Mark-sf
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Looks like a nice find! If you take the bottom off you will find where the RCA cables were attached as well as the terminal that is grounded to the chassis where you can simply solder a stranded single wire for your ground. As for belts, check out http://www.beoparts-shop.com.
It most definitely can blow as those contacts conduct when you plug it in.
Before attempting to disassemble the transformer, I would measure the primary and secondary windings with an ohmmeter. This will let you know whether it has opened. If there is resistance on both sides then you can simply hook up the primary to a raw power cord and measure the secondary voltages. If they are fine I would look deeper into the power supply.
I would check whether there is a short instead of a 4ohm measurement. You would need a multimeter.
B&O made the switch of sides in all of their turntables in the mid 1980’s. They still perform the same record detection function. They became wider to display the speed while the cartridge carrier became narrower to support the smaller cartridges. The older service manuals for the 400x series provide the most detail on the tracking system.
By muting the unit I meant going into standby. The relay does not switch all the power off.
First you need to confirm that your standby voltages are fine. TP9 should read 6.5v DC. You should also have 5V DC at pin 5 of the P11 connector. If those are fine, then you likely have a fault in the power amp section that is muting the unit. There is no need to replace the relay as what you have observed is its normal operation.
Finding a fault in the power amp circuit is more difficult since the +/-30v supplies share the same board and there is no easy way to disconnect the power from one channel without pulling the output transistors. Since you are able to get it on for a time, I would try looking for a DC voltage on each channel w/o speakers connected while the relay is engaged and figure out which one is tripping the fault circuit as a start. This all assumes the 6.5 and 5v supplies are fine.
The fact that the relay does activate even for a short time does not mean it’s broken but that it is losing its 6.5 volts. This will take some technical skill to fix and the service manual is online so it does not require a B&O service tech. How comfortable are you with using a multimeter and desoldering/soldering parts on a PC board?
What is broken about the relay? It’s a simple DPST relay that is activated by 6v and most like rated at 1A for contacts. You might check whether https://www.beoparts-shop.com/product/relay-for-beomaster-5000-5500-6500-7000/ will work if it truly is bad.
Ninni, virtually all speakers that provide for two separate pairs of binding posts also include internal crossovers and jumpers and to bridge the two inputs to use a single pair of wires. True bi-amplified speakers without internal or included amps are predominantly a DIY offering.
I would not connect your speakers that way. Simply run one set of speaker wires and use the jumpers on your speaker terminals. You cannot bi-amp with a single amplifier. What you are proposing is ‘bi-wiring” and it’s not likely to benefit given the speaker switches and DIN connections.
You won’t be able to detect movement from midrange drivers. You should hear them by placing your earn close in front and using pink noise.
Martin is referring to capacitors, not relays which I believe are all 5000 mF and are C4, C17 and C18.
Actually, those caps are almost 50yrs old so they definitely are a recommended starting point! I would then check closely for the listed voltages on the transistors in the servo motor circuit as it could be a bad transistor, diode or simply a broken solder joint or trace.
As I responded to Colin, the control of 45 starts with the disc indicator switch. If that is not opening and closing properly you will get this symptom. Only after checking this should you check for the correct voltages around TR1 and 2. There are no likely cap issues in that circuit.
I would check that the Disc Indicator switch under the center 45 adapter is making good contact first. If it is opening and closing properly, then your problem is in the logic that it drives which is TR1 and Tr2. There are voltages in the service manual for these.
Since both the at rest position and set-down are skewed it sounds like the arm had been moved too far right and there is a threaded pin under the counter weight that secures the arm to its post if I remember. Never saw many of these but that was how the 3000 did it. You need to remove the dustcover and adjust it from the rear.
When you say “return and stop” do you mean if you press Stop during play it does not return or only at the end of the record? If the later that is typically a leaf switch problem as these easily corrode or get out of adjustment. Do either the “>” or “>>” work when the are is cued up? If they don’t then I would look at the electronics focusing on the caps first.
