Denon AVR 1804 amp won't switch on

[davenn]

OK first diagram

I have coloured the 3 power rails of interest

blue --- from 5.5V reg to pin 11 on brd connector .... this is 5.5V rail for the CPU
red --- from 5.5V reg to pin 9 on brd connector .... this is the outgoing pwr to be switched by the cpu for return to the relay
yellow --- this is the return power from the cpu via pin 10 on the brd connector

 

[davenn]

the links from the previous board go to the connection board, they go in on the same pin #'s

Red -- 9
Yellow -- 10
Blue -- 11

but as you can see they come out of different pin #'s to go to the CPU brd

Red -- 16
Yellow -- 8
Blue -- 12

 

[davenn]

once they get to the CPU brd, things get a lot more complex as they as they split into going to different sections

 

[bushtech]

Wow Dave Thanks. You are beyond awesome!

Will now work my way through them

 

[bushtech]

Please excuse my lack of knowledge.

Is the 5.5V reg you mention the 7805 (IC104)?

If it is I can't find anywhere on your diagrams where the blue & red lines reach the 7805.

I have spent some time on the yellow line and it looks as if there is continuity there. I cannot be quite sure that I am touching the correct pin on the cpu until I can disconnect the board and to do that I need an answer to my post #140

Thanks again for your awesome help

 

[bushtech]

Just to be clear:

I found CP552 on bottom left of page 77 of manual and pin 9 = CNT_MUTE and pin 13 = CPU_GND

 

[davenn]

Is the 5.5V reg you mention the 7805 (IC104)?

If it is I can't find anywhere on your diagrams where the blue & red lines reach the 7805.

yes and look at the bottom of the first diag and I also posted it as part of the PSU diag earlier in the thread


Edd is going off on some unrelated tangent at the moment don't worry about what he was saying till he confirms his intentions
he's looking at the tuner board for some reason

@73's de Edd what are you aiming to achieve ???

 

[bushtech]

Thanks davenn

"look at the bottom of the first diag" On that diag the red and blue lines stop on either side of R158, a 4k7 resistor.

I'm probably being stupid.

 

[davenn]

Thanks davenn

"look at the bottom of the first diag" On that diag the red and blue lines stop on either side of R158, a 4k7 resistor.

I'm probably being stupid.

the point is you can follow both of them back to the 7805 output

 

[bushtech]

On the red line between pin 77 PWR_DOWN on on the ic and out leg of 7805 I get 1681 with my dmm set to continuity. Could be 1681 mΩ

 

[bushtech]

On the blue line from the out leg on the 7805 to pin 54 (AVDD) on IC I get 715 with dmm on continuity.

Hope I have interpreted correctly from where to where to measure

 

[davenn]

On the red line between pin 77 PWR_DOWN on on the ic and out leg of 7805 I get 1681 with my dmm set to continuity. Could be 1681 mΩ

not really a valid test path as it involves multiple components




in volts mode, and + of meter on the junction of R158 and Q151 and - of meter on the negative of C158, confirm that there is around 5V ( it may be less cuz of the voltage drop across

R158 ... I will be interested to see what you read)

Then move the + meter lead to pin 16 of the CP552 connector on the CPU board and you should read the same voltage

Then move the + meter lead to the base pin of Q201 on the CPU board and you should still have the same voltage


this was to be posted last nite, but I lost net access and it still wasn't going this morning .... need to ring the ISP from work
maybe it is the cable modem ?


Dave

 

[davenn]

On the blue line from the out leg on the 7805 to pin 54 (AVDD) on IC I get 715 with dmm on continuity.

Hope I have interpreted correctly from where to where to measure

not sure how to interpret the reading from your meter without actually seeing it

the only thing inline with that rail between those 2 points is a diode D213 on the CPU board
so with the negative tip of your meter on C158 negative, you should see about 5V on that pin 54 of the CPU IC

That rail also supplies 5V to pin 89 of the CPU --- +5V Backup Power via DD202 and beaded inductor CB203

the diode is the only component inline, tho there are other components hanging off that line

 

[bushtech]

Hmmm. Quite a voltage drop lol

0.67V on one leg of R158 & one leg of Q151
Other leg of R158 = 0V and 0V as well on other 2 legs of Q151



DMM was set on continuity/diode checking

 

[bushtech]

Dang it ! Red light on set not coming on any more.
But readings still the same as 2 posts above
Reading 0V on pin 16 of CP552

 

[davenn]

Hmmm. Quite a voltage drop lol

0.67V on one leg of R158 & one leg of Q151
Other leg of R158 = 0V and 0V as well on other 2 legs of Q151

you should have 5.5V on one side of R158 ... the side going to the output of the 7805 reg

Dang it ! Red light on set not coming on any more.

OK back up ....

there should be ~ 17V on the input to the 7805 and around 5.5V on its output

 

[bushtech]

Checked it again one leg of Q151 and one leg of R158 = 0.68V
Hope something else hasn't gone with the red light not coming on anymore


Voltage across C158 now 19.75V
Was 17.1V when we started few days ago

 

[davenn]

Checked it again one leg of Q151 and one leg of R158 = 0.68V
Hope something else hasn't gone with the red light not coming on anymore

yes, but what about either side of the 7805 as asked

 

[bushtech]

And 0.1V across R151


All 3 legs of IC 104 the 7805 at 0V

 

[davenn]

All 3 legs of IC 104 the 7805 at 0V

check either side of the IC105 fuse

you may have accidentally shorted something out with the tip of the meter probe