Resistance (ohms) failure

[Doc B]

Folks this is another of the situations that happens occasionally where a lot of people are showing really good intentions in offering suggestions, but I fear the OP may be getting overwhelmed by all the posts. I would respectfully suggest we let PB work with the OP to sort this one in a methodical fashion.

Roger, don't turn the amp on again until PB posts some guidance. At this point the transformer is probably just fine, but a short somewhere else in the circuit is forcing it to draw way too much current when you turn it on. Eventually that will fry the transformer, and we need to figure out where the short is before running it for any duration. Now that you have resoldered a lot of the connections your best bet might be rechecking all of the resistances and posting any deviations.

 

[rogerthatmand]

Thank you for the comment.
I'll check again everything. But can you please explain what do you mean by "PB"?

 

[Strikkflypilot]

PB is Caucasian Blackplate AKA Paul Birkeland.
The one to listen to here.

Good luck BTW!

 

[rogerthatmand]

Oh, ok.. thank you very much.
By the way, about the ohms testing, the black (negative) lead should be placed at 12L all the time? and the red one at the target terminal?
I'm not 100% sure what should i do with the black lead of the meter and I didn't quit understand it from the manual.

Thanks again in advance.

 

[Strikkflypilot]

I know it can be hard to slow down when building this great kit.
The manual is however very clear on this. Page 37 under resistance check tells You to attach the black test lead to ground and preferably terminal 12. Use a clip lead or gator clip so You can concentrate on hitting the right terminals with the red probe.

 

[Paul Birkeland]

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? 

Did any of your faulty measurements clear up with some reworking of the amplifier?  Failing resistance checks generally indicates that the amp will blow a fuse when you try to power it up, so there's no need to do that until we clear up the majority of these issues.

I can't quite see for sure in your photos, but it's possible that the 270 Ohm  resistor that crosses over the power transformer may not be connected to the correct terminals.  That in and of itself would be enough to blow fuses endlessly, and that resistor would get nice and toasty in the process.

-PB

 

[Deluk]

The pictures of the jack plug certainly seem to show a small solder blob  joining the top two wires, the red and white. PB has circled it on one picture but it's more obvious on one of the other Imgur ones.

 

[rogerthatmand]

Thank you again for the comments! really appreciate it!
I'll go check soon everything you said.

But please - I'd like to know about the testing - How should I really check the ohms with the meter? I'm not sure about the manual explanation.
Should I touch the black negative lead to 12L? I don't really understand the meaning "To the ground of terminal 12". By "ground" it means the plate itself?

It seems that I don't do the checkings right..

And what do you mean by "installing backwards"? Does it matter the direction I put the wire in the terminal?


Looking forward for replies,
Thanks a lot!!

 

[Grainger49]

Try this sticky:

http://bottlehead.com/smf/index.php?topic=4812.0

I think if you go through this you will either verify your ground or find where you have problems.  It traces it as you should have it wired. 

Where I say "Clip your meter lead" I want you to use an alligator clip jumper to connect the black lead and the first ground point.  If you don't have one you need some.  Go to Radio Shack and buy some.  They are cheap and very handy. 

 

[rogerthatmand]

Thank you, but I forgot the most important question I had  ;D

How do I check for shorted circuit? I truly believe there's a problem somewhere with shorted circuit at the transformer area.
I don't know what I should do to check it right.

 

[Paul Birkeland]

Thank you, but I forgot the most important question I had  ;D

How do I check for shorted circuit? I truly believe there's a problem somewhere with shorted circuit at the transformer area.
I don't know what I should do to check it right.

You perform the resistance checks.