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Tux320
Copper Member
9 Posts |
 Posted - 08/21/2008 : 03:15:49
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I recently purchased a Japanese boss dd-3 digital delay that was reported slightly broken in order to fix it. The problem is that even with the level and feedback controls all the way up you can only just hear the delay. Then I adjusted the internal trimpots to maximum, on the first test after the adjustment there was no audible difference to me. I tested it again about five minutes later and when I plugged in to the input there was a tone which now occurs most of the time I plug in. Now I cannot get any signal with the effect bypassed or active through either of the outputs  although sometimes if I knock it hard the sound pops on and of quickly so it's probably a short circuit issue.
If anyone has any ideas of how to get the the feedback time up to a normal level I'd be glad to hear them. Also, does anyone know of any good mods for this pedal?
Thanks, Sam |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/21/2008 : 03:21:43
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Hi Tux320 and welcome!
Is it the "long chip" version of the DD-3? |
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Tux320
Copper Member
9 Posts |
Posted - 08/21/2008 : 03:27:39
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| If you mean the large chip in the middle of the board that goes from one side to the other then I think this is the version you mean. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/21/2008 : 03:38:24
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OK... that's the long chip.
We are woring on a DD-2 (which is identical internally to your DD-3) in another thread - it has the exact same symptoms you initially describe "level and feedback controls all the way up you can only just hear the delay". When we track that problem down, it's probably going to be the smae thing in yours.
As for the more recent issues, can u post some close-up pics of all over the board (both sides) and the pedal wiring? |
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Tux320
Copper Member
9 Posts |
Posted - 08/21/2008 : 05:06:52
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I can't upload pic's right now because the upload button won't work but I think they mentioned something about the tone problem on the thread that you told me about before
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 08/21/2008 : 09:41:55
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| If there's a problem uploading, just e-mail the pics to me (borgetx@hotmail.com) and I'll copy them up. |
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Tux320
Copper Member
9 Posts |
Posted - 09/12/2008 : 19:59:43
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| Just wondering, what do the trimpots do in the dd-3 |
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 09/13/2008 : 22:18:40
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quote:
Originally posted by Tux320
Just wondering, what do the trimpots do in the dd-3
Assuming it's the long chip DD 3, the trimpots are only there to make adjustments to the oscillator which controls the clock in the main control chip. I don't think these are as critical as the ones on BBD delays (no green goop, for starters). If you've adjusted them, just put them back to where they were (or as close as you can get). If you look at the schematic the oscillator circuit (IC8), although positioned/represented slap bang in the feedback loop, is actually totally seperate from it. If yours is anything like mine (and it sounds like it is) the oscillator is fine.
Stay tuned because I've got a good feeling I've finally identified what the problem is. I'm currently waiting for a part but I'll post as soon as I've tried it out. |
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Tux320
Copper Member
9 Posts |
Posted - 10/20/2008 : 00:50:02
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| Unfortunately tony's problem did not turn out to be the same as mine. Q9 appears to be fine so could anyone give me any more advice? |
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 10/21/2008 : 22:22:22
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| Do you have the equipment (mostly a multimeter and a probe as described in my DD 2 thread) to take measurements? |
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Tux320
Copper Member
9 Posts |
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 10/25/2008 : 00:05:27
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Bit of an obviously, but check for any loose wires, especially coming off the switch and volume boards. Some of those joints are very small and delicate.
Forgot to ask, can you hear the dry signal?
Also, have the faint delays returned, or are they still gone?
quote:
Originally posted by Tux320
I have access to a multimeter but what do you mean by probe. For checking continuity between two points or something?
Do you mean this http://www.diyguitarist.com/PDF_Files/DIY-AudioTester.pdf
Yes, something just like that. Just look here, about a fifth of the way down, Dr Bob describes that sort of thing:
http://www.bossarea.com/forum/topic.asp?TOPIC_ID=5030&whichpage=2
It's just a normal unbalanced guitar lead, with one end removed. Attach the shield to something metal to ground it and solder the hot wire to a lead from an (approximately) 1uf cap. It's to stop DC coupling, popping and general damage that might result from DC going where it shouldn't.
In fact, I'd recommend just trying out some of the stuff in that thread. You need to isolate the problem. Make sure the voltage regulator (IC10) is working - should be 9v in and about 5v out. I hear D6 is a common culprit so make sure it looks OK. All these parts are down the bottom (foot switch) end of the board. As you look down on it they're on the right.
If the voltages are fine, the problem might possibly be in the feedback loop somewhere between the two halves of IC2 (the NE570). If it's delaying at all it means the digital bit is probably OK.
Not to idiotically reiterate my own problem, but how did you check Q9? It really is in a vulnerable spot and it causes the exact symptoms you describe, whilst looking just fine. |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 10/25/2008 : 01:31:13
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quote:
Originally posted by tony
EDITED
quote:
Originally posted by Tux320
I have access to a multimeter but what do you mean by probe. For checking continuity between two points or something?
Do you mean this http://www.diyguitarist.com/PDF_Files/DIY-AudioTester.pdf
Yes, something just like that. Just look here, about a fifth of the way down, Dr Bob describes that sort of thing:
http://www.bossarea.com/forum/topic.asp?TOPIC_ID=5030&whichpage=2
It's just a normal unbalanced guitar lead, with one end removed. Attach the shield to something metal to ground it and solder the hot wire to a lead from an (approximately) 1uf cap. It's to stop DC coupling, popping and general damage that might result from DC going where it shouldn't.
Hi tony, Tux320 & Guys
It is better to use a 0.1uf = (100nf) UN-polarized polyester cap.
Use a low voltage one, like the 100nf bypass chip caps, on most digital IC's on computer boards.
But if working on TUBE gear, get one of at least 450V, better still 600V
Because they are usually made of Green polyester, they have become known as Green Caps, even though they are now sometimes Brown or Blue.
Most 1uf caps are electrolytic & therefore polarized.
I have been thinking of doing a little photo build, of a simple probe, it just depends on my free time.
Here is the material list for my Idea:
1off Used plastic Biro pen case.
1off 100nf chip cap.
1off Pop rivet or small to med nail.
2off Some flexible wire. 12 inches-(300mm). one black one red.
1off Some quick drying or hot melt glue.
1off small alligator/crocodile clip.
Anyone getting the picture?
Regards Dr. Bob |
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 10/29/2008 : 20:57:05
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quote:
Originally posted by Dr. Bob
It is better to use a 0.1uf = (100nf) UN-polarized polyester cap.
Yeah, sorry, I meant that.
Tux320, are you making any progress? |
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 10/29/2008 : 21:00:19
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quote:
I have been thinking of doing a little photo build, of a simple probe, it just depends on my free time.
Here is the material list for my Idea:
1off Used plastic Biro pen case.
1off 100nf chip cap.
1off Pop rivet or small to med nail.
2off Some flexible wire. 12 inches-(300mm). one black one red.
1off Some quick drying or hot melt glue.
1off small alligator/crocodile clip.
Regards Dr. Bob
That would be cool. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/30/2008 : 00:48:05
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| Let me know when you have a probe made... this should (after tony's DD-3) be easy to find! |
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Topic |
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Boss DD-3 Repair Project - Help Please
