Recommendations for Test Equipment Wanted

[tmlesko]

I have renewed interest in repairing tube amps and old radios after 40 years of being in a totally different field. I am asking those of you who do this work to recommend some basic test equipment. When I worked in electronics we had just about every piece imaginable in the Air Force, but mostly I used a signal generator, a portable meter, VTVM, o'scope and frequency counter.

I recently acquired an Eico 666 tube tester, what else would you recommend? Seems like a signal generator and scope would do, what are the best brands to look for?

Thanks,
Tom L.

[Gtr_tech]

Audio sig generator, scope, *good meter*....don't waste time and money....just spring for a Fluke and be done with it. I use a 79. Depending on what type of repair you are doing several meters can be needed. I have a couple bench meters I use....one just for monitoring current and the other set for voltage so I can keep an eye on more than one thing at a time. Invest in good quality soldering gear as well. On a budget a Weller WP35 iron and several tips from the "ST" series will do you just fine. THe larger chisel tips work great for terminal strip/eyelet boards and the smaller conical/narrow flatted tips are better for pcb work since they don't tend to retain heat as well. A 100w or better gun will be useful for chassis ground connections....or an 80-100w iron will do as well. THe freq counter may be useful for calibrating tuners in the old radios....I don't do that sort of thing tho so I can't say for sure.

[loudthud]

For fixing old radios you need an RF generator that covers the frequencies that the radio covers as well as the form of modulation. Pretty simple for AM, more complicated for FM stereo.

It's handy to have something to check capacitors. Some DVM's can measure capacitance. It's usually a stand alone instrument that measures ESR or can form electrolytics.

[Enzo]

I agree with a good meter. That is your primary instrument. MY FLuke meter has served me on the bench and in field service for decades. I am still using the same meter I had when Gtr Tech first met me.

A scope is important. I'd say most any working scope is fine. For radios you want to cover their freq range, but for guitar amps, they don;t make scopes that can't cover us. Nothing wrong with a 100MHz scope, but for guitar amps an old 500KHz scope works fine too.

A basic signal generator is very useful. YOu don't need anything esoteric or with .00000001% linearity or something, so a function generator would work too. ANything call3ed sine wave generator, audio generator, signal generator, function generator. AS long as it covers the audio band.

There have been other threads here recently on this topic. Use the search feature and look up test equipment and oscilloscopes. No need for a freq meter here, though maybe in radio work. ONly thing I EVER use a freeq meter for is setting the speed on tape decks.

[tubeswell]

As one who has become an enthusiastic hobbyist over the last couple of years I would add:

+ a variac (for testing trannys)

[tmlesko]

I have a Radio Shack Digital meter, that's no Fluke ) and my old military PSM-6, picture attached. How are the Fluke digital meters, like the 8000A? Picture attached. If anyone has *specific* recommendations for a scope & signal generator - brands, models, etc. that would be especially helpful.

Tom L.

[drewl]

Yikes!
Flashbacks....I've probably fixed more 8000A's than amps!

[Mark Black]

Used a Fluke 8000A for 20+ years with only one failure (of the LED display).

Currently have a Fluke 8012A and a trio of 8050A's for benchtop, 179 for hand-held. Solidly-built pieces of test gear.

Bear in mind that Fluke has discontinued parts and any other kind of support for most of the older benchtop meters, so if you ever end up needing a proprietary part you may have some trouble there (part of the reason I bought three 8050's...).

[PRNDL]

Tektronix is the scope to get. The older ones are fixable.
http://www.logwell.com/tech/oscillos...Tek_T922R.html
35 MHz is fine for a tube amp scope

Fluke 8600a is the auto-ranging table top DMM

I also have a capacitance meter and would like to get an ESR meter, but they're extras.

Here's a cool solder station that comes with a free DMM.
http://circuitspecialists.com/prod.itml/icOid/7501

[drewl]

Nothing wrong with those Flukes, I used to repair test equipment before amps right out of school so I saw alot of blown up stuff.
I've also got an impressive amount of gear from being inthat biz......I could have had thousands of those little glass tube things if I'd known I was gonna be an amp freak
But luckily I grabbed a bunch for the few tube amps I had at the time, like some Gold Lions, and Amperex, Mullard....had no idea what they were, they just happened to be the right tubes for my Fenders and Marshalls.

[CaptainKirk]

I swear by my Fluke 87. It includes a finely graduated bar graph across the bottom of the display. Makes it easier to see trend of moving signals.

For solid state power amp repair, it's vital to have an AC mains current limiter. I have a Variac with voltmeter & current meter. It's saved me from blowing up newly installed parts and helps with finding bad parts before the fuse blows. You can also make one by wiring a 100 watt light bulb in series with the AC main. If it glows brightly when you plug it in, there's probably a short in the amp. The light bulb limits the current and indicates the short.

I also made myself a tube bias checking tool. Makes output tube bias checking quick and easy.

One of the most important tools I have is a heavy duty chopstick. Great for probing parts and solder joints safely with the power on.

[Metro]

I concur with the Captain above. Most importantly, a plain solid DRY chopstick.
Also its great to have a decent tube tester, fluke DMM, scope. A nice homebrew bias probe or 6 too, KT88 metal bases give you lots of space to cram in the wires and 1ohm whilst keeping the height down so you can test without pulling the chassis in some cramped heads. Although you do have to bend down the tube retainers on octal types.
I have just ordered another new fluke as I fried my faithful $50 Mastech testing a trans the wrong way round. expensive and stupid mistake.

[Garydean]

A dummy load comes in handy as well as an all purpose bench speaker(s). I use mostly my 83III and a B&K 5491A bench DMM. An ESR meter is a great item for testing caps in-circuit. A desoldering gun by Hakko is a great time saver if you're working on DIPS. A signal gen for tracing and Variac of some type to raise voltages little by little. My power strip has a digital current draw meter built in, love that thing. Tube testers are good, I have several but always use my Sencore MU150 for fast results. I use my scope very little... be sure your probes are rated for high voltages as not all newer ones are. Flashlight, chopstick and a magnifying glass are great basics.

[jbltwin1]

Equipment

One of the most important tools, if you are right handed is your left pocket. As in keep your other hand out! Seriously, all the suggestions are good. I use that old lightbulb in the circuit as a first test for ANYTHING suspect. THEN I start with the basics. Saves fuses. Like stated above, almost ANY scope will work for audio, but I would suggest a good votage stepping probe, epecially if you work on any Music Man amps-700v. Also, even though I don;t seem to use mine much, a chassis stand made from some scrap wood with an angle built in(or adjustable) and adjustable for width is a great thing to have. After that, it's a matter of good leads too. Geez, I could go on but it seems like you never have enough!

[Mars Amp Repair]

Say PRNDL,
this is a nice looking soldering station & the price is certainly right...I bought one of the Tenma cheapies about a year ago & the first time I tried to change the tip, it was fused into the flakey metal collar that fit over the ceramic heating element.

These tips look very similar to those & I wonder if you've had any trouble getting the tips off of this iron...I shelved the Tenma as I wasn't going to spend any money on another pencil when I only paid about $60 on the station in the first place. I just went back to my tried & true (and expensive) Wellers. Thanx, glen