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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Sun Apr 12, 2009 8:34 am Post subject:
Clock Divider |
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I've just tested my recently built Clock Divider and facing a problem I can't solve on my own.
Channel 1 and 3 are working as expected but Channel 2 is always high!
At the moment I just have one 4017 which sits in channel 1 but I don't think the lacking IC is part of the prob.
On the channel 2 IC socket I have 14V to 15V on pin 13, pin 14 and pin 16. Guess the constant 15V on pin 15 are the culprit!?
Any help appreciated.
Thanks to Yves for a cool design! |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Mon Apr 13, 2009 9:18 am Post subject:
Re: Clock Divider |
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e-grad wrote: | I've just tested my recently built Clock Divider and facing a problem I can't solve on my own.
Channel 1 and 3 are working as expected but Channel 2 is always high!
At the moment I just have one 4017 which sits in channel 1 but I don't think the lacking IC is part of the prob. |
I guess you checked channel two with the 4017 IC in the right socket ?
e-grad wrote: | On the channel 2 IC socket I have 14V to 15V on pin 13, pin 14 and pin 16. Guess the constant 15V on pin 15 are the culprit!?
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It is weird that you measure 14 to 15V on pin 13, because this pin is connected to ground !
pin 15V is pulled down to ground by R32 (1K) and is high (15V only when a rest pulse is sent either by the RESET circuit (Q10,Q11) or by the divider rotary switch.
Check thoroughly for solder bridges between the pads of U3. Also make yourself sure that the strap in front of pin 14 is connected. _________________ Yves |
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Mon Apr 13, 2009 10:46 am Post subject:
Re: Clock Divider |
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Thanks for your reply, Yves!
yusynth wrote: | I guess you checked channel two with the 4017 IC in the right socket ? |
No! I've powered the board without any IC first. The LED on channel 2 was high.
Then I meassured the pins and inserted my sole IC into channel 1!
yusynth wrote: | It is weird that you measure 14 to 15V on pin 13, because this pin is connected to ground ! |
I AM SORRY! I meant pin 3! (Pin 13 = 0V; Pin 14 and 16 as reported: 15V each.)
yusynth wrote: | Check thoroughly for solder bridges between the pads of U3. Also make yourself sure that the strap in front of pin 14 is connected. |
It is.
I think I've checked for solder bridges on the IC sockets but will do it again. Again thanks for your assistence! |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Mon Apr 13, 2009 11:26 am Post subject:
Re: Clock Divider |
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e-grad wrote: |
No! I've powered the board without any IC first. The LED on channel 2 was high. |
Without 4017 the outputs (LEDs) must be low (without clock pulse). If not either Q6 is burnt and in permanent short-circuit. Other D9 is dead. Can you measure the voltage (without clock and without 4017) et the connexion point betwen D9,D1,R21 and R22 ? _________________ Yves |
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Mon Apr 13, 2009 2:51 pm Post subject:
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Will do it tomorrow. Your help is highly appreciated! |
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Tue Apr 14, 2009 6:09 am Post subject:
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I think Q6 is on the right (slightly higher) than the IC socket of channel 2.
With PCB laying in front of me as shown on your HP: power connector to the right and I'm viewing the parts side. I read the voltages as follows:
Resistors: on the R22 4K7 (14V on the left/11V on the right); R21 22K (14V/15V); both resisorts are above the strap from pin 3 of the IC.
Diodes: on D9 15V/14V and D10 14V/14V. D9 is next to R21 and R22 on left (vertical). and D10 next to the IC in question on the left.
So, I think, I can swap Q6? (There's no short.) |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Tue Apr 14, 2009 6:25 am Post subject:
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Normally on D9 (without IC in the socket and no clock signal in) you should have something quite low (close to 0.45V) on the cathode of D9 and something slightly higher on the anode (0.85V). Without clock signal Q5 is acting like a closed switch and the voltage on its collector should be close to ground level (0.45V). If not check the track and connections of D6,Q4,Q5,R18,R19 and R17. If these are good change Q4 and Q5. _________________ Yves |
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Tue Apr 14, 2009 6:31 am Post subject:
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Thanks! I'll check it later this day/evening and report back! Merci beaucoup! |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Tue Apr 14, 2009 8:35 am Post subject:
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Yes it does, actually it only requirse a positive supply (+15V or +12V). _________________ Yves |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Tue Apr 14, 2009 9:47 am Post subject:
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It's up to bridechamber to make it available... Ask Scott Deyo _________________ Yves |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Tue Apr 14, 2009 10:52 am Post subject:
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I swapped Q4 and 5 and everything went fine. I powered it off, inserted all 3 IC. Powered it up again and the same story.
However, LEDs for channel 1 and 3 are flashing lovely!
I'll check tomorow D6,Q4,Q5,R18,R19 and R17.
Again, thanks! |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Tue Apr 14, 2009 11:07 am Post subject:
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Change Q4 and Q5 _________________ Yves |
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Tue Apr 14, 2009 3:32 pm Post subject:
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I had changed Q4 and Q5 = everything was fine. Then I switched off the power and - since I thought i'm on the safe side - inserted all three IC and:
Channel 2 was high again!
Probably I made a mistake which burns Q4 or 5!?
Even with only 2 channels it's a way cool module you've designed! |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Tue Apr 14, 2009 11:11 pm Post subject:
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if there is no solder bridge and diodes are oriented the righ way, then I would check very thoroughly the values of all the resistors involved (eventhough you already checked it or think they are OK).
Can you send me a detailed photos of your PCB : component side and track side. I will check visually that there is no problem. _________________ Yves |
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Sun Apr 19, 2009 9:43 am Post subject:
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Salut Yves, I've managend to take some pics. Hope you like my frontpanel and if you can spot the mistake even better.
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sun Apr 19, 2009 9:49 am Post subject:
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HI
I'll check your PCB ...
By the way the link on your panel (3rd image) is broken... _________________ Yves |
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Sun Apr 19, 2009 9:56 am Post subject:
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On the first attempt I'd uploaded 4 pics which I changed the next moment. By now the panel should be visible.
BTW There's an unused mounting hole for the PCB above the output row. At the moment the pcb is solely mounted at a single screw above the inputs. Last edited by e-grad on Sun Apr 19, 2009 9:59 am; edited 1 time in total |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sun Apr 19, 2009 9:59 am Post subject:
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It's fine now _________________ Yves |
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Wed May 06, 2009 2:12 pm Post subject:
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Found the flaw. I had one bad solder joint. Now everything seems to work just fine. |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Thu May 07, 2009 7:27 am Post subject:
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e-grad wrote: | Found the flaw. I had one bad solder joint. Now everything seems to work just fine. |
That's a classic one two. Quite difficult to find the problem unless one systematically resolder all pads. _________________ Yves |
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