ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Following the completion of the main PCB I thought it would be a good idea to check the functionality of the machine so far, I'm probably around the halfway mark...so powered up. To my dismay only one control panel scale illuminating LED is working! everything else looks good and seems to be operating fine....this is what I have discovered, the circuit for the two scale lamps shows them connected in series with a 24vdc power supply.
I know the last pic is rubbish.....never mind, when I look at what I actually have I find that the lamps are connected in parallel to a 24vdc power supply.
This means one of Rudi's LED's is reversed when installed in the correct orientation to the light box into which it must fit, rotating the LED through 180 deg enables the device to work....but will be out of kilter.
Clearly not something Rudi would be aware of....the circuit diagram matches his design, a later modification perhaps....will send an email to see what can be done....oh joy!
Having given the LED issue some thought I can see a couple of solutions so I'm not overly concerned, push comes to shove I can always replace the incandescent lamps, however I will wait for a reply from Rudi before I start to effect any circuit board mods or replace the original lamps. Meanwhile I have made a start on the reservoir caps...and as they are out of the way it seems like a good time to replace the transit bushes with Rudi's shapeway parts.
Re assembled, bit tricky lining everything up but easy enough.
Got the rest cleared out, took lots of pics to ease re assembly......
And the first two new ones back in place......they are also the easy ones.
Completed the big cans this evening.....powered up and all is well.
Pleased with the result I decided to take a closer look at Rudi's LED devices...as these are polarised it stands to reason that they only require unsoldering and reversing on the board and off we go, these are bi colour LED's to give the correct warm glow that Rudi favours (I read up on them on Dialight website) so with the help of a piece of blu tack I found lying around, to hold the little devil still I unsoldered first one LED...
And then the other.....this really does call for a steady hand and nerves of steel ;¬)
Reversed both LED's and soldered them back onto the board.....the pic is taken through my desktop magnifier so is not the best.
However when I applied a 9vdc battery to the device it burst into life with a very greenish hue, I was amazed it illuminated at all to be perfectly honest, even with a magnifier I couldn't be sure I had nailed all four contacts on each of the two LED's. Realisation dawned that the resistors which are soldered in series with each LED, to tune the colour, would also have to be swapped over.....with a shudder I unsoldered them
And swapped them over before re soldering them back to the tiny board....
Tested with the 9vdc battery again and was rewarded with a nice amber glow...…...couldn't believe it! soldered it back into the control panel and powered up.......
Finished article, without the travel indicator in place looks just fine, this is not something I would recommend.....leave it to Rudi.
Steely eyed missile man, as Rich would put it, good job, I am always afraid of soldering in tight spaces
Collecting Vintage B&O is not a hobby, its a lifestyle.
Well...clearly the other members enjoyed the LED experience a lot more than I did.....very fraught. Next up sensor arm incandescent replaced by another of Rudi's LED's old lamp ready to be removed.
New LED package in place with the small wedge popped on with a spot of super glue to hold it in place....
Seemed like a good time to make sure the lamp and sensor where providing a the proper signal....part assembled the required pieces and everything is well.
Tracking sensor next up.....quite a fascinating bit of work, cant imagine why anyone would want to play an album backwards but there you go....
Original lamp exposed.....
Rudi's creation in place.....following the setup procedure and looking at Rudi's video allowed me to setup the prescribed 4 revolutions of the turntable before the motor started to crank the arm along was fairly straight forward, combination of mechanical adjustment and LED intensity got me where I needed to be.
Final electronic components installed on the power supply board pretty much concludes the soldering iron work, need to install the remaining two transport locking bushes and then the cabinet guiding washers.
As the Perspex cover has lost, mostly, its feet I have bored out the remaining roots and glued in pieces of an old drive belt....will trim them to size when the glue sets.
Guide washers next...this one is clearly a replacement fitted in the past, will put a black one in its place which wont show up as much between the top plates.
The original screw has also been replaced, this may be ok...will find out when I replace the top plates.
The rest where straight forward
RPM set up using Rudi's little tachometer....running a bit slow on 33.3
The 25 turn pots make it fairly easy to get a good setting...
Hmmm......don't know about that, how hot are they supposed to run? typically if something is too hot to touch its over 60degc, not much of a guide I know but I'm sure someone on here will know...Martin ;¬) I will give it an extended play when we have the information to hand and go from there.
I read this on my travels - Martin mentioned checking the motor phase adjustment
https://archivedforum2.beoworld.org/forums/t/14733.aspx
Dave....will digest that and set up my scope, see what's going on
Ok...following a good read I have set the beogram away at 33.3rpm and went off for a pot of tea, on return some 15mins or so the motor did indeed feel quite warm to the touch, ran very quiet though.....hooked up my ancient scope and DVM and set her away again...this is what I was getting with 5v per division on the scope....its around 16-17v p-p with the DVM measuring over 8.15v rms and there is clipping
Not the best picture.........however, following the required adjustment of the MOT potentiometer I'm getting a very clean sine wave at just over 5v rms and the motor has now been running for around 20mins and is only warm to the touch...…..I', happy with that.
I think that's about it...…….gave her a spin with both 33.3 and 45 discs and everything looks and sounds fine through a BM4400.
Dave....let me know when your next on tour, I'm off windsurfing in Greece 9th Sept for a couple of weeks......so before or after works for me ;¬)