I will check those capsIf only one is conducting this will give a low voltage.
If the rectifiers are OK it is a possibility the Electrolytic is open?
Max.
The output of d 333 is -72v
The output of D332 is +69
I will check those capsIf only one is conducting this will give a low voltage.
If the rectifiers are OK it is a possibility the Electrolytic is open?
Max.
Electrolytics check out, both close to 470uf.If only one is conducting this will give a low voltage.
If the rectifiers are OK it is a possibility the Electrolytic is open?
Max.
That is R340 and 341. I have checked them and they are spot on in terms of their value. Not sure they effect the voltages we are supposed to get at C335/336?Do I see a resistor between the output and the line with 85 volts noted on it? This would imply that it is under load and the voltage would be lower because of the resistor.
A DMM diode check function is good for checking the forward volt drop of a diode - for reverse checking its best to use the highest Ohms range, with normal diodes any leakage is a fail.Hey Max ...
The Fluke does have a diode testing setting ...
I just checked both full wave rectifiers again, voltage drops look normal in forward position (as recorded above), no continuity the other way (when leads are reversed) on either side of each unit. I am not sure what you mean by "open".
OK, can do. Presume these will have to be pulled, and that cannot be done in circuit??A DMM diode check function is good for checking the forward volt drop of a diode - for reverse checking its best to use the highest Ohms range, with normal diodes any leakage is a fail.
There is an exception to that statement - Schottky-barrier diodes show some leakage as normal, they can be identified by a Vf of 0.2V or less. You probably won't find any of those in a mains frequency rectifier anyway.
On the diode setting both show to be good ... no continuity when the leads are reversed.I don't think you will find they are that abnormal, I have measured stud diodes and have got inconclusive readings with the ohm's range, what does the diode range show?
Max.
The D333 pair have their anodes connected together as the -ve rectified point, D332 have their cathodes connected for the +ve rectified point, the opposite end of each pair is an AC voltage.The two inside contacts are marked for D333 and the two outside contacts for D332.
I am wondering what the significance is of these points, as there is no voltage stated.
I get no voltage on any of the inside contacts of either diode, only on the outer contacts of both.
I am wondering if that means there is an issue with one of them??
Voltages recorded above are measured from the outside contacts of both.
The print show a single secondary (apart from the lamp pair) with 5 taps for four supplies.You really need to decide if it is dual secondary or centre tapped secondaries before throwing the transformer out.
Hey Max,The D333 pair have their anodes connected together as the -ve rectified point, D332 have their cathodes connected for the +ve rectified point, the opposite end of each pair is an AC voltage.
You have checked the transformer output and it appears OK, so the next step is to connect the rectifiers and if necessary remove any load just a suitable voltage rated electrolytic capacitor, its not critical, from common to the cathode or anode pair.
And see if there is any anomaly, if the load is disconnected the voltage may be higher than shown on the print.
Incidentally I assume you are trouble shooting with the 10 pin socket/plug on the left removed?
Max.
It would be unusual for a winding to increase in voltage if there is a fault just in that winding.
If a couple of turns got shorted then I would expect the output voltage to decrease.
I would disconnect the transformer from the circuit and check it for resistance in each winding and compare the two 60VAC windings.
You could then power up the transformer and read off the various voltages to see if they are correct.
You really need to decide if it is dual secondary or centre tapped secondaries before throwing the transformer out if you think the two 60VAX windings are shorted.
Nothing jumps out as being wrong.
Max.
by Duane Benson
by Duane Benson
by Duane Benson
by Jake Hertz