Your technical advice... Yet again

FruitarGeek

A while back, I was told on GFSA that my DD3 has given up the ghost, I left it at that. But, after reading and reading and reading all over the net, I came across an article that gatherd my hope. The person had the same issue with his DD3 that I had, and he fixed it. I found more posts on the same problem and it all stemmed to one location on our DD3's... The IC1

Good people of GFSA, I need your help now, Ive only started embarking on the technical side of things, and so far so good. But If it is the IC1 chip on my DD3 that is faulty, then I obvioulsy need to get a new one, the problem is I dont know which one, and how. The original guy who said he had the same problem as me, said he replaced his IC1 with an LF353, however looking at the schematics of the IC1 chip, it doesnt say anything about LF353, but rather M5218L, or simply 5218. Now I have no idea what all these numbers mean, but Im guessing I have gotta get a similar IC for my pedal to work again. So please push me in the right direction.

I took a photo of the IC1 on my DD3, just so you can see, and suggest the correct chip I need, and also where I can get it from. I dont know what use the picture will be to you, maybe just to confirm that I am looking at the right chip ?

Now the writting on the chip says: 14558
645H
JRC

Now please, can someone tell me what these all mean, and what exactly I must be looking at. Im going to yebo electronics today, and I see they have a LF353 http://www.fort777.co.za/index.php?main_page=product_info&cPath=269_456_605_627_628_633&products_id=7282

but I cant be certain how far off/close I am to getting the right thing.

Thank you all.

*This is the original forum I read with the guy that had the EXACT problem as me
http://music-electronics-forum.com/t11424/

makepeace

Weeeeell.. The JRC4558, LF353 and the M5218L are all dual op amps. They work in much the same way with small variations in electrical characteristics. You could go with either of those op-amps and still get a working pedal. They might sound marginally different to one another, but they perform the same base function. Seeing as you have a choice; what I would do is to get an IC socket and get a few different chips and try them out. They are pretty cheap anyway.

Another variation to try is the TL022. The JRC4558 (what you have in that pedal) is a little higher gain, and I've read the TL is great with delay circuits, but haven't tried it myself. My Ibanez PUE-5 multi-effect has about 20 M5218L's in total, and a guy found out that if you swap some of them with 4558's and TL's, it really opens the pedal up.

But to answer your question, if you want it to be fixed and sound the same as it did before, go for the JRC4558.

http://www.smallbearelec.com/Detail.bok?no=202

http://www.smallbearelec.com/Detail.bok?no=578

http://www.smallbearelec.com/Detail.bok?no=213

http://cgi.ebay.com/1-TL022CP-TL022-Audio-AMP-IC-ICS-DIP-8-NEW-/260710508704?pt=LH_DefaultDomain_0&hash=item3cb38ea8a0

Good luck!

edit: i've just looked at your picture properly.. you have surface mount components there (http://en.wikipedia.org/wiki/Surface-mount_technology), inc the IC. that will prove tricky as they are damn small and hard to solder. i don't know what to suggest wrt this :-\ you'll have to look for an SMD ic like this one:

http://www.goldmine-elec-products.com/prodinfo.asp?number=G388S

and you won't be able to use a socket.

AlanRatcliffe

+1 to all the above. SMD circuitry is not designed to be repaired, it is usually just replaced and few have the specialised tools needed to work on it anyway.

You can try order a replacement board from the Roland distributors (TOMS or Bothners), but chances are it will cost more than to replace the whole pedal.

Welcome to the modern throw-away culture. ☹

FruitarGeek

Ah wow, I didnt see that before. Thanks makepeace, I appreciate the effort you put in.

Even if I had to get very thin solder, would this repair be possible. As I said, the other guy on the forum had done it before

makepeace

FruitarGeek wrote Ah wow, I didnt see that before. Thanks makepeace, I appreciate the effort you put in.

Even if I had to get very thin solder, would this repair be possible. As I said, the other guy on the forum had done it before

you can definitely try it. you don't have much to lose. you'll just need a very cool hand and maybe a magnifying glass to check for possible solder bridges you may create by mistake ?

i'm about to mod my dano fab echo and also has SMD's, but i've read that lots of people have done it successfully with basic tools, so try your luck ?

AlanRatcliffe

I think the older DD-3s were still conventional non SMD construction - it might be one of those that was repaired. Otherwise, AFAIK, you need special reflow soldering tools, with a tip for each different component. I'll leave other more knowledgeable types to comment on the feasibility of working on SMD stuff with regular tools.

EDIT: Makepeace beat me to it. ?

Gearhead

Couple of things:
1. you run the risk of frying the opamp if you do not use a temperature controlled soldering station, and even then... it only controls the temperature of the back of the tip, not the tip itself. Set to low temperature and only raise until it works, with a little patience.
2. the trouble with smd components with more than two lugs is not so much putting them onto the boards as it is getting them off. You want to get a proper solder sucker - forget braid (as mentioned in another thread) for smd. You also want to make sure you don't pull the foil off of the board - the lugs must be positively loose.
3. when soldering on, your problem is to get the solder just on the lug and not between the one lug and the next. Use only tin with flux core, obviously the thinnest wire you can get.
4. Your soldering tip must also be sharp as a needle - you can get special ones for most soldering stations.
5. For easier assembly, use presstick to keep the smd in place before the first couple of lugs fix it in place. Solder out to in to minimise the mechanical load.

As said before, you have nothing to lose.

aja

the guys at work do this stuff all the time on SMD's with no special tools. To remove simply add poop loads of solder until all the legs are joined - then heat each side in quick succession (the copious amounts of solder will allow you to heat up every leg at once since the heat will travel along the solder and not only to where the tip can reach)

The thinner the iron tip, the less heat can be transferred to the solder - so the more solder you have the thicker tip you need - a thinner tip does not necessarily make working with small components easier as you are limited by how much solder (in terms of volume or mass) you can melt at once.

When placing the new IC on the board - add enough solder to ensure good contact on all legs. Too much solder is no problem - even one or two legs will attach the IC to the board firmly. So if you have too much solder, hold the board in one hand and iron in the other hand - heat up the offending piece of solder (i.e. between two legs or very large blob) and as soon as the solder is liquid whack the whole board onto its edge on the desk - the liquid solder will fly off and land somewhere on the desk because the PCB's are covered with a special coating that the solder doesn't stick to. so no copper braid or pump needed. By the way, I believe the proper name for the copper braided wire is "solder wick"

Disclaimer - I am a mechanical engineer who has been electrocuted by mains more times than I have ever soldered in my life, so please accept this complimentary bucket of salt to use with the above information ?

FruitarGeek

Guys, thank you all.

The thing that sucks is that I dont own half of the equipment needed, I just have a standard 30w soldering iron without temperature control. Its literally just a plug and go. And solder that is much to thick.

It sounds very costly to afford all this stuff, I think what I may need to do is pay one of you guys cough cough ? with the right tools, to help me with this. makepeace, let me know how your modding goes.

In the meantime, I guess Im going to have to wait for my Monte Allums mod to arrive ?