Pilot FA-590 SA-232 console ensemble overhaul. So hot right now.

[pete1729]

I picked up a Pilot 1078 console two years ago. Last year I went through the power amp and did a thorough refresh. This year it's the FA-590's turn.

 

[pete1729]

Some before and after pictures of the FA-590 power supply.

 

[pete1729]

I went back into the SA-232 to check voltages and reupgrade the main power resistor. The 10 watt original got scorching hot. The 50 watt replacement got scorching hot. So I got a 100 watt chassis mount resistor. It too gets really hot.

 

[pete1729]

A little later on this evening I will hook it all up to my Cornwalls and see how it sounds. Next fall I'll dig a little further into the FA and address the coupling caps etc. The plan is to put it all back in the console. I have been offered some real estate in the dining room

 

[gadget73]

The FA590 isn't bad but I find mine to be a bit on the dull side. Check the AC heater wiring up front. I found one to be mashed right into a lead from one of the grids and it was pumping hum right into the preamp. Moving the wiring around made a huge difference.

 

[pete1729]

The FA590 isn't bad but I find mine to be a bit on the dull side. Check the AC heater wiring up front. I found one to be mashed right into a lead from one of the grids and it was pumping hum right into the preamp. Moving the wiring around made a huge difference.

Alright then, that may address the noisy phono section. What does come through is nicely detailed. There are controls and tube sockets that still need to be cleaned.

I have occasionally gotten a rising hiss punctuated by a pop. I assume this is a failing capacitor in the preamp section.

 

[gadget73]

possible, or a dying resistor. I never took pics of after I fixed it, this is a "before" shot but the wiring problem is visible. I simply pushed the heater wire away from the lead to that capacitor.

 

[zackthedog]

I'm a little concerned about the "scorching hot" resistor. It's only 100 ohms and it's dropping 20 volts, for 4 watts dissipation. A 12 watt resistor would be more than adequate. I restored one of these a while ago and I don't recall having any such problem. Are you sure there isn't a short to the chassis somewhere, maybe one of the multi-cap boards? I guess if the voltages check out, it is what it is, but it seems odd to me.

 

[gadget73]

yeah it'll get warm but it shouldn't need anywhere near that much of a resistor to not get alarmingly hot. 4 watts is basically the heat output of a night light bulb. Probably worth confirming voltage drop across that thing.

It does appear there is a second heater winding on this to power the SP210 preamp that you aren't using. Could possibly implement this as a bucking winding if the voltages are too high.





it would be the 23vct winding. Using half of it would drop about 11.5 volts or 10%, maybe a little much depending on the specifics but it could be implemented by shuffling around some wiring on the jumper plug. Jumper pin 4 to pin 3, and jumper 2 to 5. If that boosts the voltage, switch the jumpers so its 4 to 2 and 5 to 3.


I really wouldn't mind getting my hands on one of these to tinker with. I think there is more potential in these with relatively minor modding. Swap the resistor for a choke, convert it to fixed bias using that extra power supply winding, maybe mod it into a floating paraphase. Where to put the parts becomes an interesting question though, there isn't a lot of extra room in these.