AVR-1905 Denon receiver amp fooled me

[jango2]

Symptom: does not switch on. Will switch on unpredictably once every
50 tries. Digital 5volts is always available. Clock oscillator can be
observed at the syscons pins only if other vertical boards are plugged
in. Grounds for digital and analogue seem to be floating. Display may
either be blank or have some leds glowing.
The first time i powered up it worked. I gave an estimate. Now i'm
fooled. Ever since then it switched on just once. Help. What role does
the 6ch input board play in the syscons clock oscillator (a 12 Mhz 3
legged ceramic resonnator).
Jango

 

[William Sommerwerck]

Ouch. I'm glad I'm not working on that one.

I'm going to make a really stupid suggestion. It sounds like a bad solder
joint. Somewhere.

Have you called Denon? It's possible this is a known problem.

 

[jango2]

I'm going to make a really stupid suggestion. It sounds like a bad solder

joint. Somewhere.

Hey William, thanks a ton, you were right. I found a print cut leading
to pin 40 (RESET) of the syscon. Damn break was under the ic. Your
"stupid" suggestion kept ringing in my head and it was'nt until i got
the entire mainboard with all the vertical boards plugged in (ground
wires soldered from all boards too), off the chassis that i found it.
I would have ordered a syscon, replaced it to no avail, next i'd have
suspected the VFL drive ic, replaced that too........
Looking back heres a clue that might have given me hope that the
syscon was'nt bust, Clock oscillator would be visible only when i'd
drain Vcc off the ic (set powered down) and repowered the unit. This
should have led me to suspect improper reset. I couldnt access reset
pin of the ic as the smd was under the pcb. I did solder a wire to the
reset transistor's collector to monitor it and found a clean reset.
Thanks again mate,
You have a good day
Jango.