Continuing...

I spent the next few days with both Beograms opened to understand the differences and how the turntables worked.

When you press the button, the motor starts and the tonearm moves to the start of the record , 17,25 or 30 cm diameter, according to what you choose in the speed selector (more on how that works later on)

That movement of the tone arm and it's return to the resting position is governed mainly by the cam wheel, which you can see in the following two pictures (Source http://beoparts.com/) :

Before pushing the Lift Button, the gear in the platter axle is not engaging the cam wheel, as it sits in one of the two large baps between the cam wheel teeth (The lower one in the second picture).

Pushing the button,  a clear plastic tab on the cam wheel is kicked in, "creating" an extra tooth , which now engages the axle gear.

.When the cam wheel moves,  the bean shaped lower part (seen in 2nd picture of the cam wheel) guides the movement of the arm positioning guide (part 98 pg 5-6 of the service manual, seen in the blue circle in the picture below) , which in terms, alows the cueing arm (part 104, pg 5-6 of the service manual, seen in the red circle in the picture below) to move the tone arm to the start position of the record. 

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Meanwhile, in the upper part of the cam wheel, along it's inner track runs a pin connected to lifting arm, which makes the tonearm lower.

The camwheel has now rotated 180º from it's starting position, making the gear from the platter axle reach the other large gap, thus stopping the cam wheel motion (the platter continues to spin)

The stylus follows the record grooves and as the tonearm reaches the end of the record, the cueing arm kicks the brass part of the cam wheel, creating another "extra tooth" and starting the motion of the camwheel, doing the opposite of before, lifts the tonearm, sets it to it's resting position and the motor stops spinning. The cam wheel has now completed 360º

The main difference between the two types of Beogram 1203 is the way that clear plastic tabs are kicked in

Type 5239 a switch sits beneath the lift button. Pressing the button, a relay is energized.

The lower arm of the relay kicks the first little clear plastic tabs on the cam wheel (the lower one in the next photo), while, the upper arm follows the outer track of the cam wheel, keeping the motor on up until the cam wheel completes 360º turn

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I'm missing the relay spring BTW 😳...  must source that somehow...

The 5243 has a purely mechanical "kick" mechanism. A tiny rod connected to the lift button torsions just a little, engaging a switch which starts the motor and kicking in the same plastic tab as above. You can see the mechanism in the following pics:

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I hope this was clear...It's kind of difficult to put to words...If I was somehow incorrect, or wrong in my explanation please do correct me.

That's it for today. Tomorrow of friday I'll continue, this time to tell you what was wrong with my turntables, what parts I'm sourcing...etc...

Cheers,

Duarte

Great pics

Hi again!

Having understood how the turntables worked, I could proceed to setup the working one (Type 5243).

Issues to be addressed:

1. Slow motor;
2. Tone Arm not lowering or raising in the right position;
3. Sometimes the cam wheel didn't engage;
4. Replace RCA plug for a DIN Plug

Starting with the motor.

It was running slow.I mean, really slow. As I had another motor and, like a kid who wants to play with it's new presents, I decided to swap the motors, cross my fingers and hope that the speed on this one was right.

Opened up both turntables, and took pictures of the original wirings. 

Here are the pictures of the original wirings

Type 5239:

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Type 5243:

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The two motors side by side, the one on the right is from Type 5243 and the other from Type 5239:

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Notice the different disposition of the wires, the pair red/yellow and pair blue/black are on different sides. I only noticed this after swapping the motors and connecting the wires in the same disposition they were in their original turntable. Altough the motors spinned in the correct direction that puzzled me. Even more after I went to look at the schematics to see where they connected the wires.

Schematic for Type 5239

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In the schematic for 5239 was (from right to left in the connector): Red / Blue / Yellow/  Black

And the schematic for 5243 was (from right to left in the connector): Blue / Red / Yellow / Black

When I opened the two turntables for the first time, both of them were with the Red / Blue / Yellow/  Black arrangement

I wonder if anyone here can explain me these two differences, the physical one in the motors and the one in the schematics?

Since the motors were spinning in the right direction, I let it be.

Turned the turntable around, belt on, released the transport screws and crossed my fingers...YEEEAAAHHHH....The speed is nearly good, a few turns on the adjustment knob and ...voilá...33.3RPM

The other motor not spinning will be addressed when I restore the second turntable.

What I noticed now was that two more problems arose:

1. Platter very much off center and tilted towards the motor axis
2.  Very Loud rumble coming from where the idler wheel touched the step cone.

I figured that the problem was the belt being too tight, forcing the platter not to be in the right position. Another thing was that when I pressed down on the adjusting wheel, the rumble would disappear. I ordered a new belt from Axel and continued on with problems 2,3 and 4.

 Just a little fast forward to when a I got the new belt. It was perfect quality, no visible joint marks. Installed it and the platter was now centered and leveled. The rumble has now pratically disappeared. To make the turntable dead silent I still have to push down the adjusting wheel a little bit, so the next time I open the turntable, I'll be addressing that.

[Tomorrow I'll edit this post to cover the rest of the problems]

Cheers,

Duarte

Hi,

It's been a while... A job and a house change took all the time from me...

I'll try to remember how I got around the other problems with my BG

2.Tone Arm not lowering or raising in the right position;

3.Sometimes the cam wheel didn't engage;

4.Replace RCA plug for a DIN Plug

As for the tone arm, I thought it would suffice to do as ther service manual says and adjust the two screws in the bottom of the turntable.

No luck there. I don't know what the previous owner(s) did but the whole mechanism would need a reset..

I started by putting the screws with the arrows pointing as they were in the manual

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After that, I disconnected the cueing arm (part 104 service manual) from the Coupling (Part 134 service manual). I then secured said coupling with one hand and rotated the tone arm with the other hand (very slowly and carefully!!) I could feel the springs making force (135 and 137) and then it would stop. Pushing a little more allows to change the position of the tonearm relative to the coupling,

If I remember correctly, the tonearm and the arm of the coupling where the cueing arm connects have to be parallel in the resting position of the mechanism.

I would do that a bit, connect the mechanism, rotate the platter by and and follow the movement of the tonearm, where it raised and lowered and where it raised again near the center of the turntable. The process was time consuming and trial and error. 

No cartridge in place, just to be safe, which made the task even more difficult because I had to ballpark the position where the stylus would be. 

When I tought the tonearm was near enough to be adjusted with the screws, I put on the cartrige, set the tonearm balance and tested it again. This time even with greater care because i could allow the cartridge to actually touch anything.

After a couple of more adjustments, the arm was near enough its positions to adjust with the screws. Frome here on is pretty straightforward, just following the manual.

This whole process was nerve wrecking, but now the record it starts and ends playing in the right positions.

Going to see why the the why the camwheel didn't engage, i noticed two things, the gear wheel (Part 84 service manual) had some broken teeth, so I swapped with the one from the other turntable. (When I restore the other turntable I'll draw the gear and have it 3D printed as replacement). Here are the two side by side where you can see the one on the right with the broken teeth

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But the change was not enough. It would engage more often but not always. I then inspected the camwheel and it turned out that the two clear plastic tabs on the camwheel were too tight and wouldn't rotate to create the extra tooth I told you a few post above. So, with a very small screwdriver, I pushed the rivets hoding them a bit out to loosen the tabs. they now rotated freely and that was enough to make the cam engage and disengage.

The only thing missing from my initial problem list was to change the RCA plugs for a DIN Plug. Followed the wire diagram and soldered a new DIN Plug. I thing I never cursed so much in my life, trying to solder it.That has such small solder tabs. But I managed to do it.

I now had a fully functional and cosmetically beautiful Beogram 1203 altough still with a barely noticeable rumble coming from where the idler wheel touches the step cone. The following video was made before I got a new belt but serves just to let you know what rumble I'm talking about

Connecting phones to the computer and with max volume you can hear it. I had a folded paper wedged between the speed knob and the chassis to prevent the rumble

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And Here's the working turntable and that darned folded paper;)

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