Resistance (ohms) failure

[rogerthatmand]

Hey guys, I'd like to get some help. I finished building the Crack but I have some issues with the resistance check (the first step, the ohms).
I have a volt-ohm-meter which I configure to 20K Ohms:

Terminal 6, 10 - gives me 1.2K, instead of 2.4K.

Terminals 14, 20, 22 - Doesn't show me nothing, instead of 0.


Everything else is perfectly fine.
I doubled checked, I tripled checked and everything is soldered really well and everything goes exactly where it belongs.

P.S - I did the REVISION part where I attach to terminal 14U instead of 22L, and I soldered it at the end of the procedure of building the Crack :

"REVISION 5/6/10:
Making this wire 3” long and
connecting it to Terminal 14U
instead of terminal 22L may
yield more quiet operation."



Please help me enjoying my Crack working as it should be 

 

[fullheadofnothing]

This sounds like a bad solder connection or mis-wire somewhere on your ground buss (aka the black wires). The manual says to connect the black lead of your meter to terminal 12. There is a piece of wire that joins 12 and 14, so if you do not have 0Ω between these two points, something is clearly wrong.

 

[rogerthatmand]

Thank you for the comment. I'll check that out.

And what about terminals 6, 10, which gives me 1.4K instead of 2.4K?
(Besides, is it OK that my meter only has a 20K-200K-2000K option and not 10K-100K-1000K option?)

 

[rogerthatmand]

Then I can assume that Terminal 6, 10 are also faulty?
Since I get 1.2K, while at the manual it says 2.4K...(?)
What could be possibly the reason for that?

 

[rogerthatmand]

So the ohms test was OK, then I move over to the volt testing, power on the amp, and after a few seconds the tubes glowed and smoke came out.

I guess there's nothing I can do now and it's total loss?

 

[fullheadofnothing]

What did you do to resolve your resistances?

Smoke is a sign that something is in backwards or otherwise improperly connected. Can you post pictures of your build?

 

[Doc B]

It's not a total loss, but we need more info to help you sort what happened. Yeah, pictures of the wiring around the power supply in particular would be good, and some of the sockets might help too.

 

[rogerthatmand]

Actually I did nothing to resolve the resistances. It seems that I didn't check it right. Right after I put the negative lead to the 12L, everything was OK.
Except, terminals 6, 10 still gives me 1.2K instead of 2.4K.
In addition, terminal 13 doesn't raise slowly towards 270K, not even close. Barely pass the 1K actually. But since the manual had asterisk sign, I assumed it's OK.

The smoke came out of the transformer, after a few seconds when I power the amp on.
Here are some pictures:

http://imgur.com/a/293t7

(I created an online album since it crashed twice when I was trying to upload it here)

 

[Deluk]

Black and red shorting on transformer to the left of the 5W resistor on picture #1?

 

[Strikkflypilot]

Any solder on 12L?

 

[Grainger49]

Any solder on 12L?

I have noticed on a number of terminals the solder is used like chewing gum to stick the leads or wires in place.  It is a good practice to wet the terminal till it flows through the hole. 

I suspect you have a number of "cold solder joints" in your build. 

But those would not cause smoke.  They would cause no voltage in a number of places.  We haven't found the answer.  Although the transformer wires in the first picture, as Deluk points out, makes it look like those terminals are shorted.  Try measuring resistance from one lug to the other.  It should be low but not under an Ohm.

 

[Paul Birkeland]

Except, terminals 6, 10 still gives me 1.2K instead of 2.4K.

Can you add some photos of the relevant parts of the amplifier for this particular issue.  (One of the headphone jack, then another of the terminal strip/octal socket combo)

There is a potential miswire that could cause this issue, and it would be quite tragic if you were to power up the amp under these conditions.

 

[richmi]

The five-colour code for the resistors on the headphone jack should be red, yellow, white, brown, brown for 2.49k ohms.

I looked at the Crack's part list and could not find any resistor with a value of 1.2k ohms. You would have to have two 2.49k ohm resistors in parallel to get half the value.

Perhaps, you created a bridge between the red and white wires at the headphone jack.

Richard

 

[rogerthatmand]

Thank you very much for the response.

I actually didn't understand what you meant by "red black wire shorting" in the first picture. What's exactly is wrong again?
And do you think the soldering isn't good enough? I really tried to bend the wire into the hole so it would stick there, and only after that I soldered it.

And here's another album of the other terminals (plus some headphone jack pictures):

http://imgur.com/a/sBzBA

Thank you again! I'd be glad to get additional help to solve my issue.

 

[Strikkflypilot]

Hi!

You have very much solder on several joints, especially obvious on the jack connector.
Some kinds of solder are hard to work with. Do You know what kind You have?

I have learned a great deal from these professional but easy to grasp videos: https://www.youtube.com/playlist?list=PL926EC0F1F93C1837

Also some of Your leads are dangerously long, and should be stripped.

Anyway, I know it is hard to slow down the build, but I am sure You will get the hang of it. It all comes down to practice and quite a bit of patience.

All the best and good luck!

 

[Paul Birkeland]

Here are some things I would work on. 

Can you use your DVM to measure the resistance from terminal 3 to terminal 7?  How about terminal 3 to terminal 9?

-PB

 

[2wo]

Also, on the tube socket is the white wire at pin 2 touching pin 1? may be labeled A1,A2, not sure...John 

 

[Rocketman248]

What's the wattage on your soldering iron.  It looks as though your iron is getting just hot enough to melt the solder on the tip, but not hot enough to adequately heat the junction.

 

[Strikkflypilot]

And make sure You have standard issue electronics solder (60/40 tin/lead) with rosin core.
None of that silver crap, damn hard to work with.
I read on a product page it would flow better than standard solder.
Still waiting for that to happen

 

[rogerthatmand]

Guys, the frustration is strong with me.

I double checked everything you mentioned. I did fix everything you suspected was wrong (the white wire at the headphone jack seems to touch other wires actually).
But again, I tried to power it on and again - smoke.

The smoke is coming out of the transformer only! nothing else. It seems like the transformer getting over heated.
Any suggestions now?