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kriwil
Copper Member
Indonesia
17 Posts |
 Posted - 03/10/2010 : 07:01:40
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hi all, just received another Japanese DD-3 with distorted delay sound.
Replaced all the cap around 570 already, and problem still there.
I did traced the sound and i found that it begin to distorted on output of 311. At the (+) input side, sound is normal.
I believe 311 here functioning as comparator. Can i suspect that 311 is not working? |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 03/10/2010 : 14:29:01
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| Hi kriwil! Are these commercial repairs, or for your own collection? |
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kriwil
Copper Member
Indonesia
17 Posts |
Posted - 03/11/2010 : 05:18:35
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hi laurie,
this is for my own collection. I collected boss stomp box quite a lot. I have around 40 stomp box currently. As for Japanese DD3, i have 5 stomp box, 3 working fine and the other 2 not.
btw, last night did compared with my working DD-3, seems that distorted output of 311 is normal |
Edited by - kriwil on 03/11/2010 06:07:17 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 03/11/2010 : 06:15:33
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Yes - the 311 comparitor does that to the sound. It's normal.
Is there undistorted sound going into the base of Q10? |
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kriwil
Copper Member
Indonesia
17 Posts |
Posted - 03/11/2010 : 07:08:31
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quote:
Originally posted by Laurie
Yes - the 311 comparitor does that to the sound. It's normal.
Is there undistorted sound going into the base of Q10?
Did check at C39 and still have the distorted sound. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 03/11/2010 : 14:14:23
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| And is it distorted at pin 10 of IC4? Is IC4 being properly strobed (do you have a scope to check the SAH signal on pin 12 of IC4?) |
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kriwil
Copper Member
Indonesia
17 Posts |
Posted - 03/12/2010 : 02:22:46
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The sound is good until pin 2 (IC 5), and very distorted at pin 7 (but seems to be normal). It remains distorted at pin 6 (IC 6) onward.
Is it worth to try replacing IC 6 ?? Btw, i dont have a scope.
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 03/12/2010 : 02:39:15
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| This will be hard to track without a scope. We need to know if the D-A function is working properly, and thats something that's visible on a scope trace... |
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kriwil
Copper Member
Indonesia
17 Posts |
Posted - 03/12/2010 : 05:56:34
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hmm.... in this case, the biggest possibilities of error would be at 4066 or Roland IC?
since i dont have scope, what i can do is replace the part of AD-DA except the roland IC... |
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Dirk_Hendrik
Copper Member
Netherlands
28 Posts |
Posted - 03/12/2010 : 19:18:03
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No.
If you have a distorted output it seems that the AD/DA conversion still works. Therefore the question remains if the signal is still good when it goes into the first 4066 section. Just as Laurie said.
Do not assume, never. Assumptions are the mother of all mistakes (credits; Albert Einstein). Measure and draw founded conclusions (or let us help you with that) from the measurements.
And try to score a scope. Makes life way esasier ;)
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kriwil
Copper Member
Indonesia
17 Posts |
Posted - 03/16/2010 : 05:14:30
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haven't got the scope yet, did traced the signal again.
Got distorted signal at pin 8 ic 4c and its remain distorted at pin 9 IC 4c,
while at working DD-3 the signal distorted at pin 8 ic 4c and get clean signal at pin 9 ic 4c
Any clue for this? is that anything to do with 4066?? what is the function of C42?
thanks |
Edited by - kriwil on 03/16/2010 05:21:54 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 03/16/2010 : 13:18:44
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C42 looks to be for RF suppression.
With distorted at pin 8 and still distorted at pin 9 it sounds like one of two things:
1) the SAH signal on pin 6 of IC4 isn't there
2) IC4 has failed |
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Dirk_Hendrik
Copper Member
Netherlands
28 Posts |
Posted - 03/16/2010 : 15:33:27
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He says the signal is clean at pin 9 again. That suggest the sample and hold works.
Question for kriwil,
Do you get a clean, delayed signal at IC 3a, pin 1 and 2? |
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kriwil
Copper Member
Indonesia
17 Posts |
Posted - 03/16/2010 : 16:04:06
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quote:
Originally posted by Laurie
C42 looks to be for RF suppression.
With distorted at pin 8 and still distorted at pin 9 it sounds like one of two things:
1) the SAH signal on pin 6 of IC4 isn't there
2) IC4 has failed
looks that option 2 more possible in this case. SAH signal should be there since it works fine for 4a and 4b (sound is clean there) and there is no broken route to pin 6.
Let me try to replace IC 4 |
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kriwil
Copper Member
Indonesia
17 Posts |
Posted - 03/16/2010 : 16:05:37
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quote:
Originally posted by Dirk_Hendrik
He says the signal is clean at pin 9 again. That suggest the sample and hold works.
Question for kriwil,
Do you get a clean, delayed signal at IC 3a, pin 1 and 2?
Hi dirk, the clean signal at pin 9 is for working DD3. In my case here, the signal remain distorted at pin 9, theredore delayed signal at IC3a pin 1 and 2 still remain distorted |
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kriwil
Copper Member
Indonesia
17 Posts |
Posted - 03/17/2010 : 02:39:55
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hi all, did try replace 4066... problem still there.
Now, the possibility only check the SAH signal. Since I don't have a scope, is it possible for me to try get SAH signal from other DD3 (the working one) and see the impact ? |
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Topic |
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Japanesse DD3 again
