DOD 670 Flanger - Repair

[cjlectronics]

If you look at the transformer in the 670, there should be an unused red wire on the primary of the transformer. Wire it and the green wire to the power cord. Now you are wired for 220vac and no new transformer is necessary. The secondary of the transformer is 36vCT.

CJ

[beatnik]

i don't know very much about transformers because i only did lot of pedals without any transformer.

but here is a pic of the inside

[ATTACH]3801[/ATTACH]

the only disconnected wire is a green wire, then i have one black + two red wires going to the pcb and blue and red wire going to the power switch.

many thanks for the help, hope to resolve without mounting a new transformer

[oc disorder]

The transformer primary has 3 wires.
For 220 volts all the windings have to be used.
The blue and green wires connect to the outer extreems of the winding
and the red wire connects to the middle.So the red wire connects to half the windings and only requires half the input volts .
Yours is like that and you want the 220 volt tapping so you need to disconnect that red wire and insulate it and connect the green one
(coming from the transformer) to where the red one was connected.
It must connect to the power cable coming in ,your photo doesn't show it.
So now your blue wire is still connected to the power switch but now you are using all of the windings for 220 as the green wire is now used.
MAKE SURE EVERYTHING IS SAFE AS THIS CAN BE FATAL.
Good insulation and proper termination.

[cjlectronics]

Oops, good call. The 120 looks like a 220 from the schematic I have (and vise verse)

[lamperys]

Same problem on same unit

Hi there!

I had the same issues with this amazing stomp box, the led flashes accordingly when the pedal is on but I just get some noise and the signal is bypassed when disengaged... I´d been looking for the schematics but didn´t find them...

how you fix it?

So much thanks in advance!!!

Xavi

[spartadrive_in]

Hi there!

I had the same issues with this amazing stomp box, the led flashes accordingly when the pedal is on but I just get some noise and the signal is bypassed when disengaged... I´d been looking for the schematics but didn´t find them...

how you fix it?

So much thanks in advance!!!

Xavi

Someone else had the same problem and emailed me his fix. Turned out it was the Reticon SAD512D chip. Problem was that it cost him about $40.

The schematic is up top on the original post.

Sorry but I can't remember the website he bought it from. I wish I knew because I still want one.

BTW: We did not get noise. It would be quiet and when you bypassed you got your regular clean signal.

[magnetbox]

Sorry to bump this thread up yet again...

I'm having a slightly different problem with my 670 Flanger-- it works, but the effect mix is weak and slightly distorted.

My first instinct was to remove the rear panel and check for broken leads, etc. I discovered that when I remove the input jack from its mounting hole-- breaking the ground connection between the jack's ring and the case-- the effect becomes pronounced, like I expect it to be. Of course, I don't get any guitar signal at that point-- but the flanger seems to be doing a great job on the hum.

Does this suggest anything obvious? I've built a few easy pedal projects but it seems like this design is a little obscure / unique.

Thanks!

[nbabmf]

I just got one a DOD 670 Flanger off eBay. It seems to have the same symptoms as OP's. I wonder if he ever got it fixed...

[nbabmf]

I took the CD4001 out and put a socket in it's place. A new one didn't change anything. It's audio probing time.

[Rxnykurt]

I need help, i just recently got a 670 and when i turn the regen up , it does sound like an ambulance can anyone help me with this? do i have to change something on my pedal? pleaseeeee!!!

[ilcaccillo]

The transformer primary has 3 wires.
For 220 volts all the windings have to be used.
The blue and green wires connect to the outer extreems of the winding
and the red wire connects to the middle.So the red wire connects to half the windings and only requires half the input volts .
Yours is like that and you want the 220 volt tapping so you need to disconnect that red wire and insulate it and connect the green one
(coming from the transformer) to where the red one was connected.
It must connect to the power cable coming in ,your photo doesn't show it.
So now your blue wire is still connected to the power switch but now you are using all of the windings for 220 as the green wire is now used.
MAKE SURE EVERYTHING IS SAFE AS THIS CAN BE FATAL.
Good insulation and proper termination.

Just for reference not all 670 pedals have a transformer with 110V and 220V taps.
Some pedals have a transformer with only one 110V primary without any other tap.

It's the case in my pedal, it's a 110V power input, the transformer primary has 2 red wires and it's not possible to wire it to 220V.

For these pedals if you want to power them from 220V/230V you need to replace the power transformer

[ilcaccillo]

I'm trying to repair my 670 Flanger at the moment.

Symptoms are similar to other users, the pedal powers up, the led flashes accordingly to the speed dial setting, I have Dry signal but not any Effect (wet signal).

Voltages seem fine in all the propper supply pins of the IC's.

I traced signal along the circuit, I have signal going into the SAD512D Pin6 but no signal the the same IC outputs at Pins 3 and 4.

It seems I'm joining the broken SAD512D club.

Any reason for so many pedals with broken/shot SAD512D chips?
Why are these chips failing so much?
Do they have something inside that degrades over time?

I dont see a voltage problem, as the 7815 takes care of the regulation, there's caps doing the proper filtering, so what might be the culprit for SAD512D keep failing while other similar chips are much more sturdy?

Thanks

[Enzo]

Failing so much? You are the latest victim of internet bloat. If a diode fails or a common op amp IC fails, no one has to go online and ask for the part or what to do about it. But the SAD chips are hard to find, and people have no idea how they work anyway, so they go online. Most units using SAD chips are still working. The MN3000 series might be more robust, but they are also decades newer. And they do fail.

My MXR analog delay has an SAD1024, and it still works, and I have no reason to think it won't continue.

[ilcaccillo]

Failing so much? You are the latest victim of internet bloat. If a diode fails or a common op amp IC fails, no one has to go online and ask for the part or what to do about it. But the SAD chips are hard to find, and people have no idea how they work anyway, so they go online. Most units using SAD chips are still working. The MN3000 series might be more robust, but they are also decades newer. And they do fail.

My MXR analog delay has an SAD1024, and it still works, and I have no reason to think it won't continue.

Hello Enzo, thanks for your input. And I understand what you are saying, it makes sense.

But I have a repair shot for the last 5 years, we just repair audio/music equipment.
I receive a lot of stuff to repair, but to be honest I never had an unit not working because of a failed 4558 IC, a TL072 or a NE5532,
But at the moment we have at the shop 3 guitar pedals with shot SAD512D chips, maybe it's a coincidence maybe, but I don't think so.

Going through a lot of internet threads of different projects repairs (I always research first, before even opening the unit), I see shot protection Diodes, a lot of failed aged electrolytic caps, failed max1044, broken pots and switches.
And to be honest I see much more failled SADxxx chips in Delays, Flangers and Chorus effects than any other IC.

So even if you are right and the chips itself are sturdy, what I would like to know is what can make these chips fail in normal operating conditions?
The "few" that failed what might be the reason?
And knowing that what could be done in the circuit or implementation to provide a better protection for the expensive and rare SADxxx IC's?

Thank you so much

[antobusets]

Gonna try reusing this topic
Bought some time ago a Dod Flanger 670. After some time of usage, it started randomly distorting according to the wave or leaving signal dry, with no effect at all. I brougth it to some techs, and they suggested to change the SAD. Sah changed a week ago, it goes well for a good amount of time and then, first it distorts and then it stops flanging and stays clean.
I imagine it could be some problem with the power supply? It happens when the pedal gets hot after some usage, and I'm in Italy, so I need to use it with a 220/110 converter (maybe it helps with failing).
I opened it, and the wirings seemed a bit different from the other I saw in the topic. I doubt (and I hope is not)it is a broken sad again, I've used it 2 times!
Need your help, thank you in advance