New builder / blown fuses / a touch of smoke

[Agweeks]

Hello all:

I am building a kit for the first time.  I measured the voltage as instructed early on in the build.  It measured low and so I wired the kit in accordance with the first set of instructions. 

I have completed the build and was attempting to perform the resistance checks but it gave up a bit of smoke from the 220 capacitors and blows fuses. 

Please help.

AGW

 

[Agweeks]

Here are some photos of the amp.

 

[Paul Birkeland]

What part of the world are you in?  What was your measured wall voltage?  Which of the transformer voltages did you select for wiring?

All of this may have nothing to do with your problem, if there are wiring mistakes (like a backwards capacitor or diode), you could create the same problem, so posting some photos of your build would help too.

 

[Paul Birkeland]

You have a miswire on the 9 pin socket.

Your amp had to have failed the glow test.  Half of the 12AU7 will not light up. 

 

[Agweeks]

I'm in the united states.  Arkansas actually. 

AGW

 

[Agweeks]

Please understand that I am a total nube. I’m posting a photo of the multimeter to make sure I am measuring with the proper setting. I used the alligator clips to measure voltage using the meter set to this setting and it initially showed a little less than 100 volts. I thought that was strange but I’m in the country, new house, just in the sticks.

 

[Agweeks]

Photos

 

[Agweeks]

I’ve fixed the wiring to the 9 pin socket.

Thank you.

AGW

 

[Deke609]

Photos

You've got the red meter lead plugged into the current ("A") socket of your DMM. You need to plug it into the one on the right with "V", etc.

cheers, Derek

 

[Paul Birkeland]

You've got the red meter lead plugged into the current ("A") socket of your DMM. You need to plug it into the one on the right with "V", etc.

A little more on this, the "A" socket is for measuring current, and there's a current shunt between that socket and the black socket that is a very, very low resistance component.  As soon as you touched that red probe to a high voltage terminal, that current shunt will blow your fuse immediately.

You're still missing a wire on your 9 pin socket. 

Since you are in the US, even if your line voltage is 120V and you wire for 110V mains, this isn't going to create immediate problems, so no worries there.

 

[Agweeks]

You've got the red meter lead plugged into the current ("A") socket of your DMM. You need to plug it into the one on the right with "V", etc.

cheers, Derek

Thank you so much.  That fixed my measurement issues.  My current at the outlet is 122 v.  I'm off to the hardware store, hopefully to get 1 amp fuses.  I'll rewire the transformer to match the voltage later tonight. 

I really appreciate your help you guys.  Happy holidays.

AGW

 

[Agweeks]

I now have no volume in the left channel.  I read other posts on similar issues and have attempted to follow those suggestions.  To that end, I have played a 60 hertz signal through the amp.  I get signal that is almost even at the rca jacks.  It is similar at the volume pot.  Then the right channel is the same in the middle.  The left signal gets super weak in the center of the volume pot and continues on through to the preamp tube.  I've flowed and then resoldered all the connections.  The problem persists; it's late; I'm out of ideas.  Please help.

AGW

 

[Zimmer64]

Double check the wiring on the volume pot.

 

[diynewbie]

In your original pictures, the white wire on the 8 pin socket (nearest the transformer) is on the wrong lug.  Was this fixed?  As Paul wrote, it looks like there is a wire missing on the nine pin socket.  Every terminal on both sockets should have a wire attached.

 

[Agweeks]

After examining the circuit over and over again and reflowing all the joints, I discovered one of the legs of a capacitor was broken. I soldered it back together and the amp works.  Woohoo!

I assume that I need to replace the cap and will do so.

Thank you to everyone for all the help and support. I appreciate you.

AGW

 

[grufti]

You should be just fine as is. It works! There is no real need to replace anything, if all resistances and voltages check out and nothing rattles you're good.