i just took one of these on a trade, it sounded great. then i noticed that the reverse polarity protection diode was blown, removed, and bypassed with a jumper wire. seems to be a common issue with these. anyways, it worked, then i decided to re run the blown traces, and put a new diode in (i used a 1n4001). shazam it doesnt work anymore.
any problems using a regular diode in lieu of the zener? i tried putting it back to the way it was before i re ran the traces etc.., and nothing. i also noticed the boss adapter was putting out 13 volts, is this normal?
thats what i get for trying to fix something that still worked i guess.
Quote from: freak scene on December 26, 2008, 09:04:48 PM
i just took one of these on a trade, it sounded great. then i noticed that the reverse polarity protection diode was blown, removed, and bypassed with a jumper wire. seems to be a common issue with these. anyways, it worked, then i decided to re run the blown traces, and put a new diode in (i used a 1n4001). shazam it doesnt work anymore.
any problems using a regular diode in lieu of the zener? i tried putting it back to the way it was before i re ran the traces etc.., and nothing. i also noticed the boss adapter was putting out 13 volts, is this normal?
thats what i get for trying to fix something that still worked i guess.
Have you tried running it from a battery, and also tested it with both PSA and ACA adapters respectively ? I'm sorry that I'm not knowledgeable enough to be of much help, but I just got one of these myself and was careful enough to read about how to properly power the thing before I plugged it in the first time. I currently bypass the PSA vs ACA adapter problem by powering the DM-2 via a BOSS NS noise suppressor (which is powered by a PSA adapter).
Check out these threads, maybe you find some interesting hints which might lead you to a solution:
http://www.bossarea.com/other/aca.asp
From what I have read elsewhere, the older ACA adapters read 9 volts but are in fact closer to 12. Check out this info:
http://www.cioks.com/faq/faq.htm#difference
And this is a quote by user "Andreas" from the Harmony Central forum:
"The old ACA pedals wants to see 12 volts DC on the adapter jack, which is why your LED won't light up properly - it isn't receiving enough voltage. But they will also work with 9 volts DC if it is part of a daisy chain where there's at least one PSA (regular 9 volt) pedal as well, and if there's a signal cable connecting it to the other pedals. The ground connection between the pedals will then cancel out the components that lower the voltage in the DM-2."
I'm sorry that I can't be of more help...
no that was a bit of help, i have tried to power it up with a battery, and the same thing. LED works, turns on and off appropriately which leads me to believe that i didnt put the diode in backwards, but nothing else. i used the adapter that was outlined on the bottom of the pedal which was the ACA 120.
The power supply doesn't seem to be the problem now. AFAIK, the dm-2 supposed to run from a ACA. The fact the LED's work means a good part of the circuit is working.
I suspect you may have upset something.
If you aren't getting any signal at all in dry or effect modes check you haven't broken off any wires to the input and output sockets (for that matter any where else too).
wires all seem fine. i went through measuring votages, and the voltage seems to stop at a 100 uf 16 volt electrolytic, i replaced it with a known good one, and the voltage still doesnt pass that point. then i checked into the switching circuit. this is all greek to me as far as the switching circuit goes so forgive the following terrible description: q6 and q7 seem to be working (the c1689's? with their collectors? tied directly together and to ground). i couldntt really tell if q5 (k30A...) is working so i tried replacing it with one from a scrapped out ds-1 and it didnt work (the one in the ds-1 worked last time i used it). i cant find voltage on any of the IC's.
i then went at it with my o scope. it seems the signal dies at Q1 (c732) so i dunno.
Is this the schematic you're working from?
http://www.freeinfosociety.com/electronics/schemview.php?id=128 (http://www.freeinfosociety.com/electronics/schemview.php?id=128)
You really need to post voltages and describe the problem properly.
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0
Does it bypass?
If the sound don't get pass Q1 then why do you replace Q5?!
No voltage at the 100u cap?... Is this C37 we're talking about... then surely you shouldn't be seing any voltages anywhere else in
the unit!?
Quoteq6 and q7 seem to be working...
What voltages?
Quotethe c1689's? with their collectors? tied directly together and to ground
on the schemo above they're 2sc945's ( "Emitters" to ground... )
Hm... did I link to the right schematic? Is there another DM2... ??? :)
Quotei cant find voltage on any of the IC's.
Good heavens!!!
Take voltage readings then at. D1, R2, R10/R33 junction ( Vref ), D4 (zener)...
Is the battery getting warm? What voltage is the battery. Both out of and in the circuit?
ps. This circuit is a bit beyond my competence... beware! :P
Oskar
Quote from: oskar on December 30, 2008, 12:36:24 AM
Is this the schematic you're working from?
http://www.freeinfosociety.com/electronics/schemview.php?id=128 (http://www.freeinfosociety.com/electronics/schemview.php?id=128)
You really need to post voltages and describe the problem properly.
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0
Does it bypass?
no it doesnt bypass, but that is the schem i am working from
Quote
If the sound don't get pass Q1 then why do you replace Q5?!
because i had one of q 5, but i dont think i have a q1. ill have to dig a bit more.
Quote
No voltage at the 100u cap?... Is this C37 we're talking about... then surely you shouldn't be seing any voltages anywhere else in
the unit!?
yes c37, and yes no voltage past this, except at q6 and q7 when the footswitch is being operated. and then on to q5 where there is .05 ish volts, ill have to measure and write it all down again, but i think q6 and q7 were getting 9 volts when the footswitch was operated.
Quote
on the schemo above they're 2sc945's ( "Emitters" to ground... )
Hm... did I link to the right schematic? Is there another DM2... ??? :)
im reading off of the transistors, the writing is tiny so i may have misread. but thats what my schem says as well.
Quote
Take voltage readings then at. D1, R2, R10/R33 junction ( Vref ), D4 (zener)...
Is the battery getting warm? What voltage is the battery. Both out of and in the circuit?
will do
Quote
ps. This circuit is a bit beyond my competence... beware! :P
Oskar
obviously mine as well.
my schem has a bit more info:
(http://img184.imageshack.us/img184/2633/dm2pg2ta0.th.jpg) (http://img184.imageshack.us/my.php?image=dm2pg2ta0.jpg)
It seems weird you are getting voltage across C37 but the LEDs work. For the LEDs to work power must be getting to the board. C37 is pretty much across the main power supply!
A possibility is there is a broken track, either on the ground or on the positive rail.
A good start would be to probe the +ve rails and see which parts have voltage and what parts don't. The look at the PCB and see if you can find a track which connects between those areas.
Quoteit worked, then i decided to re run the blown traces, and put a new diode in (i used a 1n4001). shazam it doesnt work anymore.
If it was me, and it had worked before, I would assume that it was something really simple such as this that I had messed up.
Quote from: gkoerselman on December 31, 2008, 07:13:52 AM
Quoteit worked, then i decided to re run the blown traces, and put a new diode in (i used a 1n4001). shazam it doesnt work anymore.
If it was me, and it had worked before, I would assume that it was something really simple such as this that I had messed up.
i also assumed that, and re checked, and re ran them several times.
voltages:
d1: 0
r2: 0
r10/r33: 0
ic4 pin 4: 0
d4: 9.2
battery in circuit: 9.2
battery out of circuit: 9.2
battery is not getting hot.
You need to measure all the +9V rails around the circuit:
- pin 8 of the opamp,
- the top of R10,
- +ve C37,
- collectors of the transistors Q1, Q2, Q3, Q4.
Note which places have voltage. Follow the pcb tracks between +v rails that have voltage and +ve rails that don't, you should find a broken track somewhere.
Quote from: freak scene on December 29, 2008, 11:02:48 PM
...i went through measuring votages, and the voltage seems to stop at a 100 uf 16 volt electrolytic, i replaced it with a known good one, and the voltage still doesnt pass that point...
Does this mean that you do get a 9V reading from C37 (apart from around the switching logic ) or that C37 is the first instance where 9V is missing?
I found this gutshot on a japanese page.
(http://www.geocities.jp/hirock2001/diy2/dm-2c.jpg)
Quote from: oskar on January 02, 2009, 11:00:46 AM
Quote from: freak scene on December 29, 2008, 11:02:48 PM
...i went through measuring votages, and the voltage seems to stop at a 100 uf 16 volt electrolytic, i replaced it with a known good one, and the voltage still doesnt pass that point...
Does this mean that you do get a 9V reading from C37 (apart from around the switching logic ) or that C37 is the first instance where 9V is missing?
I found this gutshot on a japanese page.
(http://www.geocities.jp/hirock2001/diy2/dm-2c.jpg)
c37 is the first instance of no voltage, also i measured the resistor before c37 and it is getting voltage, then i measured across the resistor, and it seems to be pulling all of the voltage (voltage drop equals total voltage if that makes sense). i pulled this resistor out of the circuit and it measures fine.
here are some gut shots of it before i got it:
(http://indytone.com/Images/equipment/boss_dm-2_01.jpg)
(http://indytone.com/Images/equipment/boss_dm-2_02.jpg)
> also i measured the resistor before c37 a
Do you know which resistor it is on the schematic? (Find where it is on your board, then find the "R" designator on the overlay of the schematic you posted).
r41
That voltage doesn't help as the resistor is part of the switching circuit - you need a direct +ve measurement, say where R42 and R43 connect and there's that "+" symbol marked on the PCB.
Anyway I think I've worked out your problem:
http://www.geocities.com/george_giblet/effects/dm2_repair.jpg
You need to add two wires (in yellow) to repair the broken tracks (in cyan).
+1 bridge it... I would bridge all the way to C37 though. Your fix is around D3 and that's where the flip-flop gets it's voltage right now.
Via the LED.
ill give it a shot and report back tonight.
seems to be working, but the LED isnt now. i had retraced that portion of the board before, but i guess not far enough. i havent gotten to plug it in yet (the little one is sleeping) but it gets a signal oscilloscope.
Quote from: freak scene on January 03, 2009, 09:43:10 PM
...but the LED isnt now.
Awwwh... give me a break... :'(
Quote from: freak scene on January 02, 2009, 10:27:14 PM
r41
Put that thing back where it came from, or so help me! :icon_biggrin:
Quotei had retraced that portion of the board before, but i guess not far enough.
What part and how?... but clearly far enough, it was a closed cirquit before. ???
Which parts did you bridge now? Did you do anything else to it?
Measure continuity C37 to D3, pad 10 to D3
Or give us D3 voltage reading. ( referenced to ground ) I'ld rather see both :icon_biggrin:
If it isn't getting any, bridge from V+ to D3. ( george's suggested bridge should do it )
Now I'm going to eat filmjölk.
Quote from: oskar on January 04, 2009, 04:05:08 AM
What part and how?... but clearly far enough, it was a closed cirquit before. ???
Which parts did you bridge now? Did you do anything else to it?
Measure continuity C37 to D3, pad 10 to D3
Or give us D3 voltage reading. ( referenced to ground ) I'ld rather see both :icon_biggrin:
If it isn't getting any, bridge from V+ to D3. ( george's suggested bridge should do it )
Now I'm going to eat filmjölk.
i re ran the trace using a stripped solid 22 gauge copper wire from the power in to c37 hitting r41 as well, then did the same thing to the ground side to the point you mentioned earlier (d5 i think).
the whole circuit board seems to be working (im getting signal from the clock and the bbd etc on my scope.) just is stuck bypassed. i havent opened it up yet. im hoping its just the switch as it was a bit intermittent before.
Quote from: oskar on January 03, 2009, 12:11:09 AM
+1 bridge it... I would bridge all the way to C37 though. Your fix is around D3 and that's where the flip-flop gets it's voltage right now.
Via the LED.
Sorry, I'm not a native english speaker so I'ld like to clarify a couple of things.
The first sentence means bridge C37 - side to ground and C37 + side to V+. Nothing else.
With sentence no. 2 I'm trying to logically motivate why.
Your in your fix. is George. You should have listened to George. He drew a fine map for you.
http://www.geocities.com/george_giblet/effects/dm2_repair.jpg (http://www.geocities.com/george_giblet/effects/dm2_repair.jpg)
In any case there was just two wires needed.
Quote from: freak scene on January 04, 2009, 11:28:19 PM
i re ran the trace using a stripped solid 22 gauge copper wire from the power in to c37 hitting r41 as well...
You connected R41 to V+?
If you've connected R41 to V+ then please do unconnect it before you do anything else.
Look up R41 on the schematics with main goal to try and find it's connection with V+.
Quote
then did the same thing to the ground side to the point you mentioned earlier (d5 i think).
I think not. Turn your magic eightball off and think again...
Quotethe whole circuit board seems to be working (im getting signal from the clock and the bbd etc on my scope.) just is stuck bypassed. i havent opened it up yet. im hoping its just the switch as it was a bit intermittent before.
Think V+ without resistance to Q6 base...
Quote from: oskar on January 05, 2009, 04:22:41 AM
Sorry, I'm not a native english speaker so I'ld like to clarify a couple of things.
The first sentence means bridge C37 - side to ground and C37 + side to V+. Nothing else.
With sentence no. 2 I'm trying to logically motivate why. Your in your fix. is George. You should have listened to George. He drew a fine map for you.
that is what i did. i did what george said.
http://www.geocities.com/george_giblet/effects/dm2_repair.jpg (http://www.geocities.com/george_giblet/effects/dm2_repair.jpg)
i must be explaining it wrongly. my apologies.
I sort of knew before I posted that I hadn't got it right so... sorry. :P
also I got sloppy. I didn't read your post with the gutshots properly because I just saw a picture I had just seen over at another forum.
So I thought it was gutshots of another unit for reference.
This is what your pedal was doing one year ago... ( bottom of the thread )
http://www.bossarea.com/forum/topic.asp?TOPIC_ID=3248 (http://www.bossarea.com/forum/topic.asp?TOPIC_ID=3248)
... So, is that red wire still in there?
What pads is/was it bridging?
oskar
Quote from: oskar on January 06, 2009, 03:56:21 AM
I sort of knew before I posted that I hadn't got it right so... sorry. :P
also I got sloppy. I didn't read your post with the gutshots properly because I just saw a picture I had just seen over at another forum.
So I thought it was gutshots of another unit for reference.
This is what your pedal was doing one year ago... ( bottom of the thread )
http://www.bossarea.com/forum/topic.asp?TOPIC_ID=3248 (http://www.bossarea.com/forum/topic.asp?TOPIC_ID=3248)
... So, is that red wire still in there?
What pads is/was it bridging?
oskar
well the pedal was working fine when i got it (2 weeks ago). my friend gave me the link to the thread he posted asking about the red wire. i took the red wire off (it was bridging v+ to R41). i re did the broken traces and installed a reverse polarity protection diode and it didnt work. i went through this whole thing in the thread to find out i didnt go far enough with the trace repairing. the circuit works, the pedal passes clean signal, but now wont turn on (no echo). i tested the momentary switch and its good, havent gotten past that point cause i got busy with some other things.
but i need to trace out the bypass circuit and see whats not working.
any ideas or pointers? should i try to make it a true bypass pedal?
I thought it was all working except for the LED? You could try replacing the LED and/or the transistor driving it, they may have been damaged.
OK!
Q6 should be pretty toasted don't you think? The red wire connected to it's base so it was shorted to ground.
Change Q6!