild I dug into the preamp boards, replacing the transistors, electrolytics, and any other caps and resistors whose value had drifted off more than 10%. For the transistors I had a few lengthy email chats with Dan Vigin on the best substitutes to use and settled on some BC series replacements strictly because of their lo-noise attributes. The end result was noisy and hissy. I slapped myself in the head and went to a bar.

When you think about it, what's so different about an X77 and a B3? Both have a tone generator. The TG's frequencies route to the manuals through resistance wire, are then collected through the bus bars, sent to the drawbars, and finally presented to the matching transformers. And even considering reactance and inductance and henries and cubits the matching xfmrs can't be THAT different, for the love of Zeus. So, we're back to the electronics, and even after replacing everything save the PC board itself, do you think it's safe to say that Hammond's design for these circuits was just downright flawed? I do, which is why in my second rebuild I chose to throw out the electronics and start over.

Granted, that Leslie abomination is another story in itself, but let's look at the components. The power amp boards are the same ones that have been used in the solid state Leslies since they introduced them and, like their 40-watt tube counterpart, are durable and hard working. A cranked 760 can cause an involuntary vasectomy, so why can't the X77's Leslie do the same? Well, if you take a look at the schematic, you'll see all sorts of things going on with relays switching the amps' outputs to various passive xover circuits and speaker loads. The first thing I do with it is get rid of all that extraneous switching and xover circuitry, pitch the space generator and tremolo generator, put the 15 where it belongs, replace the spinning 6X9 with an actual bass rotor. put in a lower 2-speed motor assembly, and THEN go to work on the console commands so that the motors are spinning in sync. Lots of work? Sure is. It's actually simpler to part the thing out and start over, which I've also done.

I know this isn't much assistance to Zack, for which I apologize, but it's Saturday and I'm out of beer and there's nothing good on TV, so I just sit here and rant on my favorite forum.

I'll go now.

(Did I really say, "for the love of Zeus" ??)

[Roger Memphis]

(Did I really say, "for the love of Zeus" ??)

Careful there, Nelson ! Isn't that Zeus guy the dude that tosses lightening bolts around? I hear they're way worse than a good dose of B+ from an AO-28 !

[indianajo]

The chance of any ordinary mortal doing all that work is slim & none.
OTOH boosting power out of the stock X77 from 1/2 watt (2 v on speaker) to 40 watts (18 v) is like mowing the lawn. Identify electronlytic cap, replace it. Repeat.
the pity is, the reviled H100 I own has none of those hiss & hum problems. Just some crackling from loose tube sockets (replaceable) and sound dropout from loose push pins (easily soldered). Same tone generator and mixer transformers as an X77. Plus H100 doesn't have the (according to 99.99999% of the rest of the world) obligitory leslie rotary speaker. Personally, I don't miss it. I'm not buying a Leslie, I'd rather have something else in the music room. Oh, I have some high overtones that allow me to make sounds Jimmy Smith would run screaming from. Dspiffy was seriously afraid of highs, too. wouldn't touch an H100 or X77 with a 10' pole.