perry
10-09-2009, 09:41 PM
Anyone know the mechanism that causes the tape to advance when it senses no music? One of my RX-505s has an annoying tendency to sometimes FF advance, like it thinks the music is over for 30 seconds, while the music is still playing. Is there some type of sensitivity adjustment for that circuit? What is the trigger?
Edit1: I just think I noticed something. I don't think it ever does it more than once during a playing session. Once it does it and I stop and play again, even if I change tapes, it doesn't do it until I power down and start using it the next day. That means it is almost surely a cap issue...well the hunt on the schematics begins....I need to find where the timer completes and signals the FF on.
Edit2: OK, timer is built into IC602, where the k.ff output comes from and there is a music input. I'll have to check caps on that circuit and signal level of music input. I also have to see if it ever does it with blank skip turned off, which will tell me if I'm on the right track.
Edit3: Problem solved. With blank skip turned off it never did it. Thorough clean & Deoxit of that switch (and all the others while I had it apart) has eliminated the issue. So far. Only time will tell if it is really gone, but I really believe it is. What's funny is that this particular RX505 is an older lower serial number unit, like 29xx or so, yet it beats my other newer unit with serial 16xxx in every single way, better W&F, better, flatter, recordings and playback, and I have rechecked, tried different belts and new pinch rollers, etc and re-cal'd both decks a few times; always thinking I must have missed something.
Edit4: It's been months now and the problem has NOT returned, the deck continues to perform flawlessly. Just a pleasure to listen to. And watch flip tapes.
Edit1: I just think I noticed something. I don't think it ever does it more than once during a playing session. Once it does it and I stop and play again, even if I change tapes, it doesn't do it until I power down and start using it the next day. That means it is almost surely a cap issue...well the hunt on the schematics begins....I need to find where the timer completes and signals the FF on.
Edit2: OK, timer is built into IC602, where the k.ff output comes from and there is a music input. I'll have to check caps on that circuit and signal level of music input. I also have to see if it ever does it with blank skip turned off, which will tell me if I'm on the right track.
Edit3: Problem solved. With blank skip turned off it never did it. Thorough clean & Deoxit of that switch (and all the others while I had it apart) has eliminated the issue. So far. Only time will tell if it is really gone, but I really believe it is. What's funny is that this particular RX505 is an older lower serial number unit, like 29xx or so, yet it beats my other newer unit with serial 16xxx in every single way, better W&F, better, flatter, recordings and playback, and I have rechecked, tried different belts and new pinch rollers, etc and re-cal'd both decks a few times; always thinking I must have missed something.
Edit4: It's been months now and the problem has NOT returned, the deck continues to perform flawlessly. Just a pleasure to listen to. And watch flip tapes.