trinityamps.com

Hello all.

I just scored a set of free Wurlitzer organ guts!

Pics of the old beast can be found on page 6 and page 7 of this guys page.

It's got nice big iron, capable of running 6L6's and 6 ocatal pre-amp tubes. I've decided this is going to become a 5D8 tweed twin clone with a 5U4G recifier.

This image shows my loot and their contents. There are about 50 black beauty caps and a ton of resistors. I'm planning on using the chassis on the top (the tone generator). It's 19.5" wide. Perfect for a nice big amp. Right now it's holding about 36 .022 uf caps and a million 60 year old transistors.

The chassis on the left with the big steel cage around it... That's a selenium rectifier the size of my fist. I'm glad that wasn't the failure point on this old organ. The chassis is a good size for a champ, or a firefly, or anything small. I don't know what that transformer does/is.

Part 1: Deconstruction.
Question: I've hit a snag with the output transformer. (for reference: The one in the middle of the rats nest Point-To-Point mess) These organs came stock with a 12" feild coil speaker. There is a selector switch marked Tone Cab 1,2,3,4,5. And there is an Aux Speaker output on the chassis. Does anyone know what the output transformer is capable of driving? I'm tempted to buy a schematic of this old beast but I'm not sure what it would tell me about the load on the OT. I have a strong feeling it's capable of driving a 4 or 8 ohm load, but I'm not sure how to find out.

Should I just mark the OT and PT wires and disconnect everything? Test it later...?

Some of these black caps have small cracks in the bakelite.

The Tube Store sells similar black sprague caps with the same crack. I've highlighted it in this picture.

Next Question Does anyone have experience using 50-60 year old capacitors? I'm tempted to build a test rig to find out if any are good. For the price they're selling at it makes me think there might be something there...

If everything goes to plan I should be well on my way to a new amp. If everything goes to S#1T I still have a decent PT and a chassis to build on.

Thanks for your help guys!

I'm a little slow on the uptake, but I'm getting there.

I did some research on field coil speakers. Pretty clever things they are. From what I understand the field coil serves double duty. Creating an electromagnet so the voice coil could do it's job, and also as a choke. Since the 5D8 is chokeless, I don't need to worry about any of that. Am I on the right track?

I've been told the original voice coil was a 6 ohm load. This OT has multiple secondary taps so I just might have some speaker options...

There's an organ parts supply company in Mississippi. Maybe if I ask nicely they'll know what this thing is... Failing that, they'll probably sell me the schematic.

Nice haul. I'm sure you can make something out of it.

I've had amps with 50-60 year old capacitors in them and they were still working OK. You would need to test for leakage and would need a to build a rig for that, or just use em and if it hums bad, replace the electrolytics first.

If the iron is in good sahpe, measure & tag it all. You will probably need to reverse engineer the OT to determine it's impedance. Most of that will go into your parts bucket.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps