Power supply is still good, transformer is putting out 15.5VAC. No output to speakers, suspect main board. Board shows no scorching of components, or venting of caps. Fuse good. May be IC related. may have been a victim of a UPS slowly discharging (linear voltage drain-off --110 to 0VAC) How do i get a new main board?
If your speakers have a warranty can you return that to the store with the receipt because the store will replace a new for defective product..or you can go to the web site of the brand of your speaker if you intent to buy the main board you can order trough the online shopping.
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Probably not. The fuses would have blown if the transformer had been overloaded.
These amps do not have output transformers. The transformer you see inside are likely switching transformers to increase the supply voltage substantially. They are pretty rugged. There likely fuses on the circuit board that you don't recognize. If there are surface mount components on the board, look for white rectangular that are square when looking from the end. Usually they will have xxA marked on them, a 1 or 2 digit number followed by an A. There are other shaped fuses, but they should all have a similar marking. Usually, the left and right amplifiers will each have TWO fuses associated with thir power supply and sometimes an additional one for the speaker.
It could be the main board. The main board controls the standby light on the front of the set. Check and verify that your 5vdc standby voltage is working. Next, I would check the "on" or "ps on" input on the power supply board. When you turn the set on (either my side buttons or remote) the main board should send a 3.3vdc signal into the "on" terminal on the power supply. This "on" signal from the main board turns on the other half of the power supply thus turning on your set. If you are not getting this signal from the main board, I would suspect the main board. To test your power supply, you can simply put a jumper from 5vdc to the "on" terminal on the power supply. Your 12vdc, and 24vdc power supplies should then become active.
sounds Like a power supply issue and u should always have speakers connected before u turn on maybe power supply is about done open case an check for any leakage on power supply unit or small cracks on it ...if so its pretty well done
Never good to power up without speakers connected can blow power outputs
Please check the horizontal output transistor for leak, base-emitter. Change it.If there is any kind of short in the board, the power supply will sense int and will shuts down. Line out put transformer [LOT] may also suspect. On the secondary supply stage from LOT, the secondary power supply section, check all the rectifier diodes, and its filter capacitors for leak. Even a slight leak will effect the proper function of the set. Check it with good qulaity analongue multimeter, with setting it to meg ohms range; check the suspected componets off board. Likewise check the primary rectified DC voltage at SMPS stage. It should be aroung 380V DC accross main filter capacitor. If it is not check the main filter capacitor [usually 330Mfd 450V] for low capacity. and check the four main rectifier diodes.
Check the Pico fuses fromthe power supply to the main board, the convergence board. trace using the power output from the power supply. if you notice any suspected components visibly showing out a fault like a capacitor or a burnt resistor, check it out and replace.
Check for possible dry solder joints or failure of the IC.
Remove plug off while checking and test by tapping board for any loose connection.
If your speakers are making this noise on switch on please disconnect them and check out if they the speakers are damaged by a continuity test of the impedance. It must show the marked resistance without a short. Then you are lucky. Next open the amplifier and check out on the output side and the power side for failure of mains capacitors/ output drivers/faulty coupling capacitors. Connect a resistance loaded test- speakers whenyou do this test .Switch on and put the set on fopr voltage checks from the output to the preamp. By a signal test you will be able to analyse the gain factor of all teh corresponding stages.It might be possible that your amp is old and some electrolytics have dried up.If so put the amp on for some considerable time and confirm if there is response building up on the controls and panels slowly. If so check onthe board for the suspected passive components and replace all suspected capacitors. Also resolder the main pcb for bad connectivity. I am surre this must work but attampt only if your are familiar to doing this repair. Good day
The power adapter that blew damaged the amplifier circuits inside the sub (or a damaged circuit caused the power adapter to blow)... in either case, if you have electronic skills and access to a oscilloscope, you can trace the signal on the circuit board. The suspect components to look for would be around the connectors for the power supply to the circuit board.
Can you check the power transformer, voltage & resistance.
You may have to unsolder some components to test them...such as the rectifying diodes and the transformer. I believe that the outputs from the power supply board are all DC voltages. Is there all so a IC chip on the power supply board? Does your insurance cover lightening damage?
can you be more specific as to "plastic tabs that show signs of slight melting"? Like where are they in relation to components / power supply / heatsinks / power transformer? A first shot... it may be output power fets/transistors (one is open or shorted) that is making one or more of the speaker outputs go to the PS rail. DC shutdown. Does this receiver indicate any "overtemp" or "protect" warnings? I really need a little more specifics.