Need help with EP / LP detection of a SHARP VZ-3000

[Funkateer38]

Hello to the forum, I need help with EP / LP detection of a SHARP VZ-3000.
With an LP, everything works fine,
On the other hand with an EP, the tone arm does not move at the beginning of the vinyl.
the values of R585,586,591,592,593,594,612 and 613 are correct,
I changed the Q533 and Q534, I have the 5v of the CNP506 connector in 1 and 2 up to the emitters of the transistors.
But only 1.2v instead of 5v at the collectors of the transistors to points 26 and 27 of the IC which control the position of the tone arm.
The CNP506 connector is connected to two phototransitors Q538 and Q539 which I do not know how to test them.
Do you have an idea please?

 

[fyj2972]

What are the voltage readings at pin1 and pin3 of CN506?
If they are below 5v, q33 and q534 will be turned on and you will get low at both pins of IC501.
There is a only reason making CN506 pin 1&3 is that IR light source, which might be an IR diode?

Happy repairing.

 

[Funkateer38]

Bonjour sur le forum, j'ai besoin d'aide pour la détection EP/LP d'un SHARP VZ-3000.
Avec un LP, tout fonctionne bien,
Par contre avec un EP, le bras de lecture ne bouge pas au début du vinyle.
les valeurs de R585.586.591.592.593.593.594.612 et 613 sont correctes,
J'ai changé les Q533 et Q534, j'ai le 5v du connecteur CNP506 en 1 et 3 jusqu'aux émetteurs des transistors.
Mais seulement 1.2v au lieu de 5v au niveau des collecteurs des transistors aux points 26 et 27 du CI qui contrôlent la position du bras de lecture.
Le connecteur CNP506 est relié à deux phototransiteurs Q538 et Q539 dont je ne sais pas comment les tester.
Avez-vous une idée s'il vous plait ?
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[Funkateer38]

What are the voltage readings at pin1 and pin3 of CN506?
If they are below 5v, q33 and q534 will be turned on and you will get low at both pins of IC501.
There is a only reason making CN506 pin 1&3 is that IR light source, which might be an IR diode or a bulb ? . I dont that VZ3000 manual with me).

Happy repairing.

Thank you for your quick answer, I am correcting I have 5v in 1 and 3. I also think that the phototransistors are defective but I do not know how to test them with a multimeter.

 

[fyj2972]

Ok, got service manual.

Check CNS 505 pin(4) and pin3 voltage.

 

[Funkateer38]

Ok, got service manual.

Check CNS 505 pin(4) and pin3 voltage.

CNS 505 pin4= 13v and pin3= 0v and 2.6v in ep/lp record sensor

 

[fyj2972]

CNS-505 pin(4) should be 2.6-3V . if CNS-505 pin4 reading is 13V, you might have a bad IR diode.

 

[Funkateer38]

CNS-505 pin(4) should be 2.6-3V . if CNS-505 pin4 reading is 13V, you might have a bad IR diode.

Thank you very much for your help. I changed the PWB-A8 to a corpse from VZ-2000. I think both PT-350 phototransistors are defective. Impossible to find these phototransistor in France apart from a seller on Ebay but refuses to deliver in Europe.
Everything now works in EP and LP mode.

 

[fyj2972]

I dont think both photo-transistors go bad at same time.
I would check Q538/359 with any TV remote.
Connect you Muilti-meter (V) to emitter of Q533 or Q534,
Aim your TV remote to Q538 or Q539, check any voltage change( going little bit up and down or not)
If voltage changes , photo-sensors are good.

 

[fyj2972]

TYPO: Collector of Q533 or Q534 instead of Emitter.