HUGE ISSUE with DIDDEN DCX mod - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Closed Thread
 
Thread Tools Search this Thread
Old 4th March 2013, 02:31 AM   #1
diyAudio Member
 
Join Date: Mar 2013
Default HUGE ISSUE with DIDDEN DCX mod

wow where does a 5 yr luker start..
I usually figure stuff out myself by reading on here. great site
HOWEVER>> every attempt to solve my problem has turned up a blank or no reply( yahoo groups, search here, audio circle, etc)

Simply, I have a full kitted DCX2496 ( i.o board, clock, regs) supplied and assembled by Pilgham Audio .

OK it doesn't work!!!! well.
Specifically the ANALOG INPUTS do not function correctly, with any preamp I have, or at least any preamp or input source with a 3-wire plug.
CONNECTION>
PREAMPS TO DCX via RCA to XLR cable..pin2 +/center pin3 -/gnd using mogami 2534 cable

ok hook the tuner to the PREAMP and the PREAMP to the DCX.. and the DCX craps out.. tons of channel crosstalk and the balance control(preamp) goes to crap
in other words the balance doesn't even work..all that happens is the levels get lower in both channels at the DCX input!! you can see this on the input meters on the dcx, along with listening to the output.

switch to balanced connections even worse.

ok remove either channel of the input from the PREAMP to the DCX .. hmm no crosstalk.. and the balance control works now!!
IE turn to the disconnected channel, no sound, no input level lights, turn to the connected channel ...sound and input lights at proper level

secondly How the HECK when I check from pin 2 input to Pin 1 OUTPUT do I get dead short?? WTF? I know he uses some weird circuit R to convert unbalanced to balanced on the output but??? no way the pin1 output ground should show a short to the input hot pin!!

I can't get a schematic of the DIDDEN i/o board and really have no clue to where to start trouble shooting
other than BOTH preamps work perfectly with all my other gear/ amps/ crosovers, etc. and signals look good on scope and no huge amounts of dc( 20 ma max.)

Please help before I throw this $1000 POS in the garbage!

Last edited by nolikeydigital; 4th March 2013 at 04:27 PM.
 
Old 5th March 2013, 02:52 AM   #2
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Well, it's DIY so time to jump in there and figure it out. Sux that you have to undo what someone did, but maybe it's a simple fix. Often is.

The digital input is working OK? If so, sounds like the problem is just the interface the the ADC chip.

Do you have good pics of the mods?
__________________
Take the Speaker Voltage Test!
 
Old 5th March 2013, 03:01 AM   #3
diyAudio Member
 
Join Date: Mar 2013
ya it major kungfu sux.. but
I've scanned all the forums and found nothing ,,.I assume most people don't use the analog input

but ... this is on the DIDDEN Rev 2 i/o board.. so its not in the analog to adc unless its screwed up on his board.. and agian why is the pin 2 input hot! showing a short to the output gnd(pin1) the output has to go thru a opamp(s) i mean this circuit is really screwy!
 
Old 5th March 2013, 03:14 AM   #4
gootee is offline gootee  United States
diyAudio Member
 
Join Date: Nov 2006
Location: Indiana
Blog Entries: 1
Did you email Jan Didden?

Sounds like something was just wired wrong during the build. Or it could be your cables.

Who performed the mods?

Are both channels wired identically? Does only one channel have the hot-to-otuput-ground short?

Have you removed the board(s), to check for shorts/solder bridges?

If there are two channels that should be identical, you could measure (with unit unplugged) resistance to chassis at corresponding points in both channels and look for differences.

Do you know of anyone else who has one that should be identical, to compare photos?

Is the schematic available at a link anywhere?

Do you have photos of the input connections?

Last edited by gootee; 5th March 2013 at 03:21 AM.
 
Old 5th March 2013, 03:17 AM   #5
diyAudio Member
 
Join Date: Mar 2013
yes...
probably but the board has been back to ward ( twice)" worked fine in my dcx"
not that i can find if so i could locate the problem
I can take some but they are posted all over the forum .. what specifically are you looking for>??
its just 2 wires from pins 2/3 to his board.
let me know I can post some
 
Old 5th March 2013, 04:24 AM   #6
diyAudio Member
 
Join Date: Mar 2013
OOPS missed half your post
Did you email Jan Didden? yes

Sounds like something was just wired wrong during the build. Or it could be your cables. not cables.. works fine on all my other assoc gear see above.. even substituted different cables.. been checked on scope and ohm meter too

Who performed the mods? Pilgham audio

Are both channels wired identically? Does only one channel have the hot-to-otuput-ground short?yes from my preamps to the dcx no both channels do it.

Have you removed the board(s), to check for shorts/solder bridges? yes

If there are two channels that should be identical, you could measure (with unit unplugged) resistance to chassis at corresponding points in both channels and look for differences. none
input a input b on dcx pin 2 shorts to any output pin 1

Do you know of anyone else who has one that should be identical, to compare photos? ita alin the board.. not a issue of hooking 2 wires per input to pins on his board. his board only had 2 pin for input a+pin 2 a- pin 3 ditto for input b

Is the schematic available at a link anywhere? not that i can find..jan said no schem available!!!!

Do you have photos of the input connections?what 2 wires to the pins?? see last page of pdf.. this is all the info i have
Attached Files
File Type: pdf DCX2496 AA Construction Guide.pdf (939.4 KB, 72 views)
 
Old 5th March 2013, 05:13 AM   #7
gootee is offline gootee  United States
diyAudio Member
 
Join Date: Nov 2006
Location: Indiana
Blog Entries: 1
Well, the other ends of the wires must go somewhere too?

I loked at the PDF and it seems like there might be a significant potential for errors when constructing and connecting the internal cables. They seem like the most-likely source of error.

You might want to start by making a diagram or table that maps out all of those connections, starting with the ones at the inputs and outputs. i.e. Work from the actual wiring and draw the connections out. Then compare them to what the PDFs says they should be.

I would map them out both visually and with a meter. Pin-header types of connectors are not known to be the most-reliable and trouble-free connectors. And the wires in ribbon cables are sometimes easy to connect in the wrong order, when they are split and soldered by hand.

Last edited by gootee; 5th March 2013 at 05:18 AM.
 
Old 5th March 2013, 06:27 AM   #8
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
yes, honestly I find your attitude pretty rude and your seeming unwillingness to even consider the possibility its your error is unlikely to get you far trouble-shooting. you have said nothing of the power supply hookup, posted no pics and jumped straight to obnoxious mode.

Jan is a well liked and well respected long time member here and he does generally know what hes doing, so your posts, which basically insinuate that Jan is lying about it working fine and testing fine at his end, or is an idiot that sells dysfunctional garbage. I think its totally uncalled for...

I can only echo what gootee has said above given the nature of the malfunction, the fact its been back twice and confirmed by a man I consider to be reliable and generous to be functional, the ribbon cables, or your internal hookup/grounding seem the most likely source of error

Last edited by qusp; 5th March 2013 at 06:36 AM.
 
Old 5th March 2013, 10:55 AM   #9
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Let's keep personalities out of this, shall we? If the digital section works, then it can't be the output section. That leaves some miswiring or bad component on the input.

I don't know your mod, but the mods I do to the DCX simply replace the stock opamp input circuit with a new one that is simpler and uses higher quality parts. It's not very difficult and works well. If you can solder, you can make one. To troubleshoot this you'll need to trace the wires. Is that something you can do?

AFAIK, the Didden mod does not include the input. Or am I missing something here?
__________________
Take the Speaker Voltage Test!
 
Old 5th March 2013, 11:35 AM   #10
diyAudio Member
 
Join Date: Jun 2007
Unfortunately the OP is not being clear about the specific problems and beating up on Jan is not helping.

As others have pointed out, it is probably a poor connection or something has been mis-wired.

It is also clear that a simple phone call between the OP and Pilgham audio
would probably solve this quickly. My advice: keep the phone call on a friendly and respectful tone.
 

Closed Thread


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Denon DVD 2200 mod - PCM out issue Mfly Digital Source 1 20th May 2010 09:06 AM
WTB Behringer DCX active mod asturias Swap Meet 0 14th January 2010 03:19 AM
soundcard OPAMP mod stability issue Leolabs Digital Line Level 0 17th September 2008 01:59 AM
Alw,Jan didden, Guido please help with TL431 kimschips Digital Source 48 25th September 2005 03:54 PM


New To Site? Need Help?

All times are GMT. The time now is 04:28 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2