HellasTechn
- Apr 14, 2013
- 1,579
- Joined
- Apr 14, 2013
- Messages
- 1,579
Hello friends !
I have a weird problem with this Hitachi htd-k150 home cinema system.
It works all right but some times when i power it on i get noise from the speakers and then i can no longer control volume. It either play sound at steady low volume or not at all. when i press the volume + and - buttons the display shows the volume level but the speakers nothing.
At firast i thought that it's amplifier IC's may be bad so i replaced them (TDA 7497) but that did not solve the problem. Later i noticed (with the o-scope) the presense of a 150-200mv saw tooth signal between the heatsink and the metal case of the powersupply 6.800uf filter caps.
Then while still probing that weird signal i tried to raise the volume and after hearing noise from the speakers it started working normally.
After a few power on and shut down cycles the problem came back and i was only able to eliminate it by placing the o-scope probe same way as before.
I also noticed the same weird signal on a number of other caps.
i will post o-scope pictures tomorrow.
Could it be that theese caps need to be replaced ?
I have a weird problem with this Hitachi htd-k150 home cinema system.
It works all right but some times when i power it on i get noise from the speakers and then i can no longer control volume. It either play sound at steady low volume or not at all. when i press the volume + and - buttons the display shows the volume level but the speakers nothing.
At firast i thought that it's amplifier IC's may be bad so i replaced them (TDA 7497) but that did not solve the problem. Later i noticed (with the o-scope) the presense of a 150-200mv saw tooth signal between the heatsink and the metal case of the powersupply 6.800uf filter caps.
Then while still probing that weird signal i tried to raise the volume and after hearing noise from the speakers it started working normally.
After a few power on and shut down cycles the problem came back and i was only able to eliminate it by placing the o-scope probe same way as before.
I also noticed the same weird signal on a number of other caps.
i will post o-scope pictures tomorrow.
Could it be that theese caps need to be replaced ?