Fender Princeton Chorus solid stater - no signal thru input

[soundguruman]

I always buy the Radio Shack brand cleaner that has lubricant added for cleaning pots and use other cleaners for various stuff. I guess it comes down to cost that I never bought Deoxit ever before... Good to know why it is worth the little bit extra in costs.

Radio Shack Cleaner is mineral oil, in a spray can.
It doesn't last. It will temporarily clean the dirt out of the controls, but will also create a sticky surface that attracts more dirt.
You have to consider the more expensive cleaners, like deoxit G100 / D 100 that cost 5 times the price, plus shipping.
They will last (more than) 10 times longer than the Radio Shack Cleaner, and prevent oxide from forming over a very long period of time.
So, I use the mega expensive cleaner on ALL repairs. I have given the customers the best that is available...
but at some point, I suppose there has to be a limit, at cost VS. profit margin.
I have zero returns, concerning noisy controls and jacks. To me, that was worth the extra $$$ I put into the shop supplies. Especially since we live near the ocean,
where the salt in the air tends to oxidize anything exposed.
But I do charge, it works out to about 25 cents a squirt, or $3 or more per amplifier. Good investment, the way I am looking at it.

I never clean tube sockets. The way I am looking at it, there is no cleaner that will actually solve oxidized plating, in a high heat condition. I would favor replacing the sockets instead. or just tightening the contact springs...
and there are so many good sockets available, that don't cost much.
I will use scotch bright metal polish in the tube base pins. But never spray cleaner into the socket or onto the tube pins.

[Jazz P Bass]

My local Radio Shack sells deoxit.
Search Result

[Mr Johnny Birchwood]

This has turned into a very informative thread. I've never tried the expensive deoxit. I mostly do work for my friends and I don't charge a whole lot. There's only one professional tech in my town and he's only open 4 days a week, booked up 3-6 weeks in advance doing warranty work and factory authorized service, and frequently turns away simple repair jobs. I've been getting a ton of repairs coming my way because my friends(and their friends) are gigging musicians and people need/want stuff in a day or two and I can usually do that.

Scotch brite on the tube pins is a great idea. I've gotten good results using welding tip cleaners in the tube socket contacts, filing off any crud then retensioning the socket. The tip of the cleaner has to be snipped off but I can always find one that fits into the socket contacts. Rubbing alcohol helps to remove any dirt but obviously doesn't remove oxidation. I will order some of the expensive deoxit spray for cleaning pots, since you guys say it's worth it. The Radio Shack stores in my area sell consumer electronics and have very limited stock of components, mostly low voltage stuff. I have to order everything I need online. I usually order from Antique Electronic Supply, or from other suppliers for specialized parts. Where's the best place online to get tech supplies?

[52 Bill]

Everybody has their own favorite way of doing things. I like Deoxit and use it for everything now. I used to save the Deoxit for tough cases and special uses, but it proved to be faster and better than messing with multiple cleaners. On more than one occasion, I've sprayed a quick shot of Deoxit into a noisy pot that was unsuccessfully cleaned with some other spray, to have all of the noise go completely away.

Alcohol can damage some plastics, so you should test it before using it.

As for cleaning contact surfaces like jacks and tube sockets, I try and stay away from anything that is too abrasive in order to avoid damage to the plating.

AES is a good source, but if you are a real business try and contact CES their dealer/pro division.

[Mr Johnny Birchwood]

AES is a good source, but if you are a real business try and contact CES their dealer/pro division.

I didn't set out to be a full time amp tech, but it turned out to be a very under-served market in my area. I'm glad this forum is here and I really appreciate all the help. When the pro tech dude in my area retires there will be no full-time amp repair shop, so I'm curious what is involved with becoming a factory certified tech for the various gear companies. Is there an application process, training, testing? How does the warranty service business work? What are some good resources for learning the ropes of being a full time factory authorized service center? It's not a bad gig but I want to make sure I am providing the best service possible. I have no engineering background, but with enough patience, superstition, prejudice, and ignorance I can usually fix just about anything.

On another note, I don't own an oscilloscope, though a buddy has an old clunker that I can borrow if I need it. What is a good model of entry-level amp tech scope I can get into for a minimal investment? What are the essential features I am gonna need to do a wide variety of typical repairs and diagnostics? Anybody know a good resource for basic solid state theory? My solid state knowledge and diagnostic ability is sorely lacking.

[Enzo]

You may have to hunt for titles, but up in the Music Electronics section we have had many discussions of exactly this. Getting into repairs, buying scopes, pretty much anything you'd think of.

But first... I buy the 5oz spray cans of Deoxit D5, and in my commercial shop, a can of the stuff lasts me a LONG time. For the amateur or low volume shop, the investment into a can of the stuff will be returned over the course of possibly years. You won;t be buying a can a month or anything. Well, not unless you just BATHE things in it.

80-90% of repairs are simple - busted jack, cracked solder, busted jack, snapped off control, busted jack, oh and the occasional busted jack. An experienced tech has learned a lot of things, things that cannot be taught in a course. What might have been a mystery to me a year ago, might now be no challenge, just from one little fact I might have learned. On the other hand, even the best of us get a mental block from time to time and miss some glaringly obvious clue. Point is, you start at whatever level you start at. The other guy retires or he doesn;t, it may mean you face more challenges than before, but it doesn;t make you any less or any more able. Have the inner honesty to look at any repair for whether you can help the person or not. The equivalent of a doctor pledging to "first, do no harm." "This is not something I can do for you." is just as valid as "Sure, I can take care of that." Just be straight with the customer. And be ready with a place you can refer repairs that are above your level. Even if it is 100 miles away.

Warranty service center policies vary with the client. Fender has a tech exam you have to take, most do not. Most are going to want to see photos. Photos of the exterior and interior of the shop, the work bench, the parts storage, "what the customer sees", in other words, they want to see some evidence you have a real shop, and not just a corner of your mom's basement. They will ask you for some business references, after all, most of them will be extending you credit for your parts purchases. So credit references then.

You usually have to provide an equipment list, and a resume. They will want to know your bank, and they will usually want some evidence, even if nothing more than your statement, that you have been in business for some minimum time, a year is a comoon amount.

Not every factory even wants more service centers. If a company already has a service center in a town, they usually won't hand out competition for that guy. He got there first, this market is his, so to speak. None of this is set in stone though. It helps to have a sponsor. Any local dealer shpould be happy to have local service available. SO look to any music stores near you that have no service shop of their own. Talk to them. I have gotten any number of authorizations by starting out "Music store XYZ has asked me to become a service center for your products, since they sell your line in their store." Some companies are freer than others, and some companies just absolutely do not have service centers.

It starts by contactting a company and asking what they need for a shop to become their service center.

You do not have to become a warranty center to be a good shop. I like the warranty work for several reasons, but some shops would rather pass on it. I charge $60/hr here, and if an OEM pays me $45-65 an hour, I am happy with that. But someone like Frondelli working in the middle of Manhattan faces far higher costs, and charges twice what I do, so working for $50 and hour on warranties is a real discount for him. I suspect your situation is a lot closer to mine than to his. What I really like about my warranty center status is the free advertising. SOmeone needs a Fender amp repaired, they go to Fender.com and the service dealer locator will point them to me, if they are in my area. That is a free new customer to me. I fix their Fender, but now they know I am here, and in the process they become aware that I work on most everything, not just Fenders. I used to have an ad in the Yellow Pages, but it never paid of nearly as well as those listings on factory web sites. I just got a call from Peavey yesterday, they asked if I would do them the favor of helping out a customer of theirs with a situation. You bet! Guy was not aware of my shop, now he is, I get to be a minor hero, we both win.

Repairs are repairs, I don;t do them any different for warranties. I just bill the company instead of the customer. As a service center, though I do get to order parts direct from them, and at the wholesale prices. That is worth something right there.

ANy scope that puts a picture on the screen is useful for amp repair. This ain't rocket surgery. They don;t make scopes with specs too low. Find a working scope, buy a $30 probe for it, and start learning about this valuable tool. SOmeday you will want to upgrade, and by then you will have learned what to look for in a scope, what you need and what you don;t need.

[Mr Johnny Birchwood]

Thanx Enzo, great info. I've learned not to take on more than I can handle. Anything under warranty or anything above my level of expertise gets referred to the local pro. He turns down enough work to keep me pretty busy.

What about stage/pro lighting companies, same deal? Been getting inquiries from club owners about lights and I'm tempted to take on some of the work. I imagine the stuff is pretty simple to work on, but I'm curious if they support their products by releasing schematics. Is that something that you would take on?

[Enzo]

My shop used to share a building with a PA company/retailer and a lighting company/retailer. And we were right across the street from Elderly Instruments, a world class stringed instrument store. What a great location. Alas, the building was sold and we all had to leave. But I did a lot of lighting repairs for the lighting company at the time. He had mostly NSI stuff, and some basic systems he rented out. The rentals almost always came back with damaged controllers. I replaced a tone of sliders in those things. The dimmer packs ranged from small 600-1200 watt litle boxes up to rack units controlling large amounts of power. I sometimes worked on the large ones, but mainly saw the small ones.

At the time, and we moved maybe 9 years ago, I could get parts from NSI (a division or Leviton I think). There were a few custom ICs in the controllers and dimmers, but mainly I got the sliders. ANything else would just be commodity parts, like triacs and other components, so for them Mouser or Allied or whoever.

Prior to 1994 I worked at a store that sold ETA lighting gear. I had a small but steady amount of that work too. The ETA things we saw were all older control voltage stuff, rather than multiplexed stuff. One wire per light channel up to the dimmers, that is.

But since we left the little show-biz collective over there, I can;t think of any lighting repairs coming to me. If someone else in the area does lighting repair, I don;t know who it might be, but it ain't me. Point beinbg, if you have a market for it, go for it, but I wouldn't expect it to be a substantial part of your business from the general public. Find out specifically the gear they are using, then contact the manufacturer and ask after support - schematics and parts - and will they sell to you direct. If any lighting came to my door, I'd at least consider working on it, but would look at the specific case.

Are these clubs looking for repair service or wanting you as a contractor to install the stuff too?

[Mr Johnny Birchwood]

So far they have only asked about repairs, I assume that the issues would be mostly mechanical parts failure(sliders, controls) and maybe power supply issues(ps caps, loose solder joints) and just general wear and tear. I would refer any lighting installation work to a buddy who does industrial/commercial lighting installations full time. There are a couple pro sound outfits in town that rent gear to the bigger clubs, lights and PA gear, and have their own tech/techs on staff. If I do any lighting repairs it would be stuff from smaller clubs. As long as I can get good schematics I am usually pretty confident about taking on different kinds of work(no TVs please). I don't know much of anything about lights, that was never really my interest. I imagine there's a learning curve just like anything else but If it's gonna be steady work it would be worth the effort(especially when I'm getting paid to learn, I can bid repairs by the job, not by the hour). The pro amp tech guy in town usually turns down the work or they gotta wait 3-6 weeks like everybody else. If I can get the work done competently and quickly I'm pretty sure I would see plenty of it. If I'm stumped I can always post and let you guys figure it out -wink-

[Enzo]

So just take it like it was another amplifier you have never seen. SOme club starts asking about lighting, you confidently respond by asking for the make and models involved and exactly what their complaint might be. That way you can turn around and contact the maker of the gear for schematic availability. If they provide drawing and make specific parts available, then you can tackle the repair. If they wish to remain aloof at the factory, you have the option of telling the customer you MIGHT be able to help, but would have to see the item first. You'd explain that the factory of that brand does not provide any support.

[Mr Johnny Birchwood]

That's basically what I told em. Have make/model/and serial number ready when they call for a 'free consultation'. Without a schematic a visual inspection could still turn up a loose connection or wire. Beyond that I'm not sure how I much I could diagnose, as I'm not familiar with the circuitry or voltages they operate at. What kind of lamps do most smaller stage lights use? Will they have a hi-voltage supply for the lamps?

Also, I've got a ENGL Classic 50 2x12 combo E358 inbound with a broken speaker jack. ENGL did not respond to information request by email. You know anybody on here that does ENGL factory service that could give me a part number? It's the #4 speaker jack on the back(from L-R).

[Enzo]

Commercial stage lighting you might work on will use 120v, or 240v split to 120v. Lights that need fancy voltages will have power supplies to drive them. Some lights work on low voltage lamps, but have transformers inside them. I don;t care what kind of bulbs the lights use, all I care about is dimming the output of the dimmer pack. I use plain old light bulbs in porcelain sockets in the shop.

If you want to work in lighting, forget the word "bulb." A bulb is called a lamp, and the thing you put the lamp into is called a light.