crown xli 3500.NTC Thermistor

[spiros.p]

i have amp that sometimes on startup trip the 16A cirquit breaker.I see on distro amp meter over 20A to 30A current .the amp use the 10d20 ntc and relay. can i connect two ntc 10d20 in series (not paralel) to avoid this shutdown? or i have to keep the ntc s resistance to 10R?and use instead two 20R ntc s?or use one bigger amperage 10R ntc? thanks for any help.

[stj]

Re: Ntc

it sounds more like the relay circuit is bad.
remove the ntc and see if the amp still starts

[SMDFlea]

Re: Ntc

i have amp that sometimes on startup trip the 16A cirquit breaker.I see on distro amp meter over 20A to 30A current .the amp use the 10d20 ntc and relay. can i connect two ntc 10d20 in series (not paralel) to avoid this shutdown? or i have to keep the ntc s resistance to 10R?and use instead two 20R ntc s?or use one bigger amperage 10R ntc? thanks for any help.

Post the amp model number please...

[spiros.p]

Re: Ntc

i have all ready replace the ntc with same type .nothing change and instal again the original part.the amp is crown xli 3500.before replace i have measured the original ntc and looks ok i only change to be sure.

[R_J]

Re: crown xli 3500.NTC Thermistor

Check if the power in delay relay is operating correctly, maybe the relay contacts are sticking. Is the 16amp circuit breaker weak? I would think an amp this size would require a 20 amp circuit

[redwire]

Re: crown xli 3500.NTC Thermistor

Assuming the 24VDC rail has come up part ~13V, there is the on/off switch opto-coupler and time delay, whereby the relay will pull in.
Crown XLI3500 schematic but I see some versions have SMPS.

[spiros.p]

Re: crown xli 3500.NTC Thermistor

the psu is linear with massive traffo.i think to the relay have problem and sometimes sticking. the fuse breaker is ok.one time a week a go is triping the 25A mains three fase breaker.is not happen all the time one's in ten times when i power on.that's strange.

[redwire]

Re: crown xli 3500.NTC Thermistor

What is happening is the power transformer has residual magentism when you turn OFF the amplifier.
It depends upon where in the mains sine-wave you switched it off, but the core gets some magnetism.
If you switch ON power at the same sine-wave polarity, I think the transformer saturates and causes very high inrush current.

You're not supposed to have this problem if the NTC and relay are working properly.

[spiros.p]

Re: crown xli 3500.NTC Thermistor

bad news guys after desolder and instal the optocoupler and relay to measure and check is booth good the amp goes in protect mode the fans at full power and front red leds light.no clicks and other action from amp.i keep only seconds on just to measure if low voltage is present and close because the ntc gets hot.��opto is ok with variable volt input and measure the resistance changing.the relay clicks ok with 18v and close contact on the other side.i think i have sean the low voltage for soft start supply 13v is not ok.on manual said 24v anyway i check again.under the main board i measure all the smd components for delay start and found nothing suspisious.i miss only the Q64.the Q63 is on board together with D92 zener.is other version the schematic from my amp?thanks again for any info .

[spiros.p]

Re: crown xli 3500.NTC Thermistor

ok i check i have 13v and 10v to delay

[spiros.p]

Re: crown xli 3500.NTC Thermistor

[spiros.p]

Re: crown xli 3500.NTC Thermistor

found broken smd darlington transistor on relay supply.wait for replace part and see if it works

[stj]

Re: crown xli 3500.NTC Thermistor

was going to say, if the relay clicks on and the contacts are o.k. then the ntc should cool down - because it's bypassed.

[spiros.p]

Re: crown xli 3500.NTC Thermistor

so the supply darlington trans is ok the problem was bad solder on smd's.i descover that when i want to move a little the amp and heard the relays clicking.resolder all part's on soft start supply side and relays click ok.so far so good.problem keep going now on jfet.the amp starts but the output protection is on found a jfet short.don't know what causes jfet to fail.i desided to resolder the whole smd part's of the amp.and now wait again for the new jfet part to replace.will see what comes next.

[spiros.p]

Re: crown xli 3500.NTC Thermistor

hi change jfet change all op amps now i have everywhere - and + 15v like on manual but protect still on.i have check 10 times all parts on output all diodes and resistors i get mad.the only thing on power in delay i have 13v instead of 24v says on manual.there is only q63 and on manual is q63 and q64.

[spiros.p]

Re: crown xli 3500.NTC Thermistor

just for future reference the amp is repaired.the Q63 was leaky i have desolder one's last week and measure and looks ok and solder again thats confuse me and search the whole cirquit for fault.yesterday i desided to change the Q63 LMBT5551 because the 13.4volt don't look good on manual say 24v.solder one TO92 2n5551 the original SMD part is not available here.give power and everything clicks.the only negative the amp don't power of when push the power button.i suspect there is problem with the 2n5551 is bit diffrent i instal one other 4 pole rocker switch and now the amp powers of.no more inrush current on start up.