Do techs need schematic to repair

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1,501
Hi im getting work done on my Fuchs lucky 7 and I was surprised that the tech asked my (the person bringing the amp in for repair) for a schematic so he can work on it.

Is this usual business , didn't add up to me . I'm a player not an electrical engineer with a schematic.
 
Messages
4,369
It depends on how complex the amp is and how complex the problem is.

If “work done” means biasing the amp, he shouldn’t need a schematic. If it means making modifications, or tracking down the source of an intermittent problem, that’s tough without a schematic in a complex amp. Some amps are clones of classic circuits that most techs know well. Others are complex and foreign without a schematic.
 

VJF

Member
Messages
1,544
I always wondered if this is a risk when buying a boutique amp with a proprietary or complex design, especially if the builder is no longer in business. Do most boutique builders supply a schematic with purchase?
 

technomancer

Supporting Member
Messages
1,383
Lets put it this way... if the amp is in for an issue the tech having a schematic will save you money as he doesn't have to spend time tracing the amp to figure out what is going on where. Normally tech work is a flat bench fee + hourly.

As has already been stated it also depends on the complexity of the design and how busy the tech is, as a really complex amp with no schematic can be a large time sink that a really busy tech might not want to deal with.
 

LaXu

Member
Messages
5,451
I always wondered if this is a risk when buying a boutique amp with a proprietary or complex design, especially if the builder is no longer in business. Do most boutique builders supply a schematic with purchase?
They certainly don't and it might depend on the manufacturer if they are willing to provide one for a tech or owner.

Having looked inside my Bogner, it looks like it would be reasonably straightforward to follow as the PCB is clearly marked for nearly all components and only the pots are less accessible without removing the PCBs.
 

67super

Member
Messages
1,506
I always wondered if this is a risk when buying a boutique amp with a proprietary or complex design, especially if the builder is no longer in business. Do most boutique builders supply a schematic with purchase?
I believe it is a risk, especially the more complicated and proprietary the amp is. I do my own work and a very simple amp can often be diagnosed by just doing basic measurements. A complicated amp with no schematic is not something I like to waste my time on. I traded for a 2011 ToneKing Imperial a couple years back and was able to get the schematic from Mark Bartel. Now I know I can service it if necessary, in fact I have had to replace a bad resistor already and it was a breeze.
 

Sweetfinger

Silver Supporting Member
Messages
12,110
Something like a blackface Fender or a tweed Deluxe, no. Anything with channel switching, overdrive, effect loops, etc., yes. Anything built on a PC board in the last 50 years, yes.
It saves a lot of time and guesswork, even on simple amps.
I got a fairly simple, small, "boutique" (I use the term charitably) tweed tube amp made for harmonica players in a while back because the tone control didn't work. The maker claimed the amp was working properly, that there was no way it could have been incorrectly wired, and that the owner and myself simply couldn't appreciate the subtleties of the tone control operation. His thing was so precious that he wouldn't supply me with a schematic. I went round and round, traced out the tone control, sent it to him. He said it wasn't right, but hey, that's what was IN the damn amp. So, after a LOT of wasted time and the least amount of help possible from the maker, I ended up tracing and drawing out the entire amp schematic, figuring out that the tone control had been mis-wired, fixed it, got the customer going, and have a cautionary tale about small builders who think their design is too good for another tech's eyes, or their production is infallible, or their product indestructible.
The stand-up guy would have looked at my first drawing, said, "hey, if this is what you have, it looks like the assembler stuck this wire to the wrong lug. Move it there and it should be good. I apologize and let me take care of the fee. I really want my customer to be happy with my product and know that I stand behind it."
I'd have gotten the customer going in a short time, wouldn't have wasted tons of time, and wouldn't have exactly what the builder didn't want to send, a full schematic of the amp.
 

guitarjazz

Member
Messages
21,002
In Q's autobiography he said he used to go over to Ray Charles' apartment when they were kids in Seattle and Ray would be fixing radios, So I guess the answer is 'no'.
 

Tone_Terrific

Supporting Member
Messages
31,543
Even on simple amps it saves time.
Dr. Z does not release schematics.
What do you do?
You spend the time to trace everything out and then you have a schematic?
Really? so what? Give me a break.:bkw
 

Seymour Cash

Member
Messages
490
Fuchs might be forthcoming, they seem like a pretty customer friendly company. Or, maybe look on Ampgarage. I'd try to save bucks anyway I could. YMMV
 

nowhere

Member
Messages
959
Always had a schematic taped inside my Marshall’s in the 70’s. On the road back then the only places to get them fixed in emergency were often TV repair shops.
Had this happen two or three times.
The old Traynors I've owned all had this from the factory - undo the screws holding the top panel in place, flip it up and the schematic is right there... and the parts are all laid out before you too. The only way to make it more convenient would have been to have the top panel on a hinge and to give it a spring loaded catch like a car hood.
 

Jr Deluxe

Member
Messages
2,749
Try to get your 20k Dumble fixed. Not only are the circuits supposed to be secret but the boards are gooped with epoxy to hide the componants.
 

ahhlou

Member
Messages
778
Troubleshooting an amp without a schematic is tedious work. Most often the tech is drawing out the signal path as he/she troubleshoots which you are paying for.

As an owner, you should have the schematic for any amp you own, if only to save you money in the future...
 

ripoffriffs

Supporting Member
Messages
3,144
A good & established repair tech will contact the manufacturer to get the schematics. I know the one in my town does it all the time. He's never turned down a repair.
 

samdjr74

Member
Messages
8,805
I have two amp techs (Andy Fuchs being one, Dave Hirsch being the other) and I've only had to provide 1 schematic to an amp for Dave which was a home made Mesa clone. Other than that all my amps are pretty straight forward nothing crazy and I think the schematics are readily available. Even when I had Dave work on the mesa clone I gave him the schematics, he didn't ask for them, but I figured it would save him time
 




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