Hi all,

After many trials and tribulations, I have completed a total overhaul of the BG6000 Quad, which I bought last year on Ebay from a used HiFi dealer in Toronto. Previously, I thought I that had fixed all the problems, but as I progressed, hidden defects came to light, which the previous owner/technician had intentionally hidden quite skilfully.

This obviously highlights the well-known adage - "buyer beware".

To spare the rest of you BeoFans who own this (or are considering owning this magnificent turntable) most of the troubleshooting I had to go through, I have compiled this list of what mostly needs to be repaired on a unit with an unknown history.

Menahem

Here's the first step on the road to recovery:

Lubrication of ALL these points is incredibly important.

If the arm does not lower (barring any severe electrical problem), the cause is dried/coagulated lubricant on the RED circled areas.

If you can see any dried grease, remove it. 

Then gently squirt Sewing Machine oil onto:

1. Both ends of the Yellow Solenoid Piston (Thick and Thin parts)

2. The Piston of the Copper Damper

3. The Axle pivot connecting the Solenoid and Damper

I had to replace the 1N4004 Diode, so I used a high-speed UF4007 - this also helped to solve the problem with the arm not lowering at the correct point, when starting to play an LP.

I also replaced the 22nF Capacitor with a Panasonic Polypropylene unit.

This absolutely solved the "Arm not Lowering" problem 

 

I also converted the Photoresistor bulb to a White high-intensity 3.0V LED and a 1K resistor (see post below).  This is by no means necessary, but it's one less thing (burnt-out bulb) to have to worry about in the long run.

The next problem to solve was this 33/45 Speed problem, which is more detailed in this post:

http://forum.beoworld.org/forums/thread/95021.aspx

In short, there was a problem in the 33 circuit, which the previous owner had skilfully hidden by disconnecting the 33 indicator bulb.

When I connected the 33 bulb to the circuit, this above problem appeared.

It was fixed by the following:

1. Replacing D6 - 1N4148

2. Replacing C4 and C5 - 3.3nF with Panasonic Polypropylene units

3. Restripping and Resoldering all the coloured wires onto the PCB - many were frayed, and a couple were hanging on by their last strands.

4. Replacing all Electrolytic and Tantalum Capacitors as follows:  >10uF with Panasonic FM units, and < 4.7uF with Wima MKS2 and Panasonic Propylene units. Note that some of the Capacitors must be mounted horizontally, to prevent contact with the suspension plate underneath the PCB.

Now that I had the machine working physically, I naturally wanted to listen to some LP's.

So I put on one of my CD4 Quad LP's, and ended up with this problem:

http://forum.beoworld.org/forums/thread/66387.aspx

Beogram 6000 Muddiness with CD-4

Basically, I replaced all the Electrolytic and Tantalum Caps with a nice blend of Elna Silmic II, and Wima MKS2 caps.

IMHO, this CD4 demodulator is actually one of the finest RIAA amplifiers ever made. So I wanted the best audio capacitors possible to extract every last nuance of sound from this board. 

Then, I got challenged again with this problem, which Mika in Finland helped me, by solving the problem before I had to deal with it.

http://forum.beoworld.org/forums/thread/87400.aspx

Beogram 6000 prematurely ends play

________________________ 

Mika wrote: 

A final observation, which I'll post in case it might help someone searching the forums for troubleshooting information later:

At first I was scratching my head over why the selection of record size & speed for 45 rpm singles only worked every other time, i.e on the first time the arm always tried to lower at the LP landing zone.

Then it occured to me that the worn out belt was slipping, and the platter didn't reach correct speed in time for the detector circuit to "see" it!

On the second try, it was already turning... there's a filter in the detection circuit, and it needs the correct frequency of moving bars under the sensor.

Wicked people, those Danish engineers!
_____________________________________ 

As Mika also wrote, on PC8009032, there is an ongoing problem with the Photo-transistor, and having to adjust the lamp, so the light reaches the transistor correctly.

I decided to go for overkill - I replaced the 24V 25mA lamp (IL1) with an opaque white medium-intensity 3V LED. This light from this LED is highly directional, and much more intense than the original lamp. So the Photo-transistor, on my unit a Motorola 2N5779, should be able to sense the light more precisely now.

The 82 Ohm resistor (R4) from the Cathode to Ground must also be replaced by a 1Kohm 1W resistor. 

Before replacing the clear plastic logic-strip with the black stripes, make sure that it is absolutely clean, with no finger- or other marks!

It is too early to tell if this improves the situation, but if there are no more unscheduled returns halfway-down the LP, then this could be a worthwhile solution. 

The last problem (I hope) I had to deal with, was the 33 and 45 indicator lamps heating up, and burning/deforming their plastic housings.

I am a fan of LED's, primarily because of their long-life, cool operation, and highly-directional intensity, even though the associated resistor warms up while killing excess voltage.

And I also know that some purists on this forum object to the use of LED's - and that's OK. I respect their opinions, and I have learnt a lot from them!

Anyway, this LED upgrade works beautifully, and does so without adversely affecting the required voltages on the Flip-Flop circuit (called a "Vienna-Bridge" in the Service Manual). I had feared that it does affect the voltages, but further testing shows that all is OK.

In the picture, on the white plastic hinged shields, you can see the yellowish damage, due to heat emitted by the standard incandescent lamps.

Parts required (total cost less than $1)

2 x Yellow LED's 1.8V,  Intensity >10,000mcd

1 x 1000 Ohm, 1 Watt metal film resistor

Some heat-shrink tubing.

Current to illuminate the 33/45 Speed lights is supplied by the Red wire. 

The voltage present on the Red wire is 22.8VDC positive, which has to be reduced to about 2 Volts.

I chose a 1 Watt resistor (1/2 Watt would normally be enough), because the resistor carries the excess voltage, and heats up. Using a 1 Watt resistor, results in a much cooler resistor.

I unsoldered the Red wire from the PCB, and soldered one end of the resistor in its place.

I soldered the other end of the resistor to the Red wire.

I placed the resistor at a small distance from the white plastic housing (around the metal bolt), to eliminate the possiblity of heat damage.

The LED's must be sanded lightly to give an opaque appearance, to distribute the light evenly.

I marked the -ve lead of the LED with a blue marker, which you can see faintly on the upper edge of the LED. If the LED's polarity is incorrect, it will not illuminate.

In the picture, the LED's upper conductor is -ve, and the lower is +ve.

20 minutes work, and a great result!

 

Hi i recently purchased a 4002 and had similar problems with the tonearm not lowering, mine however had a fault in a different place. where the arm pivots on the aluminium bracket. The pivot pin is made of steel and the bracket of aluminium, humidity had caused the aluminium the corrode and lock the arm in place. Lots of penetrating oil and moving the arm carefully up and down by hand free'd it up. Now works great.

yachadm:

I also converted the Photoresistor bulb to a Yellow low-intensity 1.8V LED and a 1K resistor.  This is by no means necessary, but it's one less thing (burnt-out bulb) to have to worry about in the long run.

I have the LED and the resistance. How exactly do I do this work? My knowlodge about electronics is very low level. Where do I put the 1k resistor. On one filament of the led?

Thanx

Hi Loris,

I don't want to discourage you, but this is not a simple job, if you are not very comfortable with a soldering iron,  and if you can't read a basic circuit-diagram - there is too much room for error, and likely destruction of the turntable.

IIRC, the resistor should replace the existing one on the PCB, and the LED must be wired the correct way, or it will not work.

On my previous post on this page, I specified a 3V LED - I'm not sure from where you got the above clipping about a 1.8V LED.

If you use a 1.8V LED which is not suitable with the 1KOhm resistor - your 1.8V LED will burn out. On this circuit, the LED must be a 3V LED to work with a 1KOhm resistor, to not be damaged.

If you haven't got a friend/technician who can help you, I would much rather that you sent this beautiful turntable to Dillen in Denmark - he is one of our most technical members, with an excellent workshop, and he will restore this for you, with much more than just the LED upgrade.

Regards

Menahem.

yachadm:

I also converted the Photoresistor bulb to a Yellow low-intensity 1.8V LED and a 1K resistor.  This is by no means necessary, but it's one less thing (burnt-out bulb) to have to worry about in the long run.

 

I read about the led here, in the second post. Well actually I didn't write I was telling about the photorestor lamp in the carriage, and not about the arm lamp.

Is this an easier work to do?

Loris

ps anyway I was thinking about sending all do Dillen. I only have to gather some money for the shipments and the repair....

Loris,

My apologies - the Yellow 1.8V LED is for the 33/45 speed indicators, but the Photoresistor is a 3V White LED.

I have now corrected the 2nd article above.

Menahem

Well, I'll get the right led but will it be an easy task?

Have I to put the resistance in the right place on the board or somewhere else?

How can I check if the photoresistor is good bofore attempting to do the work?

Thanx

Loris,

This is not an easy task. It requires disassembly of a few PCB's, and wires, as well as the tracking arm and ruler. You had better be really sure that you can do the job before you start pulling apart the turntable. You cannot be sure of the photoresistor, until you put it all back together and test it. You may have to pull it all apart again to align the photoresistor with the illumination.

Again, if you make a mistake, there is a good chance that this turntable will be unrepairable - a real shame.

While a lot of repairs on vintage equipment can be done with little effort, this particular repair is not a job for the faint-hearted and inexperienced. Best to leave it to a technician who knows what he's doing.

Menahem

Replacing the bulb only, seems something I can do. Is this bulb available? Is it a standard bulb?

Thanx

Even replacing the bulb, requires you to disassemble and remove the PCB's, the track ruler and wiring.

If you have a technical friend, have him assist you while you do it.

And note the exact position of the ruler for reference when putting it all back together.

Martin

well seems you succeded in dissuading me from making anything inside the 6000. You don't want to have a murder on your shoulders

Dillen, ( Martin ) I'll send a pm..... but I don't know how. Seems I can't send you a mail.

Loris

Click on my login name above the crocodile. Then click on "start a conversation", fill in the
subject and text fields and click "start conversation".
You can check your inbox in the top right corner of this page.

Shipping a Beogram from Italy to Denmark is probably not very economical, especially since the rates
from Denmark have increased twice a year for several years. I'm sure that someone else nearer to you can assist.

Martin

:)

Manahem, can't I measure with a voltmeter if there is some current reaching the bulb? I see the two points where the lamp is soldered. I guess I can't harm the 6000 just measuring these points. How many volts should I read?

Loris

Yes, I thought of you Eugenio. 

Martin

As you can see on the Circuit Diagram, there is 22.8VDC on the +ve side of the lamp, relative to GND.

Measuring from +ve lamp terminal to GND, you should see 22.8VDC.

Measuring from -ve lamp terminal to GND, you should see a couple of volts less than 22.8VDC (but if the lamp is shot, you won't see any volts at all).

As for voltage across the lamp, you cannot be sure from the diagram, because of the 82Ohm resistor (which must be changed to 1KOhm for the LED) - the measured voltage passing that resistor will depend on the current draw.

So, if you've got your 22.8VDC, then the lamp should illuminate (assuming it's serviceable). If it doesn't illuminate (and the lamp is serviceable), then either the 82Ohm resistor is shot, or you've got cold solders, which is fairly common with these older machines.

I see 23 volts ( with a chinese voltmeter) at the the lamp filaments. So the lamp should be burnt.

Loris

Sorry but are we talking about...

- the position ruler lamp that Menahem shows in the schematics
or
- the tracking lamp in the closed housing at the foot of the carriage that Loris just emailed me a photo of

?

I feel there is a slight misunderstanding here.
Loris, please let us know what the problem is with your Beogram - exactly !

Martin

Dillen:

- the tracking lamp in the closed housing at the foot of the carriage that Loris just emailed me a photo of

I'm talking about this and everything started here

http://forum.beoworld.org/forums/t/27172.aspx

Anyway since this is a 6000/4002 thread:

when the arm lowers on the record the carriage doesn't move. The cartridge arm goes for a while
and when the free play is finished the arm stands still and jumps back the groove
The servo works ( If I understood right) because I can move the arm where I want on the record,
even if it seems to me that it's a bit slow.
The ruler/sensor lamp works properly.
Loris

ps maybe my english is not very good in explainig technical problems