my 1'st time changing an xstr, and my 1'st post here :)

[Jave]

I have a Digitech genesis 1 ..
two the transistors are definitely burnt.
they are:

70-4014, v-reg, 7805, +5v, 1.5 amp, to-220

70-4146 v-reg +3.3v low dropout 1 amp to-220

I am not a tech, have never done this before, and don't know what to do..
but I haven't found the xstrs any ware . .am I to substitute them?? how do I know the specs are the same?

Any info would be great thank you!

[BobEllis]

Those are voltage regulators, actually an integrated circuit in a TO-220 package. WHY are you so sure that they are bad?

Have you looked at Digikey or Mouser? A 7805 is a pretty standard part, and there's bound to be a substitute for the low voltage reg. Look on the part for more numbers.

The bad news is these are fairly rugged parts, and something else is probably bad that caused them to blow. Simply replacing them probably will just lead them to blow again.

[Jave]

I opened the case, and on the inside of it was a melted black mark imprinted ware one of these were, the pcb is also darkened around it. I thought it'd be best to replace both, just in case the other is defective, and not showing it visually.
I still haven't bought a multimeter .. just not sure ware to find a good one.

These Genesis units don't have an on/off .. just a plug for the wall.
I heard something about them overheating a while ago,but must have been brain dead at the time, becouse I accidentally left mine on over night ..
I came back turned it off, and that was the last time it worked.

I'm totally new to this.. in fact I may be two weeks into electrical study, I didn't know what Digikey, & Mouser might be untill just now googeling them .. thanks.

I have the schematic if that's of help, but the numbers on the actuall parts are:
BAO33T 123 L62 (the burned one) on the schemo it says thats the 70-4146

7805A JRC M0241JM is the other

should I be looking for other visual signs?
I tested it with a different power supply of the same model, and still nothing, the old power supply is now being used in another of my units, and does fine...

my personal motive is to use this as a stepping stone for learning to mod effects, and what not, but I have to fix it before I can mess with it :P

Thank you for replying

[BobEllis]

OK, that sounds like they are gone. I was just checking because of your stated inexperience.

Do you have a DMM or any test equipment? At a minimum, go buy an inexpensive digital mult meter.

Pull the burnt out parts and measure pin to pin resistance, you'll likely find all three pins shorted.

Hopefully someone with some experience with this unit will step in to help out.

[Jave]

just wanted you to know I have not disappeared. .
I'm buying a multimeter this coming Friday.
I found one for a hundred bucks that is insured for life.. even if I run it over
I found plenty of the 7805's, and have some on the way, but haven't located any of the ldo's just yet, but I am planning a trip to radio shack on my day off, and I've got studying to do about these regulators, I'll let you know what happens asap... thanks!

ps. I found an unopened "Electra-force" 30 watt soldering iron, and some "rosin core" solder is this stuff gonna be ok to use, or should I get something different?

[c2cthomas]

Hi Jave - If you are looking to learn electronics see this site: http://www.bcae1.com/. If you just want to get the unit fixed so you can do other things then simply buying a replacement will most likely save you time and money - I just saw a Gen 1 for sale on eBay for $45 and that's less than half the $$ you intend on spending for a meter alone.
The solder should be 60/40 or 63/37 lead / tin ratio and rosin core is common. The rosin acts as a mild acid to clean the metal surface in order to bond the solder joint well. You should clean the flux off after it cools with some denatured alcohol and a short bristle solder flux brush - available at most hardware stores. Take a look at http://www.epemag.wimborne.co.uk/solderfaq.htm#howto for how to solder. They use lead free solder in Europe (RIOS compliant ) but you don't want to go with that for you project just yet (it's harder to solder without the proper tools). Hope that you find this information helpful and good luck with your project and welcome to diyAudio!

[iUSERTLO72p]

and my 1'st post here

Hello and welcome



iUSERTLO72p

[c2cthomas]

Bob - Chk ur 6!!! From a fellow Shellback, Mossback, Brownback and Bluenose!!

[BobEllis]

I became a bluenose in westfjord, near Bodo, but never had the joy of becoming a shellback. Being "defense counsel" at a Chief Petty Officer induction was close enough.

There are quite a few of us here with military backgrounds. Wonder what draws us to DIY things?

[c2cthomas]

Originally posted by BobEllis
Wonder what draws us to DIY things?

Keeping things that are 30 years old up and running for one thing. Installing the latest and greatest Technical Change Order on said 30 year old gear is another.