Crack Voltage Too High [resolved]

[Nignoog]

Hello friends,

I recently completed my Crack build. Resistance tests passed. However, the LEDs do not light up when I power it on, and when I tested the voltage, my results were unusually high on terminals 1, 5, 7 and 9. All four of them read 148V. The other terminals were fine. I gave all the wires a jiggle test. I checked the soldering on all my joints and touched up a few that were poorly covered. But still, no luck. I am bummed I couldn't get it to work, but I am looking forward to resolving it so I can dive in to some tunes! Any help or advice would be greatly appreciated. Thank you!

Voltages:
T1 147
T2 165
T3 0
T4 165
T5 148
T6 0
T7 148
T8 0
T9 148
T 10 0

[Nignoog]

I uploaded a bunch of pictures. I am not sure what to focus on or what needs to be sign to help with the diagnosis, so I took a few from different angles. Happy to upload more if it helps. Thanks again to whoever reads this.

[Paul Birkeland]

Here are a few things to do to get you up and running.

1.  When you install a component, you need to trim the leads.  The photos in the manual are a good guide for this.
2.  The wire at A7 has too much insulation stripped off (the manual calls for 1/4", that looks more like 1/2") and it's touching terminal A8.  We refer to this as a "short".  This should be remedied before you try powering up the amp again.
3.  The solder joint at A9 is likely preventing the 12AU7 from heating.  Did your amp pass the glow test on page 31?
4.  There's a component lead coming out of 9L that appears to be touching the chassis.  This will damage the amp if it does touch the chassis. (It looks like 7L has a similar potential issue)
5.  If the black wire leaving the headphone jack and heading over to terminal 3 is not secured by the solder at the connection to the headphone jack, you'll have some issues like those you are experiencing.
6.  2L and 3L need to be reflowed.  Make them look more like 4L.  Heat is your friend for this.
7.  The solder joint at B8 looks like it may not be functioning.

[Nignoog]

Thanks for your prompt response.

1. I did the best I could but the only tool I had to cute the leads was on my wire stripper and I couldn't do an adequate job clearly. I have some scissors that can get in closer to the joint but they won't cut through wire. Should I invest in another tool to clean up the stray leads? If so, what?
2. I tended to give myself extra slack later in the build since I was getting the insulation really close to the soldering joints. There is now space between A7 and A8.
3. The amp passed the glow test. Both tubes light up in on both sides.
4. Good eye! Both of the 10W 3K resistors have their wires sticking out because I didn't trim them short enough but I curved and curled them to ensure they are not touching anything.
5. The solder connection looks pretty thorough and complete to me. No visible gaps and when I tug, it's stuck pretty well.
6. I will give it a touch up.
7. Is there any way to test it? Should I add more solder? Maybe remove some?

Thanks again for your help, it's very much appreciated!

[Nignoog]

Touched up the soldering in the locations you mentioned and made sure no stray wires are were touching other terminals, but still no LED activity and the voltages still read the same as when I first posted.

[Paul Birkeland]

To trim the wires, I'd recommend a proper wire cutter. Here's an example:
https://www.mouser.com/ProductDetail/Plato/170?qs=sGAEpiMZZMuqHt7hmXVVHuxRWIVYEtqjZUxggsptywk%3d

B8 has one wire that looks unsoldered.

If your tubes are all glowing and you have high voltages at terminals 1 and 5, that indicates that there is an issue with the black ground wires that go between each 6 lug strip and wander up to the headphone jack, then over to terminal 3L, then to the volume pot/center pin of socket A.

[Nignoog]

I am going to upload some pictures.

[Nignoog]

I am getting an HTTP 500 error every time I try to reply to my post from yesterday with more uploads so instead I have uploaded the other pictures to an imgur album found here: https://imgur.com/a/Kj7hwn1

I am hoping that through the pictures posted here and from yesterday, someone more knowledgeable than i can help me better diagnose whether I need to clip some leads, un-solder, re-solder, or do something else. With my lack of experience, I am hesitant to perform surgery without being properly informed.

It seems like a lot of other posts with this problem have have simple solutions so I am going to go back through the manual and retrace my steps to see if there is some small error on my part. To anyone who helps, thank you, I really do appreciate it. 

[Paul Birkeland]

I would heat up and reflow all of the joints where more than one black wire meets.  I see a couple different contendors that could cause the issues you're having.

[Nignoog]

I think I have made a little bit of progress because the A3 LED is now lit, but Terminals 1 and 7 still give a slighter higher voltage reading than before. Here are my new voltages:

T1 152
T2 171
T3 0
T4 171
T5 77
T6 0
T7 153
T8 0
T9 105
T 10 0

Should I send more pics of my reflowing job? Or are you able to diagnose the problem just with the information provided. Thank you again! I am excited to have made a little progress!

[Nignoog]

I figured I would just upload a few pictures for the discerning individual who can help me figure out why Terminal 1 and 7 are so high.

Link to 5 pictures with updated soldering: https://imgur.com/a/TUA8ryI

[Paul Birkeland]

I would guess that your LED at A8 has been damaged by the amount of rework that has been done to this amp.

Once you have a pair of side cutters that will allow you to clean up those component leads, you can wire A3 to A8 to bypass this issue.

[Nignoog]

Thanks for your response. I am not surprised to hear it. I am fairly confidant that I touched the solldering iron to the LED during the initial installation. I will do as you say and report back tonight or tomorrow.

A few follow-up questions:
1. Is purchasing the clipper and trimming all the lead slack necessary or more of a precaution for future use?
2. Is there a way to test and verify the LED is actually fried?
3. Would it be prudent to buy an LED and replace the broken one? Or is your A3–>A8 fix just as viable? Forgive my ignorance, but should I be concerned about any audio or technical issues arising from your suggested fix?

Thanks for all your help. I cannot wait to get this crack up and running!

[Paul Birkeland]

1. Is purchasing the clipper and trimming all the lead slack necessary or more of a precaution for future use?

Absolutely necessary.

2. Is there a way to test and verify the LED is actually fried?

A bad LED will make 12-13V on A8, but it can be hard to get your meter probe in there.

3. Would it be prudent to buy an LED and replace the broken one? Or is your A3–>A8 fix just as viable? Forgive my ignorance, but should I be concerned about any audio or technical issues arising from your suggested fix?

Either or.  Having one LED on and one LED out is a helpful diagnostic, but having separate LEDs isn't completely necessary.

[Nignoog]

That seems to have done the trick! Resistance check still good. New voltage readings are as follows:

T1 83
T2 178.5
T3 0
T4 178.5
T5 80
T6 0
T7 110
T8 0
T9 108
T 10 0

My last question is in regards to temperature ranges that are safe. I used a laser infrared thermometer to take the temperature of different parts of the crack. The power supply hit about 120 F, the large tube broke 200 F, the small tube hit about 140 F, and the topside of the chassis hovered at 95 F. It's a lot of ambient heat. Because this is my first tube amp, I don't know what is normal. At what temperatures should I start to be concerned?

Lastly, thank you so much for your help. This is a truly glorious piece of audio equipment and I am indebted to you, Paul, for your quick, articulate answers. There is a special place in heaven for people like you. Let's mark this [solved] and I will move on to installing the speedball soon!