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 was working on my Beogram 4002 and I tried to re-oil the platter motor. I inadvertently plugged the motor wires into P2 instead to P1. Not sure what the difference between the two. Motor was running but then stopped. I checked the line fuses and they were both blown. I replaced the fuses but not getting any power to motor or the tone arm. I checked voltage output from the transformer (two blue wires) and it looks like I'm getting 25 volts AC? I thought the motor was DC voltage so not sure how the change is being accomplished (diodes?). I'm don't know a lot about PCB electronics. Do you think the board is blown? Does anyone have any ideas?
GreenAcres: I was working on my Beogram 4002 and I tried to re-oil the platter motor. I inadvertently plugged the motor wires into P2 instead to P1. Not sure what the difference between the two. Motor was running but then stopped. I checked the line fuses and they were both blown. I replaced the fuses but not getting any power to motor or the tone arm. I checked voltage output from the transformer (two blue wires) and it looks like I'm getting 25 volts AC? I thought the motor was DC voltage so not sure how the change is being accomplished (diodes?). I'm don't know a lot about PCB electronics. Do you think the board is blown? Does anyone have any ideas?
Hi, unfortunately plugging the plug into the wrong board connector was probably a bad misstep. I never messed with the P2 connector. It isn't on my Beogram 4002, type 5523 schematic and service manual either so I don't really know what P2's purpose is for. Maybe Dillen can enlighten us. I do remember Dillen (Martin) offering this information on an old Beoworld thread from 2011 - "Don't fit the platter motor plug to the wrong connector - the board and motor WILL suffer damage.Most boards have a silk-screen printing near the connectors, telling the color of the nearest wire in the cablethat should be connected."It's too late now but whatever damage is repairable.Regarding oiling the Beogram 4002....The service manual describes what things need lubricating. The DC platter motor is not one of them (look at section 3-6 of the service manual). Over time the DC motor can wear down and need re-fusing with oil but that isn't something you can do by spraying or squirting oil on the shaft. Check out Beolover's Blog on how to restore the Beogram 4002/4004 DC platter motor. I recently sent him two of my motors to restore as I don't have the proper equipment to do it myself.About your AC voltage on the transformer...AC is what you should get. The transformer scales the line voltage to the proper AC signal the Beogram power supply expects so the power supply can turn it into DC voltage for the turntable circuitry. It is impossible for me to tell you what damage occurred by the plug mistake but as I said, an experienced technician for Beogram 4002/4004 turntables can fix it. A word of advice for anyone working on vintage audio equipment though is that you should always get a service manual for the component and do some research on its repairs before diving in. I know from my own experience that it is very tempting though . One lesson that can be passed on to other Beogram 4002/4004 owners (with DC platter motors) is to put some tape over the P2 connector so it doesn't accidently get used.
-sonavor
When taking things apart, today, many people expect that the things are fool-proof and can only be assembledback again one way - the correct way.Don't expect anything like that with the older things.It's a fact, that these Beograms can be put together in many wrong ways. Almost all plugs will gladly insert one or even two pins off to one side.
The "wrong" socket was originally for a LED placed on the front of the black base, just under the wooden trim.
Martin
I was afraid these were the answers I was going to receive. I admit I was a little surprised that two identical plugs were fitted so close together. I also admit that I've grown accustomed to today's engineering that won't allow you to make such careless mistakes. I now realize these are very well crafted and engineered machines that don't follow today's rules of mass production. Lesson learned the hard way. Looks like this fine turntable is now doomed for the garbage bin due to carelessness. Thank-you for the replies.
Modern again; It's broken - throw it away.
Not at all!It just needs a little repair.
GreenAcres: Looks like this fine turntable is now doomed for the garbage bin due to carelessness.
Not so, these beautiful antics are repairable, that what we do here in the vintage forum, we save them all (well nearly all) we all make failures but that is not a reason to give up, learn from it and go forward. As Sonavor says, get the manual and start finding the failure, help is available here on the forum.
Good luck
Collecting Vintage B&O is not a hobby, its a lifestyle.
GreenAcres: Looks like this fine turntable is now doomed for the garbage bin due to carelessness. Thank-you for the replies.
I am located in Missouri. I've poked around online and I'm not convinced that I can actually find a service manual for type 5523. There are so many different types! To be realistic I'm probably going to need a platter motor and I don't see any where to purchase one. I suppose there might be a way to test the motor that I have? It seems that if I really wanted a Beogram 4002 it would be more cost effective to purchase one from ebay and start the process over again. This table was purchased from Craiglist and I thought it would be interesting to try and get it up and working. I still do but I think there are too many problems to overcome.
We can help you get the 4002 saved. I have a service manual for the type 5523. If you want to send me the motor and the main board that the motor plugs in to I can test them out with one of my Beogram units and let you know what your options are. Post some pictures of the turntable so we can see the condition of the rest of it. How does it look cosmetically? Also, take some pictures of the inside of the Beogram. You can send me a message through Beoworld if you want me to look at it.-sonavor
I take it, you pulled the motor from its holding bracket and out of its housing.It's not just sitting like that, - right?
Yes, I just placed the motor back in the plinth after working on it. I still have all of the mounting hardware for the motor. Does anyone know the voltage for the motor? I assumed it was 5 volt but I'm not quite sure. I have applied 5 volt DC to the motor but it doesn't seem to be enough voltage as it requires a slight spin by hand to get it going and even then the RPM's seem slow. I suspect that I may have damaged the motor.
First step in getting this Beogram back in working order (or anything else for that matter) is to stop guessing!It's a DC servo motor.If you are in doubt, ask before assuming or trying your luck.
Some Beograms use 3V motors.Which type is yours?
I have no idea. Documentation seems to be esoteric. Multiple versions of same turntable creates confusion. Reminds me of complicated modern auto repair. You can take your new car anywhere to be repaired but only the creator (dealer) can repair it since they are the only ones with access to the esoteric data and tools.
Stereo equipment cannot be repaired by just anyone, that's correct, and Bang & Olufsen tangentialdecks are definitely not the easiest things to work on.You cannot just look up a Youtube video that will tell you how to do it and you cannot just 3D-print a new one.I wouldn't expect any and all baker, carpenter or shoemaker to be able to repair and restore one let alonehave the instruments, experience and the most common standard parts in the drawer.Sorry, it's nothing like that.Electronics mechanic is a 3-4 year long education, and first then you can start building experience.You will then learn to understand circuits, often by merely looking at component types and values.B&O servicemanuals will not tell you how to repair anything - that's a general misunderstanding - and they will not educate you.The manuals will tell you how the thing is made - allowing the trained tech guy, using his education, tools, instruments and experience, todiagnose and repair the thing.
Do you have a reasonably well equipt repair facility?Do you understand the motor driver circuit and the way a servocontrolled DC motor works?Is there a label with a type number on the motor housing?
I did not see a label with the type number on the motor housing but I will look again. This project is obviously only a labor of love since it makes no financial sense to repair. Your points about needing advanced education and training to diagnose and repair are well taken. I do not have a good understanding of the motor driver circuit or they way a servo controlled DC motor works. My assumption is that the DC motor runs faster or slower depending on the voltage level. What this voltage range is unknown to me. My guess is that 5 volts would be somewhere close. Since the voltage going into the board is 25 AC I assume that the DC voltage would be less than 25. I see what looks like four diodes by the board power input. What points on the board would should be yielding the DC voltage? Perhaps a diode is burned out?
I did not see a label on the motor housing. I have a few tools to perform work. I understand your point about the need for electrical engineering training and education. I do not have such education. This turntable is obviously a labor of love as it makes no sense financially to repair it. Given the age of the Beogram 4002 it would probably take considerable time and effort to find a repairman trained, and more importantly willing, to undertake such a project...at any cost. The fact that I have probably overloaded something causing a fault makes it even more difficult. This is beside the fact that parts are no longer available.
Since the transformer output voltage is 25 volts AC can I assume that the DC board voltage is going to be less than 25 volts? Looking at the board I see what appears to be 4 diodes by the power supply input connector. Are there points here that can be tested? Would it be safe to assume that the diodes need to be tested as they can burn out? We still need to establish what the DC voltage should be.
True - Here in the USA it is not common or that easy to find technicians that work on this type of turntable. The demand for turntables has only recently increased and there aren't many repair shops. All of the audio shops (and stores) from the heydays of the 70's and 80's are gone now. Modern electronics are mainly use, then throw away. That is what I like about the audio equipment from the era of this Beogram. They can be repaired and when fully restored, they perform as well as anything. With a turntable restoration there is more than just electronic restoration though. The Beogram has a lot of mechanical and electro-mechanical adjustments. So to produce a beautiful performing Beogram 4002 it does take quite a bit of work. Whether it is financially feasible to restore the turntable is up to the individual. With the price of new turntables going well over $1000 I would say yes. The Beogram is very well built and durable. I have two early Beogram 4000 turntables I restored that are like tanks. The Beogram 4002 turntables are very similar tanks as well. My Beogram 4002 Type 5523 that I purchased new in 1977 is still performing beautifully. I have kept up the maintenance and did restore worn electrical parts on it to keep it functioning at its original performance.In any case, please don't junk it. From your pictures it appears it is in pretty decent shape. The control pad section is heavily worn but that can be reworked to look like new again. What amount do you view as too much to restore a turntable? Any vintage piece of audio gear (from the 70's or 80's) requires restoration if you want to really have it perform the way it was designed to sound. I have purchased a number of vintage pieces that were original and still functioning (amazingly). On some of them I used them for a while in that acquired condition until they eventually failed. After restoring them it is like a whole new experience of how well they are supposed to sound.
Update: The main PCB seems to be okay. I installed and hooked everything up and it seems to be working. I don't have the platter motor but I tested the voltage at P1 and it's showing about 3 volts. Everything else also seems to be working. I sent the motor to Rudy to see if he can bring it back to life. Maybe, just maybe.
Very good. Once you get the motor back you should be in business. I would recommend checking the service manual procedures for the various adjustments to make sure everything is still setup correctly. It sounds like you will soon have a serviceable Beogram 4002.