Hey guys, just finished a 117 (SAD1024) and well...... ...it's not flanging!
It passes dry signal perfectly when ON, but no matter how i set the clock or BBD bias i don't get the faint of a flange.
A link to the MXR service manual would be really helpful.
I have a 10pf in Ca at the moment. when i jumper it i hear the clock whine.
Checked the voltage of the LFO and it's ramping.
I will post voltage shortly, in case we need them.
Thanks
Rej
Here are my voltage, all trimpots set to noon, all pots set to noon.
Using a 18V supply into a Filtering/15Vreg setup.
Source: 18.54
PCB Pads: 14.62
IC1:
1: 7.36
2: 7.23
3: 7.01
4: 0
5: 4.85
6: 7.19
7: 7.19
8: 14.62
IC2:
1: 7.28
2: 7.28
3: 7
4: 0
5: 7.21
6: 7.28
7: 7.28
8: 14.62
IC3:
1: 13.95
2: 6.52
3: LFO
4: 0
5: 7.21
6: 7.27
7: LF0
8: 14.59
IC4:
1: 6.18
2: 6.18
3: 5.74
4: 0
5: 6.97
6: 7.28
7: 7.31
8: 14.6
IC5:
1: 1.4
2: Float 6.04
3: Float 7.3
4: 0
5: Float 7.1
6: Float 7
7: 14.59
8: Float 6.9
9: 14.59
10: Float 6.7
11: 8.35
12: Float 8.3
13: 0
14: Float 7.1
15: 6.11
16: 0
IC6:
1: 6.87
2: Float 7.3
3: Float 13.8
4: 0
5: Float 7.2
6: 0
7: 0
8: 14.58
9: 14.58
10: 7.63
11: 14.58
12: Float 13.9
13: 14.58
14: 14.58
Q1:
E: 0
B: 0.49
C: 0.49
Q2:
E: 1.35
B: 1.83
C: 7.77
Q3:
E: 0
B: 0.51
C: 1.36
Q4:
E: Float 7.6
B: 14.45
C: 14.45
Rej, I am exhausting my resources trying to find you some documentation. I did stumble on a factory schem that may offer some help.
http://s82.photobucket.com/user/bainzy007/media/flangerm117_12.jpg.html (http://s82.photobucket.com/user/bainzy007/media/flangerm117_12.jpg.html)
Ill keep looking.
Cody
By Ca I assume you mean the clock cap, in which case 10pF is way too low, for the SAD1024 the value should be selected between 33-62pF as specified on the original schematic.
Also your SAD1024 ground pin (1) isn't at ground.
Quote from: Scruffie on May 13, 2014, 07:13:19 AM
By Ca I assume you mean the clock cap, in which case 10pF is way too low, for the SAD1024 the value should be selected between 33-62pF as specified on the original schematic.
Also your SAD1024 ground pin (1) isn't at ground.
I agree with the clock cap statement. The build document is incorrect when it says that the clock cap should be "6.8pF to 22pF" Those would be acceptable values for a MN3007 based circuit. The SAD1024 needs more. I have used 47pF up to 68pF. The best way to find the cap you need is to measure your clock rates with Manual at full CW and full CCW. You want the clock going into the BBD to be between ~32KHz and ~950KHz
As for the Pin 1 Ground note.... I have built this circuit 3 times with this PnP and never had a problem. I do see that Pin 1 of the SAD1024 is not connected to ground on the transfer but, I still had 3 working units!! :o
Thanks for input guys. :)
So pin1 should have a reading of 0, right?
Will fix the Ca cap, i had put a 15pf in there for the moment, it's socketed, so no biggie.
I'm working tonight so i'll have a look tomorrow.
Muchos thanks!
Gig have been cancelled, let's fix this thing!
So looking at the factory schematic (Thanks Cody) and the one in the build doc, the SAD1024 is grounded in factory and floating in MB doc, should i ground it?
Other than that, is there something that seems odd in the V that i posted?
I have the factory schematic as well. It does not show power or ground pins in the schematic being connected although, it does give a description of the pins at the bottom.
Like I mentioned before..... I have built this 3 times and it has worked as-is all 3 times. That is not to say that the pin should not be grounded. You can try it of course but BE CAREFUL!!!!!!
I would try a larger clock cap before messing with the ground. Try a 47pF cap first and then measure frequency at the BBD clock input. You should see about 32KHz with Manual fully CW and about 950KHz at full CCW. turn the speed pot all the way down to help with fluctuations in voltage.