Denon PMA 1060. Somethings really wrong

[silversweden]

Hi! I just bought a Denon PMA 1060 in great condition.
Except one thing, its doesnt work.

When i bought it he said that he and his girl hade been
on vacation and it had been som thunder during the weekend.

So he went to the repairshop and they taught is was
a fuse that blown during a discharge.

I Found a fuse (placed near the on-off switch) that was
blown. So i replaced it.

Turned the Amp ON and BANG! Something broke.
(but the fuse is OK, maybe because i used another
type used more in cars, dont know, stupid me!)

A piece on one of the outputs had been blown away :S
(the one with the yellow wire on the downside of the
circuit board. (isnt it strange with a wire?? maybe it has
been repaired before, dont know)

One of the Caps also blown. (the brown one between the two
biasing pots) It came some stuff out of the cap, hard to see
on the picture.

And before i got the power cord out it starded glowing somewhere didnt have time to see exactly what part.

But i found that a GREEN transistor is in very bad shape.
Nearly shattered in two. Hard to see but its the same picture
as the broken CAP.

The other channel seemes to be OK. I cant see any other damages, sure there is taught. The amp goes in protection i think, red light.


Now to the questions, can this be the result of a discharge
during thunder??

What should i check for? Is it some basic checklist to do?
Check all the outputs, and drivers.. I know.

But do i have to desolder ALL the transistors on the board
and check them, a very time consuming thing to do.

I dont think proffiesionals have the time to do that, but some people claim that its the only way to be sure.

Anmyone have schematic for the Amp?

Im greatfull for all the help i can get =)

[silversweden]

pic

[silversweden]

pic

[silversweden]

ive been doing some measuring. Conlusion.
For the left channel all the outputs read
0.5 volts 58 volts 0 volts.


But for the other channel many of the pins
have 58 volts, how come?

[aparatusonitus]

Originally posted by silversweden
Anyone have schematic for the Amp?

Hi silversweden,

Mail me, I have a service manual (3,8Mb) for you

[aparatusonitus]

Hi silversweden,

Service manual sent...it should be on your screen any second now

[TheMG]

Originally posted by silversweden
ive been doing some measuring. Conlusion.
For the left channel all the outputs read
0.5 volts 58 volts 0 volts.


But for the other channel many of the pins
have 58 volts, how come?

That indicates something is wrong with the output stage of that channel, bad transistors that have become shorted is the most likely scenario.

That fuse you put in, was the same value as the original, was it? Putting in a higher rated fuse is a complete no-no, something you NEVER want to do.

Other than just the output transistors, some other parts will need checking such as the driver stage, which may or may not have been damaged also.

Start by checking the output transistors one by one (you will probably have to remove them to do this) and replace as necessary. Then move on to checking other things, BEFORE powering up.

[silversweden]

After a couple of hours measuring i got this far.

www.itxpress.se/2434.jpg
komponents marked with yellow was broken.
and marked with green are tested OK.

A strange thing is still after replacing what i found broken.
On the Output pins (i just removed them for now until i
sorted out the problem, have new ones waiting)

Something is really crazy here. Full schematic here.
www.itxpress.se/1060.pdf

TR523
p1 55 (for other channel 0.5V)
p2 58
p3 55

TR527
p1 55 (for other channel 0.5V)
p2 58
p3 55

TR529
p1 55 (for other channel 0.5V)
p2 -58
p3 0.0 (THE 0.22 5W RESISTOR OPEN)

TR525
p1 55 (for other channel 0.5V)
p2 -58
p3 55

[silversweden]

Anyone please take a look and tell me what you think ?

[silversweden]

okay, now im getting frustrated!! :S :P

i found a trace on the board that had been burnt of.
i repaired it with a small isolated wire from the two
solderingpoints instead.

And now i have the same readings on the fets that i
have on the other channel!!

About
0.6 58 0 volts. and so on.

I measured several times. Then i solderd the new Outputs
back in place (4 of them).

I replaced the 4A fuse with a 1.6A fuse just in case.


I plugged the amp in, and it went in protection as
usual. Red light, but some relay clicked. Not the speaker
relays. a smaller one on the same board.


I observed the amp for a few seconds, felt like a long time
but maybe 15 seconds. Then i heard some nasty noise :S

Disconnected the amp within a second.


TR519 blowed!!!! And R549 is just a piece of burnt material.
Dont have the strain to investigate if there is anything
else at this moment.

Anyone have an ideo of what the hell is happening??
And why isnt the fuse blowing before anything else :S