Trying to repair old luxman amp - fuses dead

[Zinzin]

So here I am with a luxman L190A that sounded quite good but suddenly suffered a severe drop in volume

I opened it to check what was going on and it turns out half of the fuses are dead; right next to a component which seems to have heated quite a lot;

My question is – will changing the fuses be enough? Should I get the same ones or more resilient ones? Should I also change the component d112 next to them/check for problems elsewhere?

I hope my request isn't too annoying, thanks for any input, and have a nice day

[shooter]

LEAVE fuses as marked
both the diode AND C133 should get changed
R 152? should be checked to verify it's within tolerance of it's original value
a good pic of the 2 leads near the damaged area, that head off to the "right" of the pics would be handy
a schematic would be amazing

[PRR]

Fuses don't blow themselves. They protect other parts. "more resilient ones" will just blow the parts they are supposed to protect.

But if those 3A 250V fuses are blowing, you may have a catastrophic output stage melt-down, and need an experienced technician.

AFAICT the C113 circuit supplies power for a lamp. Which explains the char, but not the drop of audio.

There are probably better places to ask, who do transistor Hi-Fi all day and night. (This place is more tube guitar amps.)

diyaudio.com is a place:
https://www.diyaudio.com/community/threads/luxman-l190-l210-l215-l-225-l-235-l-230-l-400-burned-d112-and-reason-f-distortion.364689/

> schematic would be amazing

Best I found in a quick look.

[shooter]

Best I found in a quick look.

works for me, thanks. 
as for the blown fuses, I'd be inclined to just put a couple chip amps in place of the complicated stuff n call'r good.  That's a tangled mess of Transistors, caps just waiting for some foil runs to get burned up trying to fix it. 

[glass54]

Hi Zinzin
DO NOT upgrade Fuse values. You could try new same value Fuses (Luxman know what they were doing)
Power Supply section with D112, C133 and R153 are for lamp ONLY, consider suitable LED??
If you blow fuses again (F102B, etc), I suspect Power transistors in output stage are s/c, or drivers or all (Drivers and Output and possibly Vbe Multiplier)  I suggest B channel is faulty, so you have A channel to compare. You will need a good Multimeter and reliable Schematic and good skillset OR GET HELP!!
Regards
Mirek

[Zinzin]

Hello,

Thanks for all the answers and links;

I'll probably go try my luck at diyaudio since I'm a bit lost right now

Just so you know where things are at : I've been sent this link http://audio.mezei.fr/pages/LuxmanL190A.html explaining the classic problem of this amp and that repair has already been done long in the past

Some pictures showing the swapped parts https://imgur.com/a/mN7ywSl

My flatmate is an electronic engineer (not specialized in audio but he can solder and conduct tests) so with good guidance we should manage to do something

[Latole]

Service manual downloaded
;
https://elektrotanya.com/luxman_l-190a.pdf/download.html#dl

Often the issue are from the output power transitors