EM84 magic eye does not close on FM on Philips B4X92A (Techniek Radio/TV)

door Maurice , Dordrecht, 24.10.2022, 19:15 (552 dagen geleden) @ ejrietbergen

Its very straight forward.

Measure the voltage across C40, there must be a DC voltage.
Of course when receiving a station.
R18-21 to ratio voltage level EM84, 27//6,8, app 4::1
So if C40 voltage is 40Vdc - EM81 is 10Vdc. app.

Rectifier EM84 voltage is B4(EABC80) 3-2 diode.

AC on pin 3-2 diode rectified diode B4 and smooth by C40.
C41 is HF decopling.

Rule out , investigate, Cold /Broken Solderings.
Check from pin to pin, zero Ohm connections.

Radio -OFF.
Cut C40
Switch to FM:

Path B4-2 to B3-1 is 27k Ohm
Path B4-7 to B3-1 is 6k8 Ohm

Path B4 2<->7 is 27k +6k8 = 33k8
Don't bother some 10% deviation.

Still think B4 EABC80 must be faulty.
Take off both wires B4 2 and 7
Replace diode B4 with f.i. 1N4004 or simulair.

In that way you rule out B4.

Lets see.

--
"I haven't even turned this on to see if it works because as long as I don't it might"