memphis 1500d

[timwebb]

ok i got another 1500d i just rebuild the power supply and these two resistors started smoking.

 

[Perry Babin]

Those probably feed the voltage regulators. Are the regulators or any of the capacitors connected to the regulators shorted?

 

[timwebb]

ok i changed all the capacitors and the resistors still over heat.

 

[Perry Babin]

Do they overheat if you remove the regulators from the circuit?

 

[timwebb]

no they stay cool.

 

[Perry Babin]

With the regulators out of the circuit, do you read anything near 0 ohms when you measure the resistance from the ground pad for the regulator (pin 2 for the 78xx and pin 1 for the 79xx) to either of the other pads?

 

[timwebb]

yes it reads 0 ohms

 

[Perry Babin]

Which one?

Have you disconnected the capacitor across the shorted terminals to see if it's shorted?

 

[timwebb]

i got my hands on one of these.anyone ever use one?

 

[Hectorscaraudio]

I have that Z meter to it works grate cause you can be sure of the cap under its rated voltage (up to 500 volts hell ya ) and the inductor meter as well for custom audio passive crossovers inductors I have alot of copper alot haha and the price on inductors WOW Ill make my own !! How much did you paid for it ? Oh I also have the owners manual and circut manual Sencore LC53 in pdf file if you need it i can email it to you .

 

[timwebb]

i got it free from my old school all it needed was a fuse.i dont have the manual to it.

 

[timwebb]

how does the leakage works?

 

[Perry Babin]

That's electrical leakage (DC) across the dielectric. You may be able to get a copy of the manual here:
Sencore LC53, manual

 

[timwebb]

this one is the problem when i put this one in it causes those resistors to over heat. the cap is a 10uf 25v.its connected to the transformer.should i look at the driver card?

 

[Perry Babin]

If those are in series with the transformer, they're not likely the problem. Removing them simply disconnected the transformer from the rest of the circuit. If it's a faulty capacitor, it's likely to have both legs connected directly to the regulator.

 

[timwebb]

i took out all of the capacitors and left those still got the same problem.Those two caps run to those resistors and they run to those diodes. i took the 79 out it ran like it should.could those ceramic capacitors be a problem too?

 

[Perry Babin]

The ceramic capacitors can fail. The cylindrical types tend to fail much more often than the disc type.

Is one of the diodes shorted?

 

[timwebb]

i did a diode check but i couldn't get a solid reading.the reading keep going up slowly.and when i reverse the probes i get a reading for a few seconds.

 

[Perry Babin]

Go back to posts 6, 7 and 8. Answer the question in #8.

 

[timwebb]

ok i got it.found the short.