Philips 4407 noise from one speaker on shake, tap

[sylar2a]

Hi! I have recently restored philips 4407, almost. I have tried it a little bit, sound is great (a least I think, I may be wrong), but when it shaken a little bit, like when i press buttons which are not most gentle, right speaker starts putting out noise, distortions. But when i tap it again (gently or not so gently), noise either stops, or at least it reacts somehow. I wonder if that is due to bad connection somewhere, or capacitor etc. Not sure where to start looking.

[ben]

could be:
-dirty contacts on rec-playback internal slide switch.
-internal-external speaker switch.
-failing germanium transistors.
-loose connections on track switches
-loose connections in audio stage/cracked solder joint, etc.

Be very careful if you remove the chassis from the housing. The bias oscillator coils are very exposed at the edge of a circuit board, and can be broken if you handle it carelessly. I remember almost knocking one when I worked on my Pye version of this deck.

[sylar2a]

Yeah I noticed, frankly I have no idea how to put it while checking circuit board or anything bottom side.
I payed a little with switch and had no effect on noise. Do you maybe know where to look for these transistors since it is on one speaker. Also I am not sure what do you mean by "track switches".

I will look into diagrams

[sylar2a]

I have opened it and managed to locate where the problem might be. First i checked germanium transistors AD162 and 161 both left and right, in shematic, but on taping those a little nothing happens. Than I touched board next to it and there was noise. I attached picture of that board, because I am not sure which one of those is guilty (if capacitors could be a source of the problem ). Somehow I suspect it is that silver transistor marked AC128, noise is loudest when that part of board i tapped, and what are those big black things, they are next to AC128.
So what do you think?

[Jimmyhaflinger]

that coud be the AC128 transistor but before you replace it make sure you don't have cracks or dry joints on the print

[Boater Sam]

"Big black things" are heat sinks for the output transistors which are mounted on them.
AC128 and similar transistors could have the tin whisker disease. The pcb looks to be a low quality early production, could have some poor soldered joints or even cracks in the tracks.
Probe and wiggle around both sides of the pcb with an insulated tool till you find the epicenter of the "noise".

[sylar2a]

It is hard to determine problem because entire pcb is touch sensitive. I have experience with electronics but all joints and tracs seem fine, altough there is something brown on joints, and it seems to me like it's from soldering.