1100 diode specs?

[wdln]

Howdy all... I'm working on an R-74 with the 1100 mech.  The small circuit board on the left side of the mech with one cap and a bunch of diodes looks like it's gotten a little hot a few times, and I'm questioning whether the diodes are OK on it.  The board also looks like it's been worked on in the past, so I'm also questioning that work.  There are three kinds listed for the board in the book:

Rowe-AMI part #702-00350 - D1, D5, D6, D8
705-00350 - D2, D4
706-00350 - D3, D7

The book gives specs for resistors and capacitors throughout the manual but not diodes.  I've searched for variations on the part number; this sticky talks about the changes in part numbers over the years, but I've not had much luck looking around online.  I did find a TI-1 manual page listing 702-00350 as a 1A diode, so maybe that's a simple 1 amp low voltage diode like a 1N4001 or 1N4002? Those diodes do look like they have an 002 printed on them, and the physical size would be right.

D2 and D4 are definitely 1N4004's; that text is printed on the side.  D3 and D7 are a bit of a mystery though.  D7 has no printing on it or it has faded away, and it looks a bit roached.  D3 has been replaced in the past, and it looks like an ECG-5802, a large 3-amp rectifier diode capable of 200V reverse voltage.  That diode (D3) is physically much bigger than D7 so it seems over-spec'd maybe.

So I guess the action item here is whether a 1N4002 will work for 702-00350, and what the factory specs should be for D3/D7.  I have 1N5404's in stock (3A/400V) but is that overkill?

The problem I'm chasing down on the R-74 at the moment is constant magazine rotation while the mech is on.  It also had some mechanical issues in the transfer linkage... one of the posts had broken off the crank and pin assembly on the transfer motor linkage, as well as the plastic guide for that long piece of linkage.  I got all that fixed and (I think) clocked and engaged correctly with the linkage.  I can walk through the transfer cycle using the allen screw on the end of the shaft.  Just trying to figure out why it constantly spins the magazine.

It could also be the magazine detent switch stuck closed, as I stare at the schematic.

[Ron Rich]

Hi Dave,
I have no answers on the diodes-- I think-- the 002's are correct as you state----
On the motor-- have you oiled the 2 large felt oil pads, & armature shaft, on it, with a 20 wt oil ? A '"dry" motor will continually "run" if not properly oiled ! Ron Rich

[wdln]

I will give that a try! Thanks Ron.

[wdln]

Continuing this thread... new problem, same machine (R-74/1100 mech).  No question here... just posting my progress in case it helps someone else.  I did work out the magazine spinning issue by oiling the motor and adjusting the stop switch.  I then had to disassemble the search motor mechanism and free/lube up several gear shafts that were completely stuck.  It's currently off by one record, but I know how to fix that... I must not have gotten the wipers quite aligned correctly.  Now that it will execute a full play cycle, I'm back to the transfer mechanism that I thought I had fixed.

When I originally removed the cam switch plate and transfer motor to get at the crank and pin, I found that the long pin was broken off and MIA.  I looked everywhere inside the jukebox but could not find it, so I fabbed up a new one from a small piece of brake line (I guessed at the diameter and length based on photos) and a small bolt running through the center, which I tack-welded a nut onto so that it couldn't come off.  I suspect that 1) the chunk of brake line is not close enough to the diameter of the original pin and 2) it may be flexing around a bit as it moves through the cycle, as it doesn't quite move the gripper arm linkage far enough to completely release the record in the magazine.  The oval-shaped wheel that rotates to make the gripper release does not rotate all the way.  The record will release, but records usually make slight contact with the gripper as the magazine spins.

When I initially removed the crank to create and mount the pin onto it, it looked like the long-pin arm of the crank was a little twisted.  I tried to straighten it out but was afraid of breaking the casting.  I suspect that tweak in the arm is also causing issues.  Doing some research, I found this post among others where amiman66 was talking about how these pins are common points of failure as they are riveted in from the factory and they work their way loose over many cycles.  I've worked on a number of 1100-based machines so it's surprising I haven't run into this yet.

So long story short (too late, I know), I found a replacement crank/pin assembly on needles4jukeboxes and ordered it today.  My homebrew fix was defeated.  It will be interesting to compare my fix with the real thing.  On the upside, when I was looking around underneath the mech I did find the missing guide pin for the underside of the tone arm mechanism, so that is now back where it belongs.

Getting closer!