Technics sh 8066 defekt

Hi Antonello, welcome to our community!

When I was a student I visited Porto Torres. That's long ago. But I remember well.

To your problem.
A service manual can be downloaded via ...
https://www.vintages...6-Service-Manual.pdf

On page 18 (numbering by pdf) you'll find the power supply.
First ideas ...
1. If nothing happens, the thermal fuse of the transformer should be checked. Between the contacts of the mains plug the resistance must be low.
2. The power supply seems to switch a lot of voltages on the secondary side of the power transformer. You should check it. (resistance between contacts when the mains plug is not connected to 230V AC).
3. Next step would be to check the voltages which you can find in the service manual. Maybe a rectifier or one of the regulators IC 1 to 3 is defective.

Quando ero uno studente ho visitato Porto Torres. Questo è tanto tempo fa. Ma ricordo bene.

Al tuo problema.
Un manuale di servizio può essere scaricato tramite ...
https://www.vintages...6-Service-Manual.pdf

A pagina 18 (numerazione in pdf) troverai l'alimentatore.
Prime idee ...
1. Se non succede nulla, controllare il fusibile termico del trasformatore. Tra i contatti della spina di alimentazione la resistenza deve essere bassa.
2. L'alimentazione sembra commutare molte tensioni sul lato secondario del trasformatore di potenza. Dovresti controllarlo. (resistenza tra i contatti quando la spina di alimentazione non è collegata a 230 V CA).
3. Il prossimo passo sarebbe quello di controllare le tensioni che puoi trovare nel manuale di servizio. Forse un raddrizzatore o uno dei regolatori IC da 1 a 3 è difettoso.

CarlM. (Beitrag #2) schrieb:

Hi Antonello, welcome to our community! When I was a student I visited Porto Torres. That's long ago. But I remember well. To your problem. A service manual can be downloaded via ... https://www.vintages...6-Service-Manual.pdf On page 18 (numbering by pdf) you'll find the power supply. First ideas ... 1. If nothing happens, the thermal fuse of the transformer should be checked. Between the contacts of the mains plug the resistance must be low. 2. The power supply seems to switch a lot of voltages on the secondary side of the power transformer. You should check it. (resistance between contacts when the mains plug is not connected to 230V AC). 3. Next step would be to check the voltages which you can find in the service manual. Maybe a rectifier or one of the regulators IC 1 to 3 is defective. Quando ero uno studente ho visitato Porto Torres. Questo è tanto tempo fa. Ma ricordo bene. Al tuo problema. Un manuale di servizio può essere scaricato tramite ... https://www.vintages...6-Service-Manual.pdf A pagina 18 (numerazione in pdf) troverai l'alimentatore. Prime idee ... 1. Se non succede nulla, controllare il fusibile termico del trasformatore. Tra i contatti della spina di alimentazione la resistenza deve essere bassa. 2. L'alimentazione sembra commutare molte tensioni sul lato secondario del trasformatore di potenza. Dovresti controllarlo. (resistenza tra i contatti quando la spina di alimentazione non è collegata a 230 V CA). 3. Il prossimo passo sarebbe quello di controllare le tensioni che puoi trovare nel manuale di servizio. Forse un raddrizzatore o uno dei regolatori IC da 1 a 3 è difettoso.

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hi Carl I'm glad you visited Porto Torres
I live in the province of Sassari, about twenty minutes from Porto Torres
then I tell you my tests with the multimeter
I checked all the various resistors and transistors and at the test they seem ok
the equalizer turns on the signal enters but the buttons do not work there is no switching between the buttons
if I disconnect some j9 j16 connectors from inside then some buttons work

Please confirm:
If you are disconnecting the power switch some buttons are working?

Most important is to check the voltages of the power supply. You have to verify the marked voltages:

Hi Carl, then I took the measurements you suggested
they look ok
IC1=-22 -15 vcc
IC2= 14,9 21,3 vcc
IC3 -5,6 -11,8 vcc
Q2= base -6,7 Collettore -10,7 Emettitore 6,06
Q4= Base 6,51 Collettore 10,42 Emettitore 5,88

CarlM. (Beitrag #4) schrieb:

Please confirm: If you are disconnecting the power switch some buttons are working? Most important is to check the voltages of the power supply. You have to verify the marked voltages:

Hi Antonello,

I read the manual again. On page 8 (= page 5 of PDF) I found the chapter "Convenient functions".
Did you check the function "lock button"?

C.

The lock button is used to prevent someone from touching the panel and varies the frequencies
and in any case he too does not work

CarlM. (Beitrag #6) schrieb:

Hi Antonello, I read the manual again. On page 8 (= page 5 of PDF) I found the chapter "Convenient functions". Did you check the function "lock button"? C.

Normally now the CPU should be checked. But it is not possible without an oscilloscope.
Therefore you can check the wires and connectors and at the end you can only continue checking the voltages: I would start with the
Zener-diode D17 and the transitors of the buffer area like Q709 an following ...

D17 =-27,7/-30,3
Q 709= B -30,6/ C -31,1/ E- 30,5 vcc
shortly a video what happens if I disconnect some points

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CarlM. (Beitrag #8) schrieb:

Normally now the CPU should be checked. But it is not possible without an oscilloscope. Therefore you can check the wires and connectors and at the end you can only continue checking the voltages: I would start with the Zener-diode D17 and the transitors of the buffer area like Q709 an following ...