Turned the amp on and let it warm up. Set the bias just above 12V. Diodes are on but I get no sound. My kit did not come with the ground bus wire so I made one with three 22 awg bare copper wire strands twisted well.. Amp does get nicely warm, all four Q's seem to be putting out even heat. I could have put one of the diodes in reversed. I soldered the mosfets on the under side of the board just to be certain. Pictures will have to wait until tomorrow. Except this one of the V 1.8 rear panel wiring.
O.K. then, the diagram in post #1290 is for running in bridge mode, sorry about the mistake.
Center legs to ground. Hope the above pics show the resistors well enough. The out and in wiring on the boards shows up well enough.
Right Q1 = 12.6V, Q2 = 24V
Left Q1 = 12.2V, Q2 = 24V
Any more tests I could do? More pics needed?
Casting about here; Cold joint on rca inputs to board? Resistor out of place on board?
Right Q1 = 12.6V, Q2 = 24V
Left Q1 = 12.2V, Q2 = 24V
Any more tests I could do? More pics needed?
Casting about here; Cold joint on rca inputs to board? Resistor out of place on board?
Last edited:
R13 is not wrong, It was changed from a 10k on V1.6 to a 33.2k on the V1.8 to dim the led. Dim witted I may have shorted the inputs ( remember hearing a sharp snap as I was moving it ) Capacitors were charged and the input cables dangling off the back. Is there a way to check the transistors ( D3, D4 ) for damage?
Last edited:
Yep. Thats why @6L6 build guide specifically recommends measuring every R and C, and laying them out in an ordered way on your bench so you can be methodical. I also strongly recommend that people "measure twice and solder once" and not just because you might be new, but because it ensures you don't solder the wrong one in by accident because we all get distracted, etc... when building so this keeps things neat and tidy.
I personally still get a blank 8x11 sheet or two and place all the parts on that sheet and write the general value of the part under it. Then when it comes time to stuff that part, I have my handy auto-ranging L-C-R meter there and heck the value before I stuff it. This is the meter to which I refer, which is fantastic for $140 but there are other options of course. But if you don't have one, consider it. Its auto-ranging and will detect all 3 parameters (L,R and C - up to a max C) after you simply clip the part in. https://www.amazon.com/gp/product/B00S298KJO/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1
Then when that grouping is ready to be soldered, I go back and visually inspect every spot and double check the board's spot with the parts list/schematic. Only then do I solder.
This is not a newbie thing BTW - I've been building hifi for a long time, and this is the only way I've found to not let the smoke out (at least when assembling).
--Tom
^
I violated a good practice the other day... An amplifier was 99% complete, then poof. Trying to save 5 minutes cost me two days and some nice parts. False bravado, and ignoring that the hands ain't as steady as they used to be. I'm keeping the cheeks good and clenched from here on out.
A pro tip for desoldering: apply a generous amount of solder flux to the joints you are desoldering before you put the solder braid over to desolder. The flux will help dispurse the heat and better melt the current solder. You may have to do this a couple of times too depending on how much solder was used on the joint, etc... Also make sure you remove the MOSFET from the heatsink before you start because a lot of your iron's heat will get shunted there making heating up the joints so the solder melts, challenging.
--Tom
You have all heard the old saying that "it is not the doing but the knowing". I think that is the elephant in the room with diy electronic projects. I find my mind wishing i could take a guided tour into the ACA through the rca inputs, hearing the purpose and effect each part has on the signal all the way to the speaker outputs. There is a chalkboard with a nicely drawn schematic of the amp circuit, an Einstein type with a pointer giving a clear and engaging narrative. If I spent days going over posts here I might get part way to some kind of enlightenment, or not. Was electronics, math and physics discovered or invented?
Last edited: