Crown CE 2000 Relay Constantly Clicking

Thread Starter

jasonsmith559

Joined Oct 30, 2016
14
I have a Crown CE2000 amplifier with a relay constantly clicking. The relay that is clicking is K100 which is on channel 1 of the amp. The timing of the clicking slows down the longer I leave the amp on. Channel 2 seems to work fine. I have tested the transistors to make sure they are not shorted. Also I am testing this without any speakers plugged in. Does anyone know what would cause this amp to have this type of issue?

Thanks,
Jason Smith
 

drc_567

Joined Dec 29, 2008
1,156
... One possibility is that the transistor Q129 is weakening and causing the relay k100 to click. So to check this you could see if that transistor has at least 0.6 volts between the emitter and base, indicating that it is 'on'. That would be between terminals 1 and 2. Even better, desolder it and see if it seems to be working properly. ... Did not see any other relays on the available schematic, so that must be the one causing the problem. The transistor is listed as an NPN 3904 type. ... That seems to be the most likely scenario at the present time. ... Curious to know the base to emitter voltage though.
... Second idea ... when the relay clicking begins, use a heat gun or even a hair dryer to add heat to Q129. If the clicking shows any change related to the heat flux, you have found the problem.
 
Last edited:

Thread Starter

jasonsmith559

Joined Oct 30, 2016
14
Thanks for the suggestions. I replaced Q129 and the issue still persisted. The version of the board I have is actually 127452-4. I do have the schematic and it is a bit different than the version posted. I am seeing pulsing voltage that matches what I hear from the relay on Thermal 2, mute 1 and the short areas that are labeled on the schematic. Not for sure what would cause this. I do not see this issue on the channel 2 side. I am thinking possibly either an open resistor I have missed or a bad op amp? Any further suggestions?
 

Thread Starter

jasonsmith559

Joined Oct 30, 2016
14
Thanks for the help. I tested both of them with my fluke 115 and they showed good. I went ahead and replaced c121 and tested 123 by applying about 15 volts to it which it held the charge. I powered up the amp and it was still doing the same thing. Any other ideas? Again thanks to everyone for helping me out on this.
 

dl324

Joined Mar 30, 2015
16,846
Could you post the entire schematic?

What are the voltages on the outputs of comparators A, B, and C of U104?
 

bertus

Joined Apr 5, 2008
22,270
Hello,

There are several conditions that will activate the relais:

CE2000_fault_conditions.jpg

CE2000_output_relays_muting.jpg

So you can check sevaral things that are related to the relais.

Bertus
 

Dodgydave

Joined Jun 22, 2012
11,285
Measure pins 4,6,8 of Ic U104, any of these pins going high will turn the relay off, they each monitor different items of the amplifier.
 
Last edited:

Thread Starter

jasonsmith559

Joined Oct 30, 2016
14
I do not have the lm339 available to build that external circuit. I measured the voltages on 4, 6, and 8. On pins 4 and 6 I see the same pulsing type of input as what was shown on the scope. On pin 6 I measured 2.3 volts. I have that same voltage value on pin 6 of U204 for channel 2. The issue seems to be whatever is causing this pulsing input. Not sure where that is coming from. I also made sure there is not dc voltage on either output which there is not.
 

Thread Starter

jasonsmith559

Joined Oct 30, 2016
14
I tested those inputs and outputs and they are stable. I am wondering what could have failed to cause an oscillation. Would you have any idea what component would have failed that could cause the comparator to turn into a pulse generator or oscillator? Could the comparator be failing causing this issue? I did use a smd desolder station to swap u104 and u204. The pulsing issue disappeared for a while and the amp actually powered up normally. However after some time, I would assume due to cool down k100 starting clicking again.
 
Top