Sherwood S-7900A Fire

[Frog Rock]

Hello All,

New to this site. Joined after seeing how helpful the members are to folks wanting to recover vintage equipment. I am in that category now.

Last year I pulled out my stereo equipment, purchased in 1975, after a few years of storage. It included a Sherwood S-7900A and a pair of Sansui LM-330 speakers. Until last year the only repair was for a bad volume control knob.

Last year I resurrected the units to play streaming music From my phone. With an adapter I connected my phone to the tuner using the front input jack. All was good for a few weeks. Then one day shortly after turning it on the speakers began to hum until the amp popped and flames came out of the top vents. Today I removed the outer case. The result can be seen in the photo.

From the schematics I would guess this is the protection board. Are reliables available to repair this damage? If so, who might still have the ability to repair this. Electronics has never been my in my skill set.

BTW, I still have the schematics and owners operating manual. Would be glad to scan those should anyone with a similar unit need a copy.

Frog Rock

 

[quaddriver]

interesting, i found a sams service manual on hifiE and it shows a dual op amp as part of protection, and if I look had at your pic, below the relay I see an empty 16 pin socket...

 

[Tom B]

Its best to post your location to see if someone local can help.
Its pretty unusual to have that catastrophic damage on the protect board, but the hum before the fire and smoke could have been shorted outputs, as nothing on the protect board can usually cause a hum on the audio out.

 

[Frog Rock]

interesting, i found a sams service manual on hifiE and it shows a dual op amp as part of protection, and if I look had at your pic, below the relay I see an empty 16 pin socket...

Quaddriver, the socket you refer to has 14 sockets. There is an 8 pin chip on the left end. The back of the installed chip is visible, but not very obvious.

 

[Frog Rock]

Its best to post your location to see if someone local can help.
Its pretty unusual to have that catastrophic damage on the protect board, but the hum before the fire and smoke could have been shorted outputs, as nothing on the protect board can usually cause a hum on the audio out.

Tom, maybe that is not the protect board. It was my best guess.
And thanks for the tip about location. I had put that on my profile, but it must not have saved. It is now there - Wilminton, NC.