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
I have a problem with my Beogram 4002.
Basically the arm doesn't lower most of the time after I have pressed start. I actually think it is a problem with the electronics but have no clue where to look.
So after I press start, the arm moves to the record and once it reaches the record you here a soft "click" but the arm does not lower. If I press, up and down later in 50% of the tries the arm will lower.
I have cleaned, greased and adjusted all involved mechanical parts as shown on the "restoring beogram 4002" video's available on youtube. So I'm confident that is not the issue.
With the cover plate off I looked at what is happening and I see the solenoid pin slightly retracting (maybe 3mm or so) and then immediately going back out. So this is the soft click that I hear. If the arm is in postion and I wait some seconds and press down again the solenoid retracts as needed and the arm lowers.
So my common sense thinking suggested that the arm movement and the solenoid share something in the power supply and as a result there is not enough power available for the solenoid immediately after the arm is in postion. (Its like a capacitor has drained) give it a few seconds and the power is back to the needed level and after that you can lower the arm.
Is this even possible? If so, what can I do to fix it or to further diagnose it? If not, what else can cause this?
thanks
Eric
Sounds like the solenoid only gets the "hold" current. Not the "pull in" current.Check the switch associated with the solenoid circuit. It's operated by the lowering mech. and sits to the left of the solenoid.
Martin
Thanks for the quick answer, but I'm probably missing something. There is nothing to the left of the solenoid except the sliding mechanism?
After checking page 2-4 of the service manual where the magnet coil circuit is described, I came to the most likely cause that 1C23 must be broken/worn out. Does anyone know what a replacement for this is?
If I check the parts list in the same service manual, I cannot find it. I can find 6C23 but that has a complete different value.
I Replace the Tantalum capacitor without any change.
Next I decided to replace some of the transistors, because I saw other people describing that they did that.
Unfortunately I placed (swapped C en E) Tr9 and Tr10 incorrectly because I used the wrong specs of the replaced transistor. And as a result the fuses in the power supply blew.
So I soldered them in the correct position and put new fuses in. Now I have exactly the opposite problem, the arm goes down (solenoid engages) as soon as I pot the power cord in the wall socket.
My guess is that I broke something when the fuses blew, but I do not have a clue what. I also replaced the Tip125 and Tip120 but this gives me the same problem.
Anyone know what might be broken in the magnet coil circuit if the arm goes down immediately when there is power on the board?
Because of my error I basically have blown or damaged the darlington so after replacing all of them with new ones i returned back to my original problem.
after help from one of my colleagues I now found a “sort off” solution for this problem.How erver the problem still occurs once in a while, albeit the occurences are 1/10th of what they were before.
He measured that the power supply dropped from 30 to 25 volts briefly when pushing the start button and he recommend to change the transformer setting from 240v to 220v (we actually have 230v here).
This reduced the problem significantly. He also checked the main capacitor in and in his kind this is still okay.
But as said, sometimes the problem still occurs and it seems to be related to the platter still busy to get speed stability. Because it happens more often with 12” rtrpm records.
so, is there anything in the circuitry that I can look at which might cause the drop in available voltage?