Author Topic: Philips N2225  (Read 774 times)

0 Members and 1 Guest are viewing this topic.

Offline ensoniq

  • Contributor
  • Posts: 5
  • Country: ro
Philips N2225
« on: January 11, 2019, 07:40:24 am »
Hello guys,

I tried to repair an old cassette recorder made by Philips in the '70, model N2225.

This thing is not starting. Replaced the belts and everything and still no fun.
Then i got serious and started to meassure some things.

This particular recorder has an automatic stop feature (:) which, when it works, it cuts power to the motor by means of a rotating switch which keeps closing and opening while the cassette wheels turn. No problem whatsoever with the switch tough.

The sound signal is hearable in the speaker so the sound generator circuit is engaged which makes me think the problem is related to the automatic stop circuit beeing stuck.

Emiter of TS462 - 0 V.
TS460 is always open. Emiter of TS460 11.7V which is normal.

Points A, B, C all meassure 0V always. What are theese points anyway? Power rails? If so, the whole thing powers via TS460?!?  |O |O :-//

Power supply seems to be ok - that is i do get 11.7 V.

I don't get it.

Any help / ideas will be much appreciated.

Thanks
 

Offline Armadillo

  • Super Contributor
  • ***
  • Posts: 1725
  • Country: 00
Re: Philips N2225
« Reply #1 on: January 11, 2019, 09:22:03 am »
I suspect C777.
Change C777 capacitor.
 

Offline ensoniq

  • Contributor
  • Posts: 5
  • Country: ro
Re: Philips N2225
« Reply #2 on: January 11, 2019, 09:32:59 am »
Yeah. BUT.. A,B,C -> why is all dead there ? Are these power rails?  :-//
C777 will unblock autostop which can be bypassed all together by shorting TS480 and still no power.  :palm:
 

Offline Armadillo

  • Super Contributor
  • ***
  • Posts: 1725
  • Country: 00
Re: Philips N2225
« Reply #3 on: January 11, 2019, 09:38:18 am »
Easy Elimination;

Take out TS462
Take out C755
Short emitter and collector TS460.
 

Offline ensoniq

  • Contributor
  • Posts: 5
  • Country: ro
Re: Philips N2225
« Reply #4 on: January 11, 2019, 09:45:35 am »
Did that. TS462 is ok. emiter of TS462 -> 0 Volt
shorted TS460 -> emiter of TS462 -> 0 volt,

so now, i wonder where power comes to points A,B,C -> are these power rails or ? if so, the whole thing powers thru TS460. If so, that is absurd. And if not, how power get to amplifiers and to the rest of circuit ?

Forget the motor, autostop and all that circuitry at the bottom. Suppose I only want to power the amplifiers at the top of the circuit. How power gets to these circuits? According to schematic, from A, B, C which are simple resistor dividers if they had something to divide. But at that point of emiter of TS462, we get 0 Volts. :)) Messed my head mate.  :scared:
« Last Edit: January 11, 2019, 09:49:23 am by ensoniq »
 

Offline Armadillo

  • Super Contributor
  • ***
  • Posts: 1725
  • Country: 00
Re: Philips N2225
« Reply #5 on: January 11, 2019, 09:59:00 am »
Relax;
 

Offline ensoniq

  • Contributor
  • Posts: 5
  • Country: ro
Re: Philips N2225
« Reply #6 on: January 11, 2019, 10:02:16 am »
yeah. and ? :))) We now only powered autostop which is great. Further down the road, TS460 needs to open.  We shorted it and bypassed autostop. Still no joy. I'l try C755 and C777.
« Last Edit: January 11, 2019, 10:52:29 am by ensoniq »
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf