You Don't See 1 of These Everyday

[RicharD]

Much less 2.

This is the Wurlitzer Sideman drum machine.  It is truly a machine where as the triggering is a round contact plate with a motor driven brush.

The contacts are routed through a 24P12T switch to select the different rhythms.

Here is the control surface.

The sounds are generated by mostly 12AX7's and a plethora of capacitors.

The amplifier has a 12AX7 PI and a pair of 6BQ5 outputs driving a single 15" woofer and a pair of 3" cone tweeters.

I have 1 of them mostly working although it needs a belt.  This one slips and has a flat spot.  I had to rebend the tines on 10P1T switch which was stressful.  A lot of contact cleaner and a couple of tubes was all it took to get this one going.  The other one looks to be in worse shape.

Very odd day in the shop.  Dropped off a bass preamp at the studio for them to demo and picked up a Telefunken V76 to service.  You don't see those everyday either.  I also got to repair a SCHWEET 64 Vibrolux.  As much as all Fenders tend to sound the same, this one stood out in a big way.

[kagliostro]

Hi Richard

What an interesting thing !

YES, we don't see one of that everiday 

Kagliostro

[FYL]

Wow.

[chocopower]

yes.. wow!

And look how it works!

http://www.youtube.com/watch?v=55DnnMWm5Tg&feature=related

[RicharD]

These thangs are flat out insanity.  Now we know where the term, "drum machine" comes from.  That 24P12T switch is just shy of 7" tall.  There is a schematic available but they want $20.00 for it.  I may have to break down and buy it when I get into the 2nd unit.  I should snap a picture of the underside of the tone bank.  There's a lot of funky old caps in there.  One of the owners wants a clock out mod which somebody has tried to do by tapping a 1/8" jack in parallel to the neon tempo lamp.     Yeah!  250VDC triggering.  Where does one get a belt for a 1959 drum machine?  I have some belts that are just a tad too short in my collection of crud. 

[Tiny_Daddy]

Wow, fantastic, my jaw drops! Try MCM Electronics for a belt. Don't use an o-ring, it won't last.

[dynaman1]

That's freakin' awesome and only slightly more reliable than a real drummer (me included).

[RicharD]

They are both running!  They both need belts but I'm gonna leave that to their respective owners.  Unit 2 had a pair of dead tubes and the 12P1T relay wasn't pulling in.  I read on the web last night that this was a 'common' problem and one could simply bypass the relay with a rubber band.  I found this hard to accept, especially since there was no burn spot on the exposed coil + there was no voltage present.  The silly thang has a remote control octal plug on the bottom that has to have a jumper between pins 3 & 4.  BINGO!  

[eleventeen]

I'll take Rhumbas for $200, Alex. An amazing piece of techno-wizardry. Incidentally, the reason white people dance they way they do is entirely due to these machines.

[mresistor]

What an awesome machine! and an awesome video of it posted above. Shared it with all my friends and their jaws dropped in amazement.

Very cool....

[RicharD]

This was a totally fun project.  There's a lot of happy people down at the store right now.  The next project is a Mellotron.   

[Fresh_Start]

The photos of that gorgeous/insane thing were great, but the video just blew me away.  Getting that variety of sounds with vacuum tubes, caps, belts, pulleys, and that whacked out "switch" is simply amazing!

Thanks so much for sharing!

Chip

[jojokeo]

I'll take Rhumbas for $200, Alex. An amazing piece of techno-wizardry. Incidentally, the reason white people dance they way they do is entirely due to these machines.

That is funny as hell 

Buttery:
I bought one of those SideMann power amp chassis for $20 almost two years ago not knowing exactly what it was & took a chance. It didn't work for what I was looking for votage-wise exactly and the chassis was funky so I gutted the parts and kept the trannies. I believe the unloaded B+ measured 133v and by the size I figured it had a lot of available heater current available. Is there only 9 more 12ax's in there besides the pi & output tubes for it to power? (I didn't want to pay for schematic either, glad I didn't). Up to now I didn't know kind of ratings it might have to know what I could with it.

[eleventeen]

It's sometimes amazing when you see from the standpoint of what we take for granted today, how primitive some of these things were..and yet they worked!

Watch this from 4:00 on...its the Penna railroad reservation system from 1952...I wonder if they charged extra baggage for bringing a Fender Broadcaster on board! I showed this to a database guru I know and he was literally rolling on the floor. Very charming.

[sluckey]

I want to hear some Moody Blues or King Crimson when you get that going.

[FYL]

I want to hear some Moody Blues or King Crimson when you get that going.

Then you'd need another mechanical wonder: the Mellotron.

[sluckey]

Ugh yeah. Like the one pictured in Buttery's last post.   

[Jack1962]

wow for sure , that's cool very cool 

                                                        Rock On

[RicharD]

I'm not sure when the Mellotron gets here.  I'm hoping tonight.  It's gonna be an exciting challenge.  When I dropped those Sidemen off at Switched On, it was a big deal.  Business came to a halt because everybody wanted a demo.  One of their in house techs joked, "You gonna fix the Mellotron?"  I said, "Why not."  Apparently there's a studio here that has one that's been down for about a decade and nobody will even look at it.  The fact that it's mechanically intensive and been down for so long worries me a little.  Beyond that I can't wait to get my paws on it.

>I believe the unloaded B+ measured 133v and by the size I figured it had a lot of available heater current available. Is there only 9 more 12ax's in there besides the pi & output tubes for it to power?

I measured 329VDC.  I didn't pay enough attention when inside the amp chassis, but it was probably a voltage doubler supply.  I did see "Cuff Link" diodes.  I didn't want to make a career of of this repair.  I didn't replace the caps or diodes.  It was enough work just to get these thangs rolling again.  The only reason I got into the power chassis was to install a grounded cord.  Nothing leaves here ungrounded.  There are 9 additional tubes, 5 of which are 12AX7's.

>I didn't want to pay for schematic either, glad I didn't
Ya know..... I understand everybody needs to make a living, but selling pdf copies of somebody else's published work just rubs my fur backwards.   I think it was the same place wanted twenty bones for a GK schematic. I called GK and all they wanted was a number off one of the PCB's.  I had the schematic for free before I got off the phone with them.

[FYL]

I'm not sure when the Mellotron gets here.  I'm hoping tonight.  It's gonna be an exciting challenge.

Challenging, yes.

[plexi50]

Man they couldnt even build that at NASA today. Thats an ingenious piece of work and craftmanship

[billcreller]

Awesome pieces.  About three cans of Deox would clean those wipers & contacts!!

Sort of makes "modern" stuff look really chap-built!

[eleventeen]

I keep thinking about the '64 Vibrolux you worked on. Even though I am not the biggest fan of 10" speakers, I am mentally drooling at the image of such an amp.

[RicharD]

Here's a little irony.  The next Fender to come across was a PCB cream colored Twin.  Probably the worst sounding Fender I've worked on.  Maybe the Vibrolux Reverb was still too fresh in my mind but this "Evil Twin" was just lame.

[Platefire]

Wow That's great! Just think of the design that went into that. After all the design and special manufacturing requirments, I can't imagine them selling a whole lot of those. I kind of imagine that was an extension for a dedicated unit of the rythem machines that they installed in organs in those days. Anyway that is a new one on me. Didn't see any rock-n-roll setting on there:>)Very Cool. Platefire

[eleventeen]

So.......when do we get the Mellotron report?

[RicharD]

I dunno if the Mellotron is gonna happen.  It's been pretty quiet and I haven't been pushing it.