View Full Version : Channel 16 and 17 come on together

02-03-2008, 02:31 AM
As the title suggest, channel 16 (last channel on first chip) and channel 17 (first channel on second chip) are coming on when i turn on 16. When i turn on 17 it starts with 18, 18=19 19=20 and so on. I only have the first two chips installed...
Also channel 32, last channell on opposite side of second chip, stays dimly lit untill i start turning on some channels on the first chip, then it randomly comes on full......
Whats going on here? (encase your wondering what lights im refering too, I have designed this Grinch to include indicator leds, its essentially an Olsen 595 Grinch hybrid)
Im using the Olsen 595 plugin for Vixen.

02-03-2008, 04:26 AM
Have seen similar issues to this raised in other threads. It could either be related to the parallel port setting in bios (set to EPP mode), or to issues with the port itself (try using another computer).

02-03-2008, 05:12 AM
Sounds like a short between the outputs of the 2 chips - cheack and double check, and if you cant see anything obvious, disconnect the board, unplug the 2 chips, unplug SSR's and then using a multimeter check for shorts between the 2 pins using a resistance measurement.

It does sound odd tho - I'm at work and dont have the grinch cct diagram handy, but it is possible that your board is in error rather than a short. Have you tried 2 new chips just in case chip 1 has failed in some way?

02-03-2008, 06:09 AM
If they always come on together then it could be something like what Daviddth said if its intermittant then is probably because of issues with the port or your grounding. Try a shorter lead if your using an extension lead then try a shorter one.

If you have another computer try that one. its possibly something to do with the voltage comming from the port. some ports dont have enough voltage output and need to have the power supply dropped slightly on the grinch to make it more reliable. try a 1amp diode in series with the 5v supply to the board this may help.


02-03-2008, 11:42 AM
I played around with the board for a while last night and fixed a couple issues some how. The two remaining issues are channel 16 and 17 coming on together and channel 18+ being one channel higher then what it should be. And there are a couple leds dimely lit, the first couple and last couple leds of chip two (the leds closest to the first chip, input side of second chip) I have replaced both chips and nothing changed.
No it isnt intermitant, it does it every time.
I do notice that the indicator leds for chip two are noticably dimmer then those of chip one when full on.

02-03-2008, 12:05 PM
I gather this is a home-etched board? If so any chance of a copy of the schematic to check it? It does sound more like a power issue or a connection issue from chip 1 to chip 2

02-03-2008, 12:20 PM
I checked the port bios settings, it was set to ssp, i changed it to epp, no change to the problem.
I attatched a pdf file of the board. I couldnt figure out a better way of attaching a picture of it.

02-03-2008, 01:36 PM
While I cant see anything at fault with the board (but it IS 4:20am lol) there is one thing I noted If you have etched the board exactly as shown. Pin 20's track that goes out to the SSR connection goes awfully close to the jumper connecting pin 21 to the next Chip. This could short pin 20 to earth.

Another couple of noteworthy things - Some pf the LED's have tracks that ALMOST short, assuming there is really a round/square pad on the boards. See chip 1 outputs 4, 10 & 12 for example (and there are a few that are almost as close).

I also wonder how the power supply will go - the grinch at all outouts on could draw quite a bit of current, thus dropping the volltage on the board to a point where it wont work. Have you measured the voltage between pins 1 and 24 on the chips to see that it is really 5v?

I'll have another look when I wake up (The red bull has yet to kick in lol)

02-03-2008, 03:34 PM
Found the problem, didnt connect a ground jumper.......
Im guessing the second chip was getting enough power through the cap to work in a limited fashion.
As i said, i only populated half of the board, i also didnt bother connecting power and ground to the output rj's. I forgot that the second, third, and fourth chip get ground from the same jumper as my rj's.
I finnaly found the proplem when i checked the power input of the second chip compaired to the first per daviddth's suggestion, and found 5.08 on #1 and 4.22 on #2 chip!
Thank you all for the help!

If anyone is interested in my design for a Grinch with indicator leds pm me and i will send it! It seems to work great.. now!

02-03-2008, 04:04 PM
Glad you found the problem :)

02-03-2008, 06:19 PM
Yup I had the same issue with mine at one stage thats why I mentioned it.

Glad to see that you fixed it :)