New Build Will Not Power Up. [solved] ( Solved for real again. I hope!)

[Mordicai]

Any suggestions will be appreciated. Finished the build this morning. All resistance checks were o.k. Tubes do not light up. Fuse is o.k. Did the ground tests talked about in an earlier post and everything checks out. Checked all connections 5 times and touched up a couple of joints, but really everything looks o.k. First instict is to turn it on and start probing with the voltmeter to see where I have power but thought I should ask some advice first before I screw it up......Max

 

[Paul Birkeland]

If the tubes don't light up, you need to trace your AC voltages. 

You should have line voltage (120V or 240V AC, depending on where you live) at power transformer terminals 1 and 2.  To measure this, you need to set your meter to AC volts on a scale that is large enough to display these values, then put one probe on 1 and one probe on 2.

Next, check the AC voltage at power transformer terminals 4 and 5.  This is the source that makes your tubes glow.

Report back and let us know what you find.

-PB

 

[Mordicai]

I have 123 at the switch, and after checking it the tubes lit up. Go figure. Thanks for the repley. Hopefully all be ok...max

 

[Paul Birkeland]

You probably have a loose solder joint back there.

Keep us posted on anything else that pops up.

-PB

 

[Mordicai]

Paul, thanks for you help. I have found the problem....I am sight challanged( one eye) so doing your kit is a fun challange with no depth of field. Seems that in snipping off the extra wire on transformer # 4 I cut the lead leading down into the transformer. I have 120V at 1 & 2, 5.8V at 4 & 5. The transformer lead is actually just barely touching each other. So....How do I fix it? Solder it; solder on a wire jumper buy a new kit; find  new hobby??? Thanks Max.

 

[vetmed]

If you have enough slack and can get a pair of wire strippers where your break is strip a short piece of insulation off each end and solder together. If you are concerned about the newly exposed connection shorting to other things then slip a short piece of shrink tubing over your wire before soldering. Slide the tubing over and shrink, I find a hair dryer set on high works fairly well. You can probably get shrink tubing at Radio Shack or similar outlets, you likely will have to buy a lot more than the inch or so you will need ;D Cheap at the price and you will have extra on hand for covering exposed connections, whether deliberately or inadvertently made

Regards
  Robert Lees

 

[Mordicai]

Hi Robert, I'm a little confused. There isn't any insulation on the lead coming from the Tranformer that I can see. Its just a thick metal lead. I just don't know if just soldering that small gap be sufficiant.

 

[Doc B]

Yes, you can carefully solder the cut ends back together.

 

[Mordicai]

Thanks Doc

 

[Grainger49]

Be certain to remove the "varnish" on the wire before soldering.  It is the insulation.  Try a little sanding.  (Not possible as Dan says below)

 

[Doc B]

Grainger, sanding the hair thin wire barely protruding from the transformer coil that we are talking about is not going to be possible or desirable. Max, just get heat on each of the thin wire ends just long enough to get each one lightly tinned as the varnish melts off and then tack the tinned ends together.

 

[Mordicai]

Still trying to get this puppy fired up. All resistance checks are good; all voltage checks are good, but no sound at the phones. Anyone know what the voltage should be between 4 & 5 terminal on the Tranformer?

 

[Paul Birkeland]

Do the tubes glow?  Between pins 4 and 5 on the power transformer, with tubes in the sockets, the AC voltage will be between 5.8 and 6.3V.

-PB

 

[Mordicai]

Thanks Paul, I have 5.8 So all resistance and voltage checks are good. Resodered RCA's, still nothing over the headphones.No noise, no static. I'll try a new power tube in the morning. Good learning experience.

 

[Paul Birkeland]

Thanks Paul, I have 5.8 So all resistance and voltage checks are good. Resodered RCA's, still nothing over the headphones.No noise, no static. I'll try a new power tube in the morning. Good learning experience.

If all the voltages are what they should be, then the power tube is working.

How is the resistance between center pin and shell on each RCA jack? 

I would also be pretty suspicious of the solder connections on the headphone jack, as those can be somewhat marginal and the voltages can still look OK.

 

[Mordicai]

Paul, after another round of checking everything including RCA and headphone jack connections I fired it up again with no luck. An RCA nos tube I ordered on the net arrived yesterday, so I stuck it in and the amp works like a champ. After listening awhile, I wanted to try the original tube again. As soon as I turned the amp on the tube started sparking and spitting until I could get it off. I am relieved that my two days of abject failure are over and I can enjoy my well build Crack...Max

 

[Mordicai]

Three hours and just getting better and better. Boy this thing rocks! Everything is so smooth.