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
Dear members,
I thought, I'd better put this in a new thread. After adjusting the sensors beneath the cart, the tonearm of my Beogram 4000 lowers although there's no record on the deck. It does so at varying points of time. Most of the times very early after start, but sometimes it also moves all the way and back again like it should. Any ideas what the problem can be? It didn't do anything like this prior to my adjustments to the metal brackets that are touching the sensors beneath the cart.
Rgds,
Kai
Does the detector arm light flicker?
Jacques
Double post, sorry.
You mean the red one beneath the plate? Yes, it does. Recognized that today in the morning when I was trying to fix the Beogram.
If that's the cause, I would consider it strange that nothing went wrong prior to my adjustment...
I mean the B&O red light at the extremity of the left arm. If this flickers then yes that could be the issue.
I'll take a closer look tomorrow. However, I don't think that it flickers. But let's see first.
No flicker on the light. So, I'd guess, this was not the reason.
No mat of course.
Sorry for asking, but what do you mean by "no mat"? Just to be more precise:
Of course, the mechanism only works with a rotating mat. I'm not 100% sure how. The mat does have some pattern beneath it which is obviously recognized (at least whether it's moving or not) by the red light inside of the Beogram beneath it. At the same time, the lamp on the arm recognizes the pattern on the top of the mat when no record is on. However, I do not understand, how the two mechanisms interact. What do the mirrors on the inside do? They just seem to reflect the light to the outside of the Beogram.
What happens in my case is the following. Whenever I put the mat on, rotate it manually and then press start, the mechanism seems to work as it should for like 2 or 3 times in a row. Then, there's one try, where the tonearm is lowered too early and after that it is almost lowered immidiately after pressing start. Not sure, whether this pattern is robust though. Only robust thing I can say is that sometimes it works, but most times it doesn't. And most of the times, no matter what other factors are (mat on or not, rotating yes or no), the tonearm almost immediately starts to lower after pressing start.
As far as I've understood it, the light on the inside recognizes the mat rotating. The corresponding signal prevents the tonearm from lowering. However, as soon as one of the metal parts beneath the cart touches one of the early microswitches, the tonearm receives a signal to lower, which it only does if there is no other signal initiated by the lamp to the outside of the Beogram when it sensors there's no plate on the mat. Not sure, whether this is correct. If so, however, then the cause of the problem is the signal that is initiated by the red light inside of the Beogram since the arm already lowers before the first microswitch is pushed in. This would mean that the Beogram fails to recognize the mat rotating. No idea what the reason might be though. I was cleaning everything (lamp, mirrors) and prior to doing so, it seemed to work. Maybe it's got to do something with the angle of the inner lamp and mirrors? In this case, I'd need to know better how this precisely works.
Does this make any sense, or am I getting it completely wrong?
Thanks very much!
A turntable mat is the rubber or felt piece that usually covers the platter. I've seen such Beograms fitted with those and of course it's a mistake.
Now the orange light is just the strobe light and serves no other purpose than that!
The platter ribs detect arm position and yes it works reliably.
They will also "sense" - well, not really of course - EP and 25 cm records so that the arm drops accordingly and so that speed switches to 45 RPM when no LP record is detected.
Perhaps the detection bulb has become too weak to work as it should. Also worth checking is the voltage that feeds it.
Voltage might well be an issue. Strange thing just is that it worked prior to my adjustments until yesterday. It also seems to work when moving the arm until the beginning of the plate, stop it by pressing the corresponding microswitch, then rotating the plate manually and pressing start. Seems to be a problem that only occurs during the first few centimeters of arm movement.
I think, I'll have to take it to a repair shop. Seems to be an electrical issue. I was testing it a little more and now instead of lowering the arm the motor speeds down and I can't even turn the system off after that. So I have to use the right arrow button to get it back to its starting position and only when the first micro switch on the bottom is touched it turns off. Even when I press "Off" instead of turning off, the motor just slows down and continues to move slowly in the same direction. Weird.
Be careful... A lot of repair techs nowadays don't have a clue on how to fix these wonderful pieces and WILL make a mess of them, pretending that they are beyond repair (of course).
A few members here can do that in their sleep though.
I know. I'd really love to give it to somebody from here. However, I'm located in Munich and am not sure if any Beogram 4000 expert is nearby. If so, I'd be happy to get in touch. These things don't ship well. That's why I'd better not have them shipped.
You are welcome to come for a short holiday in Israel, and I'll take care of it while you're here!
Menahem
Hi Menahem,
I've been to Israel before and loved it. I don't particularly like to travel, neither am I interested in culture, but Israel just blew me away. Amazing experience and great memories!
Greetings,