What specialty tools am I going to need?

[DüTerra]

Trying to step-up my game. I'm beginning to build/covert my first two amps. Wondering how pertinent it is to have things like a variac, oscilliscope, impedance/turns-ratio-meter?... I don't expect I'll become anyone's paid tech but it's a hobby.

I've had a soldering iron and a DMM for a while. I built my own speaker and instrument cables, did a small paint by numbers mod to an amp and replaced some parts on my guitar, rebuilt a speaker or 3, repaired another amp. None of that required me to use equations to troubleshoot nor did it take anything but basic tools and a basic understanding.

[Enzo]

You have a good selection of hand tools? Someone once asked to borrow my pliers. I asked, what kind, because my field service tool kit has 12 different pliers. Cross point screwdrivers? I have of course phillips, but also posidrive, frearson and every size from big #3 down to 000. Allen wrenches? In both metric and imperial. And I use nut drivers ALL the time - metric and imperial. Make sure you have the basics before getting fancy.

I use my variac a lot, but at your level, a light bulb limiter will cover that base pretty well, you will realize when you need to add a variac to your bench.

Impedance meter? I have soldered for 65 years without the need for that. A signal generator would be a lot more useful.

At this point in your career, a scope will teach you more than help you. Wax on, wax off. A scope is incredibly useful, but you have to have some idea what it is showing you. You need to learn to use it, then it lets you become aware of many things you had no idea about... Nothing fancy needed, pretty much any scope that puts a trace on the screen will be sufficient for guitar amp work, and certainly enough to learn with. After getting some chops, then you can worry about a scope with more features or capability.

Make sure your solder station is good quality. I would build a basic dummy load.

[DüTerra]

I have most hand tools, bits, wrenches and such.

I worry that a light bulb limiter is more trouble than it's worth. I could just spend $20-30 more and buy a new variac. What do think?

Unless a $50 variac is likely to be a lemon? Idk about how reliable these are across brands. Seems like a simple tool but I could see it being dangerous if it were poor quality. Something like this specfically:

https://www.google.com/aclk?sa=l&ai=...kaApjaEALw_wcB

You also mentioned a signal generator. Which is a good lead and exactly the kind of thing I was asking about. I'll look into one of those. And building a dummy load thanks.

[nosaj]

I have most hand tools, bits, wrenches and such.

I worry that a light bulb limiter is more trouble than it's worth. I could just spend $20-30 more and buy a new variac. What do think?

Unless a $50 variac is likely to be a lemon? Idk about how reliable these are across brands. Seems like a simple tool but I could see it being dangerous if it were poor quality. Something like this specfically:

https://www.google.com/aclk?sa=l&ai=...kaApjaEALw_wcB

You also mentioned a signal generator. Which is a good lead and exactly the kind of thing I was asking about. I'll look into one of those. And building a dummy load thanks.

You are wrong on that. A light bulb limiter is similar in effect to training wheels on a bike. When you make a change on the amp and maybe create a short that fries your Power transformer and plug it in poof.. A light bulb limiter would light bright saving the amp. A variac requires you to understand when to back off the voltage to prevent damage. I use a variac and a dim bulb tester. The DBT is more or less a go no go test.
i will say it again check your local ham radio clubs make some friends and you will most likely find someone who has equipment that would gladly give to someone just learning.

Good to see someone else from the gulf coast. I'm in Pace on the other side of Pensacola. Ham fests are a bust right now. but put some feelers out you will find someone.

nosaj

[DüTerra]

Hey nosaj! Good to hear from another Gulf Coast resident.

I guess most HAM radio groups are on FB these days huh? I have got a couple of Eminence Texas Heat speakers up for sale on Reverb I might post them on CL, FB and such for trade for a signal generator, oscilloscope or variac.

Btw thanks for explaing the different perks of a DBT vs a variac.

[Enzo]

The thing with a variac is you need to know what you are doing. A bulb limiter is kinda fool proof. So many times some one writes in, "I could get it up to 90 volts before it started smoking. Well it isn't about how high you can "get" the voltage. Your vaiac needs a current meter as well, either as part or as a separate item, and when you start to run it up, if your unit is already trying to draw two or three amps and the voltage isn't even to 20, STOP.

I have no reason to think that Circuit Specialists variac will be unsafe.

A bulb limiter is a bulb socket and an outlet. A power cord and a light bulb. Certainly under $10. Screw them to a piece of wooden plank, doesn't need to be fancy. And frankly it is not like you can have only one of these tools. Have both.


A signal generator need not be fancy, these are just guitar amp. I have some nice ones, but frankly, most of the time I use music rather than a sine wave. WHen I test an amp, I plug a CD player or a line from my FM receiver into an amp...Music has the whole frequency spectrum, I can hear if it is distorted or missing something. I still have my signal genny if I need it but mostly I just listen to album rock. Actually I listen to country instead of rock, as country tends to be sonically cleaner. SOme rock I can't tell if the distortion is in the music or in the amp.

And when it comes time to fix a 31 band graphic EQ, I can go up the panel moving the controls and hear exactly what I need, much easier than adjusting a signal generator 31 times.

[DüTerra]

Alright so right now I'm planning on building a DBT and a dummy load.

And if I were to buy any of the aforementioned tools I'd be best served by an oscilloscope but I don't really NEED either at this stage. Got it.

[Enzo]

Keep an eye out locally for a WORKING scope cheap.

[garytoosweet]

As someone who has just done this over the past year, in order of importance in my opinion:
- GOOD solder station (Hakko, Weller)
- Multimeter
- Dim Bulb Tester
- Dummy Load (These may be the best deal going for resistors to build one: https://www.mpja.com/search_results....Power+Resistor)
- Signal Generator
- Oscilloscope (Any basic one is fine, don't stress over it)
- Variac with voltage and amperage meters

[DüTerra]

I have a Weller WLC100 station with a SPG40 iron. I bought it from radioshack I think, around 10 years ago.

What's you opinion of this setup?

I feel like it leaves something to be desired. I've had trouble heating up the back of pots more than once. I finally bought new tips for it last year, that helped some but not as much as I had hoped....To be fair I've used it for wood burning and to put holes in the bottom 5 gallon buckets for tomatoes. So I may be responsible for any faults it has.

My DMM is a fairly new one. I recently purchased it. It's a Southwire 10031S.

[Enzo]

Weller is a good old brand of solder gear. Keep a good clean tip in it and don't use it for burning wood, plastic, branding cattle, or anything else OTHER than soldering. The back of a pot is a large piece of metal and hard to heat, especially for a low power iron like that. I used a 100/140 watt Weller gun for jobs like that.

[DüTerra]

Ok so I just need to get a larger iron to pair with my WPC100 and it would work better on pots and ground?

[Enzo]

Probably. Chassis are hard to solder to. Also must make sure pot body is sanded clean.

[galaxiex]

Soldering to pot backs and amp chassis is all about thermal inertia.
You need an iron with a big ass tip.

I use this one...



Weller 80 watt cheap as chips, works great.

https://www.amazon.com/Weller-SP80NU...2420244&sr=8-5

A small hot high wattage iron iron can do it, but it takes longer, you have to heat the pot or chassis for a loooong time.

This one gets it done in seconds.
.

[glebert]

As far as needing a signal generator, you can get free signal generator apps for a phone or tablet and then just use a 1/8" stereo to 1/4" mono adapter and use that for your input.