On Wednesday, October 19, 2016 at 5:43:10 PM UTC-4, Jim Worthington wrote:
Please note the interpolations.
To start, I'm replacing all of the paper electrolytic and non-electrolytic paper capacitors in the amplifier and will go from there. I checked the tubes. They're all good, but the 12AX7s are a little low on emission. The power cord is frayed. I'm going to replace this with a 3-wire power cord.
Before you do this, make sure that the chassis is actually fully isolated - no fault in the transformer and that this is not a transformerless design. Unlikely, but with this sort of thing, adding a 3-wire cord can sometimes have untoward results. If there are line-bypass caps in place, be even more careful, and replace them with properly rated (X or Y) type caps. And check for hum loops after installation. Unlikely, but worth attention.
The electrolytic capacitors in the crossover network will probably have to be replaced as well. I'm concerned that Polarized electrolytic capacitors were used in the original design instead of non-polarized capacitors. This is not good design practice. Reverse voltage on an electrolytic capacitor can damage the capacitor.
The original design likely upped the voltage to avoid the need/cost of NP caps, which were relatively more expensive back in the day. Certainly more costly than going up on voltage. In any case, shifting to NP caps can only make it more stable and will do no harm.
The motor is frozen on the turntable. Removing the dried out grease and lubricating should fix the problem. The rubber roller may need to be replaced. I'm also looking for a replacement for the original Collaro RC456 changer as another possibility. Modern turntables should provide less wear on the vinyl media.
You can "restore" an existing dried out roller by lightly machining a groove into the existing hard roller - if it still has its integrity, that is - and then use a neoprene or silicon O-ring of the appropriate size secured with super-glue. It is only an idler, after all. I find that synthetic greases are very good for lubrication where no slop is required:
http://www.mscdirect.com/product/details/00257006
You will likely have to replace the cartridge and stylus - there are many sources for such
Good luck with it!
Peter Wieck
Melrose Park, PA