New analog convert, looking to learn repair/restoration

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btzmacin

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Hello, all. I'm a new convert to the universe of analog audio. The training I received during the course of my bachelor's in "Music and Technology" (that's what they call it when your audio engineering degree comes from the humanities school of the university...) was grounded in the practical application of engineering theory to the digital domain, with very limited hands-on experience with analog gear. Thus, it was only recently that I came to appreciate this vintage equipment for the gems they really are.

What I'm looking for is a bit of help getting into the repair and restoration of analog equipment in an attempt to build my repertoire of outboard gear.

The reason for this long-term project is, in short, Pro Tools 11. More specifically, the fact that the library of plugins that served me loyally from Pro Tools 7 through 10 won't be supported henceforth. For now, Pro Tools 10 and 11 are able to coexist on the same system, which means that I have some time to get my collection off the ground before I will be entirely unable to mix anything.

But the day will come when PT10 exceeds its useful life...probably right around the time when Mavericks comes out. When that happens, I'd be forced to actually buy the plugins I've become accustomed to using for the past 5 years. You see, upon enrolling at my school, I received a handful of very nice Waves plugins along with an Mbox 2 and a relatively nice HP elite book. Fast forward four years, the elitebook is on its last legs, and so it's replaced with a shiny new Macbook Pro "retina." Much to my chagrin, PT7 doesn't play nicely with Mountain Lion...thus my purchase of a student-discounted license for PT10. Funny enough, student licenses from Avid come with free upgrades for four years from date-of-purchase, and so I've just received a complimentary upgrade to PT11...which is what led me to explore the state of my plugin library.

As it were, Waves has yet to release AAX versions of their plugins, and aren't even giving updates or discounts to people who paid full price - much less a student. So, I figured, why spend all this money on new versions of plugins that may sound completely differently than the ones I'm used to (its not like they changed the audio engine or anything) when I can spend the same money on the analog gear that the plugins are supposed to be emulating?

There's just one problem...I have no idea what I'm doing. Ok that's not entirely accurate, but I only really have the faintest clue. I understand a bit of the theory that goes into EE, but I have next to zero practical application. My real problem is that I don't actually know what any of this stuff is supposed to look like.

For example: My ex-advisor (as I've since graduated) just gave me a broken CAD CGM-2 CHAMP stereo compressor that he says seems to have "a ground loop or something." This thing is supposed to be the guinea pig for me learning to do these repairs, but I don't even know where to begin looking for the errant solder point, component, or trace...or even how to test the unit to make sure that the professor's diagnosis was even accurate.


tl;dr:
I really need a crash course from the gurus on this forum on basic outboard gear repair procedure. How do you recognize certain common faults, and where should I look for the most likely culprits?
 
I wonder if auto mechanics get asked similar questions from people who have never done anything more then put gas in their car? :D

It's a pretty involved field of study to learn electronic repair and service diagnostics and much like trying to do your own car repairs with no prior experience, its a bit optimistic to think anyone on the Internet could just spit out a quick synopsis for you. Most of the folks here who are good at this took years to learn what they know and are on a continuous learning journey.

The average protocol is to take a 2 to 4 year course at a technical school, then apprentice at a repair shop to build up your experience at working on a number of different types of gear.

Cheers! :)
 
Well, actually, I was fixing my truck a couple of months ago...and the mechanic down the street was awfully helpful, even to the extent of loaning me an obscure Ford-proprietary tool. But on that I digress.

In trying to be as humble as possible - what with this thread being my delurk - I suppose I did diminish the extent of my electronics knowledge. I've done about two years of study in basic electronics design during my college career. I can read a schematic and visually identify most passive components and basic circuits. I have extensive experience building projects on the arduino platform, as well as doing simple part replacements for electronic gear (mostly PCs, laptops, cameras, and camcorders) that essentially involve taking the unit apart and putting it back together. I'm trying to progress to the next step, which would be to actually diagnose the components responsible for common failures and repair a part as opposed to replacing it.

This, to continue using the car mechanic analogy, seems more tantamount to the driver who is competent enough to change his own oil and install a set of speakers, but needs help doing a more extensive work like changing plugs/coils or installing an amplifier. I can do quite a bit more than pump my own gas - even though that's illegal in my state =D! All kidding aside, I'm quite well aware that none of what I'm trying to accomplish is going to happen overnight. I'm also aware that I'm probably going to wreck some gear along the way, thats why my first "patient" is an ruddy old CAD compressor and not something that someone's going to miss if and when things go wrong, like some vintage tube preamp or something.

What I was really asking for was a starting point, and unfortunately, since I'm currently undertaking a masters in computer science, going to a technical school isn't within the realm of possibility. I'd like to self-teach the skills necessary to be able to accomplish this stuff on my own, and this forum seemed to be the best resource for such knowledge. This isn't intended to be a business or career for me, as I'm quite content being a code monkey while the economy gets back on its feet. That's why I'm willing to put the time into learning how to salvage some hosed gear, rather than shell out thousands on crappy-sounding plugins. I'm not going to be making much money - if any - from this, so why spend it if I don't have to?

Can anybody shed some light on what I'm looking to accomplish? Not a quick synopsis, but rather a "step one" on the continuous learning journey...if you will =)
 
What Ghost said is pretty much what it is. Other than that if you want something short and sweet in say, one word, then that word is, "Capacitors." It's almost always capacitors!

As for specific devices like the CAD CGM-2, even I google a model number when I have issues with something because chances are someone else has had the same problem in the past. It can save you some troubleshooting and false starts in the repair process. Stay in the research phase for some time before you reach for a screwdriver or soldering iron.

A note about upgrading Pro Tools. Don't!!! The constant upgrade thing is a crazy train and is primarily to put money in manufacturers and vendors pockets, not to make your recordings, "Better."
 
Beck said:
What Ghost said is pretty much what it is. Other than that if you want something short and sweet in say, one word, then that word is, "Capacitors." It's almost always capacitors!
Click to expand...

Except when it's a ground loop or something. ;-) A "ground loop" isn't something that "breaks" a piece of gear, it's hum caused by, well, a ground loop. If you want to learn to fix gear, it would help to know how to build gear, and in the process learn how gear works. I don't fully understand things like what resistor and capacitor combination affects what particular frequency, but I know how a power supply is setup, and can read a schematic, and can follow signal flow in piece of gear. Just as importand, I can usually follow the advice given here, or over in GroupDIY, and as Beck said, google a piece of gear for common faults. I got an ART "tube" preamp (starved plate = tube effect not a tube gain stage) and the XLR/Phone jacks are prone to failure; I had an inkling of that from some research. You also need to learn if you don't know already, what I just said in the last sentance.

Sometimes I'm in GroupDIY 302 when I haven't passed 201 yet, but I try.

But Beck is correct here, it usually is capacitors.
 
Oh, yes, absolutely. I only upgrade software when a) there's a legitimate cause to do so - and some would say that 64-bit memory addressing is indeed legitimate cause, or b) when my current workflow no longer...well, works or flows.

Such as was the case with PTLE 7 and Windows 7 / Mountain Lion. Since I grew up in a windows-centric environment I knew what to look for and was able to jerry-rig PT7 to work on Win7 with a few registry fixes. Not so much for ML, unfortunately. That's the only reason I shelled out $250 for PT10 in the first place - and I only did it because I had a student discount plus a crossgrade from LE7. The free upgrade to 11 came to me on Monday as a surprise gesture of benevolence from the usually stingy Avid.

As far as my original quest is concerned, however, I may not be making myself clear. I'm certainly not looking for anything short or sweet, but rather a starting point for further study without investing in even more formal schooling. For example, when I had to learn OpenGL for my graphics courses, I got the OpenGL Red Book. When I started taking classes that were taught in C, I bought the Kernighan and Ritchie. When I taught myself how to fix PCs, I got the Mueller trilogy. Do you (collectively) know of a similar sort of "bible" or go-to reference for DIY repairing and restoring outboard gear, or electronics in general?
 
Hmmmm...that groupDIY forum is very interesting. Thank you!!

I never did think of it that way...build from scratch to learn how they work so then I can figure out how to fix...that, my friend, is one hell of a starting point.

What I was moreso hoping to find out, initially, was how to go about a repair in the absence of information. Throughout all my programming courses, I've never had a problem that Googling didn't exacerbate, because I find something that I think might work and spend more time trying to integrate a "quick fix" than I would have spent applying the course material to solving the problem as intended by the professor.

I was trying to avoid that pitfall and properly learn the fundamental skills involved, as opposed to reading the answer from the back of the book...so to speak. That said, I haven't even tried googling the CGM-2 yet, but I most likely will do so come morning and try to get it working properly asap. Then I'll defer to engaging in a couple of groupDIY projects before trying to tackle restoring the Tascam 32B I inherited from my late grandfather.

Thanks for all the advice!!
 
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Hello Btzmacin

Buy this book: How to diagnose and fix everything electronic, by Michael Jay Geier. It is exactly what you are looking for.

Easy to understand explanations of how things work, what typically goes wrong with them, and how to fix them, from a seasoned repair technician.

By the way, you are starting with the more difficult stuff with a Tascam. Ironically it is way easier to fix professional equipment than semi-pro stuff. Pro equipment, while primarily designed to be high quality and robust, is also designed to be field-maintained. So it is easier to get at most components of the machine than a small Tascam or Otari. If repairing stuff is something you want to get into, look out for an old Ampex AG-440, a Scully 280, or an MCI JH-110 on Craigslist.

Anyway, good luck!

David Ollard
Multitrack Analog to Digital Transfers - Reel to Reel Tape Transfer - Audio Tape Transfer to Wave Files for Pro Tools and other DAW - Digitize Open Reel Tapes - Thin Brown Line
 
YES!! Thank you so much, David. Just ordered the book from amazon.

None of the stuff I've got on the fixer-upper pile is stuff that I've paid for. My family and everyone I work with basically turned me into a junk repository once they realized I knew how to do basic maintenance on gear. Thats how I got my hands on the CAD compressor and Tascam 32. On the latter, I started doing some light work when I first got the thing a few years ago...mostly just scrubbing it with quips and alcohol, and replacing all the various pieces of decomposed rubber inside. I don't even remember the snag I hit before putting it on my shelf "for later."

Your advice on learning to fix pro gear before semi-pro/consumer gear makes sense, though. I'll keep an eye out for the models you suggested, but eBay yielded sparse pickings on mostly-complete-but-nonfunctional units. Aside from generally looking for other units from the same brands, what other tape machines would you recommend for a beginner restoration?

Thanks again!!
 
Well the reason I suggested those particular models is that not only are they very easy to work on and easy to find parts for (esp. the AG-440) but you can often pick them up cheap on Craigslist. There aren't any other machines I would put in the same category. For instance, don't buy an Ampex ATR-100, you will find it far too complex.

As far as finding a machine goes you may strike lucky on ebay but typically prices are much higher there. On Craigslist people just want stuff gone. My best bargains over the years have all come from Craigslist. Where are you located by the way?
 
+1 to thinbrownline, also, I always recommend Craig Anderton's Electronic Projects for Musicians. You may not want to build any of the kits, (and most of them are no longer available, because he used an oddball ic chip,) but he goes into great detail from the start explaining components and symbology, and he expains his circuits in a lot of detail. You might also check out a used bookstore, (the kind with cats and have a certain smell to them) look for references and things like old issues of eg. Radio Electronics and Popular Electronics, especially from the late 60s early 70s. Lurk at GroupDIY and check out the meta files. I think there is even and "Electronics 101" over there. The DIY threads here tend to be few and far between but are usually well detailed. I've done a few mic mods and posted them. They aren't exacltly step by step, but I've posted some photos and my errors.
 
btzmacin said:
As far as my original quest is concerned, however, I may not be making myself clear. I'm certainly not looking for anything short or sweet, but rather a starting point for further study without investing in even more formal schooling. For example, when I had to learn OpenGL for my graphics courses, I got the OpenGL Red Book. When I started taking classes that were taught in C, I bought the Kernighan and Ritchie. When I taught myself how to fix PCs, I got the Mueller trilogy. Do you (collectively) know of a similar sort of "bible" or go-to reference for DIY repairing and restoring outboard gear, or electronics in general?
Click to expand...

Ok, I got ya.

There are a lot of great books. One that I always recommend is Getting Started in Electronics by Forrest Mims, as well as his series of Engineers Mini Notebooks with small projects to demonstrate basic function of various electronic components. These were once available at Radio Shack at low cost, but I don't know if they still carry them.

Getting Started in Electronics: Forrest M. Mims III: 9780945053286: Amazon.com: Books

Amazon.com: Timer, Op Amp, and Optoelectronic Circuits & Projects (9780945053293): Forrest M. Mims III: Books

Already mentioned is Craig Anderton's Electronic Project for Musicians. I've had that since it came out and had fun with the projects.

Amazon.com: Electronic Projects for Musicians (9780825695025): Craig Anderton: Books

Best way to start is with simple books like these so you can get to know what a component can do, and then how they work together as projects get more complex.

I started by teaching myself, probably around 9 or 10 years old, by taking apart stuff around the house and usually (But not always) getting it back together and working before my parents came home. :D Later I started building projects from kits, and for many years now I can take apart and fix about anything... but I did it the hard way over a lifetime. ;)


EDIT: Ok, looks like the Forrest Mims books are still at Radio Shack, but at about five times the price they were back in the day.

http://www.radioshack.com/product/i...gclid=CMD3t8yLmrgCFUYB7AodyiQAAA&gclsrc=ds.ds
 
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