Did u try more than 2 tapes?
ask yourself 2 times before rating
I suggest you have bad Electrolytic Capacitors on the Power Board. As a retired tech, I'm sure you
know that years ago in Japan, an employee tried to abscond with an Electrolytic paste formula. It was
from a Major Electrolytic Capacitor manufacturer. Unknown to the thief, she was given a bogus formula.
This formula was missing an ingredient that suppressed the 'Cap' from developing gas inside.
(Hydrogen gas) It was believed she did it, because of the firing of one of the other employees.
Off they went to Taiwan, and sold their formula to an Electrolytic Capacitor manufacturer, there.
Although this issue happened years ago, there were millions of bad capacitors made. They are still
plaguing us today. Many electronic components have these bad 'Caps'. They may go out in a few
months, or it may be YEARS! When buying Electrolytic Capacitors, one tries to get them from Japan.
I apologize, if any of this seems like a prejudices type of thinking, in any way. Such is not my contention.
I realize that if you, sir, do not have this information, then it sounds 'Pretty far-fetched'.
I list the following links to support my statements,
1.http://en.wikipedia.org/wiki/Capacitor_plague
2.http://www.dashdist.com/1u2u/company/capacitor.html
It is my contention that there are capacitors operating in a weakened state on your Power Board.
I'm not looking at the capacitors being used a filter in the input circuit, or the output circuit. I was suggesting they may have been bad, in regards as to be used for a voltage regulator for the capstan motor, or perhaps involved in a circuit with the dew sensor.
Since you have checked the 'Caps', I guess we can definitely disregard them. (Also nice to know your background, and that you have an oscilloscope. Thumbs up!)
Can you bypass the dew sensor? What circuit regulates power to the capstan motor? Could it be something as simple as it's out of time? The timing of the tape feed rollers? (Lacking in correct nomenclature here)
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I accept your suggestion about faulty electros but when i examined the player with my oscilliscope i found no evidence of lack of filtering.
Add to this the fact that it works very well once it starts , absolutely no ebidence of capacitor problems. I am hoping you can find someone who has come across the same problem in the past.
It does everything it is supposed to when loading the tape, the capstan motor goes backwards and forwards and the tape is properly installed but the moment the capstan is supposed to start, the waveform that drives the capstan motor disappears !! I wondered if it might be the dew sensor?
Anyway would you please make some enquiries for me and see if anyone else has ever had this problem. thankyou and god bless.
Phillip
I have a VC-A502X which ash developed a fault: the power must be turned off for a few hours or it wont play a tape. Does everything well except start to play when warmed inside. Would really appreciate any suggestions. have circuit duagram. Am retired tech. Phillip
Comment posted on May 05, 2009
I accept your suggestion about faulty electros but when i examined the player with my oscilliscope i found no evidence of lack of filtering.
Add to this the fact that it works very well once it starts , absolutely no ebidence of capacitor problems. I am hoping you can find someone who has come across the same problem in the past.
It does everything it is supposed to when loading the tape, the capstan motor goes backwards and forwards and the tape is properly installed but the moment the capstan is supposed to start, the waveform that drives the capstan motor disappears !! I wondered if it might be the dew sensor?
Anyway would you please make some enquiries for me and see if anyone else has ever had this problem. thankyou and god bless.
Phillip
I have a VC-A502X which ash developed a fault: the power must be turned off for a few hours or it wont play a tape. Does everything well except start to play when warmed inside. Would really appreciate any suggestions. have circuit duagram. Am retired tech. PhillipComment posted on May 05, 2009
I accept your suggestion about faulty electros but when i examined the player with my oscilliscope i found no evidence of lack of filtering.
Add to this the fact that it works very well once it starts , absolutely no ebidence of capacitor problems. I am hoping you can find someone who has come across the same problem in the past.
It does everything it is supposed to when loading the tape, the capstan motor goes backwards and forwards and the tape is properly installed but the moment the capstan is supposed to start, the waveform that drives the capstan motor disappears !! I wondered if it might be the dew sensor?
Anyway would you please make some enquiries for me and see if anyone else has ever had this problem. thankyou and god bless.
Phillip
I have tried many tapes, some at the very beginning, some 1/4 the way through and some almostr all the way through, it makes no difference. I am wondering if someone has ever found a problem with one of the ICs. It sounds to me as though you don't know much about VCRs especially Sharp HQ 4 head.
Ask around please, has any one ever experienced this problem before. So far I am disappointed with your replies and feel I should get my money back.
Have you any expetience servicing VCRs especially Sharp?
Please read my previous comments, or do I need to start from the beginning.
Phillip
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