I have a defective 2SC2458GR or 2SC1740S-R - its the Q921 in the power supply board in the 12v citcuit of an onkyo TX-DS555. I have 12v ac from the transformer, but not 12V at the coil of the electromagnetic reed relay. This is the only component in the middle.
Anyway its a small signal NPN transistor. Can I substitute any other small signal npn transistor in its place ? like this radioshack - 2N3904 NPN Small Signal Transistor ?
Thanks.
Srinath.
Anyway its a small signal NPN transistor. Can I substitute any other small signal npn transistor in its place ? like this radioshack - 2N3904 NPN Small Signal Transistor ?
Thanks.
Srinath.
If the issue is to go with something readily available, then yes, you can go
with 2N3904 - nothing bad will happen. The only issue for you will be to twist
3904 legs a little.
Your two original parts have ECB pinout, and 3904 has EBC pinout.
Transistor is used here as a switch, and plenty of TO-92 parts with sufficiently
low saturation resistance, and beta of 180-390 will do.
And, you have to check D925 to make sure it gives you DMM diode reading
(without transistor in place) ~0.6V.
with 2N3904 - nothing bad will happen. The only issue for you will be to twist
3904 legs a little.
Your two original parts have ECB pinout, and 3904 has EBC pinout.
Transistor is used here as a switch, and plenty of TO-92 parts with sufficiently
low saturation resistance, and beta of 180-390 will do.
And, you have to check D925 to make sure it gives you DMM diode reading
(without transistor in place) ~0.6V.
Wonderful. I will test the D925 diode - its part of that diode bridge right - I tested it yesterday they all seemed to have that 1 way thing right, however 2 tested .6 ohm and 2 tested 1.3 if I recall. I will test it without the transistor though, obviously once I saw the transistor could be bad and the diodes are less likely, I pulled it and started celebrating ... yea OK I am clueless.
Thanks.
Srinath.
Thanks.
Srinath.
Well, this what I am looking at.
You will need that D925 installed in any case. Look at your board.
<<make sure it gives you DMM diode reading (without transistor in place) ~0.6V.>> You may need to unsolder and pull one end of D925 to avoid distorting your diode measurment with the coil resistance in parallel.
You will need that D925 installed in any case. Look at your board.
<<make sure it gives you DMM diode reading (without transistor in place) ~0.6V.>> You may need to unsolder and pull one end of D925 to avoid distorting your diode measurment with the coil resistance in parallel.
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Schematic ?
What schematic is that, on my amp from q921 it goes onto the power pin of Q702 FL driver. However that d925 is there on my power supply board, so well, looks like your schematic is correct and whatever I pulled up as the TX-DS555 schematic isn't.
Thanks much, I will get that diode out and test it, and I have a few of those diodes I think, my 2325 has those that went. I got a pack of 10 or so.
Thanks.
Srinath.
What schematic is that, on my amp from q921 it goes onto the power pin of Q702 FL driver. However that d925 is there on my power supply board, so well, looks like your schematic is correct and whatever I pulled up as the TX-DS555 schematic isn't.
Thanks much, I will get that diode out and test it, and I have a few of those diodes I think, my 2325 has those that went. I got a pack of 10 or so.
Thanks.
Srinath.
Oooo would 13V @ that top pin in the "to NAAR-6332" indicate the transistor works and no 12V @RL901 indicate that diode is what is bad.
See I am a bit clueless, I have some solderign and desoldering ability and of course I can read a schematic but I dunno what each component does.
Thanks.
Srinath.
See I am a bit clueless, I have some solderign and desoldering ability and of course I can read a schematic but I dunno what each component does.
Thanks.
Srinath.
I swapped that transistor and dont have anything change. Same as before, the relay has no voltage and the receiver isn't doing anything like it was before.
So this is what the receiver is doing.
It wont light the standbby light, atleast not that I can see, it wont power up, and for all intents and purposes its dead. Except, it will run the fan for ~3 seconds when you plug it in (not when you power it on) and there is a very dim lighting of the digital read out - you can make out what it says but you unplug it it goes off and plug it in and it lights up very very faintly, maybe all the led's are comming on.
So what could be happening.
I received this in the same dead condition I have it in now. So I cant say what killed it.
Thanks guys.
Srinath.
So this is what the receiver is doing.
It wont light the standbby light, atleast not that I can see, it wont power up, and for all intents and purposes its dead. Except, it will run the fan for ~3 seconds when you plug it in (not when you power it on) and there is a very dim lighting of the digital read out - you can make out what it says but you unplug it it goes off and plug it in and it lights up very very faintly, maybe all the led's are comming on.
So what could be happening.
I received this in the same dead condition I have it in now. So I cant say what killed it.
Thanks guys.
Srinath.
What exactly does that relay do ? I have a yamaha rx-v795 that also has that relay clicking on then off in a fraction of second. I had a denon 3802 that had the same thing happen, and I removed it and re fitted it and it works.
So I am a bit stumped, what exactly does it do.
Thanks.
Srinath.
So I am a bit stumped, what exactly does it do.
Thanks.
Srinath.
Testing this amp
Thanks for this diagram, I am testing my power board with this as reference.
The 3 connector that is going to NAR-6332, that has the +13v dc I am supposed to have.
However there is no voltage @ the coils of the relay RL-901 and I have shorted the prongs, so its like the relay is connected.
The amp still has nothing lighting up, and its not even going to stand by when I plug it in.
What could be wrong ?
Thanks.
Srinath.
Thanks for this diagram, I am testing my power board with this as reference.
The 3 connector that is going to NAR-6332, that has the +13v dc I am supposed to have.
However there is no voltage @ the coils of the relay RL-901 and I have shorted the prongs, so its like the relay is connected.
The amp still has nothing lighting up, and its not even going to stand by when I plug it in.
What could be wrong ?
Thanks.
Srinath.
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