An H324 with several dead percussion notes

[bnelson218]

I've discovered several keys on my H324 where the percussion voices won't play. I removed the unwanted footages from the Guitar tab so it's now just the 2 2/3' voice and then found the dead notes. I worked the shifter while tapping a few of the "offending" keys with no luck, so I'm guessing the 220Ks have opened up and I don't think I want to open up the manual. If it was my Thomas Celebrity i could access the keyboard in 20 minutes. Why'd Hammond have to make this organ such a nightmare to get at. Anyway, anyone have any other ideas?

[geoelectro]

You’ll probably have to open it up. Typically it’s not the resistors opening up, but becoming disconnected from the contact.

Geo

[Jaim]

I would agree with Geo. The ends of the key contacts flex when the key is depressed and the resistor leads are rigid.

Jim

[bnelson218]

Update:
Boy, I haven't done a sling job since I owned my shop, but it's the best way to get at the manual's innards...


I just put a meter on that common buss bar (the one all the resistors are soldered to) and find around 16 vdc, and on the other side of the offending key's resistors nothing, so it's not a matter of fatigue and a wire breaking off as the resistors are not soldered to the moving key contact but rather to 40g resistance wire that then tacks to the contact. Obviously these resistors have opened up.

What a nightmare. I could just tack on a replacement resistor over the bad ones, but then I'll be back here again when more fail, so my best choice is to replace all of them. Since it's opened up this far I might as well do the job right, which probably means removing the keys and taking off the key bed. More fun.

[bnelson218]

This thing has gotten out of hand. It's like working on an old car and the more you take apart the more problems you find. I'm not even going to attempt to replace the resistors, having to solder them between the common rail and resistance wire. I think I'll just solder on a harness to the contacts and bring that out to a perfboard where I'll then add the resistors. In fact, if I'm going to do that I might as well MIDI there upper manual. Re-assembly's going to be a bitch, too, because I had to lift off the key bed in order to access the top contacts. Oh well, I've got lots of time.

[bnelson218]

Well, that actually went better than I feared. I got rid of the common bar with all the 100k resistors tacked to it, and found that, because they were tacked to the bar right next to the body of the resistor, some were cracked and came apart in my hands.
I wasn't about to attempt to re-attach new resistors to those 40g resistance wires, so I ended up pulling the contacts, tinning them, and then attaching color-coded wires (scarfed from the X77-B project <sob>).

It was time consuming (about 3 hours,) but I think still my best option. Should be fun to have a MIDI'd H324. And, of course, while I had the lower manual keys exposed I noticed more cracked sharp keys. I don't know if I mentioned it previously but I had to replace all the sharp keys on the upper (again, salvaged from the X <sob>) because a number of them had cracks in one, if not both, of the collars where the screw attaches them to the channel. I'll replace all of them today. And my poor X77-B <sob> is now an empty cabinet save for the TWG as the key-less manuals went in the dumpster.

[Saltech]

Update:
Boy, I haven't done a sling job since I owned my shop, but it's the best way to get at the manual's innards...
.

Hi, I have a similar problem with dead percussion notes on my R100 series (it's a R122). I can see the pictures of your sling, but can't figure what's going on - is it just the tabs panel assembly in the sling? I assume this is to improve access, does it mean you don't have to remove / disconnect the upper manual? Any tips for accessing the percussion resistors would be most appreciated - this is my first time working on the manuals. Is this in the same region as the "sticky foam"? That's another job I'll need to tackle at some point...

[bnelson218]

I'll have to check an R series schematic to see how it keys the percussion. Let me get back to you.

[bnelson218]

Hi, I have a similar problem with dead percussion notes on my R100 series (it's a R122). I can see the pictures of your sling, but can't figure what's going on - is it just the tabs panel assembly in the sling? I assume this is to improve access, does it mean you don't have to remove / disconnect the upper manual? Any tips for accessing the percussion resistors would be most appreciated - this is my first time working on the manuals. Is this in the same region as the "sticky foam"? That's another job I'll need to tackle at some point...

As far as the sling goes, I probably over thought this as I've seen a few videos on youtube where techs have simply used short bungy cords to strap the tab rail to the price of wood that runs from side to side at the rear of the console. Hope this helps.

[bnelson218]

Hi, I have a similar problem with dead percussion notes on my R100 series (it's a R122). I can see the pictures of your sling, but can't figure what's going on - is it just the tabs panel assembly in the sling? I assume this is to improve access, does it mean you don't have to remove / disconnect the upper manual? Any tips for accessing the percussion resistors would be most appreciated - this is my first time working on the manuals. Is this in the same region as the "sticky foam"? That's another job I'll need to tackle at some point...

Okay, I've downloaded a service manual form the R100 and looked it over. I'm assuming you also have a service manual. If not, pm me your email address and I'll send you a link where you can download it from my drop box.

It appears as though the last, or bottom, contact set is for keying the percussion. Inside the manual you'll find sixty-one 100k resistors tacked to a common buss bar on one side and then tied to the corresponding key contact by a short length of 40g wire on the other. (I'm not sure if the wire is exactly 40 guage or not. It might be 36g or maybe even 30g. Others on the forum may know for sure. But I do know that it's the same guage as the resistance wire that's used between the TWG and the key contacts. Anyway, for now I'm simply going to refer to it as "40g.")

In my case, I found that several of the resistors had either broken off where they where tack welded to the common buss bar or had sustained cracks in them which essentially opened them up. If you've found that repeated tapping of the keys that are not sounding, or rotating the buss bar shifter back and forth several times has not brought the non-working keys back to life, then it's more than likely that there is a problem with these resistors.

If the latter is the case, then you'll need to lift the tab rail enough to gain access to the upper manual so that you can drop the back cover and view these resistors. Use a Sharpie and place a mark on the keyboard's frame adjacent to the keys that are not working and then check the corresponding resistor. You'll probably find that it has either broken off of the common buss or cracked in half. To repair it you'll need to remove the key contact, unsolder the 40g wire from it, and install a new 100k resistor between the contact and the common buss. You could solder one end of the resistor directly onto the contact, but I'm guessing Hammond did not do this because doing so would likely restrict the contact's movement. Also, even though the contact's movement appears minimal, over time the repeated motion could fatigue either the resistor's lead or the solder joint and break. My recommendation would be to buy some bare, 40g copper wire and solder a short length (perhaps an inch or so long) between the contact and one leg of the resistor. The other side of the resistor would then solder onto the common buss.

I did some searching for suitable wire you could use, such as Ebay listing number

391506169904.

Again, others on the forum might have better suggestions.

It's going to be tricky work requiring patience, good lighting, and sufficient clearance of not only the tab rail but also the dropped cover so that you can get your fingers into these tight spaces. Also, re-inserting the key contact can be tricky. As the contact is slowly inserted it can tie up and refuse to go any further. I've found that some times tapping the key helps to guide the contact back in, but unfortunately it's also easy to slip it into the wrong slot in the guides. If a contact refuse to re-insert correctly, your only option then is to remove the keys and the key bed in order to be able to view the contact and guide it back into its slot. If this is the case then we can discuss the key bed's removal more later.

I hope this helps.
Bruce

[Saltech]

Thank you for your advice and your time - most appreciated. I was hoping I'd have something to report by now, regarding the resistors, but it's been a slow and much interrupted job today, and I've not got to them yet. Plus I've been cleaning up years of grime and a bit of rust as I go. My slings go around a length of 2x2 resting on the top of the cabinet, with the tabs assembly pulled tight up underneath it. This works well. I'm just trying to work out a good way to elevate the upper manual so I can get at the screws holding the cover on underneath.

[bnelson218]

Thank you for your advice and your time - most appreciated. I was hoping I'd have something to report by now, regarding the resistors, but it's been a slow and much interrupted job today, and I've not got to them yet. Plus I've been cleaning up years of grime and a bit of rust as I go. My slings go around a length of 2x2 resting on the top of the cabinet, with the tabs assembly pulled tight up underneath it. This works well. I'm just trying to work out a good way to elevate the upper manual so I can get at the screws holding the cover on underneath.

I was able to leave the manual in place by using a stubby screwdriver. Mind is about an inch long and is just perfect to get those screws out.