Jeff:

You aren't having luck with any of your turntables are you :(

I suspect bad electrolytics. Start with replacing the big power supply cannisters. I'd do those first and see if the thing comes back to life as opposed to shot gunning and changing them all at once. The risk with shotgun approach is that you introduce more variabilty (putting the wrong cap, getting the polarity wrong etc...)

Measure all power supply rail voltages and verify with service manual. Typically when capactors short out one of the rail voltages will be pulled low. So look for this and then change the cap there to see if  the voltage is restored.

When caps short out they could also take out the immediate rectifier or diode. If you can't restore the power supply voltages check for bad semiconductors.

Derek

Hi Derek,

My first reaction to your opening line is no I am not…. but that is not entirely true. I had an assortment of tiny issues with my 4002, and your last suggestion set that turntable right. Then there is my 4004 which NEVER gives ANY trouble.

The 4000 is entirely another matter, as I am on my third package of five fuses. I will try Martin’s suggestion on Friday.

As for the Beogram 8000, you do understand that the 8000 does indeed come back to life after say 20 minutes? It is like it is over heating, but once it cools down, things are absolutely normal.

It would have helped if I had been able to open the 8000 quickly enough to find the source of the smoke, but we were in the middle of a meal and I just wanted the thing out of the room so that we could finish eating.

Now I can’t get it to smoke a second time, the platter just stops.

The vibrating or buzzing platter drive motor doesn’t tell you anything? I was sure the motor was the culprit, although I am NO expert.

If you are still fairly sure that it is the power supply canisters, I will try to find a source for them. I look forward to your answer.

Jeff

Jeff:

"if you are still fairly sure that it is the power supply canisters, I will try to find a source for them. I look forward to your answer."

 It's just a guess. It could be a resistor or a diode.

I'm guessing capacitor because they are old and have a tendency to short out. Resistors typically don't fail/smoke unless there is some short causing a current draw. If anything when they age, they crack and open up. It is possible that a cap went causing some other component to go.

Next on the list are the diodes. I don't think there is enough current in the PS to cause the power transistors or ICs to smoke since they are more heavily encased. Surely if that much heat could be generated, the fuses would have blown.

Check for charred components particularly those across the power supply rails and motor amplifier since they are high current. Be suspicious of resistors with bubbled up paint.

This is all speculation of course.

I don't advocate brute force change all component approach. You'll need to probe around with your meter. Voltage references across several test points are given in the schematics. If something has shorted out, I can guarantee you that all the voltages will not be present. This is where you need to start.

Derek
 

Derek:

A fairly close inspection showed no cracking or opened up transistors or capacitors. Everything looks quiet good.

Now when I spoke of smoke, I should have made it clear that I did not actually see smoke, I only smelled it… it was definitely an electrical fire with oil mixed in, hence my thoughts that it must be the motor.

Also if a transistor shorted out due to age, would it come back over and over again after a brief “rest?”

I should also mention that I have no doubt that some capacitors are “heading south” as this 8000 has several “quirks.”

First you must press “pause” before moving the tone arm left or right as the tonearm does not lift as it should. The arms do however lift when “Stop” is pressed or “Play” for that matter making this an annoyance, not a real problem.

Also the Lamp on the sensor arm does not light unless double play is selected and then it blinks as it should.

Other than the above, this 8000 performs well.

Even with this problem and the platter stopped the arm controls work properly and the sound continues until the platter comes to a complete stop.

Then give the 8000 a short rest and it performs normally again, and again, and again.

The good friend that supplied the works for my original 8000 which was beyond repair has my original motor and will gladly supply it if the motor appears to be the problem. However I do not want him to go to that expense of shipping it if the motor is the problem lies elsewhere.

Right now I am up to my a__ in problems with my Beogram 4000 and I just don’t have the energy to tackle two Beogram problems at once.

So guys, what do you think of this 8000 problem? Derek, Martin, Peter?  

Jeff

If the processor runs under unstable conditions, it will produce unstable results.
If f.e. the main motor coils are not driven they correct way (f.e. not alternating due to a processor halt), the
driver circuit will overheat.
Replace the caps. You can take them one cap at a time if you have the patience and/or doubt your skills but it's my experience that if
one cap is bad, the rest is probably near the end as well.
Check for cracked solders, especially around the transformer plug, the rectifier diodes and the connectors
at the edge of the main board.

When these things has been taken care of, you can look for any eventual faults but the above will cure the majority of intermittent problems.

Martin

Hi Martin,

I know that you have capacitor kits; do you have one for the Beogram 8000? If so do you think that this is something the average guy can successfully replace?

If so send me a PM with the cost and I will send you payment via PayPal.

My day off was cancelled due to company need, so I will not have the time to try your prescribed fix on my Beogram 4000 tomorrow as planned, plus I am loath to taking on two projects at once, but if this needs to be done and I can do it, I will.

Thank you for your sage advice.

Jeff

Hi Jeff,

Yes, a kit is available, you have a PM.

Martin