Problem with Beocenter 7007

Right. Took the plunge and de soldered the tonearm wires and wired them to the other side of the switch, removing the switch from the equation. No change. 

I will try to put the issue more succinctly.

Radio and tape work perfectly. Equal sound to both speakers and the left to right balance works perfectly. If I touch the stylus there is no sound from it

once the tt is selected, it spins up perfectly, the arm cues perfectly but sound only comes out of the right channel at normal levels. There is some out of the left channel but it is very low. There is considerable hum which can be stopped by touching the metal part of the tt. If I put my finger near the metal of the cart the hum increases.

when you press stop on the tt, there is momentarily sound at normal levels from the left channel. The arm then returns as normal. It was at this point that If I gently ran my finger accross the stylus there is equal sound from both channels, however since cleaning up the switch there is no sound from it when stopped.

if I then turn the cart upside down the sound level from the left channel is the same, but if I turn it either way sideways it is normal out of the left channel.

i am beginning to think I had 2 issues, a dirty switch which I have now fixed, and a dodgy cart, the symptoms of which were masked by the switch issue.

the sound out of the left speaker is always clear, just very low.

grateful of your thoughts.

john

I have investigated both the cart and the arm.

The arm has continuity through each of its wires and no shorts.

The car has no open circuit ( tested each pin against the others). I have also made a visual inspection of the stylus(x100). It looks to be in perfect order, no wear spots or damage.

Really stuck now!!!!!

It could still be the cartridge. It may look perfect but that doesn't mean it is. The MMC hasn't been made since 1996/7 so they are all getting old now and are prone to failure. You really need another known good cartridge to do some testing. Unfortunately I haven't got any or I would loan you one.

Thanks for the reply. I dont have another to test or another tt to put the cart on.

Dont suppose anone here from wiltshire would be willing to loan me one or allow me to try my cart on their arm. I would bring my own lp.

I have a good digital multimeter. Any ideas on how to test and the multimeter settings?

Regards

John

When I first bought my BC7002 it had one channel not working on Phono, turned out to be bad contact between MMC20EN and the arm. Cart worked on a second set, and after removing it a couple times the contacts cleaned themselves and never had any more trouble with it.

    John.

Hi John.

Just been and tried that. Cleaned the cart contacts and treated them to de-oxit. Also very slughtly and very gently pinched the pins slightly in. Refitted, no difference. Very bad hum consistent throughout which disappears when i touch the tonearm.

I have had two B&O turntables that exhibited the symptoms you describe, namely the music coming out briefly at normal volume as the stylus lands or lifts, but being very low in output in one channel when actually playing.

In both cases, a new cartridge fixed the problem. It seems to be an issue with the suspension/coils in that the problem only appears when the full tracking weight of the arm is applied once the cueing system fully releases.

Right. It was the cart. Doh!!!!

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Edited by Dillen

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Send the cartridge to Axel at http://www.schallplattennadeln.de/B-O-MMC-Reparatur-Repair/MMC-Repair-English/ and he'll fix it.