Anybody else have an AC input problem?

[stereorob177]

After a successful build, I'd been listening to my Crack/Speedball amp quite happily this last week or so. Tonight, no sound. Tubes heaters light up, but a peek underneath showed none of the LEDs glowing. Long story short -- I traced it back to the snap-in AC input/fuse holder. If the plug that's attached is stressed a wee bit one way, the LEDs go out and no sound, but enough voltage is still getting through to make the heaters glow a bit. Push the plug the other way a bit, the sound comes back and LEDs light up. "Hmmmm" says myself to me, "Dodgy AC input, loose connection". I see that the metal parts of the AC input thingy seem to be pressed together, so I heat up and add a bit of solder to all the pressed connections figuring one may have been loose. Also re-heated all the wire connection solder points.

Alas, I still have the same intermittent problem if the plug is pushed a little bit in this direction or that. I guess I need just replace the AC input/fuse holder. The question is should I request a replacement of the same part from the good folks at Bottlehead, or should I purchase a more robust part that fits the same chassis opening? Has anybody else had a similar problem, or do you think this is an isolated incident and a direct replacement appropriate?

I should also say this was the only hitch I've had with this excellent kit. I'm listening to it now as I type -- glorious!  :-)

Rob

[grufti]

Sometimes power entry modules have manufacturing defects, but my best guess is one in a million. In that case just replace it, but you might want to test two other parts first: check the fuse itself and the fuse positioning in the holder. Next check the AC cable in another device preferably with a power on led that would go off, if the cable causes the problem when you move it.

[Laudanum]

Agreed, the input module isnt "boutique" but it's very decent.  Ive used similiar quality part in the past and never had a problem.   If it's the connector, it's just bad luck.   Bottlehead will take care of it.

[Grainger49]

I have had on and off problems with the one I bought and put in the outboard power supply for my FP 2.  I fixed it by very carefully prying the hot and neutral pins, not the ground, outward a little.  It makes them seat with more pressure.  BTW, the ground is the pin out of line with the others.

It could be the IEC power cord that has loose receptacles.  So you and I are blaming the IEC power module.  But either way bending out works.

[stereorob177]

Hi,  the problem occurred with two different cords, so it's definitely the IEC power module. Perhaps I'll contact Bottlehead about a replacement part and see if that solves the issue.

I appreciate the input and reassurance,
Rob

[Doc B.]

What happens is the pins can get more heat than really needed just to flow solder when soldering the wires to the pins. When that happens the plastic that they are set in softens enough for them to get loose. A replacement socket - which we are happy to send out, just contact Eileen tomorrow when we are back from our vacation - and a bit more judicious application of the iron should make for a solid connector.

[4krow]

Your not alone here. Years ago, I had an integrated amp that just quit working, no reason. I chased it back to the IEC inlet as well. This was a factory job, but I haven't seen one of these yet that is 'brute enough' for me. On the other hand, I will tell you that I would bet money that if you used a PS Audio power cord, your chances of a tight grip, no matter what, increase. They go in hard for a reason.

[stereorob177]

Thanks for the good soldering advice Doc B.  I'll call Eileen in a day or two as you suggest for a replacement, then execute a careful install, ramping up the heat setting until I get the melting point.

As soon as I get someone here with a decent digital camera, I'll post a few pics of the final results of the build. It's a thing of beauty, if I do say so myself ;-)

Once again, thanks to everyone who responded -- you're a great community!

Rob

[grufti]

I am not sure what you mean by "ramping up the heat setting until I get the melting point". If you mean what I think you have in mind, then this could be a way to damage your new IEC inlet.

You can easily heat the plastic past its melting point by slowly heating up the whole thing. That is not the way to do it. Instead you need to have your soldering iron at a high enough temperature that you can work quickly on each connection. Then pause to let the case temperature of the IEC inlet go down. Then move on to your next solder joint. It often helps to have a small bead of molten solder on the tip to encourage a faster heat transfer from the soldering iron to the wire and the IEC inlet contact. When both parts are hot enough the solder from your solder wire will wick and bond very smoothly.

Again, quick rather than slow is your best bet.

[4krow]

Another crazy idea that I discovered(patent pending), is to use 'canned air' if I am working on such a heat sensitive device. If you want to 'freeze' the action, tip the can upside down and let it spray propellent. Sometimes ya gotta do what ya gotta do. Last night, while cutting off a volume pot shaft, I used an alcohol soaked Q-tip to keep up with the heat.

[stereorob177]

Grufti,  nice catch. Actually, I meant that I'd try different heat settings for a few seconds each till I found one that would melt the solder quickly and not overheat the whole assembly. My last post did not explain this clearly at all!  Appreciate your reminder that soldering quickly, with adequate heat, saves parts. (a lesson I've learned the hard way in the past!)

4krow, you sound like an adventurer! Just remember alcohol is flammable, and not always for consumption! ;-)

Regards,
Rob

[4krow]

Perhaps...perhaps, but I remember frying black widow spiders found in the corner of my bedroom with hairspray and a match....I was 9