Another 610 schematic question - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Another 610 schematic question (/showthread.php?tid=22574)

---

Another 610 schematic question - Patrick - 06-21-2021

Working on another 610 and I need to get my mind straight.

The chassis is wired similar to the later model, but with a few exceptions. Thought I'd touch base on 3 items first.

First, there is no phono switch. So can I assume the top of the volume pot connects between 31 (51K resistor) and 32 (the lower 110 mmf cap)?

Second, the existing chassis has the cathode of the 78 tied to ground (looks like factory wiring).Where should it really go?

And last, on the existing chassis, the cathode of the 6A7 goes through a 20Ω resistor to ground. Neither schematic shows that.

Got more, but Ithought I'd try these out first.

Pat

[Image: https://i.imgur.com/xnCAN3q.jpg]

[Image: https://i.imgur.com/NdRdTAS.jpg]

---

RE: Another 610 schematic question - BrendaAnnD - 06-21-2021

Your chassis would seem to be an interim production between the two schematics. This isn't unusual.

1) You are correct.

2) In the late production, the cathode of the 78 goes to ground through the phono switch. The original had it connected to a network. I suspect that somewhere in between they modified it to go to ground.

3) As the 6A7 cathode is going to ground through a 300 ohm resistor while late production goes directly. As with the other modifications, this was most likely an interim change while the engineering department was tweaking the performance specs.

---

RE: Another 610 schematic question - Patrick - 06-21-2021

Thanks Brenda Ann. I'll make those changes and see if there is anything else.

---

RE: Another 610 schematic question - radiorich - 06-22-2021

Hello Pat ,
Yes I don't remember what production model of 610 mine is.
But they sure great sound little set and looks great after refinishing it to mine is the 610B

---