Philips EL3312

[Jimmyhaflinger]

Hi

i'm trying to get this thing going, the preamp electronics are as dead as a brick and the meter gets slammed to its max position as soon as i turn on the machine

found a shorted diode in GR2 voltage doubler bridge, replaced it with a pair of 1n4001 discrete diodes, no difference

tested all transistors on the preamp board with a dmm, all test good

then checked some voltages on the preamp board, found out TS102 got only about 500mv on its collector, removed the transistor, the voltage now is up to about 14v on its collector terminal,

the transistor tests perfect on a digital component analizer...

is there an explanation for this?

[Ted Kendall]

Sounds like said transistor is being turned hard on. What's happening at the base?

[radiotechnician]

The machine is old. Any movement or whiskers may be responsible.

Go over everything, swap c110, c105, and clean/examine switch switch
contact points 20, 22.

Heating up the BC 109 may have changed the specs.

I have worked on this model. After 40 years , it still imparts
a feeling of anger. But that may have been issues of not being able to get parts easily then.

[Jimmyhaflinger]

With ts102 back in its place i get 1.2v on its base and 0.5v both on its emitter and collector.

Tried to short its base to chassis ground, this totally killed any voltage on both emitter and collector

[Jimmyhaflinger]

Tried to short the base to emitter instead of chassis ground, now i get over 18v on the collector

[radiotechnician]

The voltage rail is 18 volts. Vc is 8.2, Forward bias for T102 is through a 1m8
resistor R14. This gives 4.8 uA Such a small bias, with no base to ground
path, makes for high dependence on clean paths, and a very *new*
transistor.

Try another transistor. If the other channel works, borrow that one.

If both work in the other channel, then something in the board of the
the bad channel is causing this.

The manual is available on HiFi engine with very good board views.

[Jimmyhaflinger]

the problem seems to be c104 which is leaky, without that capacitor i get about 8.5v on the collector

the component analyzer sees it as a diode

also i removed some nearby capacitors and they all test bad, they read more than double their rated value and some have as much as 84 ohms of ESR

looks like a near complete recap is needed

can i use 1mf capacitors (i have tons of them) in place of the original 1.6mf capacitors?

also C110 is 10mf on the schematic but 1.6mf in my machine, is this a factory mod or is it just that its value is not critical?

[radiotechnician]

I read 1.6 uF on the schematic. Your copy may be smudged.

[Jimmyhaflinger]

ok i'm about to give up, replaced all electrolytics and even all transistors but it still quiet and somewhat poor bass response

also i get cracking noises from the dirty rec level potentiometer on the bad channel if i rotate it during playback but not on the good channel, sometimes the volume on the bad channel rises a bit when the dirty potentiometer isn't making contact