i did not have the sub or rca's plugged in when i wired the amp up. But are you saying once ive plugged these in the power light should stop flashing? sorry if i sound dumb :/
What is the DC voltage across the B+ and ground terminals of the amp when the power LED is flashing red?
Are the other LEDs on solid or flashing?
Are the other LEDs on solid or flashing?
Perry I happen to have 2 of these amps. 1 working and one not. If you need any info. The non working one needs a 2SA1220 Do you have one?
I don't know this amp, but some amps will do that if no RCA is connected.
Check your power to the amp to be sure it is getting enough voltage first, as Perry suggests.
perry - ill check the voltage tomorrow and update you. the other two leds were solid, they were lit up green. just the power led was flashing red.
If you had no RCAs plugged in, the LEDs should have indicated that the shield was floating. Is it possible that the LED board is installed rotated 180° from the way it should be?
the led board was seperate to the main board so i had left it screwed in, there is a plug that connects it to the main board and that only slots in one way round. ill do the voltage test on the B+ and Neg on the amp and see what voltage i am getting and update you. 🙂
😡🙁
bad news... again! i just wired it up again to test the voltage, it was showing 9v's only at the amp but was showing more than 10v at the battery on the meter 😕
but.... the bad news is... the IRFZ48n's on the input side have blown again!!! i dont know how this has happened, it may have shorted when i had the meter probes on the amp terminals when it was, but whatever stupid mistake i did has blown the ones i replaced! Ive checked them with the meter and they are all showing 0 ohms between legs 2 and 3 and ive checked the other side on the same board and they seem to be showing 0 ohms between legs 2 and 3 aswell. Does that mean all 12 need changing on that board? 🙁 i feel like throwing it in the bin!
bad news... again! i just wired it up again to test the voltage, it was showing 9v's only at the amp but was showing more than 10v at the battery on the meter 😕
but.... the bad news is... the IRFZ48n's on the input side have blown again!!! i dont know how this has happened, it may have shorted when i had the meter probes on the amp terminals when it was, but whatever stupid mistake i did has blown the ones i replaced! Ive checked them with the meter and they are all showing 0 ohms between legs 2 and 3 and ive checked the other side on the same board and they seem to be showing 0 ohms between legs 2 and 3 aswell. Does that mean all 12 need changing on that board? 🙁 i feel like throwing it in the bin!
oh i also forgot.... when i did turn the amp on the outside... where the changed mosfets were... i could feel it getting really hot :S
You probably only need to replace the ones that you previously replaced. The short is from B+ to ground. The other FETs are also connected to those points so they also appear to be shorted from 2-3. When you remove the shorted ones from the circuit, the other side will no longer appear shorted.
ahh right okay well ill have a few spares then lol. any reason why the amp became so hot though? ive just checked the service manual and the first section is on adjusting the power supply voltage and idle adjustment. Wanted to ask... to set these would i need to have the amp connected to the power supply first? also do you think i was getting 9v at the amp because of the 8 gauge wiring? i know i keep going on about the wire thickness but its the only thing i can think off atm that could cause the voltage drop?
When an amp shorts it will draw power, until a fuse blows. Yes the voltage will drop down unless you have large wire and lots of power to give it. That is why its a good idea to run a 10-15A fuse when you test/work on a broken amp. It can keep it from wasting more (or new) parts inside if there are still other things wrong with it. You don't need to let it have much power until you think it is repaired and want to test it under load. You don't need a large wire to supply 10A, the amp is defective if it needs power while not making loud music. It can get hot if shorted or the fets are turned on and not supposed to be, and then they blow up. If you are lucky the small fuse blows first. If it draws your 12v supply down to ~10v or less the amp will show a power fault/protection LED if it has that feature in the protection circuitry, and this amp appears to.
However if it blew again you need to investigate what happened, or figure out how to run it without letting it blow so you can work on it. Just trying to help answer your questions.
However if it blew again you need to investigate what happened, or figure out how to run it without letting it blow so you can work on it. Just trying to help answer your questions.
thanks jol that is helpful. so should i try to re adjust the power supply voltage and idle adjustment. i think there are potentionmeters to turn, but as in previous post was wondering would i need to have the amp turned on to get a reading from the meter in dc mode? i can see this turning out to be a loooooong process to get this to work 🙁
Page 5 of the service manual tells you which test points to use and which pots to adjust. Do you have the service manual?
yea perry you sent it to me, i shall check it out again, but its just that the multimeter would not show anything on DC mode if there is not any power going into it? so just wanted to know if i should hook it up before adjusting them. thanks 🙂
The amp has to be fully powered up to make the adjustments.
Have all transistors clamped to the heatsink (or at least to the aluminum risers) when making the adjustments.
Have all transistors clamped to the heatsink (or at least to the aluminum risers) when making the adjustments.
im going to sound dumb now....on page on the service manual... it says what the meter should read when making the adjustments. but im not sure how i would read these figures with the symbols etc. im using an analogue multimeter... yes its abit oldskool lol. thanks
It's going to be a bit tougher to set these with an analog meter.
For now, set the bias post fully counter-clockwise.
For the positive rail, set your meter to the lowest range that can read 50v DC. Place the black meter probe on a non-bridging speaker terminal. Place the red probe on the center leg of Q504. Adjust VR601 so that you read 49v.
For the negative rail, place the RED meter probe on a non-bridging speaker terminal. Place the BLACK probe on the center leg of Q512. Adjust VR602 so that you read 49v.
If you place your black probe on the center leg of Q512 and the red probe on the center leg of Q504, you should read 98v DC.
For now, set the bias post fully counter-clockwise.
For the positive rail, set your meter to the lowest range that can read 50v DC. Place the black meter probe on a non-bridging speaker terminal. Place the red probe on the center leg of Q504. Adjust VR601 so that you read 49v.
For the negative rail, place the RED meter probe on a non-bridging speaker terminal. Place the BLACK probe on the center leg of Q512. Adjust VR602 so that you read 49v.
If you place your black probe on the center leg of Q512 and the red probe on the center leg of Q504, you should read 98v DC.
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