Yikes! smoke sizzling and stink

[chaz]

So this is what happened when I popped in a new 7 amp fuse into my Optonica 5151 that had blown the fuse and switched it on.

What the hell?
(This was taken after the power was switched off)

Sorry posted this to the wrong forum could someone move it to Solid State please?

 

[Robisme]

Hmmm. Could be that cap venting. Can you snap a pic of the cap? Try to get the part under the board.

Rob

 

[chaz]

It was definitely the cap venting. Moved the unit into the garage for the moment, but the top of that capacitor was flat and is now noticeably bubbled.
(There is actually a minute and a half more of that video that I cut off.)

 

[spark1]

It was definitely the cap venting. Moved the unit into the garage for the moment, but the top of that capacitor was flat and is now noticeably bubbled.
(There is actually a minute and a half more of that video that I cut off.)

Were any other changes made to the unit prior to putting in the fuse?

And was it working fine before the fuse blew? What were the circumstances of the fuse blowing? Did you notice anything unusual or odd before the fuse blew?

Generally, if a fuse blows it means you have some other problem that needs to be diagnosed and repaired before putting a new fuse in.

I bet the smell was nasty!

 

[Okke 70s]

I'd say the cap was bad, and that blew the old fuse. The new fuse did not blow (in time). That makes you wonder.. 7A you say? Sounds like a lot to me.

 

[chaz]

Yep it was, and still is pretty nasty.
Had 2 turntables, plugged into the switchable and unswitchable outlets in the unit. I was listening to the one in the unswitched outlet, when I jostled the turntable while lifting the arm at the end of a side. There was a pop and the receiver went out. Looked inside and saw the blown fuse. Removed it and saw it was a 5a fuse so I put another in it's place and it promptly blew. Got out my DBT and put that between the receiver and mains power and popped another 5a fuse in. Unit came on - red power indicator ( not green) no click from speaker protection relays and med bright DBT.
Checked the service manual and noticed the fuse should be a 7a not the 5a I took out, so I ordered some (didn't have any 7a) and posted a thread here.

 

[chaz]

After a suggestion in that thread I checked for DC coming off the left and right channels before the protection relay and posted what I got ( don't know of I did the measurements correctly). The fuses came in today so I tried one out.

 

[Robisme]

Needle drop, pop, blown output transistor, fuse blew. New 5 amp fuse blew because of shorted output transistor. 7 amp fuse installed and shorted output transistor caused main cap in marginal condition to blow.

Just a guess.

Rob

 

[chaz]

Well, looks like I gotta find someone that can do repairs nearby, cus I'm pretty sure this is outta my league.