here is a message to share my experience in solving a problem that appeared on the home-cinema amplifier ONKYO tx-DS494.
In order to sell this amplifier I had to check if all the outputs and all the functions works properly.
On the back of this amplifier you have to frontal output : A and B.
I connect a pair of speaker on A output : no problem. I can adjust volume.
when i connect the pair to the b output and turn the volume knob no sound came out of the speakers until I reach a level defined by I don't know what. :hmmm: My volume level goes from 0 to 80db ( if I remember well ). from 0 to 23 db no sound and when I reach 24 dn sound increase and stabilize.
With hearphone connected, i don' have this problem so I conculde that amplifing transistor could not be incriminated.
I checked on the service manual and saw that there are two or three component that could be the source of the problem : the main processor, some capacitors on the output PCB and relays.
I began testing capacitors: no pb. then I thought that if cannot be the main proc because it ( I think ) works in a binary mode: it works or it doesn't. so I decided to switch between themselves the two relay and :super: : it works. The relays was in fault and did not switches properly.
here is my experience in repairing an amplifier
Udv! Nos,a gondom-kicseréltem már pár optikát cd lejátszokban,de most 2x is ugyanabba a hibába botlottam:optikacsere után a lejátszok/egyik Philips,a másik AIWA/ a cd -t gond nélkul felismerik és le is játszák,de néha néha egy-egy pillanatra megakadnak-szoval kiesik a hang.Ez a jelenség nem rendszeresen történik,de nagyon zavaro,föleg zenehallgatás közben.Nagyon megköszönném,ha valaki segítene a hiba elhárításában. Udvözlettel-Stanley
Akinek megvolna el tudná küldeni? köszi!
Füstölt a trafója, gondolom tekerni nemsok értelme van, de kéne tudni
milyen szufla jön ki belőle.
3 zsínór, én 2x12V-ra tippelnék.
This receiver starts normally and has a nice blue display lighting on for 8 seconds. Suddenly you ear the main relay falling down and everything turns off and you get the red led flashing around the main power switch button. There is no special code with this continuous flashing rythm of the led. I have no diagram of the device and I have opened it and measured the voltage on pin 4 of the voltage regulator KIA78R05P1, which has a validating signal on his pin four.(2 is the output and 3 is frame (-)).this 5V(to-220)monolithic 7805 regulator is on the main PCB, close to the little transfo and ON/OFF relay...and is mounted without any heat dissipator(I was surprised of that fact!).the voltage between(4-3)is 1,88V dc and never climbs up during the starting sequence.
Can you help me to solve this problem?