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Best guess on what my 1700’s problem is

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Oldmactech
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Oldmactech Posted: Mon, Apr 13 2020 7:19 PM

New to B&O, recent acquired 1700 with Mc20e. Connects via RCA jacks. Nothing but loud hum from both channels. Cartridge/stylus appear intact. basic continuity is good.

Bad cartridge? Anyway to test the cartridge with a meter?

This should connect to phono input? or somewhere else?

 

thanks. 

Oldmactech
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Additionally, the axial capacitor (470uf I think it is) on the control board, has oozed some electrolytic, could that have sone effect or does the board only control the various movements?

Oldmactech
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Additionally, the axial capacitor (470uf I think it is) on the control board, has oozed some electrolytic, could that have sone effect or does the board only control the various movements?

Dillen
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Dillen replied on Mon, Apr 13 2020 8:12 PM

There are no electronics in the signal path.
All electronics are for the operation.

The cartridge could be bad, but I think the hum problem is more likely to be rooted in the conversion to RCA that has been attempted.
There should be a separate chassis ground lead accompanying the two RCA plugs, - it is to be connected to the metal chassis of your amplifier - typically a small fingerscrew near the turntable input sockets.

The leaking capacitor should of course be replaced. I would recommend you grab a servicekit. It has new components for all
electrolytic capacitors (axial, radial and tantal) - new speed adjustment trimmers, a new fuse and a new belt.
PM or email me.  

Martin

Oldmactech
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Oldmactech replied on Tue, Apr 14 2020 12:45 AM

Understood, thanks.  The RCA cabling seems professionally done, good quality cable. I have bypassed the cable with test patch cable, still nothing but hum.  Seems to me if it were bad cabling, I would still be able to get some cartridge output.  If I touch the tone arm the signal is active I do get loud scratching through the speakers as if the RCA connecting is at worst partially functional. 

thanks. 

Oldmactech
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Oldmactech replied on Tue, Apr 14 2020 12:48 AM

Forgot to say, there is a functioning ground cable, I will double check too that it is mounted correctly.

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