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View Full Version : 48 Channel 595, odd problems



Photovor
10-30-2008, 10:15 PM
I made a 595 on a breadboard, which has 6 IC's, for a total of 48 ports. I put indicator LEDS on each of the ports. I am using the "olsen 595" plugin in vixen 2.0 (or whatever the newest is right now).

Problem is that the first 24 ports work great, but it seems that the other 25-48 ports lag or work randomly.

I've re-arranged the chips, and I still get the same problem. If I try different parallel port modes too, same deal. I've also brought my clock and str lines in on different chips as well, and I still get the same exact problems. No matter my circuit, it always comes out the same way- it's like it's almost sequenced that way....

It's odd how 24 work perfectly....

I should also mention, when I use vixen to turn channels on 1 by one, soon as I hit channel 25, channels 25-48 all go weird/light up.

P. Short
10-30-2008, 10:30 PM
Did you set up the plugin for 48 channels?

Photovor
10-31-2008, 07:51 AM
I'm using the renard 16 and a olsen 595 48 ch.

My plugins are setup as follows:

Channels 1-48- Olsen 595, and then under the additional settings, I have Parallel 1 set to Channels 1-48

Channels 49-64- Renard 16

When testing, if I run any 3 chips at a time, I get good output, any more than that, channels after 24 are odd.

ErnieHorning
10-31-2008, 09:14 AM
I’d try adding a 4.7K resistor to both pin 1 & pin 14 on the parallel port. It will probably be the one on pin 1 that does it. I’ve seen where this pin seems to run out of current when pulsed really fast. It works fine when the IC’s are slowly stepped through the sequence, but not at full speed. It was strange that it was repeatable and always dropped at the same channel.

Photovor
10-31-2008, 11:06 AM
I’d try adding a 4.7K resistor to both pin 1 & pin 14 on the parallel port. It will probably be the one on pin 1 that does it. I’ve seen where this pin seems to run out of current when pulsed really fast. It works fine when the IC’s are slowly stepped through the sequence, but not at full speed. It was strange that it was repeatable and always dropped at the same channel.

I'll give that a try later tonight. If I do step through the channels turning each one on slowly using the "Test Channels" function, once I hit 25, things go astray.

On another note, I'm using PN2222 transistors for each channel with my 595, in order to sink a little more current (a little above 90ma). I was wondering if there was a way I could use the Allegro chips from the Grinch design to still drive these transistors. I saw that the allegro chips go low when channels are selected, vs being high when a 595 channel is activated. Any way of doing this, without using hex inverters?

John Benedict
11-02-2008, 09:09 PM
Just a desperate try but did you check the solder joints with a glass. ? I had something similar and it was one stinking pin.

John Benedict
11-02-2008, 09:13 PM
one last thing that I remembered was last year we were have issues with grounds. I can't remember the exact thing but it was about the interconnetion between the computer and the board arrangement.

Photovor
11-04-2008, 02:14 PM
I finally got the issue fixed. Not sure what was up, but I was able to drill down to which 595 chip was the odd-ball. I knew the chip worked, and I had even visually checked the wiring to it, and it was ok. In a last ditch effort, I pulled out all the wiring that went to that 595 and completely replaced it, and it started working correctly. Not sure if one of my jumper pins was messed up or what.

I had earlier shorted out a 120v circuit on that board too, so I was thinking that maybe one of the breadboard traces were welded together.

It's working now though. I also answered my question on using the allegro chips. Since I'm using NPN transistors with my 595's, I'd have to use PNP transistors with an allegro chip.

Every once in a while, I notice some of my relays activating out of sequence, so I need to try the resistor method yet. Do I just put the resistor on the pin between the chip and my incoming line, or just go from the chip to the resistor to ground?

P. Short
11-04-2008, 03:57 PM
From the chip to +5V.