Crown Xti 1000 - No power

[R_J]

Re: Crown Xti 1000 - No power

You would be better off checking the voltage on C45 to see if you are getting +30 volts.
The voltage on D26 will be misleading because it is also supplied by VK_START.

Their a fate tapping noise. would this be k1 trying to switch on?

maybe? the way to find out is to measure the voltage on the coil.

[Amraks]

Re: Crown Xti 1000 - No power

I am getting voltage at D26 and its 21v to 30v

Their a fate tapping noise. would this be k1 trying to switch on?

[R_J]

Re: Crown Xti 1000 - No power

K1 is a relay. It is there to bypass the RT6 thermistor once the power supply starts. It will go CLICK. and the relay contacts will close shorting RT6.
If you look at the schematic you will see A1 and B2, they are the relay's coil, either measure the voltage across A1 & B2 (should be 24 volts if energized) or measure from ground to A1 (should be 30 volts) and then B2.

[R_J]

Re: Crown Xti 1000 - No power

If the switching power supply is working it will provide the run voltage via T1 (pin6) and D26. If its not working it could be due to the primary winding not being driven by the fets, Check Q26 ~ Q31 and also the gate drive resistors R347 ~ R350

[Amraks]

Re: Crown Xti 1000 - No power

So now the power supply is drawing current again, but the K1 relay is not being energized to short RT6, What is the V_BULK voltage now?
So what are the voltages on V_KSTART and +15V_CTRL
Also are you getting +30 & -30 voltage on the transformer secondary, On C35 or C46 (measured to chassis)

U14 should be driving the U18 gate driverthat will be driving the two fets Q28 & Q31, I would guess they are ok, They will drive HB_OUT which drives the T1 transformer, if that circuit is working you should have the secondary voltages.
The +30 volts is required for the relay supply (via Q16) to A1, Then if the micro U1 is working it should output the SOFT_START signal to Q17 which turns on Q18 energizing K1 which will short out RT6.

Yup I went through that soft start circuit and I found no evidence of anything short. it was a pretty thorough of lifting legs and going through a series of diode and transistor tests.

What would a shorted K1 sound like would it sound like its sort of trying to switch on as I hear a fate noise and I doubt its rt6 making the noise.

[Amraks]

Re: Crown Xti 1000 - No power

V_KStart keeps rising up to 24v and drops back.

I would say them U14 chips where fake ebay ones.

you mentioned relay?

[R_J]

Re: Crown Xti 1000 - No power

So now the power supply is drawing current again, but the K1 relay is not being energized to short RT6, What is the V_BULK voltage now?
So what are the voltages on V_KSTART and +15V_CTRL
Also are you getting +30 & -30 voltage on the transformer secondary, On C35 or C46 (measured to chassis)

U14 should be driving the U18 gate driverthat will be driving the two fets Q28 & Q31, I would guess they are ok, They will drive HB_OUT which drives the T1 transformer, if that circuit is working you should have the secondary voltages.
The +30 volts is required for the relay supply (via Q16) to A1, Then if the micro U1 is working it should output the SOFT_START signal to Q17 which turns on Q18 energizing K1 which will short out RT6.

[Amraks]

Re: Crown Xti 1000 - No power

I put the original chip back down and its doing the same thing where rt6 instantly heats up

No shorts as I am doing this under a microscope for the tiny components

[R_J]

Re: Crown Xti 1000 - No power

There's not much in that circuit, something is causing V_KSTART to be 10 volts instead of 32v
Also D31 is a 16v zener and you are getting 12v on it. Q39,40,41 are acting like voltage regulators for the +15V_CTRL, D31 sets the voltage, +30v is the input to the regulators.
Is the circuit board double sided? if it is check that you did'nt damage a feedthrough when you changed C196.

If you are getting 9.83 on V_KSTART, that will be on D27 anode, that would give about 9.2 volts on the +30V_CTRL. So the Q39,40,41 must be turned on (or shorted) and supplying that 9.2 to the +15V_CTRL

You can lift one end of D27 and see if your V_KSTARTcomes up to 32v, You could lift R375 to see if you get 16v on D31

[Amraks]

Re: Crown Xti 1000 - No power

On u14 pin 12 9.20v - not enough.to run that chip
voltage on r378 is 12v - 13v

voltages on them resistors starting from v_bulk side of them

start of (r370 - 310v) (r371 - 160v) v_kstart 9.83v

[R_J]

Re: Crown Xti 1000 - No power

Have you checked any of the voltages on U14? Do you have VCC on pin 12? The ic will not work without VCC +15V_CTRL
If you have 300vdc on V_BULK, then it will be on one end of R374, then about(145v?) on R378 and then 16 vdc on D31.
You should have 300VDC on one end of R370, then less (135v?) on R371, and then 32vdc on D28 (two 16 volt zeners in series = 32v) This 32 volts MUST be there or nothing works. (I guessed at the 135/145 voltages)

Re check your solder connections on U14, maybe there is a short between pins or a pin is not making connection?
You should reinstall the original U14.

The amp was turning on before but there was likely an issue with K1 contacts not closing and all the current was flowing through RT6 instead of being shorted by the relay.

[Amraks]

Re: Crown Xti 1000 - No power

I have been using BLKRTN as ground.

As for D24 its got 302vdc there.

RT6 doesn't get hot after changing u14 which this chip is typical to go and cause not turning on faults.
As well as changing them resistors and that cap.
is it possible u14 could be faulty but then again I should have correct voltages before that.

[R_J]

Re: Crown Xti 1000 - No power

What are you using for ground when you check this voltage? you should be using V_BLKRTN or D24 (-) If you used chassis as the ground the voltages won't be right.
Just a note on RT6, it will and should get warm/hot it is a ptc thermistor.

[Amraks]

Re: Crown Xti 1000 - No power

I defiantly have them voltages at the bridge.

Forgot to add I have changed R374 and R378.

D31 I haven't checked.

[R_J]

Re: Crown Xti 1000 - No power

Check your voltage across +/- of D24 bridge rectifier, it should be around 300 vdc If its not RT6 could be open.
You might also want to check R374,R378 & D31
You need that +30V_CTRL because it is the supply for the +15V_CTRL which is needed for the VCC of U14 and U18 smps driver

[Amraks]

Re: Crown Xti 1000 - No power

If you measure a short across C196, check for a shorted D26. I don't see how you are measuring a short when earlier you had 9 volts across it?

I will recheck this to see what results I am getting.

[Amraks]

Re: Crown Xti 1000 - No power

I lifted one of the legs of D26 and if I remember correctly around about 0.400v on the multimeter.

[R_J]

Re: Crown Xti 1000 - No power

If you measure a short across C196, check for a shorted D26. I don't see how you are measuring a short when earlier you had 9 volts across it?

[Amraks]

Re: Crown Xti 1000 - No power

funny that you say this now I measured the ground to to + side of c196 and get 0.00v in diode mode
So that probably make sense.

[R_J]

Re: Crown Xti 1000 - No power

You could have defective zener diodes D28,D29, V_KSTART (32v) should be there when the AC_SW (S7) is pressed, Then the smps should start and supply the 30 volts.
If RT6 was getting hot and the amp was on, I suspect that the relay contacts in K1 are burnt and open. Once the amp is turned on, K1 should short out RT6 At this point RT6 could also be open