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starr36
Platinum Member
Canada
1172 Posts |
 Posted - 02/06/2006 : 23:23:53
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Well those with a mind for troubleshooting will love this question.
I have a near mint DD-2. Here is what it does
1. Hold mode works, but, pressing pedal ONCE, turns LED ON, and it sticks on, until you push pedal again. IF YOU PRESS AND HOLD HOLD MODE, it works like it should. IF you ADJUST TIME control, while in HOLD mode, pitch goes up or down, like it should
2. Using the Mode Knob and and switching to LONG MED or SHORT Mode, the delay sound repeats infinitely.
3. SO, you can kind of get it to work in the HOLD MODE, but other modes do not function.
4. Sound Quality is VERY VERY GOOD in the hold mode, SOUND QUALITY OF THE GUITAR ORIGINAL SIGNAL is very GOOD, in all other modes, repeat signal is clear, but it repeats infinitely., but DOES NOT Seem to recognize the feedback knob.
5. It seems like it cannot unlatch itself when you switch modes.
I was studying the circuit diagram, and I was trying to figure out what was COMMON to SML mode and I see that there is a FLIP FLOP called BA634 and a few transistors ... but, can't really figure out beyond that.
Does anyone have any ideas? would be appreciated thank-you. |
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phostenix
Gold Member
USA
754 Posts |
Posted - 02/07/2006 : 06:06:12
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I have the schematic of this one and a working DD-3. I believe they're the same, but not positive. Can't say that I've spent much time looking at it to figure out all the workings. I'll try to look at it tomorrow and I'm sure I'll have some questions. I'm not completely clear on what's working & what's not in your desciption. Maybe Stinkfoot can help if he's hanging around.
Grace and peace,
Steve
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strat714
Silver Member
USA
156 Posts |
Posted - 02/07/2006 : 17:00:03
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| Sounds to me like the feedback pot is open. It's seeing infinite resistance. Try putting a new pot in. |
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phostenix
Gold Member
USA
754 Posts |
Posted - 02/07/2006 : 18:43:53
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| Wouldn't infinite repeat be a shorted pot? Output signal sent back to input with no resistance? |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 02/07/2006 : 20:33:20
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I've looked at the schematic for 30 seconds and I've already got a headache. Not exactly light reading.
The feedback pot:
You're both right. It depends where it is shorted or open. It's a 50k pot that acts as a voltage divider. If the slider is shorted to ground we get no feedback, if the slider is shorted to the other side we get max feedback. This doesn't explain why the pedal works in hold mode so I'm not sure we're looking at the right place.
I think the main controller's mode is determined by setting some connections high (+5V) or low (0V). We have 4 modes:
S:
M: ping 56,57
L: pin 54,55
H: pin 7
There is also the difference that in L, M or S mode we power the LED but not in hold mode (unless the switch is pressed).
There's still a few things you can check.
1. Does the LED light up in L, M and S mode?
If no, then there's something funky in or around the BA634 circuit.
2. Measure the voltages on the pins above in the different modes.
If pin 7 isn't 5V in hold mode, I'm full of bollocks and hasn't really understood the circuit at all  |
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stahlhart
Platinum Member
1318 Posts |
Posted - 02/07/2006 : 22:34:52
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Do you have a voltmeter? I could take readings off of one of my DD-2s in the relevant locations and report them here, if it would aid in the troubleshooting.
C.K.
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phostenix
Gold Member
USA
754 Posts |
Posted - 02/07/2006 : 23:30:17
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Que es "bollocks"?
No hablo ingles.
Gracia y paz,
Esteban |
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stahlhart
Platinum Member
1318 Posts |
Posted - 02/08/2006 : 00:04:20
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quote:
Originally posted by phostenix
Que es "bollocks"?
No hablo ingles.
Gracia y paz,
Esteban
http://www.urbandictionary.com is your friend...
C.K.
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 02/08/2006 : 00:14:33
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...hablo cojones
not sure you can say that |
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phostenix
Gold Member
USA
754 Posts |
Posted - 02/08/2006 : 01:36:05
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quote:
http://www.urbandictionary.com is your friend...
C.K.
I found this:
2. v. The act of a fat person running in a lopsided manner
2. He was bollocking along at a fair old pace in an attempt to escape the rozzers.
What's THAT all about?
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Edited by - phostenix on 02/08/2006 01:36:56 |
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phostenix
Gold Member
USA
754 Posts |
Posted - 02/08/2006 : 01:37:38
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| ...and now we return you to your regularly scheduled thread. |
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starr36
Platinum Member
Canada
1172 Posts |
Posted - 02/08/2006 : 03:25:49
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I knew you folks were a bunch of smart bananas .
Your collective posts pretty much confirms the Feedback pot is suspect. NOW ... here is more detail ...
1. Hold mode works like it should. I cleaned the switch and it off and ons perfectly, before it was a bit intermittent and would result in slight variable dimming of the LED. Now led is clear and no flickerings.
2. When in HOLD MODE, and HOLD WORKING RIGHT, FEEDBACK CONTROL OBVIOUSLY HAS NO EFFECT, MOVE MODE SWITCH TO LONG MODE< AND HOLD MODE DOES NOT TURN OFF. PRESS PEDALand HOLD MODE GOES OFF. I THINK MOVING FROM HOLD TO LONG SHOULD STOP THE HOLD EFFECT AND TURN LED OFF (it doesn't).
3. Pedal goes off and on properly in S M L Modes LED works like it should.
4. Feedback control DOES NOT WORK IN all 3 modes.
SO - I WILL FOCUS on the FEEDBACK POT and see what I can do with it.
Thank-you so far I think I'm making progress  thanks to you guys.
By the way, when I say the pedal is about MINT, it truly is!!! circuit board is clean as a whistle and baffled me...
I'll try resoldering that Feedback Pot and or close it and see  what happens...
PS "Bossarea Admin" the circuit diagram would be a lot easier to work with if they gave a highl level block diagram of signal flow. I know they kind of do that with the Oscilliscope waveform testpoints, but would be nice to know in theory where the signal is going. I keep frigging forgetting which way a signal passes through a diode  |
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starr36
Platinum Member
Canada
1172 Posts |
Posted - 02/09/2006 : 03:34:17
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Well, here is now where I am at.
1. the pot sweeps from 0k resistance to 22KOhms - compared that to volume pot and it is identical
2. checked #1 where leads #11 and #12 meet the main effect board. all good.
So, forward we go, component by component ... |
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DD-2 with mind of its own Help!
