[Wire Nut]

There is a post called Jolida Modifications from way back when I first started modding stuff, I had a 302 then and someone said I could run KT88's if I changed the resistors. The recommended R14 & 15 and stated the 302 & 502 were the same except for those resistors.
I now have a 502 that I got in "as is" condition for a good price and want to run a set of EL-34's that I had from a VTA Stereo 70 I built. The trouble is that my slots for R14 & 15 are empty- so my question is on my unit are R10 & 11 the ones I need to change?
Thanks!

[FullRangeMan]

Any 502 schematic?

[Wire Nut]

here you go

[Wire Nut]

Here is a photo of my board with the R14 & 15 spaces empty:

[FullRangeMan]

IMO its the R10 & R17 at right near the tubes V3, V4.

[Wire Nut]

That is actually a 11 not 17- may be hard to see in the pix

[mjosef]

While you have the circuit board out you should replace those trim pots, they are oftentimes responsible for the bias shooting up as it loses contact with the internal track...red plating tubes. A 10x or 20-turns 30Kohm Bourns trim pot will give more precise bias settings. Got that tip direct from Jolida when I was upgrading my rebuilt Jolida Signature Reference 3205

[Wire Nut]

I looked those up and they do not look like they will fit in the holes for the screwdriver to go in? Anyone else have a 302 or 502 that have changed them?

[mjosef]

Yes they will, they did say you have to be creative to adjust the leads so the adjusting screw is centered. like so

[mjosef]

I did a lot of parts upgrades, like replacing the cheap brass rca inputs and the speaker terminals, also the AC input, the tube sockets, even the signal wiring.
The sound is way beyond what the Rebuilt Response Audio did.

[Wire Nut]

I am doing the film caps, the signal wire, silver plated RCA connectors and new 5 way binding posts as well.

[mjosef]

That's good, the signal path improvements will thank you.
Here a pic of inputs/output terminals. I converted mine to be just a power amp bypassing the volume and selector pots...100k resistor to ground. I favored the cardas Rhodium RCA over the gold plated RCA( can't remember brand).