NAD 7020e has its signals crossed
 

NAD 7020e receiver just failed most strangely. If only one source is connected to the appropriate input (such as CD),
the signal can be heard on both channels at about 1/2 volume when tape monitor or video is selected. Tuner is also
audible regardless of which input is selected.

I've disassembled it and cleaned contacts etc to no avail. There's no visible damage under illuminated magnifier.

tia in advance for help

Nigel

Nigel,

The switching in this receiver is purely mechanical, and all before the
the volume control, so what you are getting is really odd. I would have
to guess at a cracked circuit board, or some blown ground foils, unless
the switch latching mechanism has failed and allowing multiple sources
to be selected, or there is major corrosion in this unit creating
unwanted signal paths.

Regards,
Tim Schwartz
Bristol Electronics


Nigel Burnett wrote:

NAD 7020e receiver just failed most strangely. If only one source is connected to the appropriate input (such as CD),
the signal can be heard on both channels at about 1/2 volume when tape monitor or video is selected. Tuner is also
audible regardless of which input is selected.

I've disassembled it and cleaned contacts etc to no avail. There's no visible damage under illuminated magnifier.

tia in advance for help

Nigel

On Sat, 28 Aug 2004 13:29:29 GMT, Nigel Burnett
wrote:

NAD 7020e receiver just failed most strangely. If only one source is connected to the appropriate input (such as CD),
the signal can be heard on both channels at about 1/2 volume when tape monitor or video is selected. Tuner is also
audible regardless of which input is selected.

I've disassembled it and cleaned contacts etc to no avail. There's no visible damage under illuminated magnifier.

tia in advance for help

Nigel



If you want to end that kind of noise, you should add a grounding plug
to unused inputs.

When I had the audiovirus back in an earlier lifetime, I used to use
old RCA plugs cut off a cable, strip the wires and twist them
together. I actually soldered them. I forget if some people used
some special value resistor soldered onto the wires instead of just
twisting them.

I'm not sure what the deal is with your tuner, I'd think the tuner
circuits would be turned off if it isn't selected.

Damn noisy otherwise ;)

On Sat, 28 Aug 2004 14:17:31 GMT, Tim Schwartz wrote:

Nigel,

The switching in this receiver is purely mechanical, and all before the
the volume control, so what you are getting is really odd. I would have
to guess at a cracked circuit board, or some blown ground foils, unless
the switch latching mechanism has failed and allowing multiple sources
to be selected, or there is major corrosion in this unit creating
unwanted signal paths.

Hi Tim,

It is odd. I've ohmed out the signal paths and switches and everything seems ok. Disassembling the switches looks like a
mechanical nightmare given that 5 ganged xwitches need 6 contacts each desoldered. Phew. It does appear that the Tape
Monitor is the problem as any signal (even built in tuner) comes through at 1/2 vol. A signal applied to either left or
right CD input can be heard on both channels when tape monitor is pressed.

The unit hasn't moved for a year so cracked traces seem almost impossible. No corrosion or anything visible. It could be
internal to one of the switches I guess. I'm really stumped esp with no schematic. *sigh*,



Nigel Burnett wrote:

NAD 7020e receiver just failed most strangely. If only one source is connected to the appropriate input (such as CD),
the signal can be heard on both channels at about 1/2 volume when tape monitor or video is selected. Tuner is also
audible regardless of which input is selected.

I've disassembled it and cleaned contacts etc to no avail. There's no visible damage under illuminated magnifier.

Nigel,

What happens if nothing is connected to the tape in/out jacks? After
that, try one pair of RCA cables looping from the tape out to the tape
in, but no equipment hooked up to the receiver.

Regards,
Tim Schwartz
Bristol Electronics


Nigel Burnett wrote:

On Sat, 28 Aug 2004 14:17:31 GMT, Tim Schwartz wrote:

Nigel,

The switching in this receiver is purely mechanical, and all before the
the volume control, so what you are getting is really odd. I would have
to guess at a cracked circuit board, or some blown ground foils, unless
the switch latching mechanism has failed and allowing multiple sources
to be selected, or there is major corrosion in this unit creating
unwanted signal paths.

Hi Tim,

It is odd. I've ohmed out the signal paths and switches and everything seems ok. Disassembling the switches looks like a
mechanical nightmare given that 5 ganged xwitches need 6 contacts each desoldered. Phew. It does appear that the Tape
Monitor is the problem as any signal (even built in tuner) comes through at 1/2 vol. A signal applied to either left or
right CD input can be heard on both channels when tape monitor is pressed.

The unit hasn't moved for a year so cracked traces seem almost impossible. No corrosion or anything visible. It could be
internal to one of the switches I guess. I'm really stumped esp with no schematic. *sigh*,

Nigel Burnett wrote:

NAD 7020e receiver just failed most strangely. If only one source is connected to the appropriate input (such as CD),
the signal can be heard on both channels at about 1/2 volume when tape monitor or video is selected. Tuner is also
audible regardless of which input is selected.

I've disassembled it and cleaned contacts etc to no avail. There's no visible damage under illuminated magnifier.