Fuse fused during voltage test, passed the initial glow test. [resolved]

[dlam96]

Fuse fused when performing voltage test. Swapped a few wires and re-soldered a few cold/bad joints, but still fused again (250V 1A) the second time. Now I'm too afraid of testing again as I hope I didn't damage any components.

Took a few resistance reading:
* - ~.2-.3 MOhms for all but inconsistent readings.
3. 0.3 ohms
6. 0.3 ohms
7. 2.95 kOhms
8. 0.3 ohms
9. 2.95 kOhms
10. 0.3 ohms
12. 0.3 ohms
14. 0.3 ohms
20. 0.5 ohms
22. 0.3 ohms
B3. 2.95 kOhms
B6. 2.95 kOhms

RCA 
Center Pin
L. 101.5 kOhms
R. 104.7 kOhms
Ground Tab
L. 0.3 ohms
R. 0.3 ohms

See picture for wiring:
https://imgur.com/gallery/2OfSbSq

Notes:
1. I followed the "IF your voltage is GREATER than 115V AC and LESS than 130V AC" since my measurement was 118V AC.
2. I used a 99.3% tin, .1% lead solder which was included in the soldering kit. Should have just bought a 63/37 lead solder...

Any suggestions much appreciated,
Dan.

 

[Paul Birkeland]

You need to trim all those leads poking through the terminals, especially back where the UF4007 diodes are.  Those leads are touching things they shouldn't, and that will blow the fuse immediately.  I see lots of other leads poking around where they shouldn't be on the other 6 lug strip as well.  A proper pair of side cutters really helps with this.

Terminal 21 on the power transformer doesn't look to be soldered.

The green wires need to be twisted going from the B socket to the A socket.

The green wire going to A4/A5 has way too much insulation stripped off.  If it touches the plate, the amp won't work and eventually you'll destroy the power transformer.

1L, 2L, 3L, and 4L  are not well soldered. 5L looks like it might not be soldered at all.

If you are using lead free solder, I would suggest purchasing a small amount of leaded electronics solder.  If your soldering iron isn't at least 40W, I would suggest buying one that is so you can apply more heat to your solder joints.

 

[dlam96]

Thanks for the speedy reply, PB! Found a side trimmer in the garage and cleaned up as best I could.

I'm going to re-wire the green wires from A to B, and re-flow 1-5L. Had to order a soldering wick on Amazon, definitely too much solder on a few terminals.
One thing I forgot to mentioned about the green wires was when I stripped them, I cut too deep into the wire and exposed the copper but since I passed the glow test I thought it was fine. If you think it's an issue, I'll have to re-wire the green wire from B to power transformer (See pic with green wire to 7T, 9T on power transformer) 

As for the UF4007 diodes, I trimmed the leads but my question is can the leads going into the same terminal touch? For example, in 21U the rectifier and 270ohm resistor leads are touching but since they are going into the same terminal anyways I figured it was okay.

Pics: https://imgur.com/gallery/qJOMxpO

Cheers!

Also if you're reading this, good luck in Bonneville and stay safe, Doc!

 

[Paul Birkeland]

Yes, leads going to the same hole can touch.  I don't see any terminals in your build that have too much solder.

 

[Deke609]

It looks like you've fixed this, but I'd double check to be sure. In the first build pic you posted, it looks like the excess lead of a diode was creating a short to ground. I think a short like that would blow fuses for sure. See circled area. Note: the attached is a cropped image so you may need to expand it.

cheers, Derek

 

[dlam96]

Thanks for the feedback all.

I just re-checked my resistances after re-wiring the green wires/checking diodes. I'm getting 0 ohms readings for the expected terminals now!
Time to pop in the fuse and give it a go. Will update

 

[dlam96]

Amp works! Both LEDs lit up and bulbs are glowing Thank you all for your help and feedback! PB and Derek, you're all real gems to the audiophile community.

Pairing with my HD600 and jamming to Stayin' Alive by Bee Gees!

 

[Deke609]

Hah! Well, PB is. On balance, I'd say I'm more of a nuisance than a benefit  ;D

 

[Paul Birkeland]

That's what the boss keeps trying to tell me.