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Aug 2, 2024, 12:54:10 PM8/2/24

to chuclandgaci

Hi, Take some close up pictures of the systemboard and post back here. There may be some 'stressed' components which might be able to be spotted by someone here. Hopefully someone like @oldturkey03 may even have a service manual or circuit diagram available for it.

Also did that. But mine did not work instantly. After consulting a sony repair facility they suggested to check the pins of the flatcable which crosses the fan, because they might be folded. This was the case, so I folded them back and now its working :)

"protect" mode is there to prevent the speakers from damage. Basically the output lines are monitored to insure that there is no DC voltage present. DC voltage to a speaker results in heat which will damage the voice coil and thus the speaker. This is why there is usually a slight delay from the time the unit is turned on to the time you hear sound. In this case, I would suspect that the output transistors/amp pac have failed. Whether or not both channels have a problem, the unit will go into protect mode.

Thanks for your quick responses and help. I have disconnected CN101, CN4 and CN3505 (blue circles). And I have measured the first and fourth pin from CN101 (red circles). It is giving me 54,5V when the device is on. I guess that this is too high? And that the supply board is broken?

Hopefully @oldturkey03 also has a schematic which will help make it easier to track down the problem further as a quick search online for a replacement board using the part number on the board (PSC20487CM 3L3392W/W-1) only had 1 result and it is out of stock.

Initially I would look at R466, perhaps it is my poor eyesight but it doesn't look quite right in the picture unless it is just the lighting and angle when compared to R465? nearby. It is the one to the left of the connector CN101

Thanks for the schematic. It's a shame that there is no schematic of the Switching Power Supply . The best it shows is a Block showing the power feeds on p.41 and also it was right that the output should be >30V because on p.55 it shows test points on the connection from the SWR board (Power board) to the AMP board having a value of +32.3V (these are the points I think that @jorn was testing)

Does it turn on/off the 14V supplies for example. To me the +32.5V has to be there, not only because it supplies IC3100 and IC3200 but it is also used in conjunction with the protection circuits which may have to be enabled early on, maybe even as it is being turned on.

I know this is old but does any one know the voltage rating of the 4 larger SMD capacitors that are in line with the amplifier IC? The Diagram says they are 1uf so I purchased some 50v 1uf ones and they are much smaller.

Thank you for your reply, the two I am looking to replace are marked as C3318 and C3319 they are the same and the diagram says they are 1 which I guess is 1uF as mentioned I purchased a 1uF 50v capacitor but the size difference is significant

I decided to remove the other two cap in the same row as these as they are the same type and interestingly they measured 2.3 and 2.4 uf despite the circuit diagram saying that they are all 1 uf. Can anyone confirm this for me.

The 2 sets of 4 larger smd ceramic caps have different values. Not ALL are the same. I recently had one blow up on my board which led me to the service manual that tells me that in one set of 4, the two inner caps are 2.2 uF 10% 100v and the two outers are 0.1 uF 10% 50v. In the link below refer to page 51-55 of the service manual and then also page 82 gives more detailed part numbers and values.

In my case (probably also in yours since SMD ceramic capacitors often go short when they die) the capacitor was the cause and not the syndrome. Voltages were OK on mine and the system worked with the amp board disconnected.

It did also work with the burned capacitor removed. Looks like the caps only have some high frequency filtering purposes.
Unfortunately I was unable to get the correct size and shape so I had to touch the neighboring cap with the replacement ceramic capacitor. No problem in this case because C3108 are C3109 are connected in series anyway.

System is fully usable again! Possibly as well as just with the faulty cap removed and cleaned up, but the caps are cheap and available so I highly recommend to replace. Be careful to use types that are capable of standing 100 V. Capacity needed is 2.2 F.

Reading through y'alls info and I was able to find my problem after opening up the case. I tried the cold reset to see what it would do and it lit up the Amp board like a Christmas tree. I haven't seen a board go up like that since 99 when i took A+ certification in high school as a collage course lol. Unfortunately I found 1 replacement board for $117.97 so I guess I'm in the market for a new unit.