Jump to content

Recommended Posts

Posted

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).

 

post-3922-0-78825100-1369453376_thumb.jp

Posted

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?

Posted

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.

Posted (edited)

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 by s_r
Posted (edited)

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

 

 

...and I revised my wiring because of some residual hum  :P 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.

post-988-0-39162800-1369458314_thumb.png

Edited by johnwmclean
  • Like 1
Posted (edited)

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 by eggil
Posted

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.

Posted

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.

Posted

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?

Posted (edited)

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 by eggil
Posted

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. 

Posted

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.

Posted

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.  

 

largecaps_zps75f771da.jpg

Posted (edited)

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 by Victor Chew

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.