H Series service manual

[bnelson218]

I'm still searching for a service manual for the H324 and found this one on eBay...



The seller flipped through the pages and didn't see any mention of the 324 but still says it covers all the H models. Can anyone verify that it indeed covers the 324?

Admin: I wasn't sure where to submit this but at least want to get some decent eyes on it.

[JoeyB3]

The H-324 designates 2 things:
-- contemporary, Pecan finish
-- built in Auto Rhythm

That's it! So if your manual has the Auto Rhythm section in it, you're good to go.

[Bobmann]

I'm still searching for a service manual for the H324 and found this one on eBay...

[ATTACH=CONFIG]31342[/ATTACH]

The seller flipped through the pages and didn't see any mention of the 324 but still says it covers all the H models. Can anyone verify that it indeed covers the 324?

Admin: I wasn't sure where to submit this but at least want to get some decent eyes on it.

The Auto Rhythm section used in the 300 series is a self contained unit that is connected to the organ only by power input and output to the amp. There are really no easily serviceable parts inside this unit, as it is all solid state, so you would have to know how to troubleshoot and repair circuit boards.
That unit is the same as the Auto-Vari that Hammond sold as a stand-alone that can be used with any organ. These were imported from Japan, and not built by Hammond.
I have that manual, and if the one you are looking at is the same as mine, it does contain a schematic on the Auto Rhythm section with a parts layout.

There is one other H series manual that I know of, and that one is clearly titled H100 on the front page, which obviously pertains only to the 100 series.

FWIW...the 300 series functions have more in common with the 100 series than the 200 series, as both the 100 and 300 have the same features except for the Auto Rhythm. All series have the same electronics, and after serial 15000 all the TSBs have been incorporated.
The 200 series differs in that several features were omitted (reiteration on perc, a few perc sounds, etc.) and a few others added (Celesta, bells, etc.) and a different perc driver was used.

I have a spare copy of this manual, you can have it for the cost of postage. PM me if you are interested.

Bob

[bnelson218]

The rhythm unit is the least of my concerns. It works fine and I can troubleshoot if ever necessary. The electronics are NOT the same as the 100 and one of my concerns is the percussion and pedal electronics, which in the 324 are separate PCB assemblies rather than the tube version which combines both circuits and is sandwiched between the manuals. I also see some differences paging through the 100 service manual that I have, such as differing capacitor values here and there. For instance, on the power supply chassis there's a 1500uf/50v can cap that I can't find anywhere in the 100's schematic. I've already replaced the GZ34s with diodes and upgraded the filter caps as needed, and I now need to chase down this thumping that's occurring primarily in the "A" channel, but also barely perceptible in the "B" and bass channel. So, long story short, I need to chase down an actual manual for the 324. Does anyone know if Jerry Welch is still in business? I've sent him two emails with no reply. And FWIW, the serial number on this organ is 8-99752.

[Bobmann]

The rhythm unit is the least of my concerns. It works fine and I can troubleshoot if ever necessary. The electronics are NOT the same as the 100 and one of my concerns is the percussion and pedal electronics, which in the 324 are separate PCB assemblies rather than the tube version which combines both circuits and is sandwiched between the manuals. I also see some differences paging through the 100 service manual that I have, such as differing capacitor values here and there. For instance, on the power supply chassis there's a 1500uf/50v can cap that I can't find anywhere in the 100's schematic. I've already replaced the GZ34s with diodes and upgraded the filter caps as needed, and I now need to chase down this thumping that's occurring primarily in the "A" channel, but also barely perceptible in the "B" and bass channel. So, long story short, I need to chase down an actual manual for the 324. Does anyone know if Jerry Welch is still in business? I've sent him two emails with no reply. And FWIW, the serial number on this organ is 8-99752.

The early H had the tube perc, later ones were solid state.
Both versions are in the H100 manual that I have, as is the H262.
The manual lists all the H100 models, the H262 and H300 models.
The change appears to be at serial 15000, as there is a separate section with schematics thst are labled "15000 and up"
There are a few references to the 300 series, but for the most part both the 100 and 300 series are treated as the same.

If a manual that specifically references the 300 series exists, I have never seen it...does not mean that there is not one, it's just that I am unaware of one.

Does your manual have any schematics that reference "after serial 15000"?
If so, can you determine if there are similarities to your 300?

Anomalies in component values is pretty common. I have seen differences in the documentation vs any model I am working on.
I have even had a couple H100 in the shop at the same time with different value caps and resistors on the same board in both organs.
I have a box full of the various circuit boards here, and they are not all the same, although they served the same purpose and have the same part numbers.
Very early H after switching from the tube perc had circuit boards made from breadboard and point to point wiring. Hammond did a lot of engineering-on-the-fly in the early versions.

The H100 and H300 have identical electronics except for the Auto Vari for the same vintage, either pre 15000 of after 15000.

Now you get an idea of why many techs will not consider working on an H;-)


Bob

[bnelson218]

Well, while I search for the right documentation I went ahead and re-capped the amp chassis. And I'm pretty amazed at how little variance has occurred in the resistors. I checked maybe 20 at random and found 5 or 6% changes. I also discovered that one of the Molex connectors lost its mounting ears so that when its mating plug was pushed in, it was pushed farther into the chassis rather than making a complete connection. Could be the source of some of my problems. So, the chassis socket's been replaced and I'll put a new plug on tomorrow. Enough work for today.