Failing resistance test at 3U

[Jlevine11]

Hi - I got my kit all assembled.  Doing my resistance checks, and I’m getting nothing at terminal 3.  All else looks fine.  I checked the red wire from ot-2 to terminal 3U, as well as the capacitor.  Any ideas?  Thanks.

[Paul Birkeland]

How about the resistance at 11?  Terminal 10 on the OT?  Terminal 5 on the OT?

[Jlevine11]

I’m also getting no reading at Terminal 11 and at OT 10.  OT 5 I’m getting a 0.

The B side seems to be all reading correctly.

Thanks for your help.

[Paul Birkeland]

I'd be interested in seeing some build photos.  There's either something not quite wired properly on one channel, or debris causing weird readings.  In either case, this amp will be a fuse blower if you try to turn it on, so we'll have to figure out what's up first.

[Jlevine11]

 Couple of notes - I accidentally clipped the brown/white pair coming off 6 & 7 and replaced those with a blue/white pair.  As a result, I didn’t have enough blue/white at the end, so I subbed a piece of orange/white off the volume pentometer. I hope that’s not too confusing.

Let me know if I can send any clearer photos.

[Paul Birkeland]

There's a random wire poking out around terminal 3, what is that?  I would use a lot more heat and resolder all the joints on the terminal strips up front.  The lower joints in particular look not at all flowed out.

[Jlevine11]

Thanks - I think that did the trick.

On the question of the random wire, that’s the black wire coming down through the chassis that I clipped and head wrapped.  I can’t seem to find a good place to tuck it out of the way. Any suggestions?

[Paul Birkeland]

This one?

[Jlevine11]

Sorry - no.  That was a random clipped lead that was lying on the chassis.

I resoldered a few areas, and A side is now looking good.  I have unfortunately now lost some of my B side.  Specifically I’m failing at 17 & 24 - getting no readings on either.  Any suggestions?

[Paul Birkeland]

I would reflow all of your joints.  When your readings change as you move the chassis around, that's an indicator of loose components that aren't properly captured by solder.

[Jlevine11]

Thanks Paul.  Any chance you’d be up for a quick FaceTime call to make sure you’re not seeing something obvious that I’m missing?

[Deke609]

Also check this area out - see yellow arrow in attached pic. it looks like an unclipped resistor lead may be contacting the socket frame and grounding out.

I'd follow PB's suggestion of reflowing all the joints with A LOT MORE HEAT. Of the solder joints that are visible in your posted pic, I'd say at least half look like "cold joints" with a lot of "solder blobs" -- i.e., solder has been melted ONTO the joint, but not INTO it.  More heat and making sure that the soldering iron tip contacts both the wire and terminal/lug at the same time should fix this.

cheers and good luck, Derek

[Jlevine11]

Thank you - will give that a go