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Fungitec
Joined: Nov 16, 2006 Posts: 9 Location: Sweden
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
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Posted: Tue Oct 11, 2016 6:09 pm Post subject:
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what does it do in 8x2 mode? |
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Fungitec
Joined: Nov 16, 2006 Posts: 9 Location: Sweden
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Posted: Wed Oct 12, 2016 12:10 am Post subject:
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Thanx Elmegil
It does exactly the same as shown in video. Still in Random mode. Same behavior, the leds stepping forward sequentially lights up or unlit depending on random status via ext random in, or value of randomknob.
Any thoughts?
/thure |
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prgdeltablues
Joined: Sep 25, 2006 Posts: 222 Location: UK
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Posted: Wed Oct 12, 2016 5:04 am Post subject:
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Can you check the voltage at pin 11 of U9? In one mode it ought to be approximately V+, in the other, Ground. If that toggling isn't happening, that is the likely cause of your problem. Could be a shorted switch for instance.
Peter |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
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Posted: Wed Oct 12, 2016 5:23 am Post subject:
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Fungitec wrote: | Thanx Elmegil
It does exactly the same as shown in video. Still in Random mode. Same behavior, the leds stepping forward sequentially lights up or unlit depending on random status via ext random in, or value of randomknob.
Any thoughts?
/thure |
So in 8x2 mode I would expect that the B side would function "normally" and only the A side would be stuck with the input from the random. Are you saying it doesn't do that? |
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Fungitec
Joined: Nov 16, 2006 Posts: 9 Location: Sweden
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Posted: Wed Oct 12, 2016 6:45 am Post subject:
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Prgdeltablues: thanx
The voltage of U9 pin 11 digital board remains the same, 10,61V no matter what the switches (random/pattern, 8*2/16*1, normal/invert) are. I suppouse you meant the digital board, right? U9 on analouge is a TL074.
Elmegil: thanx
Yes that is correct. It dos not do that. It's the same behaviour as shown in video, no difference between the two modes 8*2 and 16*1...
I think i need to take it apart to investigate further...? Any other suggestions to messure?
Thanx a lot for taking your time!
Peace
/thure |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
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Posted: Wed Oct 12, 2016 7:02 am Post subject:
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That sounds very much like both the 8x2 and the random/pattern switch aren't right in the head. So yeah, U9 on the digital board, pins 9/10/11 are all related to both switches.
It actually looks to me like pin 11 should change with the pattern switch and pins 9 & 10 should change with the 8/16 switch so double check that again.
If they don't change though, then you could have a short somewhere around R50/R51, something wrong with the switches, something wrong at the chip.
The other day someone had issues somewhere else that ended up being a pin bent up under the chip instead of inserted into the socket. Or it could be something more electronic with the chip; you ought to be able to pull the chip out (while powered off, of course) then power it on and see if those pins change value with the switches without the chip in place. If they do, you have a bad chip.
Another test you can do is, with the power off, flip the switches. In one position (I can't remember which is which offhand, and the schematic makes it hard to trace) those pins should be tied to ground. If you don't see that, then you may have a problem with the switches themselves. |
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Fungitec
Joined: Nov 16, 2006 Posts: 9 Location: Sweden
Audio files: 1
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Posted: Wed Oct 12, 2016 12:36 pm Post subject:
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I messured pin 11 of U9. No difference, just steady voltage even when switching mode pattern or random. Same also for pin 9 and 10 with the 8/16 switch.
I took it apart and inspected the digital board. Could not see any suspicious solders or anything other than the solderjoint of the leftside switch-lug of random-pattern switch is very, very close to the pinheaders solders. I had attached a bit much solder there i thought so i desoldered that joint and made a new one.
I also took away the 4053 chip U9 from digital board and measured pin 11 again with no chip in it. Still steady voltage...
Then i inspected shorts in r50-r51 area. Desoldered them all and soldered them back again. Cleaned up some flux and put the board back on doughterboard for another test.
BAM...! All of a sudden the patternmode is running.
But now for some more sad news. It must have been two faults in the beginning. Even the 8/16 switch is not responing. It must have been faulty in the forst place.
Now i try to take it apart again for another investigation around U9 pin 9-10? And maybe also hace a look at that switch aswell?
I could have been to focused on the other switch, random and not payed to much of attention to the other...
So two faults may have become just one now... Can it be a faulty 4053 chip with intermitent faulty...? Sounds strange. It's either working or not working in my head...
Any suggestions?
Thanx a lot for helping me with this! Lovely.
I keep you updated. |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Wed Oct 12, 2016 3:03 pm Post subject:
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Have you verified the switches themselves? Mechanically, with power off, continuity switching from one side to the other?
Overheating switches can cause them to get monkeyed up inside, and that can even be an intermittent problem. |
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Fungitec
Joined: Nov 16, 2006 Posts: 9 Location: Sweden
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Posted: Wed Oct 12, 2016 4:25 pm Post subject:
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Yes the switches seems to be fine. I´ve done som continuity measurements today between different places. NV have also given me feedback to what to look for in a thread on Muffs.
https://www.muffwiggler.com/forum/post-2360978.html#2360978
After posting the last post on Muffs thread it all of a sudden just kicked in again and started to work fine. This intermittent behavior suggests it might be the cabeling anyway. I had a thought of it may be due to some light corrosion on the headers pins or cables that causes it...? This project has been put aside in a shoebox for many years in a basement...
Strange, but just now in this exactly minute it WORKS. All thing works...(knock on wood) All I did was measuring, putting in and out cables and pinheaders, putting in and out digital and analogue bords to daughterboard, in and out of 4053 IC and jerking around with the cables. I´ve done nothing to it and now it suddenly works.
I´m confused.
I keep this post updated if the status remains unclear to me. If it change and become faulty again. Would have felt good to find a problem...
Soo thankful guys like you and NV are around to help. It warms my heart!
Peace.
/thure |
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prgdeltablues
Joined: Sep 25, 2006 Posts: 222 Location: UK
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Posted: Thu Oct 13, 2016 5:53 am Post subject:
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Congratulations! So you now know there's nothing fundamentally wrong with the build. You've got an intermittent fault. My guess, from personal experience, is that it is most likely to be loose connections somewhere - cables, solder points, etc. especially as you suggest wiggling cables around solved it. It's the cables between the two switches and the board that I would look at first - try wiggling them one by one with the sequencer running. My next culprits would be tiny tiny shorts - solder whiskers - if you imagine a whisker just above a trace, bit of movement, even change in temperature - contact! Look particularly along the traces from pins 9, 10 and 11 of digital board U9. you could check the switches simply by unsoldering them - they are both spst, either unconnected or grounded i think, so simply connecting the two wires together should toggle the voltage st the pins, Or simply put new switches in.
ICs can fail of course, and in strange ways, but my experience, and I think that of many here, is that other explanations are more likely unless you've done something like putting a chip in backwards!
Peter |
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