Fender 5e3p from Wurlitzer organ amp

[Zombie_stomp]

I started with a free organ, learned a lot about what's required from transformers to run a guitar amp, and eventually built my own chassis to make this into a Fender 5e3 of some sort. Much of this thread is me stumbing through the learning process. The major progress is shown on the last page where I get it all together and start building. (skip there)

I obtained a free working Wurlitzer organ, model 4420, which appears to be from the late 60s. It works, but is quiet. The power tubes are marked as 7027, but have been replaced with 6L6s. The preamp has 4 12au7s and one 7025. This model had a motor powered tone generator box, so does not have a bunch of little preamp tone generation tubes. What I don't see on the amp is an output transformer, so either I'll have to continue dismantling to find it, or obtain one somehow once I find out what I need to get. I also do not see a choke transformer, but I don't yet understand how they work within the amplifier circuit, so I'll have to cross that bridge when I get to it. The preamp tubes section basically takes place on a primitive circuit board, so I ordered 6 nine pin sockets I can rivet in instead as well as some classic fender style knobs.

My intention is to build something that is in the power range of a Fender Deluxe Reverb, with a fender reverb unit grafted onto that. That part is at least available in it's own kit, which I may or may not have to buy to be able to build. If it's worth the $150 or so bucks, I may get that and add it on, depending on how much I'm able to learn building the basic amp. I'm not too hung up on making a blackface deluxe reverb clone, something that sounds generic, primitive, and loud like a Silvertone head might actually be preferable. I just want to have a louder amp for a reasonable price, with a fender reverb unit to get that reverb sound, and be able to try out the dwell feature that the reverb unit has that I've never been able to try out.

First I'm going to try to find the output transformer. Then I'm going to try to get something patched together where I might try playing guitar through that with the original speaker still mounted in the organ. If feasible, I may try adding tone controls to that existing design and recapping it. If it is determined that this setup might not be much louder than my 15 watt ampeg jet 2, I will try to find a schematic/ layout for another circuit design that mimics the Silvertone or Fender Deluxe, and add the fender reverb unit, provided I have the right ingredients. If I don't , I'll have to find a way to just simplify the existing circuit, rebuild all the parts, and add myself a reverb unit.

Suggestions starting out? I have rebuilt a few tube amplifiers, but this will be the first build. I know it's advanced and am up for the challenge, and have plenty of time to work on it. I've been studying tube amplification in my spare time, so pointers to learning material that might help me enough to work into this long-term advanced build are also appreciated.

[Structo]

Depends on how much power you want.

The Deluxe Reverb is 2 x 6V6 with an output around 18-20 watts or so depending on the speaker.

If you decide to go with 6L6 power tubes, there are a lot of Fender circuits that use those.

[Zombie_stomp]

I think the deluxe reverb is the sweet spot I want to hit with loudness. I owned a fender tfl5005d bandmaster with reverb and that was 40 watts, more power than I needed. The only reason I'd go louder is if I could design it to be switchable, but I'm probably just going to start with the deluxe reverb. Would it make it simpler to build if I only have 1 or 2 tone knobs instead of 3?

[Structo]

Well part of the charm of the Deluxe is the interaction between the controls.
You can dial in what kind of tone you want.

[Phil_S]

Nice acquisition. Price is right

What is the smaller black box on the deck, in the corner. Not an output transformer? Show us pictures of the inside!

Since it sounds like this is your first build, I'll urge you to simplify. While entirely possible, adding reverb in your first is a big leap. Maybe you leave room to add it later? Take a good look at the 5B6. That is a relatively easy circuit to build and I'm thinking it might actually fill your wants very well. Several of us here have built one or more 5B6 amps and everyone seems to like them. I am guessing it is about 30-35W and plenty loud. If not the 5B6 (cathode bias), look at the 5F6 (fixed bias). (For a 5F6, use 6L6 instead of 5881, and either solid state diodes or 5U4GB, which you already have, if still working.)

I think you can add reverb to either one at a later time. Just plan for the extra tubes and for the insertion points.

Were you looking for the Deluxe Reverb "vibrato" (really tremolo), too? That adds even more complexity to a first build.

Before getting started on anything, it would be good to know the rectified DC voltage at the first filter cap. I think you said this amp is working. Are you able to get a reading?

[Zombie_stomp]

I found another transformer inside. I also found a sort of output capacitor.
When I go to the schematics I will probably find the voltages at the various points on the transformers. That's where I'm not sure about this project. The other part I would like to know ASAP is what other parts in the way of pots, resistors, and capacitors I will need. And if I need one more transformer. I don't think I'm likely to stumble upon a 3rd of 4th transformer.

[Zombie_stomp]

Phil, I was just going to build a fender standalone reverb unit from a kit that I get for about $150-$180 and wire to the input of a simpler amp. But if enough people have built replica deluxe reverbs that the parts are all out there, and if I can confirm that the transformer(s) save me enough money off the kit price yet easily but most of the parts, I could build that. Or I could just try to hot rod this existing design to be loud enough and add the fender reverb unit kit to the input.

Edit: reading your post, the 5f6 sounds perfect, if these 6l6s are good, or the 5b6 if not and I buy 5881s (are those octal base?) and add a fender modular reverb unit kit inside the amp later.

[Zombie_stomp]

Here are a few gut shots from which you can probably gather what is what on the top. I've never seen disc caps get bubbled up like that in the preamp. There are 3 can capacitors. I might start mapping this stuff out on paper so I can find the point you're talking about testing.

[Phil_S]

6L6 and 5881 are equivalent for this discussion. The 5881 might have lower plate voltage limits. If you have 6L6's, you're good to go. Let's say 6L6 are 100% backwards compatible with 5881, but not necessarily the other way around. Check tube specs here: http://tubedata.itchurch.org/index.html

Inside, that's got to be your output transformer. I am thinking this is shaping up to be a decent platform. It is already using a 5U4GB, so we know the PT is compatible with it. We just need you to fire the thing up to get voltage readings so we know what you're working with. Please say so if you need directions for doing this. Someone here will explain it.

If you have the iron, you should be able to source all the parts you need fairly easily.

[Zombie_stomp]

I would enjoy as much step-by-step with this process as is available, and I really appreciate all the attention and help so far.

I am totally new to building and knowing what is actually going on, as opposed to just knowing what parts typically go bad and changing them out with parts of the correct value.

I'm kind of surprised I haven't found a step-by-step on building one step at a time anywhere on the internet, and if nobody here knows of one with detailed photos of every little process, I intend to write one with my first and second builds... that's right, I went ahead and bought another amp from a Hammond on Ebay for about $60 including shipping. I'm going to really get into this hobby all the way this time.

Any and all help is welcomed.

[eniam rognab]

i LOVE old PCBs like that, i think they are so fascinating

i hope to learn to PCB like that someday... Thanks for the picture! i dig it!

sorry, im not any help, just wanted to say thanks i think this will be my desktop background for a while

[Phil_S]

I'm thinking that taking it slow is really important. You don't state your level of experience with electronics. If appropriate, there is a decent piece on safety at ax84.com http://www.ax84.com/safety.html (Signup required, not a big deal, it's a good site.) Without a foundation on safe practice, nothing else is worth doing because this hobby is potentially lethal. Tell us about your electronics background for starters. Remember, every one of us started out at the beginning and we can fully appreciate this aspect of it.

[Zombie_stomp]

I briefly apprenticed with a tube amp tech, who rebuilt my fender tfl5005d bandmaster. I didn't learn a terrible lot about how amps work, but I started to. Then I recapped a 1952 ami jukebox amp and replaced any resistors that showed signs of getting heat damage, and that worked out fine. Then I recapped a more complex Rock-Ola stereo jukebox amp. That was a little harder and required more creativity in mounting what I believe are referred to as 'power capacitors'- replacing the can capacitors with multiple capacitor values inside. That amp worked out well too.

I can use a meter to read resistance, continuity, voltage, I have 2 inexpensive meters, one of which has a clip-on loop that can measure amperage. I've usually just been a parts changer and tube tester. I unfortunately sold my tube tester, but who knows how calibrated it was anyway. That's pretty much all I know, other than I might want to start by adding a grounded plug and having a gator clip that I hook to ground and go around touching capacitor leads so I don't get a 500 volt shock.

That's pretty much what I know how to do. I have become somewhat familiar with the vocabulary and what each part in the amp does, generally speaking. It makes more sense as I read about plates, grids, anode, cathode, power transformer, output transformer, B+, resistance, capacitance, bias, etc, but I don't know all about all of those things. It's slowly coming to me. I can lay out a circuit and solder it together from schematics, but I prefer a wiring diagram layout so it is easier to keep the wiring neat.

I am signed up on AX84.

I know it doesn't sound like I know how to do much, but if someone lays out the bones of it and has a wiring diagram and/or schematic, I can follow that and probably run with it pretty good. Even better of they can show me a few photos of certain parts. What I want to avoid is soldering together a convoluted mass of leads where certain things meet where it is ok to have a bunch of things soldered to a few central points- I don't want to fry something trying to achieve an efficient lead dress.

[Phil_S]

OK, I'll leave it that you are responsible for being safe, that you know what to touch and what not to touch, that you know how to discharge filter caps, and that you know to keep one hand in your pocket when working on a live circuit.

Stop me when I'm off course. The only stupid question is the one you didn't ask. People here will not criticize you if you are straight with them.

For starters, decide if you want to keep that chassis or move the iron and some other salvaged parts to another chassis. I'm going to work on the assumption that you can't use the PCB and it will be discarded. If the amp was in working order, I think you can probably power it up with tubes in place and get voltage readings. If you are comfortable with this, and if it looks safe to do, it would be great to get a full set of readings. Remember, a tube amp must have a speaker of the correct impedance connected to the output transformer. See if you can get VDC readings at all of the tube socket pins and at all of the filter caps. Make a chart and post what you find.

Not clear? Not sure? Ask. We can slow down.

This voltage chart will help determine how suitable the iron is for the build you want to do. No sense in planning a project that won't be going forward.

[Zombie_stomp]

I tried to play guitar through the amp with my handmade guitar jack to RCA jack adapter to no avail through all 3 of the RCA inputs: Phono, Treble, and bass. All the other plugs were in place except the treble and bass from the tone generator when using the phono input. The tone generator occupies the treble and bass RCA inputs, but I don't see how that could affect the use of the phono input. I also tried toggling the 'Wurlitzer' switch- this basically switches between the auxiliary Leslie ripoff auxiliary speaker and the stock speakers in the organ body. When the organ was all together, the Leslie ('Wurlitzer') switch turned off all sound because that cabinet didn't work at all. It's because of problems inside that speaker. I'm ready to rip into this amp and dumb it down to one input before I make a new circuit design. Just to test it and see where I'm at.