New to tubes, need help with K502

[Jhow5757]

Hello,
First off I would like to say hello to everyone here, I have lurked around the site a bit and decided this looks like the place for me. I have been into audio equipment for quite sometime and consider myself experienced (a little at least) in trouble shooting, repair, and restoration of solid state equipment. After reading the many reviews and posts on the s-5 tube kits I decided to order the K-502. Being the "hobbyist" that I am I couldn't just build the kit as intended and decided to do some mods. I built a chassis, upgraded coupling caps, installed snubbers across filaments and HV, removed dc blocking caps from signal path, used a uf4007 from bridge rectifier to filter cap, upgraded binding posts and rca jacks and upgraded volume pot. After finishing the project I get absolutely no output . The tubes glow fine and there is no sign of the obvious such as bad soldier joints, reversed polarity on components ect.. Nothing is shorting out or hot. I know there is several threads on this amp and I have spent hr researching and thought it would be best to post here and ask the experts for help. I came across a thread recently where a member was having a similar problem with a K-12 kit and it ended up being a grounding issue with the binding posts, I don't think that is the issue here though. Also I see the Voltsecond mods mentioned on almost all the threads, his webpage seems to be out of commission does anyone know where I could access this info? All info and help would be greatly appreciated. BTW I haven't took any measurement's yet and hope to get a chance to work on it a little more tonight.
Thanks,
Jason

[20to20]

Being the "hobbyist" that I am I couldn't just build the kit as intended and decided to do some mods. I built a chassis, upgraded coupling caps, installed snubbers across filaments and HV, removed dc blocking caps from signal path, used a uf4007 from bridge rectifier to filter cap, upgraded binding posts and rca jacks and upgraded volume pot

I'd undo all your mods, build the kit as designed to have a functioning amp, then do one mod at a time so if you have a problem at that point you can reverse it and find the mistake.

20

[Shannon Parks]

Use a function generator and put in a 100mV, 1kHz sine wave. There's plenty of free function generator apps for Apple and Android devices. Then use your DMM on AC. Measure at the RCA jack and see the 100mV with the Volume pot all the way CW. Also put a 8 ohm. 20W power resistor on the outputs (Radio Shack has these). Then measure at:
V1-1 (should still be 100mV)
V2-1 (probably will be around 3V)
V2-8 (probably will be around 3V)
V2-9 (probably will be around 3V)
V1-3 (probably will be around 3V)
V2-3 (probably will be around 3V)
Speaker + (red should be around 2V)

You can do the same measurements for the other channel. Find out where the chain is broken and report back. Obviously, take care measuring due to the high voltage. Also take all the voltages if you have a voltage chart and see if anything is amiss.

Shannon

[Jhow5757]

Thanks for the suggestions, lesson learned I should have just built the kit as intended and then moved on to modifying it as stated above. I didn't realize you could get signal generator apps do you know of any particular one you would suggest? I have been looking at buying one for sometime know and keep putting it off, I was thinking about a rag/tag 101. I will get the app and perform the testing and report back.
Thanks again,
Jason

[Shannon Parks]

I didn't realize you could get signal generator apps do you know of any particular one you would suggest?

Just search for "Function Generator" at Google Play or the iTunes App Store. Free is best! Maybe download two different ones, and use the one that seems more intuitive for you. With your tablet/phone and a DMM, you can accomplish a *ton* of troubleshooting.

Shannon