Crow lps 2500 amplify,faulty light indicating and the output relay not switinching

This symptom is most likely due to RLY1 (protection relay) not coming on. The purpose of this relay is to give some time for the circuits to settle during power up to avoid a "pop" noise as well as to detect DC in the output that may cause damage to the speaker. If there is a fault condition, this relay may stay off so there will be no sound. Note that the LED indicator for auto on/off is not driven by this relay so that is why you get an indication of signal even though you have no output. If you don't hear the relay click on, this may be the problem. It may also click on and off again.

One quick thing to try is to have music playing into the unit before you power it on. Power it on for 1 second and then power off and see if you hear any output, even for a short time. This tells us that the speaker and amplifier may be OK, but the power supply is having problems.

You need a VOM to check the following: (all measurements are referenced to ground) (speaker does not need to be connected) (be careful of the mains supply voltages)
1. Check to make sure you have around 50Vdc at cathode of D10 (side with the painted line on the case of the diode). This is the power supply to the relay.
2. Check connector CN2 and make sure you have +/-15V. The center of the connector is ground and this is a 3 pin connector, so each side will be a rail voltage. If either voltage is not close to +15 or -15, the relay may not come on.
3. Check anode side of D9. This should be close to 0V if the unit is normal, and close to 50Vdc if the unit is in protect mode.

If the unit is in protect mode and 1 and 2 look normal, the power amplifier has DC and is most likely damaged and will need some expertise to repair. If all seems normal and there is no output, the speaker may be burnt out. You can put the VOM in ohmmeter mode at the lowest ohm setting and measure the resistance of the voice coil which should measure below 10 ohms and above 2 ohms. When connected to the meter, slightly push on the cone and you should see the measurement change value slightly indicating that the speaker is probably not at fault.

If 1 above is normal, but 2 is not, look up (on FIXYA) how to fix this model when it cuts out at high levels as this fix should also work. If after applying this fix, the rails are not the correct voltage, you may need to replace either of the regulators U14 or U15.

Trouble shooting is the only way to approach this problem, but is you stick with it, you should have enough information to pinpoint the problem which will lead to the correct fix. Good luck.

As your complaint post indicates, there is a malfunction to its power amplifier output. Proper checking should be done to this stage by anu well experienced service technicians. Most of the components in the section carries high current, and proper care should be given whe repair this stage. Power output section of your amp is faulty, It switches on first without any problem, but after stabilisation, outputs the power to speakers [relay click indicates that]; then detects some short and shuts OFF. Thie is happening now. Get it repaired by any experienced service pwersonnel have experience in serivcing Hi-Watt amps. OK.

hi,
Blinking of power indicator means the amplifier is in protection mode.First of all remove all the speaker connections from the amplifier. After that power the amplifier and check the protect show or not . if not, then any of the speaker is damaged. If then also it shows protect you have to check the amplifiers hardware.

AV receivers shows protect mode , when there is a hardware fault in side it. Its a warning that some thing is wrong.
Normally AV receivers show this when any of the output amplifier have some problem. There are seven amplifiers in this AV receiver. May occur when the output diver transistors of any of the amplifier become shorted. if the output transistor get shorted this will lead to flow of current through the speakers. To prevent this there is a protection circuit for each channels. One combined output of this protection circuit is connected to the system control. when the any of the output amplifier fails, the protection circuit detects it and switch of the speaker and sent data to the system control. when the system control get this data it will give a warning to the customer through display that PROTECT.
You have to check the amplifier.
For that you need digital multimeter,soledring iron screwdrivers etc
Open the amplifier , then power it on. connect the negative terminal of the multimeter any where in the chase( metal body of the amplifer). then connect the positive terminal to all the output transistors emitter pin one by one . the voltage should be bellow 0.5V. If any of the emitter of the transistor shows voltage more than 0.5V., then that amplifier stage is faulty. Remove the transistors and check it. if it is shot then replace with a new one.
after replacing the transistors do not power up the amplifier directly from the main. You have to put a bulb of 60 watts in serial.
You can do this easily remove the mains fuse. put the bulb in a holder. now you have to wire from the holder. connect one of it to the one end of the fuse holder and the other wire to the other end of the fuse holder. Why using a bulb is, if there is any further problem in the amplifier stage on which the transistors replaced, there is a possibility of the new transistor get damage. if we use a bulb in serial with its mains supply ,when any overload in the amplifier occur the bulb will drop the current, by lighting itself.
After connecting the bulb in serious power on the amplifier. watch the bulb. It should light for one or two second and go dim . if so check the display, is there is protect mode is on or not . if not and come back to normal operation ,then remove the power , remove the bulb insert fuse and check
connect the power and check.
If the bulb shows bright light then there is some component also faulty in the same amplifier. after removing the power you have to check again the amplifier stage of which the transistor is replaced, for any other faulty components.
ok

Checked your amplifier connection, it supposed to be like this, amplifier has 2 audio connectors RED is Right White is Left channel, connectors cable should be connect to audio output of the receiver/DVD/CD etc.. and the other end of the cable connect to the input of the amplifier. hope this help thanks

It can be a variety of reasons but I feel that your amplifier is shutting off after powering on. There is nothing that can be done from the outside but If you are familiar with basic electronics and can attempt to take a look I can try. Open the set after you have pulled off the power, then look into the set and tighten all the connectors and cords. Power on and see where the click comes and goes off. If the relay is not holding on then your protect circuit is shutting it off. Armed with a multimeter turn on the power and check if the main +B power is coming to the output stages.If there is momentary swithch on , then disconnect power and test the continuity in the output stages. If hsort open the leads to the output section and then power on. If the relay stays we have found the fault. you can go on to change the failed outputs. If however the outputs were tested ok, then your fault could be the relay or the protect circuit, Hold a rely for a moment to see if the amplifier powers on, if so check the relay drive transistor , the biasing to the stage. Try this out and I hope my advice helps. Good day

Disconnect the speakers and try it again. Come back with results. It's trying to tell you there's a short on a speaker output.

probably blew the amps or the pre amp section

make sure your speakers are connected correctly if subs and are inside the box then check connections also at times the rca at the back of the head unit can disconnect. if power light is on then error is either speakers not connected correctly, rca faulty or not connected or speaker output on amp is blown

It sounds like the output transistors have failed. Disconnect everything from the amp except for the B+, ground and remote and turn the amp on. If it goes into protect, the amp is in need of repair. If you want to repair it yourself, email power acoustic for the schematic.