Technics RS-TR255 Cassette Decks
in [Repair]
|
From: Puddin' Man on 17 Feb 2010 13:14 This may well qualify as a "Lost Cause", but ... I have 2 dual decks per the subject line. On both, the record drive will not spin a (good, tested) tape. Same tape works OK in the play-only drive. On a workbench with the case open, I push button for play or record or rewind (forward or backward), the machine appears to do a check for end-of-tape, clicks, and stops. I disconnected a motor thinking it might be frozen: it was not. The behavior it exhibits is identical to what the device is supposed to do when I, say, tell it to play a tape that is pre-positioned to end-of-tape. I'm guessing that the problem is with the end-of-tape sensor. I am neither expert nor helpless with electronics. Any hope for repairing such a beast? TIA, Puddin' "Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."
From: bg on 17 Feb 2010 15:57 Puddin' Man wrote in message ... > >This may well qualify as a "Lost Cause", but ... > >I have 2 dual decks per the subject line. On both, the record drive will >not spin a (good, tested) tape. Same tape works OK in the play-only >drive. > >On a workbench with the case open, I push button for play or record or >rewind (forward or backward), the machine appears to do a check for >end-of-tape, clicks, and stops. > >I disconnected a motor thinking it might be frozen: it was not. > >The behavior it exhibits is identical to what the device is supposed >to do when I, say, tell it to play a tape that is pre-positioned to >end-of-tape. I'm guessing that the problem is with the end-of-tape >sensor. > >I am neither expert nor helpless with electronics. > >Any hope for repairing such a beast? > > TIA, > Puddin' > >"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule." > Usually the take up reel has a sensor to see if it is spinning. The sensor typically might be a magnetic switch, a simple switch, or an optical sensor. Sometimes these sensors are driven by belt connected to the take up spool. There could also be a function built in to activate a stop mode when the tape counter hits zero. This is so you can rewind back to the same spot on the tape.
From: David Nebenzahl on 17 Feb 2010 16:19 On 2/17/2010 12:57 PM bg spake thus: > Puddin' Man wrote in message ... > >> This may well qualify as a "Lost Cause", but ... >> >> I have 2 dual decks per the subject line. On both, the record drive >> will not spin a (good, tested) tape. Same tape works OK in the >> play-only drive. >> >> On a workbench with the case open, I push button for play or record >> or rewind (forward or backward), the machine appears to do a check >> for end-of-tape, clicks, and stops. >> >> I disconnected a motor thinking it might be frozen: it was not. >> >> The behavior it exhibits is identical to what the device is >> supposed to do when I, say, tell it to play a tape that is >> pre-positioned to end-of-tape. I'm guessing that the problem is >> with the end-of-tape sensor. >> >> I am neither expert nor helpless with electronics. >> >> Any hope for repairing such a beast? >> > Usually the take up reel has a sensor to see if it is spinning. The sensor > typically might be a magnetic switch, a simple switch, or an optical sensor. > Sometimes these sensors are driven by belt connected to the take up spool. > There could also be a function built in to activate a stop mode when the > tape counter hits zero. This is so you can rewind back to the same spot on > the tape. It's also possible that the end-of-tape sensing is done by simply letting the motor try to spin against the pulleys, and sensing the rise in current as an end-of-tape condition. Another possibility is that the drive is simply too weak to spin the tape, which could be a result of stretched-out belts, dirty drive parts (belts, pulleys), or (unlikely but possible) stuck bearings somewhere. If it uses the end-of-tape method described above, it will simply give up. I'd try to clean up the mechanics first before looking at other causes. -- You were wrong, and I'm man enough to admit it. - a Usenet "apology"
From: Puddin' Man on 17 Feb 2010 19:01 On Wed, 17 Feb 2010 13:19:31 -0800, David Nebenzahl <nobody(a)but.us.chickens> wrote: >>> Any hope for repairing such a beast? >>> >> Usually the take up reel has a sensor to see if it is spinning. The sensor >> typically might be a magnetic switch, a simple switch, or an optical sensor. >> Sometimes these sensors are driven by belt connected to the take up spool. >> There could also be a function built in to activate a stop mode when the >> tape counter hits zero. This is so you can rewind back to the same spot on >> the tape. Thanks ... I just recalled another detail. The problem drives do auto-reverse. Been so long since I used 'em I'd forgotten. >It's also possible that the end-of-tape sensing is done by simply >letting the motor try to spin against the pulleys, and sensing the rise >in current as an end-of-tape condition. Uh-oh. That makes the motor again suspect. One of the units was on a service contract. The record-drive motor was replaced in '94. Possibly relevant if the motor is simply of poor quality. >Another possibility is that the drive is simply too weak to spin the >tape, which could be a result of stretched-out belts, dirty drive parts >(belts, pulleys), or (unlikely but possible) stuck bearings somewhere. >If it uses the end-of-tape method described above, it will simply give >up. I'd try to clean up the mechanics first before looking at other causes. I didn't dissemble much, but what I saw looked pretty clean. The playback motor has a part # slightly different from that of the record-drive motor. Safe to assume I could not cannibalize a playback motor to replace a record-drive motor? A fast search indicated replacement motors are no longer available. Danke, P "Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."
From: Arfa Daily on 17 Feb 2010 20:50
"David Nebenzahl" <nobody(a)but.us.chickens> wrote in message news:4b7c5c6a$0$5744$822641b3(a)news.adtechcomputers.com... > On 2/17/2010 12:57 PM bg spake thus: > >> Puddin' Man wrote in message ... >> >>> This may well qualify as a "Lost Cause", but ... >>> >>> I have 2 dual decks per the subject line. On both, the record drive >>> will not spin a (good, tested) tape. Same tape works OK in the >>> play-only drive. >>> >>> On a workbench with the case open, I push button for play or record >>> or rewind (forward or backward), the machine appears to do a check >>> for end-of-tape, clicks, and stops. >>> >>> I disconnected a motor thinking it might be frozen: it was not. >>> >>> The behavior it exhibits is identical to what the device is >>> supposed to do when I, say, tell it to play a tape that is >>> pre-positioned to end-of-tape. I'm guessing that the problem is >>> with the end-of-tape sensor. >>> >>> I am neither expert nor helpless with electronics. >>> >>> Any hope for repairing such a beast? >>> >> Usually the take up reel has a sensor to see if it is spinning. The >> sensor >> typically might be a magnetic switch, a simple switch, or an optical >> sensor. >> Sometimes these sensors are driven by belt connected to the take up >> spool. >> There could also be a function built in to activate a stop mode when the >> tape counter hits zero. This is so you can rewind back to the same spot >> on >> the tape. > > It's also possible that the end-of-tape sensing is done by simply letting > the motor try to spin against the pulleys, and sensing the rise in current > as an end-of-tape condition. > > Another possibility is that the drive is simply too weak to spin the tape, > which could be a result of stretched-out belts, dirty drive parts (belts, > pulleys), or (unlikely but possible) stuck bearings somewhere. If it uses > the end-of-tape method described above, it will simply give up. I'd try to > clean up the mechanics first before looking at other causes. > > > -- > You were wrong, and I'm man enough to admit it. > > - a Usenet "apology" Another common problem is the tape sense switch above the (closed) cassette holder. It's a simple leaf switch, and it is very common for these to get 'sooty' contacts that *just* make when the door is closed, but then bounce and un-make momentarily with the vibration of the heads going in or the mech going into wind / rewind. When the switch un-makes, the system control thinks that the door has been opened, and immediately drops the deck back to neutral, and stops it. Easily proved by shorting across the switch from its terminals at the back, using a screwdriver blade or whatever. Also, very common for the Technics grey coloured belts to go 'spongy' and lose their grip. Arfa |