Yamaha RXV 465 no display and power problem

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

The only reason for the Q201 is to turn +3.3S on and off, Check Q200 If it has 3.4 volts on its source and 3.4 volts on its drain then maybe they don't require +3.3S to be controlled
Does it look like it was removed?

The GATE and SOURCE of Q200 has 3.3 volts but not the drain, before the new transistor mpsa92 was placed in place of Q201.

There is 3.34v at the base of Q201, when the power switch is pressed and this voltage remains for 5 to 7 seconds then drops to zero.

Will check today, if 3.3v is switched from emitter to collector of Q201.

let me know, if this is has become confusing, may be summary would be of help.

Regards,
Hemant.

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

Hey R_J,

It was during my troubleshooting, that i found about the missing Q201. Sorry if my post was confusing.

Summary of todays work,

I soldered the pins 123 &8 of both stk's and the problem reappeared then i undid what was done but to no avail.

The amp has returned into its previous state. SAD.

One thing is for sure, i was tracing the pin 96 of the micro and found that there is 3.34v when the power switch is pressed and this voltage remains for 5 to 7 seconds then drops to zero, which is guess turns ON the Q201.

Further details along with your suggestions will be posted tommorow.

Thanks for your reply,

Regards,

[R_J]

Re: Yamaha RXV 465 no display and power problem

Could it be that someone else worked on this unit? If installing that missing part restored function, what else is missing?
You should have reported that the transistor was missing, this would have saved a lot of time
Check for missing +3.3dsp likely missing Q401, Q403 & Q404

electronicspoint/threads/yamaha-rxv-465-no-display-and-no-power.288290/
Please note,

I removed the μp board while tracing the +3.3S supply and found that the transistor Q201 is missing.

I think this unit is already worked by someone but thats not my problem, as i am trying to learn more of these recievers of today.

Regards,


Hemant Choudhary, Jun 18, 2018

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

Hi R_J,

The Q201 was made with KMPSA92 PNP transistor with 47Ks, as per the datasheet of DTA144EKA, a little progress is achieved i guess , now with the very first press of the standby switch, the unit turns ON.

The Relays RY100 and RY371 show drop in voltage across their coils, i guess this is also OK, now.

In total i hear 3 relay click one after another. Now the whole board is to be turned upside down to take measurements at the power supply capacitor.

Further, the STKs pin number 123 & 8 are floating.

I will update the voltage measurements across power capacitor, stk input in the evening.

NOTE : The display is still OFF, no single sign of illumination.

Regards,
Hemant.

[R_J]

Re: Yamaha RXV 465 no display and power problem

The only reason for the Q201 is to turn +3.3S on and off, Check Q200 If it has 3.4 volts on its source and 3.4 volts on its drain then maybe they don't require +3.3S to be controlled
Does it look like it was removed?

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

Dear R_J,

I think the missing transistor Q201 should be in place, as there is no indication for IT to be meant for a different model number of the receiver.

The &2 is just for interchangeable parts from the manufacturer, as mentioned in different sections of the schematic. Also, the dashed lines symbolises a complete digital low power transistor, as per the datasheet of DTA144.

will try finding the same part or will make it by using a simple PNP transistor.

If there are any inputs from your side, kindly do let me know,

Regards,

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

With the stk pins removed, the display does not come up.
IC 100 pins removed, no change but DC offset gone on its 3 resistor.

IC 101 pins removed, no change but here also dc offset gone.

The only difference observed was with the stk pins removed and with 3 buttons pressed ..the voltage level differs that is +B is 26 v and -B is 32.5v.

Also, now there is simultaneous switching of all the relays, i think, because the relay switching noise is more but all these for very short duration.

Let me know, if this is confusing.

Regards,

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

I will try this tommorow, as its late night now.

Thank you R_J.

Regards,

[R_J]

Re: Yamaha RXV 465 no display and power problem

At this point I would either remove the stk ic or at least isolate the pins 1,2,3 & 8. I would try ic101 first

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

Here are the voltages,

IC101...
R1035...3.97
R1056..4.04

IC100
R1068..3.76
R1046..4.19
R1067..2.07v.

The display is still off...For me this is no" SLEEP"..

[R_J]

Re: Yamaha RXV 465 no display and power problem

check the center of the dual resistor and press power and record the voltage, you need to do this for all 5 resistor sets.
The 3 button press bypasses the protection (except for the excess current detect) When you did this test did you see the "SLEEP" segment lit up on the display?

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

Yes, there is voltage spike with the first relay click then it drops to zero after the second relay click..power off.

With 3 buttons pressed, there is a voltage spike after the first relay click, drops to zero..then second relay click...then the third click and the receiver is ON..but no display. Atleast voltage measurements can be taken.

So, is it that the micro knows there is problem and it switches AC_BL and not AC_BH, which is needed for the stk's.

For my understanding please, why even the receiver is turned ON with the 3 button method.

Also, is there a way to isolate the Stk's one by one or it needs to be removed check thwn remove the other one.

Regards,

[R_J]

Re: Yamaha RXV 465 no display and power problem

If it clicks on then off how did you measure the 2-5 volts on the resistors? That relay controls the main tranformer, if it turns off you won't get any voltage on the resistors.
check the center of the dual resistor and press power and record the voltage, you need to do this for all 5 resistor sets.
I suspect one of the stk's is bad.

Till now i have checked only for the DC output at the emitter resistor and there is a small ( 2 to 5 volts ) dc on them as the first relay clicks, then it settles to almost 0 volts.

the reason it settles to 0 is the relay turned the power off.

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

The relay click ON then click OFF.

[R_J]

Re: Yamaha RXV 465 no display and power problem

By pressing the power button and having ry371 activate, tells me the microprocessor seems to be functioning as it understands the key command and outputs the PRY logic
Can you explain clicks for 3 seconds, does it keep clicking or click (on) then click (off) after 3 seconds?

I am going back to your first post about the 2-5 volts on the resistors, that could be what is preventing the amp from turning on, even the display.
which resistors had that 2-5 volts, there are 5 sets of resistors

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

Readings of CB 24 are as under

+3.3M...3.3v
DGND. 0.01
ACPWR_DET 3.03
RESET 3.30
PRY 3.23
DEST 1.08

may be if this could help us to narrow down the problem.

Regards,

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

Hi,

When the power switch is pressed, the only relay that clicks for 3 seconds is the main relay RY371..the main power supply relay.

IC 22 has 3.3 at pin 8
Q200 has pin 3 at 2.88 and pin 4 at 3.33 volts
IC 21 has approx 5.41 volts at input and 3.33v as output.

Some readings of CB23 are as below,
Sp_imp ..3.3
Ps1_PRT 0.06
AMP_LMT 1.12
AMP_OLV 0.01
I_PRT 0.01
DC_PRT 0.02
VOL_SCK 0.0
DGNG 0.0
VOL_MOSI 0.0
MUTE_SW --10.8V

MUTE Z3 and Z2 are 0 volts

[R_J]

Re: Yamaha RXV 465 no display and power problem

I believe the voltage across C1055 and across C1056 is low. because RY100 is not activated and is supplying the D1017 bridge with a lower voltage, It is being supplied by AC_BL and not AC_BH. The RY100 is controled by microprocessor ic20.
Does pushing the power button have any effect on the amp?
Locate the eeprom ic22 and check the voltages on it, especially pin8 +3.4 volts


Q201 may not be used on this model, I see a (&2) beside it and it is within a dotted box around it.
Are ic21 & Q200 there? does the ic have +5v in and 3.4v out for the +3.3m supply and does q200 have 3.4 in and out? (q201 may not be used on this model)

[hemant_2222]

Re: Yamaha RXV 465 no display and power problem

Yes, the B and -B were same (25 and -27) measured across the capacitors C1055 and C1056.

Also, is the absence of Q201 a concern?

[R_J]

Re: Yamaha RXV 465 no display and power problem

Ok, so what is the B+ & B- voltage on C1055 & C1056? (page 117) The B+- could be low due to the AMP_LMT signal missing from the micro if its not functioning correctly