Help with fuses blowing at startup

[Ankaret]

I assembled my crack (first DIY kit like this) a few days ago and just can't seem to get it running, the fuse keeps blowing. Im using .5 A 250v slow blow fuses from radio shack. I completed the resistance check and everything checked out as it should. It doesn't make sense to do a voltage check since the fuse is immediately blowing, right?

Here's what Ive done to troubleshoot:

First time I fired it up a fuse blew. Second time I replaced the fuse and the tubes lit up just barely (not a full glow), and something around 13L/14L gave off some smoke. I immediately unplugged. I should also mention that this time the power transformer got very hot very quickly, to the point of beginning to heat shrink the numbered Bottlehead label stuck underneath it. The label is still on, but it's all bubbly now. Do you guys think I need a part replaced given the smoke? How to test and figure out which part needs replacing?

Some more info of what happened...

AFTER THIS...

1) I went through carefully to make sure things were all soldered solidly and no excess wires were touching anything they weren't supposed to. I found that I had forgotten to solder one end of the 270 5w resistors (15L) and a couple hooked wires on B8 and B7, so I soldered those.

2) As I went through the manual again point by point to see if Id missed anything, I noticed I had one of the bands going the wrong way on a rectifier diode (specifically, 20L and 18L were reversed), so I flipped that diode around to correct it.

3) Nothing else I could find, I did the resistance check again and everything is reading as it should be, but trying to fire it up the fuse blows on me immediately as I plug it in still...

Thank you in advance for any troubleshooting help!

[STURMJ]

switch to 1A fast blow, I believe this is a bottlehead approved fuse. I had this problem too and the 1A fixed it.

[Ankaret]

Ok Ill give this a shot tomorrow. Thanks!

[mcandmar]

Do NOT do that, if you have a short the last thing you want to do is put a higher rated fuse in there until you fix the problem.  Its possible the capacitor or transformer could be damaged so i would wait for a bit of guidance from the BH guys before doing anything.

[Paul Birkeland]

It's entirely possible that you have one of the 220uF caps in backwards. 

Often times, posting photos of your build can help us pick out what might be amiss. 

[Ankaret]

Ok I tried the 1A fuse today (before reading the above post about NOT doing so...) and still blowing. I also re-soldered/checked the direction of the caps and as far as I can tell it looks right.

Have no idea what's up, what to do? Below are some pics. I know the build is not very clean, but I was careful with solder joints and took my time and made sure things went where they were supposed to.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2197_zps2eb9f50a.jpg&hash=a0e726cc5a8d70742997f846cc545e2f4493a6d1)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2196_zps5c1f73d3.jpg&hash=59055cb8db72c6ebc2d839382114640356db1243)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2198_zps188ef845.jpg&hash=8d0c5aa8c9eceab165329fae569eb3cc1750b164)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2192_zpsa8d94821.jpg&hash=ffc7331c9f3430822778f7faff013564bc80d674)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2189_zps35d6a48c.jpg&hash=8525dce808d7f993a534b17f9a01cadd0e2b07a6)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2190_zps09fa840c.jpg&hash=d283f8e845dba5325f61d6771b923b36b9d0d79b)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2193_zpsd4f9939e.jpg&hash=7c8a865ac6a4043e8fb5be757804255840b15c7c)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2194_zps024e29a9.jpg&hash=56aa7b49c4f35ad5a21775635b4681da1fccd870)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2195_zpsd7fa0b2e.jpg&hash=654b149962f57e237a34c577850493ff4bfd956f)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2188_zps4e29471e.jpg&hash=e989f1557c8642474599081bd372715b1a645408)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2184_zpse6e5211a.jpg&hash=f098fbdbb7b01bfbd631ac587df03dc73d7ba383)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2186_zps188b984f.jpg&hash=95bf17d893adaea8415fa62b0de117911c9b3abb)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2185_zps5f0f4117.jpg&hash=5b1bd4c476feed1bdcc59e8d1299fa09c4fee770)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi633.photobucket.com%2Falbums%2Fuu51%2Fkirillnikolai%2FIMG_2187_zpsa950d4af.jpg&hash=01c1725eb0b4512a9cf06d3187588fd88a553dcd)

[Grainger49]

Sorry, it might just be me but I don't see any pictures.  There is a large blank space there.

[Chris65]

Can't see them either.

[Ankaret]

Sorry about that, should be fixed now.

[2wo]

You mentioned that you had one of the filter caps reversed, might consider replacing it...John

[Ankaret]

Would that have been the most likely thing to burn up? If I recall correctly that wasn't where smoke was coming from. Is there a good way to test whether one of the particular components was fried?

[Grainger49]

The caps are all correct.  I see the diodes on one side are right but can't clearly see the diodes on the transformer side of the terminal strip.  They should have the banded end away from Terminal 19.

The two tube sockets are correctly oriented.  This trips some folks up.

Blowing the fuse is most often, but not always, a problem back at the power supply.  And I am looking as closely as possible at the incoming wiring.  I'll save the pictures and take a closer look.

Other times something is shorted together or to ground in the circuit.  Since you have looked at this for a while, get a buddy to look at it while you call out what should be.

[Paul Birkeland]

This is a potential hazard spot.  Long leads like this really need to be trimmed. There are also many, many wires in your Crack that called for a 1/4" of insulation to be stripped, but have enough insulation removed that they can touch nearby components.  Just check to be sure that a wire soldered to a given terminal isn't touching something else.   

I agree about the backwards cap, toss it out and replace it. 

[Ankaret]

Hi, thanks for looking at this and for the suggestions.

That spot with the write is actually the excess from a rectifier diode. I mistakenly above mentioned that I had reversed a capacitor, but that was not right, it was one of the rectifier diodes (little black things) that was reversed the first time I fired it up. Should I replace this rectifier diode?? Where can I buy a quality one like that which came in the kit?

Also, given that this was what was reversed, might it have fried anything else? Still looking for any other help or ideas.

I did look over any long stripped lead areas carefully, and as far as I can tell did my best to make sure they're isolated and nowhere near making contact with anything else. That weird long diode lead that you pointed out (thanks for catching that!) is the worst it gets from what I can see.

[Ankaret]

The caps are all correct.  I see the diodes on one side are right but can't clearly see the diodes on the transformer side of the terminal strip.  They should have the banded end away from Terminal 19.

The diodes on the power transformer side have one band facing into 21L and the other band facing the other direction into 18L as per the manual. Hope that's where it should be. But the first time I fired it up I had the one that should be facing 21L facing the wrong direction.