S800 Support Thread

[MasonAtom]

Hoping to finally get started on a 2 channel S800 fitting in a 1U rack.

Anyone got a drill pattern for the front panel pots?

I did my own front panel, I don't really have a layout, I just imported the graphic of tat's cases to illustrator, scaled it to be 19" wide, and used the ruler tool to take measurements then transfered those to my panel.

I'm happy with how it came out but I had to mount the pots off board to make it work.

hmm... thanks for the idea, I can probably import that graphic into QCad which is what I use for all my layouts.

Mason

 

[RedNoise]

Hi ,
I'm finishing mine , but I mesure 15VDC @ the led connector...Is this normal?Did you add a resistor on each board for each led?
(All IC installed)
Thanks.
EDIT : Led connected and then voltage droped to 3,25VDC...
Sorry!

 

[Dr nEon]

Hi all!

I've been testing a whole bunch of electro caps, mainly in positions which are obviously in the signal path. 22uFs at C1&2,C17 etc.. and C23/26 output 100uFs.. ...using sockets to try out all the brands I have kicking around.

I haven't bothered with the 22uFs in positions C15 and C16 yet. I'm not sure how much influence these have, sonically. I'm trying to understand the purpose of these two caps...are they decoupling?

I'd appreciate an education from someone who can read this circuit better than I!

BTW it IS a lovely eq!

cheers

nEon.

 

[Dr nEon]

..any thoughts on this one , anyone ??

what are C15 and C16 doing?

many thanks in advance

nEOn.

 

[peterc]

PSU decoupling.

Regards
Peter

 

[Dr nEon]

Cheers Peter!!

OK so I was along the right lines... must be learning!

I'll just leave the pana Fcs in place then, at those spots...  I've found elna's to be my most preferred cap in the signal path places which I mentioned , but I assume that there's no point comparing anything in the psu decoupling positions, as the Fcs a decent cap anyway..

Big thanks , Peter , and well done on this lovely pcb!

nEon.

 

[RedNoise]

Actually calibrating my boards , I notice a -0.5 dbu when switching eq IN.(All *pass off , gains pots centered)
Did someone have the same issue?Could I consider this "normal" ?

 

[RedNoise]

Hi...
I have a problem with 4 of my 8 boards...I checked every solder & resistor twice...The Only difference I noticed is :
-I used 220µF 35V instead of 50V (CPSU & CPSU1)
-I used 470µF 35V instead of 16V (C3 & C4)
The issue is that I can meter -12V@ pins of DIP8 (15v & -15V are well @ pins 4 & 8 -5532- and pins 4 & 7 -TL071-)
As the problem is the same with four boards , I fear a repetited error.


Does someone have a idea where to look at?

Edit : I use Collins kit , but Electrocaps have been replaced by Panasonics.

 

[sysexguy]

Hi, just got a partially done unit (8ch) off the board and I'm working on a plan.  I think I may have an elegant way to minimize the headaches of completing this build. If anyone has some comments or sees something I missed, please speak up

I've taken 8 of the mono (single gang) pots and ground down the lugs so that they can be inserted all the way into the pcb. The center pot of each strip (Lmid-level) lines up with the chassis holes. By grinding down the lugs I get enough clearance for the adjacent freq pots and (just barely) enough room to clear the mounting screws on one side. I will have to grind down 2 of the base screws (all unused) to align the cards vertically but that's easy. The remaining pots must have flying leads but this way, they are short and sweet.

I also thinking I should go for a relay bypass board mounted between the db25s. This would mean only needing 9 wires running to the front panel as the led and the switch can share the same wires and the 3pdt can be replaced with a spst. The bypass on the pcb would then be jumpered to the on position.

The front panel Led particularly the overall power led will be glued to the front panel (as it falls smack right where a pcb goes). I'm thinking I may just want to give a little extra space for those leds to be clean (and not shorting). Instead of mounting the front panel to the sides then a spacer and the mounting panel with a nut behind, I'd put the mounting panel in front of the sides.

I'll then have lots of room to deal with the psu.

The boards can then be secured with spacers and a long threaded rod.

TIA, Andy

 

[outoftune]

anyone know of a 3pdt toggle type switch that will fit into the purusha 1U case?

 

[Davo]

Any mini 3pdt should work... I used this one:
http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMvudeGI7i40XO%252bnGhp8Hy%252bJe46O%2fBjy5XE%3d

cheers
dave

 

[sysexguy]

I'm wiring the same switch myself as we speak + Mouser's now ships free to Canada for orders over $200 which applies for this project's switches. (came in 24 hours wow!)

Andy

 

[sysexguy]

Hi, I've now wired up one channel for my first tests and when all the pots are centered and the hi pass is off, the sound is significantly darker that bypass. All bands and switches are working and I'm digging the action in the LF and LMF. Noise is very good as well and I haven't bumped the psu up to 18 yet (we're at +-15 stock green psu).

Any ideas what I may need to look at or is that kinda normal as the center detent is a mechanical approximation of 0 boost/cut?

very excited now!!!!!!

TIA,

Andy

 

[sysexguy]

more tests, the dip is in particular between 2k and 6k

Andy

 

[3nity]

on the board there are small jumpers make sure you dont forget them!
but check carefully as theres a tiny one!!

 

[sysexguy]

Hi Jorge, tiny one tucked under U3? got it....so you're saying my observations are abnormal for this project? I need to keep searching....sometimes it's easier to troubleshoot when the whole shebang doesn't work at all....but it's more fun when audio passes and all the controls work but....

Andy

 

[3nity]

but you said you have 8 boards?
check another 1...

 

[3nity]

For schematics look into the G-mail account and search on it!
Thanks

 

[sysexguy]

Yup already have the schematics, I wanted to get one installed before I paint myself in a corner building the "ship in the bottle"....trying another is a good plan, thanks

Andy

 

[sysexguy]

mybad  : shouldn't have been a hotdogger..... pulled the OPA's and put in trusty tl071's and presto works perfect.

Now,  gotta find out why.....the green psu isn't big enough for a rack full of 8 ch's with opa's by a long shot but I thought I could power one channel for testing purposes.....I guess that's a probable cause. Any other ideas?

Btw, for future builders, r43 appears twice on the schematic, the 47k resistor marked r43 connected to pin 2 of u3 is r46

Thanks,

Andy