Hum problem....

[Greg.]

Chris, clearly you are doing this in your own methodical way in the time you have available. You have had some success with the work you have done and I sincerely hope that you will eventually eradicate the hum problem. My bet is on the detached feedback wire being the cause. Let us know how things are after you’ve repaired this. I hope it all goes well.

[Chris]

Thanks Greg for your welcome support, I managed to get a few hours work done on Wednesday and hope to get more done Saturday. I find it much easier to work in natural light which is very limited during the Winter months.
The fear of failure does keep me awake at night, it's such a wonderful amplifier and deserves to be back in action.

Chris.

[bob orbell]

Has Chris given up or is he catching up on sleep . Bob

[Greg.]

Patience, Bob, patience. Clearly Chris is time limited and has his own methodical way of moving forward. I have no doubt when he has an update, he’ll post it accordingly.

[Chris]

There is news, but it's not the outcome that I wanted. I put everything back together, spent an hour checking the wiring and all the joints, then as John said I "fired" her up, but only for a few seconds, had a blue electrical storm and the start of burning smell.
I have decided to mothball the amp for now, but I really want to thank everyone for help and support that I have received on this forum.
It's a little sad as these WAD and WD amps are so good, I've heard amps that cost 10x the price that don't stack-up agains these amps, I enjoyed a demo with Dan D’Agostino Momentum amp and it's a beast sounding silky smooth but for sheer enjoyment these diy amps are hard to beat.
For now to stop the flood of depression drowning me I've bought a headphone kit that will not take up so much real estate space.

Chris.

[bob orbell]

Well, members here know my thoughts, but I still hope we are all friends. Chris, I will take a look at your 6550 if you can bring it over to me, I am in Kettering, so not too far from you, you will have to leave it for me to examine and I can try and sort it subject to how good or bad it has been assembled. Bob

[Chris]

Hi Bob, I really appreciate your offer of help in fixing my amplifier, will have to wait a while as my wife is very firm about keeping a tight lockdown, but I am sure with a new vaccine on the horizon we may be seeing the end of this virus and the damage it is inflicting.

Chris

[Richard]

Hi Chris, that's disappointing. You don't say what changes you made but it may be the feedback wires on incorrectly. You're on a steep learning curve and really it can be easier building a kit yourself from scratch, learning as you go, rather than having to wade into a problem in a kit built by someone else. But not to worry, if you still don't want to tackle it again after a break, Bob's a very good fellow and has helped many of us on here. I'm sure he'll sort it when you're able to travel again

[Chris]

Thanks Richard, I guess that doing one too many upgrades ended what was a great amp (for now) but that was part of buying into diy kits to be able to explore fully the possibilities to make change and tailor the sound to your personal liking. Like Greg said trace your steps back to any changes you made and start there, but while making changes it seems the feedback wire broke free, giving way to possibly causing the hum or not.
That led me to secure the safety grounding connections, while I had the amp on the bench I removed the out-put transformers and gave the laminates a good spray, fitted a flux band that was completely isolated from the windings, grounding to the chassis at one point each transformer. I also changed the 4 psu caps 100uf.
The only good thing to come out of this is the possibility of meeting up with Bob once I get the all clear regarding the virus, at the end of the day we can learn and progress far more as a team than in isolation. I guess this is what the forum is all about.

Chris