Hum on Emud stereo model 1010

[walterbeers]

German made (1963) stereo in console cabinet. Chassis has had a complete recap with those small yellow capacitors and all filter caps have been replaced. Four of those capacitors are .022s in the volume control circuit. C95, C100, C83, C78. The best I could do is replace them with outside foil shielded caps, and wrapped metallic duct tape around them, grounding the foil tape. That significantly reduced the hum, but it's still there when volume is turned up. Not very noticeable on AM, FM, but when you go to phono, since it has a lower output, turning up the volume control the hum gets louder. (There's no hum with the volume control turned down). It's there on all the functions, but more noticeable on phono since I have to turn up the volume higher as I had to replace the cartridge with a standard ceramic type. Hum is being picked up by EMF either within the unit or from EMF interference in the air. I have tried moving wires around to reduce it, (which helps), but can not completely eliminate it. Other than enclosing the whole unit in a metal box, (which is impracticable) does any one have any other suggestions. I really can't go with a different cartridge as the original is unavailable. The one I have in there (which was a bear to mount) was recommended by Gary at VM.
Here is a link to the schematic. I feel I have done my best, but wondering if anyone has any more suggestions.

https://app.box.com/s/3th2xptdo035qmqtw2mz

[zeno]

Other than grounding the TT chassis with heavy
wire like the seperate green wire on mag cartridge TT's
I dont know.
May be able to trouble shoot by grounding the audio line
( where safe !) to find where it starts.......

Good luck with this un.

73 Zeno
LFOD !

[N8QQD]

Could you have a tube with a heater to cathode short?

[old_tv_nut]

Did you install the new caps with the outside foil end on the same connection as the outside foil of the original caps? Generally, you want the outside winding to be on the lower impedance side, which usually is the input side, not the grid of the following stage.

[walterbeers]

I've swapped tubes with used ones, and no change, and none of those show a HK short on my checker(s). I made sure the band of outside foil also went toward the lowest side, not the grids. Actually the amount of hum I get now might be tolerable. I sort of think that it may have always had some hum, as the design is quite different from the usual american style setups. Such as the rectifier tubes are on one side of the chassis and the filter capacitors are on the opposite side, routing the power supply wiring right across the audio circuits. One problem is that the cartridge I used only has an output of .5 volts, and I have no idea what the output of the original one had. Having to turn up the volume higher when playing records introduces more hum. I'm thinking of maybe fitting some type of crystal cartridge in the tonearm, which will have a higher output, and that way the volume control won't have to be turned up so high. Problem is finding a cartridge that will fit.

[jr_tech]

If the source of the hum is coupling in the amp circuit itself, you might consider adding a small solid state pre-amp at the base of the turntable, so the main amp would not have to be tutned up as far. Of course, this won't help if the source of the hum is the cartridge/tone arm... if that is the case, shielded wiring in the tone arm could help, the trick would be to find some very small flexible, lightweight coax.

jr