Film-Tech Forum ARCHIVE: DFP-D3000 crosstalk problem on optical input

my profile | my password | search | faq & rules | forum home

»	Film-Tech Forum ARCHIVE » Operations » Film Handlers' Forum » DFP-D3000 crosstalk problem on optical input (Page 2)

This topic comprises 3 pages: 1 2 3

Author

Topic: DFP-D3000 crosstalk problem on optical input

Scott Christopher
Film Handler

Posts: 69
From: Adelaide, South Australia
Registered: Apr 2001

posted 06-09-2009 12:40 AM

So you're saying both 'hot' and 'cold' inputs are going to the same pin on the same IC (non inverting input)? Wouldn't this cancel the input signal if tied together?????

I've always known it to be one input to the non-inverting input and the other to the inverting input.

Check you're board again. Is it wired the same for Right?

I just noticed the waveform is inverted between your two images (different processors) This may be a clue

| IP: Logged

Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 06-09-2009 01:30 PM

quote: Scott Christopher
So you're saying both 'hot' and 'cold' inputs are going to the same pin on the same IC (non inverting input)? Wouldn't this cancel the input signal if tied together?????

NO, both are going to non inverting inputs, but each on each OP, this OP is dual.

quote: Gordon McLeod
I think they are using it as a hi common mode rejection circuit to create the balanced input
the common of the cell is probably the problem

Probably I think it's "problem", but where to find cell without common, I hear, but newer saw one?

Did anyone install this processor with regular solar cell??

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 06-09-2009 02:07 PM

Are you using 2 2conductor cables from the cell to the processor or a 4 conductor or a 3 conductor
On the 9pin d sub the common on the cell must be connected to both pin 6 and pin 9 so for a standard solar cell the red wire goes to pin 4 green goes to pin 5 and the black to pin 6 and 9 and the shield to 1 and 4

| IP: Logged

Kenneth Wuepper
Phenomenal Film Handler

Posts: 1026
From: Saginaw, MI, USA
Registered: Feb 2002

posted 06-09-2009 02:56 PM

Gordon,

Check your last post. It seems you have an error in the pin numbers.

KEN

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 06-09-2009 04:22 PM

Red 2
green 5
black 6 and 9
shield 1 and 4
seems one can't edit a post after a certain time frame

| IP: Logged

Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 06-09-2009 04:29 PM

quote: Gordon McLeod
Red 2
green 5
black 6 and 9
shield 1 and 4

Yap!

Just like that, I'm using two wired shielded cable (2 wires shield) one per channel.

| IP: Logged

Scott Christopher
Film Handler

Posts: 69
From: Adelaide, South Australia
Registered: Apr 2001

posted 06-09-2009 07:46 PM

quote: Marin Zorica
both are going to non inverting inputs, but each on each OP, this OP is dual

but earlier you wrote

quote: Marin Zorica
P1LH (pin2 on input dsub) is going to pin 5 of IC106, and P1LL (pin 6 on input dsub) is going to pin 5 of IC106

To me, that's one IC - You've decribed both inputs going to the same pin (pin 5 on IC106).

On a dual Op-Amp, there's only ever been one pin 5..... Therefore is this an error in you post? If both inputs are tied to Pin 5 on the same IC, I'm pretty sure that would cause a problem.

| IP: Logged

Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 06-10-2009 05:04 AM

Sorry Scott, I did write wrong, one is going to pin5 and other to pin3 of same IC (so both are going to no invert inputs.

So, I think input now looks like this:

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 06-10-2009 07:18 AM

that is a classic balanced input stage

| IP: Logged

Scott Christopher
Film Handler

Posts: 69
From: Adelaide, South Australia
Registered: Apr 2001

posted 06-10-2009 08:26 AM

quote: Marin Zorica
When I connect only one channel to input there is not crosstalk on other channel, so problem isn't either is processor

I originally thought you may be getting a small L+R mix, but not according to your tests.

Have you tried plugging it into another projector (a known good setup)?

| IP: Logged

Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 06-10-2009 10:01 AM

Yes I did, this one is good also, other one is too....but same on other.....

I know this is balanced input, nothing strange....but it looks like common wire is missing, but it isn't.....

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 06-10-2009 10:12 AM

Many newer processors have a jumper for cell vs reverse scan readers mainly because a solar cell is not a true balanced device since the two - leads are common on a cell where as a reverse scan with the internal preamp has two balanced outputs

| IP: Logged

Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 06-10-2009 10:56 AM

I know that, but I newer saw cell without common COLD, even I know they excist. Didn't find anything in manual about cell/rev scan reader....also, in schematic there is no jumper as is no on board....

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 06-10-2009 11:01 AM

You may have to get two small shield 600:600 ohm transformers to isolate the common of the cell from the two inputsof the processor

| IP: Logged

Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 06-10-2009 11:08 AM

That's what I tough on also, but better is to make some preamp than to deal with bad transformers....or to steal them from some CP50 [Smile]

| IP: Logged

All times are Central (GMT -6:00)

This topic comprises 3 pages: 1 2 3

Printer-friendly view of this topic

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.