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Yamaha RX-730

That all done, powered on with dbt. The unit cycled pretty quickly 7-10 times with the relay clicking and the dbt never going into the bright mode, glowing only. Then the unit stops cycling and remains steady until it's powered off as in the attached photo.
 

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ve ze said:
That all done, powered on with dbt. The unit cycled pretty quickly 7-10 times with the relay clicking and the dbt never going into the bright mode, glowing only. Then the unit stops cycling and remains steady until it's powered off as in the attached photo.
Click to expand...
When you say "remains steady" do you mean remains on ?

If so then I think you might be able to go to full mains, right @mbz ?

Athanasios
 
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Nashou66 said:
When you say "remains steady" do you mean remains on ?
Click to expand...
"Remains steady" is when it stops cycling through the loop. No more relay clicks and DBT going on/off. It is silent and the DBT is permanently glowing. And Yes, it will remain on. Another thing (may be lesser in importance) that this time the light on the volume control lights up. It never did before, I thought the bulb was blown-out.
If I go full mains - it will stay in that repeat mode I described earlier but the DBT will go full brightness.
 
ve ze said:
the DBT is permanently glowing.
Click to expand...
Same level as post #82 would be ok

ve ze said:
If I go full mains - it will stay in that repeat mode I described earlier but the DBT will go full brightness.
Click to expand...
Full mains means no DBT.
With those 2 jumpers lifted we've hopefully isolated the problem area (Right power amp, unregulated).
What do you think will happen if we power up without DBT? And why? Might be worth risking a fuse?
 
I've decided on trying the power up without DBT. :confused:
The unit stayed on, the fuse did not blow out. There was some noise from the left speaker when I turned the SpeakerA On/Off button on the front panel. No sound from the input source though. Well, the rest in not pretty. The right Toshiba chip on the photo (IC7) started to smoke and I shut the power off. I guess this is it, I won't be able to replace that chip and whatever else got damaged in there by now. But that was a great experience for me and I am glad I did it. Now I've got a whole bunch of free spare parts as a bonus.
I do appreciate the help I've received on this forum and do hope we'll be able to work again on some other projects.
Thanks to all. :thumbsup:
 

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Appears to be a way forward.
TSSOP16 format from mouser, 757-TC4051BFTELN
and adapter 535-LCQT-TSSOP16

Probably also available from digikey.

IC is used as part of the input selector, struggling to work out why it shat itself...
 
Aw bummer. This piece is a booger. If ya choose to take on the 16 pin chip I found a way to remove it without damaging solder pads, cuz it's easy to cause pad damage during removal.
I cut all the chip legs off with small side cutters (aka dikes). Then heat and pull the leads when the chips outta there.
I don't have have precision solder vacuums and I'm a redneck. But it works. Just note the chip polarity upon replacement.
 
The only other thought I had along this journey was the blown channel parts replaced.
One time I replaced an NPN tranny with a PNP & the DBT went bright, lol. Oops.
 
Soundscape said:
The only other thought I had along this journey was the blown channel parts replaced.
Click to expand...
Double checked, the replacements match.
Q102: C3855 => NJW0281G NPN
Q104: A1491 => NJW0302G PNP
Q28: C3421 => KSC2690 NPN
Q30: A1358 => TTA004B PNP
 
I agree, they are functionally equivalent, as per Google. But without figuring out the reason why the TC4051BP went up in smoke -- it is pointless to replace.
Thanks Pavel all the same.
 
Win some lose some brotha. Been there myself and sidelined pieces for a year or two. Sometimes the "a-ha" moment takes some time to figure out. Ya got some good experience from it.
:beerchug:
 
Receivers are challenging. I mothballed a couple. I started with power amps and speaker crossovers and worked my up to receivers from the experience gained.

Regulators are common fail points on receivers going forward.
 
I would agree with dropping your efforts. Set it aside or perhaps pass it along to someone with greater experience.

If I may ask, can you say what "other threads" you were referring to back in this early post?
ve ze said:
Some other threads mention the blown LED bulb for the back-light and its relation to the protection module.
Click to expand...
 
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