Home built amp shutting down with loud hum after 10 minutes

[Stevem]

No need to wait for new diodes for now, just put two of your 4005s in series.
Just for kicks open up your ground buss at the preamp section filter and leave that grounded as you have near the input Jack, then make a new grounding point for the other buss and land that near the PT.

[labb]

Just a note on the HO grounding scheme: I have built three of the HO type amp circuits from AX84 site and have never had a problem with them. They tend to be very quite. Those circuits and layouts have been built and tested by several builders.

[Clinkous]

At work, will try diodes this evening.

[Clinkous]

I put some 1n4007's that I found in place of the suspected bad uf4007 diodes and played for almost an hour with no problem as of yet. Hopefully this solved it (or my fiftieth resolder attempt was a success! Tempted to re-install old diodes to see but probably won't. Just try it again later then take it to a gig with a backup.

Regardless, thank you to everyone who took the time to try to help me out! This was my first amp build and I have really learned a lot from trying your suggestions and thinking from different angles. Having a blast so far.

Thanks again....and if this turns out NOT to be the fix I'll repost for sure.

Chris

[Stevem]

It sounds like your golden now, enjoy!

[Structo]

As you found out, lead free solder is crap.

Dry, crumbly, bad connections abound.

Do you own a solder sucker?

I would try to remove as much of the lead free solder then re-soldering those connections with lead solder.

I like the eutectic solder which is 63/37.

It goes from liquid to solid very quickly, preventing cold joints and other problems.

[dorrisant]

Got it going... Good deal. Happy tunes!

[Teleguy61]

Good job.
TAG is the best--awesome trouble-shooters.

[Clinkous]

[quote="Structo"]As you found out, lead free solder is crap.

Dry, crumbly, bad connections abound.

Do you own a solder sucker?

I would try to remove as much of the lead free solder then re-soldering those connections with lead

I noticed that when I emptied my solder sucker that it was all dust and kept clogging up worse than usual. I re-did the joints I used the other stuff on. Did that before I tried the diodes. My leaded solder was just on a huge roll and about 1/4 inch thick it seemed! Accidentally bought the wrong stuff.

[Structo]

Yeah the .032" diameter is what I use.

[Phil_S]

I realize there's a dislike for solder without lead. I've been using 4% sliver, 96% tin almost exclusively for years and never had a problem with it. I recently bought a 1 oz. roll of 96.5% tin, 3% silver, 0.5% copper to see how it is but haven't used it yet. I have a feeling the tin+copper without silver formulations are more difficult to work with.

Here's a good piece on how to use lead free with good results: http://www.kester.com/kester-content/up ... .19.06.pdf

[Structo]

Yeah the copper probably bonds the silver better.

Most likely a harder mix.