Resistance low at terminal 1 and 5

[Rican]

Ah-ha! If I set the rocker switch to input 2, I get 39.7K on terminal 1 & 5 (with red & white wires re-attached). Input one gives me 19.7K ohm on terminal 1 & 5.

So, I assume this means either the switch, wires, or rca inputs running to input 1 is bad? I've checked continuity to all solder joints running to the switch from terminal 1 & 5, and from the switch to the RCA inputs. I do not see any resistance on those, and they pass the continuity tests. This makes me think the culprit is internal to the switch or the rca input itself?

For now, I assume I can just use input 2, do voltage tests, set the bias and use as is?

I have more of the cat 5 wiring. Should I order a new input selector switch and a set of inputs?

[Paul Birkeland]

No, that does not mean that the problem is in the switch. 

Can you measure the resistance to ground between the loose red and loose white wires that went to terminals 1 and 5?

[Rican]

I get OL on both loose red and white from when measuring to ground. Tested in all manual positions of the meter, and tested with both meters.

[Rican]

I tested with input selector in both positions.

[Paul Birkeland]

The difference in resistances at 1 and 5 with the switch in different positions tells me that there's an issue with the input wiring or the soldering at one or more of the RCA jacks on the back of the panel. 

Seeing OL on the red and white wires once they are removed and seeing that the resistances of the attenuator resistors now read correctly is a contradiction. 

There is an issue between the RCA jacks and terminal strip 1-5.  It could be some CAT5 wires that are melted together and touching (maybe intermittently) or some kind of solder bridge on the RCA jacks.

This kind of problem is nearly impossible to encounter from a bad toggle selector switch.

[Rican]

That makes sense.

I'll go over all the solder joints again, and if still persisting, will re-wire that whole section.

Much appreciated!!

[Paul Birkeland]

No, it's not recommended to infinitely reheat the solder joints.  I suspect that could create more problems.  Try untwisting a few more twists of the CAT5 wires if you can to be sure they aren't touching.

[Rican]

I found a couple micro nicks on the blue twisted pair. Unfortunately, cutting down to clean wiring made the blue wires too short. So I had to very carefully de-soldered and replaced the entire run of cat 5 cabling to the selector switch and RCA. I gave myself another 1/4 inch on the cable run so it wasn't so tight a fit and was extra careful installing and soldering those back in place.

I'm now measuring 39.5K ohm on terminal 1 and 5 with either input selected. All resistances check out. Voltages check out. tubes are dialed in at 145V.

AWESOME! So, I am totally operational now. Thank you so much for the help PB!! You saved me many hours of trying to figure this all out, and I very much appreciate it.

It is sounding great. So far, I hear a little less bass extension than with my Lyr+ amp. But the clarity and detail of the mainline is amazing. There is a lot of high end attack, but well rounded at the same time.  A very wide sound stage with excellent instrument separation that is especially noticeable in busy and congested parts.

I am using HE1000 stealth cans which I believe are 32 ohm. The mainline definitely pushes those as hard as I need it to. I was a little worried, given the low impedance and these headphones can be a little power hungry. I do get close to max volume for some songs, but 0db would be too loud for my ears.

I'm already wondering about upgrading the coupling capacitors now.... How long would you guys say the Dayton's took to fully break in? I don't want to mess with capacitors until I have some time on the stock mainline and it's fully broken in.

[Paul Birkeland]

I would give the caps ~100 hours or so before considering replacements.  I'm glad you were able to find the issue without a ton of work.

-PB