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Sony Receiver STR - DA555ES Displays "protection fan" when turned on.
- Thread starter Rick79
- Start date
KrisBlueNZ
Sadly passed away in 2015
Use the meter on the 200Ω range when you're testing for a short circuit (which is what we're doing here).
With the probes not touching, it will show an overflow indication, something like "1 ." or "0L". That means open circuit.
With the probes touching each other, it will show a low number of ohms, probably less than 1.0. This is a short circuit.
When you measure across C960 I just want to know whether you get a short circuit reading or not. A number that steadily increases, and goes to an overflow indication, is not a short circuit.
If you are not measuring a short circuit across C960 then you need to check the two small capacitors near the bridge rectifier position, marked "103". Measure each one. They should both measure open circuit. If either of them measures short circuit, it's faulty and must be replaced.
Are you sure you measured the bridge rectifier correctly?
With the probes not touching, it will show an overflow indication, something like "1 ." or "0L". That means open circuit.
With the probes touching each other, it will show a low number of ohms, probably less than 1.0. This is a short circuit.
When you measure across C960 I just want to know whether you get a short circuit reading or not. A number that steadily increases, and goes to an overflow indication, is not a short circuit.
If you are not measuring a short circuit across C960 then you need to check the two small capacitors near the bridge rectifier position, marked "103". Measure each one. They should both measure open circuit. If either of them measures short circuit, it's faulty and must be replaced.
Are you sure you measured the bridge rectifier correctly?
KrisBlueNZ
Sadly passed away in 2015
OK, those indications are right. When the probes are open circuit, it shows "1 ." and when they're short circuited, it shows 1.6Ω. This is OK.
Does the multimeter show "1 ."? That's an open circuit indication and it means the capacitors are OK.
Does the multimeter show a number less than 2.0? That's a short circuit indication and it means the capacitors are faulty.
You need to be clear with your language otherwise you waste time.
What do you mean you "don't get any reading"?
Does the multimeter show "1 ."? That's an open circuit indication and it means the capacitors are OK.
Does the multimeter show a number less than 2.0? That's a short circuit indication and it means the capacitors are faulty.
You need to be clear with your language otherwise you waste time.
KrisBlueNZ
Sadly passed away in 2015
OK that's good. So they're OK.
When you measure across C960 do you measure a short circuit, or something else?
Also, can you measure for shorts on the 3.3V rail (probe points marked A) and 5V rail (probe points marked B). I've labelled the bridge rectifier holes so you can match the photo up to the board.
When you measure across C960 do you measure a short circuit, or something else?
Also, can you measure for shorts on the 3.3V rail (probe points marked A) and 5V rail (probe points marked B). I've labelled the bridge rectifier holes so you can match the photo up to the board.
KrisBlueNZ
Sadly passed away in 2015
OK, well, there doesn't appear to be a direct short.
There are three points marked above. They are the places where the 5V and 3.3V rails go when they've left the regulator. I would like you to disconnect all three connection points, refit the bridge rectifier, install a new fuse, reinstall the board, plug everything in, and power it all up, and see what happens.
The point marked "1" is the end of a link wire on the board. You need to desolder it, ideally using a solder sucker, and pull the link wire out from the other side so it's completely disconnected.
Points 2 and 3 are connections on a 5-pin wire-to-board connector with an orange shroud and a length of ribbon cable. It may be difficult to deal with. The best option is to desolder all five pins and remove the connector completely from the board. But you could also just desolder those two marked pins, and ensure that there are no solder whiskers connecting the pins to the board. Both of those pad-to-pin connections need to be reliably broken.
This test will be testing the power supply section (the bridge rectifier, the smoothing capacitor (C960), and both regulators), with the rest of the circuitry (on the 5V and 3.3V rails) disconnected. It's a quick way to isolate the problem. If the fuse still blows, there is still a problem in the power supply section. If it doesn't, there may be a short somewhere else in the unit.
There are three points marked above. They are the places where the 5V and 3.3V rails go when they've left the regulator. I would like you to disconnect all three connection points, refit the bridge rectifier, install a new fuse, reinstall the board, plug everything in, and power it all up, and see what happens.
The point marked "1" is the end of a link wire on the board. You need to desolder it, ideally using a solder sucker, and pull the link wire out from the other side so it's completely disconnected.
Points 2 and 3 are connections on a 5-pin wire-to-board connector with an orange shroud and a length of ribbon cable. It may be difficult to deal with. The best option is to desolder all five pins and remove the connector completely from the board. But you could also just desolder those two marked pins, and ensure that there are no solder whiskers connecting the pins to the board. Both of those pad-to-pin connections need to be reliably broken.
This test will be testing the power supply section (the bridge rectifier, the smoothing capacitor (C960), and both regulators), with the rest of the circuitry (on the 5V and 3.3V rails) disconnected. It's a quick way to isolate the problem. If the fuse still blows, there is still a problem in the power supply section. If it doesn't, there may be a short somewhere else in the unit.
KrisBlueNZ
Sadly passed away in 2015
Yes, you can desolder the whole 5-pin connector if you want.
KrisBlueNZ
Sadly passed away in 2015
OK, so the short is downstream of the regulators.
Unfortunately it's not a direct short so it may not show up with your multimeter. It's quickest to test by reconnecting those three points, one by one, and seeing when the fuse blows. I hope you have some spare fuses!
Try reconnecting the jumper wire marked "1" in post #28 and see what happens. If the fuse blows, the short is on that board, beyond that jumper.
If the fuse doesn't blow, refit the 5-pin connector and solder all pins except the one marked "3" - try to isolate it if you can - and try again. If the fuse blows, the fault is on one of the other boards.
If the fuse still doesn't blow, solder the pin marked "3" and check that the fuse blows now!
Unfortunately it's not a direct short so it may not show up with your multimeter. It's quickest to test by reconnecting those three points, one by one, and seeing when the fuse blows. I hope you have some spare fuses!
Try reconnecting the jumper wire marked "1" in post #28 and see what happens. If the fuse blows, the short is on that board, beyond that jumper.
If the fuse doesn't blow, refit the 5-pin connector and solder all pins except the one marked "3" - try to isolate it if you can - and try again. If the fuse blows, the fault is on one of the other boards.
If the fuse still doesn't blow, solder the pin marked "3" and check that the fuse blows now!
KrisBlueNZ
Sadly passed away in 2015
OK, that's the 3.3V rail. That wire goes to the "main board" but it isn't used there. It's used on the "Digital Board". It arrives at the board at the bottom of page 20 of the service manual, on pin "4-4". From there, it powers the Audio DSP, IC1112, and a lot of other ICs on that board.
Do you have a copy of the service manual? If not, you should get a copy from http://elektrotanya.com/sony_str-da333es_da555es.pdf/download.html. Underneath the preview is the text "This file is downloadable free of charge. ...processing". Wait 30 seconds and "...processing" turns into a link you can click to download it.
Can you trace the 3.3V rail through the Main Board and to the Digital Board, and take some photos of the Digital Board. Also, see if it's possible to disconnect just that wire (or lift a jumper wire, or something) on the Digital Board, because I want to check that the rail is the right voltage. That will be the next step.
Do you have a copy of the service manual? If not, you should get a copy from http://elektrotanya.com/sony_str-da333es_da555es.pdf/download.html. Underneath the preview is the text "This file is downloadable free of charge. ...processing". Wait 30 seconds and "...processing" turns into a link you can click to download it.
Can you trace the 3.3V rail through the Main Board and to the Digital Board, and take some photos of the Digital Board. Also, see if it's possible to disconnect just that wire (or lift a jumper wire, or something) on the Digital Board, because I want to check that the rail is the right voltage. That will be the next step.
Ok, i couldnt download the service manual, but heres the photo of the digital board.
For the pin you marked "3" i have that wire cut instead because i would have to take everything all apart again to solder it back on. I just tested it with the wire cut, and then tested it with the wires back connected.
For the pin you marked "3" i have that wire cut instead because i would have to take everything all apart again to solder it back on. I just tested it with the wire cut, and then tested it with the wires back connected.
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KrisBlueNZ
Sadly passed away in 2015
OK, what did you "test" when you cut the wire? Did you put in a new fuse and see whether it blew or not? Did it blow? If the short is on the digital board, which I think it is, then the fuse would not blow when that wire is cut.
We need to check that the 3.3V rail from the regulator is the right voltage, because it's possible that the regulator has failed and is sending too much voltage to the digital board. If that's the problem, components on the digital board could have been damaged. So let's hope that's not the problem.
With the wire to the digital board cut, and the fuse replaced, power up and measure the voltage across the 3.3V regulator's output. Those are the points marked "A" in the picture in post #26. You should get 3.3V ±0.1V.
We need to check that the 3.3V rail from the regulator is the right voltage, because it's possible that the regulator has failed and is sending too much voltage to the digital board. If that's the problem, components on the digital board could have been damaged. So let's hope that's not the problem.
With the wire to the digital board cut, and the fuse replaced, power up and measure the voltage across the 3.3V regulator's output. Those are the points marked "A" in the picture in post #26. You should get 3.3V ±0.1V.
Yes, I had put Ina new fuse and powered it up with the wire cut and the fuse didn't blow. The "protection fan" was no longer on display either as if the receiver was acting normal. Then I turned it off and reconnected the cut wire, I powered it up and the fuse blew.
Right now i just reinstalled the digital board and reconnected all the wires besides the cut wire. I put in a new fuse and I measured the voltage across the 3.3V regulator and got a 9.86V reading
Right now i just reinstalled the digital board and reconnected all the wires besides the cut wire. I put in a new fuse and I measured the voltage across the 3.3V regulator and got a 9.86V reading
KrisBlueNZ
Sadly passed away in 2015
Oh dear :-( Most likely, many of the ICs on the digital board are toast. You can try replacing the 3.3V regulator and reconnecting the wire, but don't hold your breath.
http://www.digikey.com/product-detail/en/BA033T/BA033T-ND/658206
http://www.digikey.com/product-detail/en/BA033T/BA033T-ND/658206
KrisBlueNZ
Sadly passed away in 2015
You'll know that devices are dead if the fuse still blows, or the regulator gets hot, or the unit doesn't work (or doesn't work properly).
The regulator might have failed because of overvoltage at its input from a power surge, but most likely it just failed internally. Semiconductors do that occasionally. Google bathtub curve for more information.
The regulator might have failed because of overvoltage at its input from a power surge, but most likely it just failed internally. Semiconductors do that occasionally. Google bathtub curve for more information.
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