Yea I dont believe I measured voltage @ FC454. I will need to get ~3.4v ac there right ? I will post tomorow, I have it apart right now. Will refit it and get that reading.
Cool.
Srinath.
Cool.
Srinath.
Hi,
It is possible that the voltage it can be 12 volt AC. They feed the relay coils but I do not know what it is the voltage of the relay coils. That it is why we need the fuse voltage so we have an idea of the voltage.
It is possible that the voltage it can be 12 volt AC. They feed the relay coils but I do not know what it is the voltage of the relay coils. That it is why we need the fuse voltage so we have an idea of the voltage.
I will measure it in a bit sir.
I have powered it up unassembled - the way it is right now, so might as well do that to get this reading.
I will do it in a few and get back to you.
Cool.
Srinath.
I have powered it up unassembled - the way it is right now, so might as well do that to get this reading.
I will do it in a few and get back to you.
Cool.
Srinath.
Its reading .4 volt ac @ the fuse. Yea its dead.
Now what else can cause that to happen other than a dead trafo ? I guess I am pulling that board off today and checking it.
I do have 120+v going into that from the power cord. I will check for blown up stuff, else I guess I need that little trafo. How to find out what its ratings are ?
Cool.
Srinath.
Now what else can cause that to happen other than a dead trafo ? I guess I am pulling that board off today and checking it.
I do have 120+v going into that from the power cord. I will check for blown up stuff, else I guess I need that little trafo. How to find out what its ratings are ?
Cool.
Srinath.
Hi,
In one of the thread you mentioned that the transformer it was getting hot. Does still get hot? Just in case remove the fuse F453 and read the voltage and see if still read zero. Something it is not right. You post that pin 4 has 5.5 volt. That voltage it is coming from the transformer unless the micro it is feeding it back.
In one of the thread you mentioned that the transformer it was getting hot. Does still get hot? Just in case remove the fuse F453 and read the voltage and see if still read zero. Something it is not right. You post that pin 4 has 5.5 volt. That voltage it is coming from the transformer unless the micro it is feeding it back.
13.3 volts ac without the fuse in. And the trafo dont get warm, of course the fuse being in, makes it warm real quick and ... man you are freaking brilliant. Trafo is fine, I got a bleeding short somewhere ... OK more pouring over the schematic, and no damn powering it up till the short if found and fixed ... I'm a bit slow, but I know better than to power up a known short in the amp.
Cool.
Srinath.
Cool.
Srinath.
Hi,
That it is good news. Now read the resistance after the other side of the fuse for Low resistance. Low resistance mean something it is loading the voltage. Did you check those 1N4003 diodes for short?
That it is good news. Now read the resistance after the other side of the fuse for Low resistance. Low resistance mean something it is loading the voltage. Did you check those 1N4003 diodes for short?
I have not tested them yet, but of course I am going to now.
I had too many interrutions, like the grocery run and friend of mine showed up with a Old 40lb magnavox cd player that wasn't reading disks. Yea had a tda1540 dac, but not reading disk.
Cool.
Srinath.
I had too many interrutions, like the grocery run and friend of mine showed up with a Old 40lb magnavox cd player that wasn't reading disks. Yea had a tda1540 dac, but not reading disk.
Cool.
Srinath.
I managed to get all the 10 diodes on that board checked, and they all tested good.
I also pulled the connections from that board and powering it up, and none of the connections made any difference to the voltage @ that fuse.
So the short problem is in that board.
Cool.
Srinath.
I also pulled the connections from that board and powering it up, and none of the connections made any difference to the voltage @ that fuse.
So the short problem is in that board.
Cool.
Srinath.
OK by process of elimination - I think -
The problem has to be in D453, r453, c465, r454, or d458uz5v1.
Why ?
I got 5.5v in pin 4, fed by the other side of the rectifier diode bridge, and that is regulated by the 7806 to 6v I believe.
The d453 etc is in the line straight off the fuse.
I will yank that out and see what it does to the voltage - or I may pull d458 first since the short is to ground.
Maybe also I need to look for a solder bridge, though the solder was all stock factory in that board.
Anyway your ideas welcome too.
Cool.
Srinath.
The problem has to be in D453, r453, c465, r454, or d458uz5v1.
Why ?
I got 5.5v in pin 4, fed by the other side of the rectifier diode bridge, and that is regulated by the 7806 to 6v I believe.
The d453 etc is in the line straight off the fuse.
I will yank that out and see what it does to the voltage - or I may pull d458 first since the short is to ground.
Maybe also I need to look for a solder bridge, though the solder was all stock factory in that board.
Anyway your ideas welcome too.
Cool.
Srinath.
I'll pull d458 out and see if the voltage @ pin 4 gets back to 6v dc.
If not, the next one would be the r454 followed by c465.
I think one if those has shorted to ground and got the voltage out from 7806 transistor to not get to 6v.
Cool.
Srinath.
If not, the next one would be the r454 followed by c465.
I think one if those has shorted to ground and got the voltage out from 7806 transistor to not get to 6v.
Cool.
Srinath.
Do noy pull out any zeners from the circuit e.g. d458. U will damage the circuits.
Gajanan Phadte
Gajanan Phadte
Hi,
My advice is now to check for a short or a low resistance value to ground using the ohmmeter. I would check the resistance to ground at the point between R455 and C466. The D455 and D457 will isolate the reading from the transformer. Check the resistance and post the reading. D453 it is not the problem because it is follow by R453 4700 ohms resistor in series too high to loaded the PS. At this point you have to be careful because the IC451 feed voltage to the micro.
My advice is now to check for a short or a low resistance value to ground using the ohmmeter. I would check the resistance to ground at the point between R455 and C466. The D455 and D457 will isolate the reading from the transformer. Check the resistance and post the reading. D453 it is not the problem because it is follow by R453 4700 ohms resistor in series too high to loaded the PS. At this point you have to be careful because the IC451 feed voltage to the micro.
Tauro0221: The r455-c466 junction to ground flashed a 120 ohm or so and went back to open. Sort of like a capacitor would.
Gmphadte: How would I damage it ? from heat ? I anyway would replace it with a new one. Desoldering takes more heat than soldering.
Cool.
Srinath.
Gmphadte: How would I damage it ? from heat ? I anyway would replace it with a new one. Desoldering takes more heat than soldering.
Cool.
Srinath.
No need for replacing the zener. U will damage if u remove and power on the circuit.
If u have voltage at pin 4 (5.5V, maybe 5.8V without load) and pin 2(5.1V), then look for the other circuit where from pin 1 returns. This pin 1 will be high(some + voltage near 5V) only when the power good detection and reset circuit works, and then only the relays will remain on.
Gajanan Phadte
If u have voltage at pin 4 (5.5V, maybe 5.8V without load) and pin 2(5.1V), then look for the other circuit where from pin 1 returns. This pin 1 will be high(some + voltage near 5V) only when the power good detection and reset circuit works, and then only the relays will remain on.
Gajanan Phadte
Last edited:
Hi,
That means that there are no shorts. We need to go back. Check the resistance for the IC451 output pin to ground. Remove fuse F453 and check resistance from the fuse load side to ground and from T451 pin 2 to ground. Also check resistance across capacitor C462. Post reading.
That means that there are no shorts. We need to go back. Check the resistance for the IC451 output pin to ground. Remove fuse F453 and check resistance from the fuse load side to ground and from T451 pin 2 to ground. Also check resistance across capacitor C462. Post reading.
Tauro0221: I will get that checked tonight.
Gmphadte: I got these readings @ cp458 - Pin 1 was 0 vdc, 2 was 2.82 vdc, and 4 was like 5.5 vdc. Now I got that reading without anything connected to 458.
Ok If removing zener diode and powering up is bad, then I could replace it with a new one and try powering it up ?
Anyway I'll let you guys - Tauro in particular 🙂, tell me what to do, you have been great. What a learning experience this has been.
Cool.
Srinath.
Gmphadte: I got these readings @ cp458 - Pin 1 was 0 vdc, 2 was 2.82 vdc, and 4 was like 5.5 vdc. Now I got that reading without anything connected to 458.
Ok If removing zener diode and powering up is bad, then I could replace it with a new one and try powering it up ?
Anyway I'll let you guys - Tauro in particular 🙂, tell me what to do, you have been great. What a learning experience this has been.
Cool.
Srinath.
Hi,
just in case one more resistance check. With the fuse F453 remove check the resistance of the transformer winding between pin 1 and 2. Post the reading.
just in case one more resistance check. With the fuse F453 remove check the resistance of the transformer winding between pin 1 and 2. Post the reading.
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