Sansui SC-3300 cassette deck - help please!

[Vitold]

Hi

Just took the SC-3300 today.
The deck doesnt react on any button push. Capstan rotates when cassette inserted but nothing more
Lumi peak meter indicators work as well as Dolby B indicator. All bulbs light.
Any help guys? SM manual?

Thanks!

 

[east electronics]

there is a chance that your fault lays in the secondary power supply look there

 

[Vitold]

there is a chance that your fault lays in the secondary power supply look there

Sakis, I think you are right.
The belt is ok and capstan rotates as it should be.
Looks like there is no voltage at all 3 solenoids and a reel motor.
There is a DC of 0.75V at control buttons.

On the right side white bus the yellow and green wires are for reel motor (no voltage) and black and red are for capstan motor (13.5 V DC always)
On the left lower corner is a bus for solenoids supply. No voltage!

What I afraid is faulty logic IC. Which open/close power to supply reel motor and solenoids when necessary.

Any suggestions?

... and anybody - SM please!

 

[Mooly]

Could the reel motor be faulty/seized and have blown a safety resistor etc.

IC's are very reliable, it's things that handle power that give trouble.
Worked on a lot of stuff over the years (it was the day job 🙂) and for some reason a common failure with Japanese transistors is them failing open circuit B-E, which is easily checked by measuring the voltage across it (cannot exceed 0.7 volts).

You need to trace one of the solenoids and the reel motor and see what drives them, and where that device then gets its power.

 

[Vitold]

Thanks to everybody! The problem was dead cold soldering somewhere on power supply/logic PB 😛
I have tested all transistors as Mooly suggested and bent the board a bit. And a deck logic has back to life!

The 31 yrs old guy is still alive and plays very well!
Picasa Web Albums - Clifford - Sansui SC-3300

Anyway, SM anybody? Want to calibrate it

 

[Mooly]

That's good... so why not give it a full resolder. Hitachi TV's were terrible for that, some component legs were oxidised and you could never get the solder to take... it was a common fault. Definitely worth a shot.