uPC1161C - anyone familiar with or similar VCO stereo radio ICs
I have in circuit details and pin 9 is the test point for
19KHz mionitoring but I only have representative DC voltages and pin-out. No stereo in a radio and only about 5mV pk-pk square wave signal on this pin. As you should be able to connect a f meter here , pin 9, to adjust to 19KHz would I be right in thinking there should be more than 5mV |
Finally dug out the service manual.
Pin 9 is the stereo lamp drive line. The manual shows no 19kHz monitor pin on the mpx chip, and vr302 is adjusted merely to light the stereo lamp when fed a stereo signal from a generator, then vr303 for maximum separation. The most likely reason for not being able to get stereo is misadjustment of L703 & L704 discriminator transformers on the IF board. Incidentally, on your previous question, the dolby fm board was optional, so most 730's don't have it & thus the dolby fm button simply cuts off the signal. -- Stephen Sank, Owner & Ribbon Mic Restorer Talking Dog Transducer Company http://stephensank.com 5517 Carmelita Drive N.E. Albuquerque, New Mexico [87111] 505-332-0336 Auth. Nakamichi & McIntosh servicer Payments preferred through Paypal.com "N Cook" wrote in message ... I have in circuit details and pin 9 is the test point for 19KHz mionitoring but I only have representative DC voltages and pin-out. No stereo in a radio and only about 5mV pk-pk square wave signal on this pin. As you should be able to connect a f meter here , pin 9, to adjust to 19KHz would I be right in thinking there should be more than 5mV |
I ended up replacing 8 bulbs as I suspected lack of radio may be due to
not knowing which functions on or off.on the Nakamichi 730. I will burrow around for more data on the uPC1161 and explore the radio a bit more. Failing that I've a couple of salvaged ones I could try in place. The odd thing there is a setting of the pots where I can get the stereo light to work but even putting a crystal earpiece to pin 6 and another to pin 7 definitely not stereo. Otherwise reception is perfectly good "Stephen Sank" wrote in message ... Finally dug out the service manual. Pin 9 is the stereo lamp drive line. The manual shows no 19kHz monitor pin on the mpx chip, and vr302 is adjusted merely to light the stereo lamp when fed a stereo signal from a generator, then vr303 for maximum separation. The most likely reason for not being able to get stereo is misadjustment of L703 & L704 discriminator transformers on the IF board. Incidentally, on your previous question, the dolby fm board was optional, so most 730's don't have it & thus the dolby fm button simply cuts off the signal. -- Stephen Sank, Owner & Ribbon Mic Restorer Talking Dog Transducer Company http://stephensank.com 5517 Carmelita Drive N.E. Albuquerque, New Mexico [87111] 505-332-0336 Auth. Nakamichi & McIntosh servicer Payments preferred through Paypal.com "N Cook" wrote in message ... I have in circuit details and pin 9 is the test point for 19KHz mionitoring but I only have representative DC voltages and pin-out. No stereo in a radio and only about 5mV pk-pk square wave signal on this pin. As you should be able to connect a f meter here , pin 9, to adjust to 19KHz would I be right in thinking there should be more than 5mV |
Found a Sony manual with uPC1161 details and it mentions
pin 9 as being both stereo indicator driver and VCO oscillator test point but this time monitoring 76KHz instead of 19. Can't get hold of the owner so I will put on hold for afew days. |
I would suggest replacing the few small electrolytics around the mpx chip before assuming the
chip is bad. -- Stephen Sank, Owner & Ribbon Mic Restorer Talking Dog Transducer Company http://stephensank.com 5517 Carmelita Drive N.E. Albuquerque, New Mexico [87111] 505-332-0336 Auth. Nakamichi & McIntosh servicer Payments preferred through Paypal.com "N Cook" wrote in message ... Found a Sony manual with uPC1161 details and it mentions pin 9 as being both stereo indicator driver and VCO oscillator test point but this time monitoring 76KHz instead of 19. Can't get hold of the owner so I will put on hold for afew days. |
All times are GMT +1. The time now is 09:03 PM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 DIYbanter