Hi. I need help from wiser guys. I am amateur in electronics and can't figure this out by myself.
I bought faulty speakers, M-Audio AV40's. Other speaker has all the electronics in it and the other speaker is just passive one powered by the other speaker's amp. Original problem with the speakers was loud buzzing. I figured out that there is something wrong with the capacitors. I went ahead and replaced every electrolytic capacitor on the PCB. The caps are good quality and have the same values as the original ones.
After replacing the caps I started testing out the speaker. It seemed to work good now. No buzzing and good audio quality. However while testing I took my thermal camera just to see if any component was getting hot on the PCB. Everything else was cool but I noticed two really hot spots. They are two zener diodes. They got quickly up to 100 degrees celsius and kept slowly getting even hotter. The zener diodes have markings on them: 1N4744A and below that is 5T. So those zener diodes are 15V 1W ones in a glass(?) package. I can see some dark coloring on the PCB's blue cover on both sides where the zener diodes are located.
My question is that is is this normal and maybe bad design since everything seems to work or could there still be something wrong with the amplifier? And since the original zener diodes are rated at 1 watt, would it help if I swapped them for 5 watt zener diodes with the same voltage value?
I really appreciate any help and I want to thank you in advance.
I bought faulty speakers, M-Audio AV40's. Other speaker has all the electronics in it and the other speaker is just passive one powered by the other speaker's amp. Original problem with the speakers was loud buzzing. I figured out that there is something wrong with the capacitors. I went ahead and replaced every electrolytic capacitor on the PCB. The caps are good quality and have the same values as the original ones.
After replacing the caps I started testing out the speaker. It seemed to work good now. No buzzing and good audio quality. However while testing I took my thermal camera just to see if any component was getting hot on the PCB. Everything else was cool but I noticed two really hot spots. They are two zener diodes. They got quickly up to 100 degrees celsius and kept slowly getting even hotter. The zener diodes have markings on them: 1N4744A and below that is 5T. So those zener diodes are 15V 1W ones in a glass(?) package. I can see some dark coloring on the PCB's blue cover on both sides where the zener diodes are located.
My question is that is is this normal and maybe bad design since everything seems to work or could there still be something wrong with the amplifier? And since the original zener diodes are rated at 1 watt, would it help if I swapped them for 5 watt zener diodes with the same voltage value?
I really appreciate any help and I want to thank you in advance.
