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
As I'm waiting for a delivery of capacitors for the Beolab I have been playing with I decided to take a look at this deck I collected from a chap in the Wirral last weekend.....bought on ebay a month or so ago and just got around to collecting it
Was sold as "Faulty" and this turned out to be an accurate description of the deck.....Perspex cover will require polishing to remove some quite deep scars, the stylus is bent double (has actually dropped off and is now hiding within the pile of my carpet) so the cartridge has been posted off to Alistair of Audio Originals for inspection....the coils measured up good at around 700 ohms so I'm optimistic it will turn out well. The seller advised the tone arm refuses to drop when a record is detected and this is indeed the case.
Manual operation of the tone arm lowering mechanism and the solenoid revealed it is in fact partially seized quite badly, this isn't a problem....and to be fair the rest of the machine looks in pretty good shape....certainly recoverable
Dismantled the tone arm lowering mechanism and found the pivot bushing under the circlip was the culprit, really was very tight and took a bit of persuasion to free off...….there are bits of wool inserted into the coils of the springs, I lifted one out before I realised what is was...thought it was just an accumulation of bits of fibre and dust, but its clearly meant to be there....but to what end?
Craig
Craig: Dismantled the tone arm lowering mechanism and found the pivot bushing under the circlip was the culprit, really was very tight and took a bit of persuasion to free off...….there are bits of wool inserted into the coils of the springs, I lifted one out before I realised what is was...thought it was just an accumulation of bits of fibre and dust, but its clearly meant to be there....but to what end? Craig
I've always assumed it was a form of damping.
Don't forget the up down pivot on the arm. The arm will drop much smoother with a clean and lubricate. Not so easy to get to though.
Regards Graham
Agreed Graham.....and while most of it is removed a drop of oil on the up/down pivot is worthwhile
Reassembled and given a test run.....arm lowers nice and gently, tone are tracks very nicely too.
Floats nicely below the knife edge too, rocks gently as the album spins
The guiding tabs have all took a beating, should be easy enough to straighten them out..
And the keypad shows signs of wear in the usual places......I know Rudi can recover these.
I may send it over to him, don't know if Frede can anodise these?.....however I have found this replacement, chap in Romania If I remember correctly, not perfect but better than the one that's fitted.
Internally looks very clean...….
Main circuit board is also in very good shape......
Craig: Main circuit board is also in very good shape......
Little used by the look of it. At least one of those higher wattage resistors and the board below usually shows signs of heat stress.
Metal work has been in the wars over past 40 or so years......
cleaned up and primed....sadly the stick 0n label had to be sacrificed for a better cause...…..
Woodwork is a little knocked around too....but to be fair is only superficial damage, corners are still nice and sharp...…..
The hood has also taken a beating....had to peel away the foil trim in order to get the hood off the rear bracket, bit drastic I know....but I also know a man who makes pretty good aluminium replacement trims, better than the original foil.
Soul destroying exercise but has to be done....this represents 3 hours with 400grit, sadly I didn't have any 200grit which would probably made things a bit quicker.....still a long way to go however, probably another 3 hours with ever increasing grit levels
To break the monotony I have made a start re-capping and replacing the trimmers…...
Couple of coats of satin paint on the rear supports...
I had these transport lock bushes 3D printed using the .stl files from Christian Leicht…..when I opened up the clamps I found that the existing bushes where in good shape....so I have left them in place, keep the new ones for another day.
Spent a bit of time on the wood trim too...….anything to break the monotony of polishing the hood!
This Beogram has the LED on the front?
Martin
Yes it has one, comes on when power is applied...works fine. This however has to go...
Bit tight in there....but the end result is worth the effort.
Moving on to 1000 grit....I hate this
Getting there...……..really just polishing for a little while more
Aproaching the end game.....all coming back together.
As the RPM trimmers have been replaced slight adjustments where required using Rudi's patent RPM device, I did download the driver and an application for this and it works really well on the PC.....don't really relish the thought of giving the motor a 24hr test in case the results point to a bearing oil infusion....not sure i'm ready for that (and I don't have a vacuum pump)
Fitted the new trim....
Over and out...………..
Hi Craig,
For what it's worth, I did an oil infusion under vacuum on a BG4002 DC motor and it was straightforward enough even without special tools. A vacuum wine stopper siliconed into a jam jar lid did the job. As for the spark snubbers, that was beyond me, but the oil infusion was well worth doing. The motor drew less current on reassembly.
Keep up the great work.
Simon
Thanks for that...I have wondered how much vacuum was actually needed to perform this exercise, I have run a 40min test and documented the results.
Should have done that before I bought a wine bottle vacuum pump! only a 40min test but it looks good to me
Well......my partner decided it was time I let one or two pieces go to people who will use them, she's right of course.....so to that end i dusted this off and prior to advertising it on a well known auction site I did some tests to ensure full functionality.....imagine my astonishment when the tone arm refused to drop at the appropriate time......very annoying, non the less checked inside and nothing looked untoward the magnetic coil flutters on sensing the drop point but doesnt pull in.........tested 1TR9 and 1TR10 of the Magnet coil circuit and both are good.....I dont have 30vdc at the collector of 1IC4 only 26vdc....so i suspect im not getting the initial current to the coil and only the hold in current, will look into this
1IC4 also checks out good.....the solenoid coil weighs in at a steady 8 ohms........not much else to go wrong really,..
I checked the solenoid's coils on one of my Beogram 400x units and I get 8.5 ohms so yours is close enough it could be a difference in our measurement devices.When you say the transistors check out is that just out of circuit testing?If so, then they could be failing when in operation.I imagine you checked all of the trace connections in the related circuit for any connection issues, right?
You mentioned that the power supply wasn't producing 30 VDC.How healthy is the signal to lower the arm?
John
Yes I have tested the transistors out of circuit, they may well be failing in operation. I have had a good look at the traces and connections and they all look good, as for the 30vdc I'm getting this at across OC1 but on start up it drops to around 26vdc at the emitter of 1IC4....i will check the Signal to lower the arm at the base of 1TR9 this evening...I will also get my scope out and check the trace at the collector of 1IC4. I did check the damper pot for lubrication and found that when the damper is removed the solenoid will pull in against the spring alone...but with the damper and lift/lower linkages connected the solenoid hasn't got the "umph" (technical term) to pull in, the damper adjustment is fully open and the lift/lower linkages feel pretty free but they could be the cause.....however i would expect the solenoid would be strong enough to pull in against the slight resistance of the linkages and fully open damper.....i will look harder at it.