i'm on a roll... the kgsshv

[s_r]

Well, I swapped all the sand save for the 1968s & 4686s and the board still doesn't work (same behaviour). Would anyone be kind enough to spare some 4686s? I'm building a new amp board at this point since it seems like it might be the output transistors that are the problem (or who knows what). On a positive note I've done all the wiring (feel free to point out any stupids).

 

[GeorgeP]

But your 4686s may still be okay. Did you check all your parts prior to stuffing?

 

Though if you still need some I think I may have some extra - send me a pm and I will check tomorrow. You are in Canada, right?

[s_r]

Probably, they did seem fine when I checked them. I really don't know where the problem is so I'm just going to replace the whole amp board.

[johnwmclean]

Looking good!

Suggest using the DLXs ground contact tabs and do not connect to star ground.

Looks like you’ve done both which is a no no.

[s_r]

I did follow an old pic of your build to ground the inputs

Just attach the ground tab to one of the mounting screws for each DLX then?

Edited May 25, 2013 by s_r

[johnwmclean]

I did follow an old pic of your build to ground the inputs

 

 

...and I revised my wiring because of some residual hum   see my latest pics in the gallery.

But this is the way it should be done, one connection point and shortest path.

 

 

Just attach the ground tab to one of the mounting screws for each DLX then?

 

No. Pin 1 to tab on each DLX.

... you can file back the anodising at one corner of the connector to ensure a good solid connection.

Edited May 25, 2013 by johnwmclean

[eggil]

S_R, do you have an extra amp board? I have a couple of LilKnights that went unclaimed. You could pay him if you need one and I could ship it to you.

The wiring looks good from your picture but details are hard to see.

Edited May 25, 2013 by eggil

[s_r]

Yea, I have two extra since batchpcb does x2 of whatever amount of boards you order. Once I make those changes to the input grounding tomorrow I'll take a better pic.

[jwzhan]

Very nice.

I grounded the way Birgir suggested. I star grounded everything on the PSU and connected the enclosure to the PSU ground. I haven't heard any hum yet. It'll be a little messier tho, because the limited grounding positions on the PSU board...

I have a few 4686s. If you need more, drop me a PM.

[s_r]

Made the changes to the xlr inputs, hopefully the higher res makes details easier to see.

 

[eggil]

Wiring looks good.

This is how I did my second built and it is dead quiet.

Edited May 26, 2013 by eggil

[s_r]

Looks mostly the same as how I did my grounding, save for john's suggestion on the inputs and connecting the amp boards to the psu. Any reason you only used one pin on the alpha pot pcb?

[eggil]

They are both connected anyway.

I get not even a hint of hum or noise if I briefly max out the volume trying to hear noise without music

Edited May 26, 2013 by eggil

[spritzer]

All the grounds on the Alpha PCB are connected to the ground plane so everything is shared.  If you ground the inputs directly into the PSU then one wire to the pot is all you need. 

[Emooze]

It's been a few weeks since I got a chance to work on my PS. I added a second thermistor so there's one per primary winding now. With everything connected, I still blow 3A fast-fuses and I forgot to order more.

 

What I did is just connect the positive rail, and it powers right up to 503V with a 2A fuse. Repeating the same process with the negative rail and it sort of hovers around 200V fluctuating about +/-10V. I swapped the LT1021s and I still get the same issue. Would it possibly be something in my diode chain for the 550V reference? To check that, I'm assuming I would measure the voltage across the whole thing.

[spritzer]

That smoked on the trainwreck board I'm repairing so it is worth a shot. 

[shipsupt]

Note to self... always double check your Mouser order.  I'm not sure I'll ever find a use for these!  Oh, and there were 4 in the box that showed up.  

 

[Voltron]

Door stops.

[jwzhan]

return them... that's what I did when I ordered like 50 of those TO-220 mounting kits by accidents..

[Emooze]

Railgun

 

I've got about 200V across those zeners so it looks like that may be an issue...

[n_maher]

I think they'd look great in a Cmoy.

[cetoole]

KGSSHVDX

[Victor Chew]

Railgun

I've got about 200V across those zeners so it looks like that may be an issue...

I would have a look at the 24v zener and the 2n3904. They are part of the protection circuit. Any leak can cause a pull in the current and drop the zener string voltage.

Incidentally, I finished building my off board. Made a sound comparison to my on-board and for some reason, the off-board has huge bass (not bloated or loose) and seems to have more power/drive than my on board. Everything is the same except that the off-board uses the alpha port instead of the dact on my on-board. Wires are also different - on-board used copper whilst the off-board uses copper coated with silver. Just an interesting observation I though to share.

And as again, thank you to Kevin for the design.

Edited May 29, 2013 by Victor Chew

[justin]

Note to self... always double check your Mouser order.  I'm not sure I'll ever find a use for these!  Oh, and there were 4 in the box that showed up.  

 

 

http://www.mouser.com/ProductDetail/Kemet/ALS30A392MJ400N/?qs=%2fha2pyFaduhepXk8cMoit%2fdC8dSkt5VN9dl8WGRRt9zMei29HTiHqA%3d%3d

 

 

mouser mistakenly has these listed as 3900pF.  there's your cause for a refund

Edited May 29, 2013 by justin

[eggil]

Are you building a power plant?

Send them to Kevin so he can design a bigger amp!

Edited May 29, 2013 by eggil