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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Hi,
I got (for free) an old JVC videorecorder. It still has direct mechanical tape controls (play, ffwd, rew, ecc) without any servo-system. The motors appear to be OK, ffwd e rew work fine but the play key dowesn't work. The problem is that the key is locked, if you try to push it you cant get it down. I opened the machine and I think it's possible that some lever isn't free to move for some reason. Another possibility is that one of the magnets that helps moving the levers inside is out of order. Is there anyone experienced with those old and wonderful videorecorders? I'm going to cry if I had to trhow it away :\ Thanx Daniele -- http://tastiere.altervista.org - THE resource for Synthesizers ! Free patches and sounds |
#2
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Daniele,
A shot in the dark that people may have forgotten about. Is the end stop LAMP burned out? Many old machines have end stop sensor lamps and will not function if the bulb is out. My long gone JVC HR-6700U did, as did the HR-7300U after that. Regards, Tim Schwartz Bristol Electronics P.S. If you post further questions about this machine, you'll likely get better answers if you include the model number. Daniele - Skrauso wrote: Hi, I got (for free) an old JVC videorecorder. It still has direct mechanical tape controls (play, ffwd, rew, ecc) without any servo-system. The motors appear to be OK, ffwd e rew work fine but the play key dowesn't work. The problem is that the key is locked, if you try to push it you cant get it down. I opened the machine and I think it's possible that some lever isn't free to move for some reason. Another possibility is that one of the magnets that helps moving the levers inside is out of order. Is there anyone experienced with those old and wonderful videorecorders? I'm going to cry if I had to trhow it away :\ Thanx Daniele -- http://tastiere.altervista.org - THE resource for Synthesizers ! Free patches and sounds |
#3
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On Mon, 19 Jan 2004 12:57:28 GMT, Tim Schwartz
wrote: Daniele, A shot in the dark that people may have forgotten about. Is the end stop LAMP burned out? Many old machines have end stop sensor lamps and will not function if the bulb is out. My long gone JVC HR-6700U did, as did the HR-7300U after that. Regards, Tim Schwartz Bristol Electronics P.S. If you post further questions about this machine, you'll likely get better answers if you include the model number. I think that's exactly what it is. On the original JVC Vidstar if the lamp, both incandescent and infrareds were used, is burned out or defective the tape will fast forward and rewind, at the risk of breaking the tape at the end, but the Play button is locked out. . Steve . Daniele - Skrauso wrote: Hi, I got (for free) an old JVC videorecorder. It still has direct mechanical tape controls (play, ffwd, rew, ecc) without any servo-system. The motors appear to be OK, ffwd e rew work fine but the play key dowesn't work. The problem is that the key is locked, if you try to push it you cant get it down. I opened the machine and I think it's possible that some lever isn't free to move for some reason. Another possibility is that one of the magnets that helps moving the levers inside is out of order. Is there anyone experienced with those old and wonderful videorecorders? I'm going to cry if I had to trhow it away :\ Thanx Daniele -- http://tastiere.altervista.org - THE resource for Synthesizers ! Free patches and sounds |
#4
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![]() "Steve(JazzHunter)" wrote in message ... On Mon, 19 Jan 2004 12:57:28 GMT, Tim Schwartz wrote: Daniele, A shot in the dark that people may have forgotten about. Is the end stop LAMP burned out? Many old machines have end stop sensor lamps and will not function if the bulb is out. My long gone JVC HR-6700U did, as did the HR-7300U after that. Regards, Tim Schwartz Bristol Electronics P.S. If you post further questions about this machine, you'll likely get better answers if you include the model number. I think that's exactly what it is. On the original JVC Vidstar if the lamp, both incandescent and infrareds were used, is burned out or defective the tape will fast forward and rewind, at the risk of breaking the tape at the end, but the Play button is locked out. . Steve . Daniele - Skrauso wrote: Hi, I got (for free) an old JVC videorecorder. It still has direct mechanical tape controls (play, ffwd, rew, ecc) without any servo-system. The motors appear to be OK, ffwd e rew work fine but the play key dowesn't work. The problem is that the key is locked, if you try to push it you cant get it down. I opened the machine and I think it's possible that some lever isn't free to move for some reason. Another possibility is that one of the magnets that helps moving the levers inside is out of order. Is there anyone experienced with those old and wonderful videorecorders? I'm going to cry if I had to trhow it away :\ Thanx Daniele -- http://tastiere.altervista.org - THE resource for Synthesizers ! Free patches and sounds That sounds like it...to the OP, if you get it working, you still have a large job of replacing all the rubber in the machine, if you want to get original performance out of it. I agree that these early VCR's were marvels of mechanical engineering. Eventually they developed error correcting electronics which made production of less heavy/precise/robust mechanical assemblies possible, while sacrificing nothing in picture quality. Further on, they carried that trend to such extremes that nowadays, most VCR transports are flimsy plastic/sheet metal crap that wears out or breaks almost out of the box. jak |
#5
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Hi all guys,
thanx for answering. You're right! It's lame not to post the model #: JVC HR3660. Now.. you say there's a problem about lamps. I noticed there are 2 optical components near the tape slot but I couldn't imagine what they standed there for. you say that their function is to check if the tape is at the end in order to stop the motors and release play key. I noticed that ffwd and rew keys are instantly auto-released if I try to press them without a tape in the slot (but pressing woth a finger the switch under the tape). so at least one of those optical controls still works. but can you tell me more about these lamps? is there a sort of reflected light system which checks the light reflected by te tape? now the question: is there a way in your opinion to cheat that lamps? I mean.. a way to let the hardware believe and that everything is alright? maybe placing a resistor instead of the lamp or cheating the electro-mechanical controls that the light itself controls Thanx a lot guys! Bye Daniele -- http://tastiere.altervista.org - THE resource for Synthesizers ! Free patches and sounds |
#6
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That sounds like it...to the OP, if you get it working, you still have a
large job of replacing all the rubber in the machine, if you want to get original performance out of it. well... it would be a miracle if I get i working ![]() replace rubbers. I agree that these early VCR's were marvels you know man.. I'm young. The first videorecorder I had in my house was servo controlled, at the and of 80's. when it died few months ago i opened it... there already was a high integration rate, but maybe nothing in comparison with my actual one, its weight is less than half of his predecessor. when I got this JVC.... I was frightened of its weight. And I don't hide you how I was surprised to see that inside there are only discrete components... the power section isn't in switching technology (a huge transformer!!) and the tape control is simply cute. several boards interconnected with free coloured wires without those boring flat cables (like ide interfaces ones). I only can imagine the great amount of knowhow essential to project that circuits! from the RF to the signal processing........ good old times! ![]() Bye Daniele -- http://tastiere.altervista.org - THE resource for Synthesizers ! Free patches and sounds |
#7
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![]() "Daniele - Skrauso" wrote in message ... Hi all guys, thanx for answering. You're right! It's lame not to post the model #: JVC HR3660. Now.. you say there's a problem about lamps. I noticed there are 2 optical components near the tape slot but I couldn't imagine what they standed there for. you say that their function is to check if the tape is at the end in order to stop the motors and release play key. I noticed that ffwd and rew keys are instantly auto-released if I try to press them without a tape in the slot (but pressing woth a finger the switch under the tape). so at least one of those optical controls still works. but can you tell me more about these lamps? is there a sort of reflected light system which checks the light reflected by te tape? now the question: is there a way in your opinion to cheat that lamps? I mean.. a way to let the hardware believe and that everything is alright? maybe placing a resistor instead of the lamp or cheating the electro-mechanical controls that the light itself controls Thanx a lot guys! Bye Daniele You need the lamp working, it serves a useful function. It's just a small incandescent light bulb, it shouldn't be hard to find something that'll work in it's place. |
#8
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if the
lamp, both incandescent and infrareds were used, is burned out or defective the tape will fast forward and rewind, at the risk of breaking the tape at the end, but the Play button is locked out. breaking news! I had that light-based tape control under my eyes but I didnt realize what it was :\ anyway, after few testing I discovered this: the lamp is a normal (well visible!!) working light (no led, no infrared). The sensors seem to work: if I push the tape switch and cover with fingers (without tape inside) the sensors ffwd and rew works. if I put my finger away (from end or start check) ffwd and rew respectively automatic stops. So I suppose that the check system still works. But playing with fingers doesn't solve the play button problem ![]() known where these machines has the play-lock switch (mechanically speaking) ? Maybe finding it will lead to discover the broken electro-mechanical device. Thanx again! Bye Daniele -- http://tastiere.altervista.org - THE resource for Synthesizers ! Free patches and sounds |
#9
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On Mon, 19 Jan 2004 23:37:35 +0100, "Daniele - Skrauso"
wrote: if the lamp, both incandescent and infrareds were used, is burned out or defective the tape will fast forward and rewind, at the risk of breaking the tape at the end, but the Play button is locked out. breaking news! I had that light-based tape control under my eyes but I didnt realize what it was :\ anyway, after few testing I discovered this: the lamp is a normal (well visible!!) working light (no led, no infrared). The sensors seem to work: if I push the tape switch and cover with fingers (without tape inside) the sensors ffwd and rew works. if I put my finger away (from end or start check) ffwd and rew respectively automatic stops. So I suppose that the check system still works. But playing with fingers doesn't solve the play button problem ![]() known where these machines has the play-lock switch (mechanically speaking) ? Maybe finding it will lead to discover the broken electro-mechanical device. First, make sure the two tape loading arms are completely unloaded, so that the tape unload switch being activated by the loading gear underneath is pressed. Secondly you may be right about a mechanical issue. The FF and RW levers are freed by default. However once the tape is loaded into the hatch and the door pressed down, with the loading arms at rest as noted, a solenoid should pull a couple of bars under the levers releasing the play lever and locking out the record button. If the record CAN be pushed down (unloaded E - E) then this solenoid is not doing its job. It may be weak, a common fault, or the driver transistor for the solenoid may be open, another common failure, or crud has got in the well freezing up the solenoid bolt, not a common problem. I had the manual for this machine somewhere. I'll try to find it. . Steve . Thanx again! Bye Daniele |
#10
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First, make sure the two tape loading arms are completely unloaded, so
that the tape unload switch being activated by the loading gear underneath is pressed. [...] I checked what happens when the tape is inside: the switch is pressed (if it wasn't nor ffwd or rew would work.. tested). But when the tape is inside I cant hear or see any solenoid working. In the whole machine I found 2 solenoids: one commands every automatic stop and works perfectly. I never saw the other working: surely it's related with play.. if I move by hand the levers I see another lever with a head upon it getting closer to the tape location. On the other hand rec buttons are never enabled. The strange thing is this: even trying to move any lever inside the videorec by hand, I wasn't able to enable play button... Another thing: there are two arms that should take the tape film near the reading head. I still didn't discover what moves them. solenoid is not doing its job. It may be weak, a common fault, or the driver transistor for the solenoid may be open, another common failure well... if the solenoid is gone... I think it's a problem. I should get some copper wire and rebuild the windings inside it (but will it work??!?). The transistor.. maybe that's a problem too without the schematic of that monster. Anyway... if you have experience.. you could tell me someting about the voltage driving the solenoid. It has 4 wires upon it: red, orange, yellow and brown. or crud has got in the well freezing up the solenoid bolt, not a common problem. I had the manual for this machine somewhere. I'll try to find it. I would exclude the crud.. it's really clean inside. Also the manual would be a great step forward!! ![]() Bye Daniele P.S. Would you continue this topic by email? you can write me : skrauso (at) infinito . it -- http://tastiere.altervista.org - THE resource for Synthesizers ! Free patches and sounds |
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