Shure SR105

[fuzz092888]

I was just wondering if anyone had any information on the Shure SR105. I downloaded the owners manual, but was looking for anyone with experience with them, schematics, or anything else.

Thanks in advance.

 

[TLS Guy]

I was just wondering if anyone had any information on the Shure SR105. I downloaded the owners manual, but was looking for anyone with experience with them, schematics, or anything else.

Thanks in advance.

They were a good solid amp back in the 70s. 100 watt per channel mono blocks. I used them in a pro installation. You should know there is no speaker protection from DC offset and you should add that if you intend to use one.

I have manuals and circuits.

 

[fuzz092888]

I had problems with one, it wouldn't even turn on without blowing the fuse. I have yet to see if the other will turn on. How do you add the speaker protection?

 

[TLS Guy]

I had problems with one, it wouldn't even turn on without blowing the fuse. I have yet to see if the other will turn on. How do you add the speaker protection?

The power transistors at least will be blown and may be more.

The easiest way to add speaker protection is with a relay to open and with DC and disconnect the speakers. However that can be too slow. The other method is a clamp circuit to short the output if there is DC offset. Probably the best way is an opto switch circuit. There is no delay with those.

 

[fuzz092888]

I haven't looked at them in awhile. I'll have to open them up and see about those transistors and see if anything visibly looks bad.