The Amp Garage

Kudos for doing all of your own work on this!

Got a link to the data sheet for the RN60's you used?

This thread belongs in the Discussion section. Can someone move it?

I'm becoming quite happy with my other YGL-3a that was completely gutted and converted to an SSS... I'm feeling like this YGL-3a finally deserves a proper conversion to an ODS circuit. ...I think I am missing out without fulling embracing some ODS preamp and perhaps a more classic overdrive circuit...

Bought the parts that go in the Skyliner as opposed to the #124. Should still be a great amp No doubt, the #124 Skyliner version (that is what you mean to say, I think) is a great amp. The schematic and layout are here, https://ampgarage.com/forum/viewtopic.php?p=55006#p55006 with the first schemat...

award70 wrote: ↑Thu May 02, 2024 11:34 pm Here it is installed in my UTracer 3+. No leaks!

You are welcome, and it's nice to see it's installed and working! I guess you were able to find a bi-color LED that works. Separate LED's are also a possibility.

Are the two jacks above the T/N switch an external heater supply?

Raoul Duke wrote: ↑Sat May 04, 2024 3:50 pm Am I reading this right?

Yes, I think so. Compare the eyelet boards .pdf. Basically, wrt the layout, the NO and NC's are swapped for "OD on" when the relay is energized.

Another common source of noise/hum is the loop jacks. If the switching contacts are dirty, you will get hum in the speaker. A good way to test for that is to put a patch cord across the send-return jacks.

Same person made a working CRT from scratch too.

Just tried lifting the resistor and cap leads and run a wire to the speaker ground as you suggested. That actually made the hum worse; back to more or less the same level as when the OD section of the preamp ground was connected to the speaker/OT ground. Not sure why that would be, maybe some other...

There is one part of the above experiment that won’t be optimum, and that is the phase inverter ground, at the junction of the 390 ohm resistor and 2.2 uF cap. That belongs to the power amp, and should be grounded where the OT secondary common is grounded. The short under-board jumper tying that eye...

Shields are the outer braid on the coaxial cables going to and from that pot. I think you can try this as an experiment. Disconnect the wire at the red X, and add a jumper on the main board as shown by the red arch. This seems to be the least invasive way to test the theory. Once you do that, you ca...

Flipping the slide switch layout it looks ok to me.

Yea, not a good idea. I'd ground the shields and the OD trim pot at the input ground eyelet at the center of the board near the 220k. That's probably why grounding the speaker/OT common at the front of the chassis worked well.

Can you post that whole C-tone diagram?

On the snip you posted above, there is an "OD trim pot" connected to the OT common ground. I assume that is the OD entrance trimmer, and I suspect that is the reason it is so sensitive. I would separate that and ground it with the preamp grounds.

You are correct! ~12V higher at 200 mA.