[hcraig244]

Sorry Alf

in my response I have stated that the contacts should close when the tone arm drops, this should read open. The contacts ground the signal from the stylus until the tone arm is on the disc then open to allow the signal to pass into your amp thus eliminating any noise from the initial contact with said disc, in my view should the noise your hearing be generated by any other way turning down your volume would not eliminate it…..hope this helps

craig

[hcraig244]

I didn’t know that earlier versions of the BG4000 came without this adjustment……this is yet another example that everyday is a school day ;¬)

However….should your version have been supplied complete with this adjustment the attached gives an explanation how to achieve the correct setting via adjustments contacts D&E…..however it should be noted that the author has confused the contacts  F and its adjustment screws G with contacts D&E in his opening description

• This reply was modified 1 day, 7 hours ago by hcraig244.

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[hcraig244]

Alf

Sounds to me if the thumping noise disappears when you turn down the volume check the muting circuit contacts that close when the solenoid damper closes fully and allows the signal from the stylus to pass into the output cable, this is designed to eliminate the thump noise when the tone arm drops onto the disc…..if the contacts are closed all the time or are closing too soon you will get the thump……take a look

Craig

[hcraig244]

I have left the machine opened up in case there is anything else you need……good luck

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[hcraig244]

the left hand side is the same….not as good a picture but you can see whats required…..remove these two screws and the panel can be lifted into the vertical position….this will make it easier to replace the top lamps

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[hcraig244]

To lift the panel into the vertical position there are two screws located at each side, these screws sit between two other screws located above and below the ones you need to undo, the other two are used to raise or lower the panel and wont need to be touched….the right hand side screw sitting in the middle can be seen here…dont touch the upper or lower ones

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[hcraig244]

The lamps on the bottom will probably be easier to replace with the panel flat with the exception of the one on the far left which is mounted very close to the ribbon, these ribbons are very delicate and can be damaged easily….avoid if possible ;¬)

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[hcraig244]

the lamps are pushed into the holders and will only require soldering if a wire pops off during the replacement o a lamp, they can be quite tight after all these years so care is needed. the holders are pushed onto a tab that holds them in place…

• This reply was modified 1 month, 1 week ago by hcraig244.

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[hcraig244]

This is how they look when powered up….

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[hcraig244]

The lamp holders are located as shown here….

 

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[hcraig244]

Ok…..so you have got this far

• This reply was modified 1 month, 1 week ago by hcraig244.

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[hcraig244]

Excellent…..these amplifiers are getting rather rare these days and need to be looked after, amazing pieces of engineering…..

craig

[hcraig244]

Just had a look in the manual myself and your correct it doesn’t detail the disassembly, I thought it did…..not to worry, is the amplifier fully functional right now apart from the lamps? It’s good to know that anything that stops working after you do anything in there is a result of what you have done which often makes it easier to correct 👍

[hcraig244]

Ok

you will need to lift the indicator ribbon display section up into the vertical position to access the lamps….2 screws as I recall, these lamps are connected in three series loops I think…so if one goes down you loose 2 or 3 lamps….its been a couple of years since I changed any. As a silver member you can access the service manual for this machine under products in here, this details how to open it up…..unfortunately im windsurfing off the coast of Greece until Sunday….if no one chips in with more help I will open a machine up and send some pictures to guide you next Monday when I return to the UK

Craig

[hcraig244]

Hi

Are you changing out all the lamps on the machine or just those that have failed? Some lamps are fitted into an enclosed plastic compartment, others are not. You will need to open the unit up to access all lamps…..check out the service manual available here for a better idea, be sure to replace the lamps according to the description provided by the supplier, the current ratings differ from location to location…….enjoy 👍

[hcraig244]

Go for it……. I wouldn’t buy one that was fully operational, the repair and restoration process is, for me, a large part of the pleasure. These decks where built with the possibility of repair in mind unlike the rubbish available on the market today….there are one or two more positives you can add to your list

• A stylus is fitted which suggests the tone arm connection tab, which the stylus snaps onto, hasn’t been damaged….lot of work and expense repairing it using the beolovers laser printed parts (which are very good it has to be said).
• The carriage drive motor and its associated forward/reverse circuitry is functional.
• The multivibrator on/off circuit is working as are the reed relays which switch the 20vdc and 6vdc supplys on……these can be problematic but are repairable.

I didnt hear the solenoid energise when the tone arm was requested to drop automatically or manually…..not a massive problem and could be down to poor lubrication on the tone arm lowering mechanism….easy fix if the solenoid energises on request.

Does the platter drive motor run? i’m assuming you’ve looked inside to check the drive belt?

A lot of problems with these decks can be traced to the control switches sticking open or closed therefore out of sequence, this will play havoc with the logic board operation, components will fail of course and some may need replacing as you progress through what can at times be a  frustrating journey but provided you have the time and a few pieces of test equipment it can be very rewarding…..it can get expensive if you choose to install the many laser printed parts available but these are mostly optional.

Enjoy Craig

 

[hcraig244]

I’m guessing you have these from the circuit diagram you have posted….however I cant find that schematic in my manual….which is a little odd, all the same its a good place to look…..I checked the operation of both of my 6000 units and one is working perfectly and the other has an issue with the drive motors for the volume/bass/treble and balance potentiometers are not driving, i suspect the common drive belt but will have a look inside….if you need any measurements while im in there let me know….

[hcraig244]

 

[hcraig244]

Not great image i know but i think this is where you could make a start

[hcraig244]

Check all the black wires that run all over the machine, common negative, these wires are for some reason, best known only to the B&O design team, single strand wires and break easily…they dont solder too well either…i have had several issues with the point in the chassis where a whole bunch of these come together….take a look ;¬)

Craig

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