Quote:
Originally Posted by mrmuzic
I just bought a SL100 made in 1973 and I am having a problem.
1) loud hum and nothing out of Channel 2
2) low volume out of Channel 1
2) I replaced all tubes and the same thing
I suspect the output transformer ? Can anyone help me here. If it is where can I get a dropin in replacement or a more robust one if needed.
Kevin
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Hi,
I'm new around here but maybe I can help.
Have you checked your filter capacitors for bubbling? When caps age and start to go they stop filtering the AC ripple in the B+ line and also reducing the B+ value. This can cause excessive hum and also reduce your output level. Take a look at the positive (+) end of the caps. If you see a bubble or even leak then they need replacing.
Please, please, please ensure that you discharge you caps before fiddling around. If you don't know how to do this then don't open up your chassis.
A quick test for your output transformer is to measure the DC resistance on the primary and secondary. You should read somewhere between 60-100 ohms on the primary between the center tap and either side. If you read a short ie. 0-1 ohm resistance or much more than 1k ohm then your OT would appear to be screwed. The secondary should read about 1-1.5 ohm depending on the winding 4/8/16. Remember the actual value of the DC resistance is fairly meaningless but it gives a reasonable indication and is easy to do.
Also can you post a gut shot, it may help and a bit of amp porn is always welcome!!
Hope this helps. Let us know how you get on.
Cool amp BTW.
Regards,
Paul.