I've been running mine for about 4 years now and noticed that the tops of the 30W 600oHm and 6Kohm Power resistors (these are the two monsters stuffed in between the power transformer and one pair of 7591's) are chipped and the ceramic has burn marks on it. I'm worried about them going into a thermal meltdown as I use the 1000A about 6-10 hours a day. right now I have a fan directed at the back, but the heat given off by them is like a blast furnace. It can't be good for the 7591's and the transformer. I've got Aluminum HVAC Duct tape on the one side of the transformer to reflect some of the heat from it, but obviously that won't work for the tubes.
I'm thinking of replacing these with something higher wattage to help with the heat given off by them (they are hotter than the 7591's @ 35ma).
I looked thru mouser and found the Vishay RH-50 series chassis mounts. Only thing is the closest to 6K is 6.2Kohms. And the only 6Kohm 30 to 50 watt is an ohmite (non stocked and 6 week wait time). As this feeds the tuner sections (drops from 420V to approx 100V) will the 200 extra ohms drop the voltage too much to the tuner. I'm no good at the math for this stuff. So I need someone to figure it out for me, please. I'm no good with letter math (flunked Algebra).
I figure I can mount them directly to the chassis in the middle in front of the 6AN8's, with Heatsink grease between them and the chassis (one big heatsink) like the newer versions of the 1000A does. Or mount them on the divider plate, between the front and back of the chassis. I think either will work ok as a heatsink for them. They should run cooler than what is there now as they won't be running close to flat out, maybe 60%.
This was taken when I got it and before cleaning. The Resistors are between the lower right 7591 and the P.T.
Excerpt from the schematic. R179 and R181 are the ones discussed here.
thanks
Larry
I'm thinking of replacing these with something higher wattage to help with the heat given off by them (they are hotter than the 7591's @ 35ma).
I looked thru mouser and found the Vishay RH-50 series chassis mounts. Only thing is the closest to 6K is 6.2Kohms. And the only 6Kohm 30 to 50 watt is an ohmite (non stocked and 6 week wait time). As this feeds the tuner sections (drops from 420V to approx 100V) will the 200 extra ohms drop the voltage too much to the tuner. I'm no good at the math for this stuff. So I need someone to figure it out for me, please. I'm no good with letter math (flunked Algebra).
I figure I can mount them directly to the chassis in the middle in front of the 6AN8's, with Heatsink grease between them and the chassis (one big heatsink) like the newer versions of the 1000A does. Or mount them on the divider plate, between the front and back of the chassis. I think either will work ok as a heatsink for them. They should run cooler than what is there now as they won't be running close to flat out, maybe 60%.
This was taken when I got it and before cleaning. The Resistors are between the lower right 7591 and the P.T.
Excerpt from the schematic. R179 and R181 are the ones discussed here.
thanks
Larry
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