Radio ok - wrong combination of unlit buttons plus
as no Dolby logo ICs I assume the missing plug in of 10 way CN-1
is for Dolby but is missing. With that set on front there is no radio
throughput.
Stereo separation is week - anyone know how to adjust
the IF coil presumably buried in large screened can LF301 ?



Success eventually.
I seem to have accidently found a technique for stereo
problems on this receiver.
Disconnect pin 1 (5 ? not marked ) from housing in the violet CN-7 connector
that connects to upc1161 pin 9.
I looked at the DC voltages on the uPC1161, supply pin is
pin 1 at 11V but the pin 9 which connects to CN-7 was 12V
and 12V coming from front panel , so thinking a fault on front
pannel. When disconnected taking
this lead via 100R to ground then the stereo light comes on dim.
Anyway with this line disconnected the pin 9 signal jumps to
a 5V or so pk-pk PLL signal but rough triangular form and 2.2V dc
Now locked into 19.000 KHz over a good 20% of VR302
and plenty of signal for a f counter to confirm.

With a screwdriver to inject hum at the ends of VR303 hum
is either in L or R channel but without stereo lamp to
indicate, touch front contact and hum is central.

The tuning slug buried in the Nakamichi IF block under cable bunch
needed adjusting slightly to bring up quadrature ? and the stereo decoding
and then
pin 9 dropping to .4V dc and 0.2V pk-pk square wave at PLL
19 KHz. Then reconnecting the CN-7 line these pin 9 ac signals
disappear and stereo light comes on. Balanced up the 3 pot cores
and VRs for minimum noise etc.


electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse