My lab instruments for testing and measuring

This is a list of most of the gadgets I use for testing my TVs and other devices.

Grundig RT5A

My trusted companion! Has my back during repairs with exposed "hot" power components like in SMPs. I hovered over eBay for quite some time until I found one in perfect condition.

GWInstek PST-3202

I bought it used from eBay in mint condition for a fair price. It is prohibitively expensive when new. Technically it seems to be a very good supply with sophisticated circuitry. No simple one-chip regulators here, all proprietary stuff with AD-conversion and processor control.

From the usability side however, it has some drawbacks:

• The fan is annoying. I already replaced it with a more silent model and put some foam on its frame. The reason for the noise is the speed control, which does not apply a linear voltage, but a pulse signal. This makes it efficient, but the motor engine answers with noise for every impulse.
• The display is hard to read. The plastic screen is a little opaque and that renders everything fuzzy. Silly idea. Later models have a brighter, white on blue display, which might mitigate this a little.
• The rotary knob doesn't work well with one finger.
• The terminals are only banana sockets. (Fixed in later model)

QJE QJ12001X

I bought this supply because it goes up to 125V, which is quite useful for LED backlight tests. Otherwise it is a basic device. When I only need one simple voltage, I prefer to use it over the GWInstek because it takes less space on the desk.

QJE PS2002H

This is a brilliant device. A fully equipped supply as big as a multimeter, which does 0-30V and up to 3.75A. As I do a lot of repairs outside my lab, this thing is extremely useful. I did a stress test under full load and it got merely hand warm. Apparently, the switching circuit has a very good efficiency.

Be aware! In Komerci's shop at eBay you get it for 100€. It is also sold under the brand Velleman for twice the price. As of today this is the only one of its kind.

Cirtest 3000E

This is my oldest gadget and I love it. I got it as kit from an uncle 35y ago. It is a continuity tester whose tone pitch depends on the measured resistance. It is indestructible due to clever (patented) protection. It won't even mind plugging into the mains. I have used it a lot. It is ideal for super quick A/B checks and finding connections or shorts on complicated boards. Just sweep over the pins and listen. It also reveals bad (relais) contacts or potentiometers with ease. They will make an unstable or crackling sound.

The EVO Ohmvariant seems to be its modern successor. A higher class device for finding shorts would be one of the Polar Toneohm models.

BKPrecision 390A

My workhorse. I am very happy with it. I chose this model because it can measure capacitance up to 20000µ. Very useful for measuring audio equipment.

Annoyances:

• It beeps with every action I take  The beeping is ok when the test leads are in the wrong sockets, but I really don't appreciate it for anything else.
• The very small "m" symbol for mV or mA. I did overlook that a number of times. There would have been plenty of space on the display for a bigger symbol. 
• The min/max mode is confusing me every time. The thing beeps at me and I don't know why until I switch back and forth to reset it. I am never quite sure whether I did my measurement correctly.

Defects:

I had to clean the switch once because the diode and continuity modes were not reliable anymore. No big deal. Contact spray and polishing the contacts with paper did the job.

Voltcraft R200 milliohm meter

With this meter you can do four-pole Kelvin measurements in the milliohm range. The device also measures voltages, current, diodes, and capacitors up to 10000µF. I got it used on eBay. I did not work properly out of the box. It would signal a weak battery although they were all brand new. Also, the display appeared weak. I spent some time digging into it, expecting to find some contact problems, until I identified a weak capacitor in a charge pump circuit. No big deal to fix.

The exact same meter is sold also as PeakTech 2705. It depends on you color preferences :-) However, the Voltcraft manual is written much better.

Kelvin measurement at work. A short piece of wire in the milliohm range:

With its six AA batteries, which are required for the 200 mA test current in the 4 Ohm kelvin test range, it will run forever. I am going to use it for my mobile repair sessions instead of the BKPrecision. It is rugged and it only has one (+) socket for V,A,R and C measurements. Might not be the safest solution but it sure is convenient.

The kelvin clips are too clumsy for tracking down shorts on boards. I am planning to build single probes with two wires each. For shorts tracking I don't need absolute fidelity. It is sufficient to have the provided resolution as it is just a matter of comparing values. The lowest value identifies the hot spot.

Blue ESR Meter by AnaTek

Indispensable for testing capacitors. Robust against residual voltages, it can even measure the inner resistance of accumulators to check their quality. I bought it as a kit and had no problem building it. The scale I found in the net and glued it onto the case.

DER EE DE-5000

A very nice and sophisticated, very precise LCR  meter, which can also measure ESR and other parasitic parameters. I don't use it that often for that, because the blue ESR meter is much quicker to calibrate. It is available for a good price directly from Japan. Its successor is much more expensive.

DUOYI DY294 Transistor tester

This is an exotic yet useful device and it is one of a kind. It can measure breakthrough voltages up to 1000V and as a transistor tester it measures the amplification factor. It drives the device under test with higher voltages, which reveals defects under load that are undetectable by any other tester.

I lately found a broken, innocent looking 1N4148, which measured perfectly ok with the multimeter's diode mode, but had a reverse breakdown of 29V! A good one has around 140V. The only test instrument that could reveal this was the DY294. Worth every cent (it is cheap).

It can also test three-terminal voltage regulators.

No-name component tester

You see many variations of this device on eBay. I use this mostly to test transistors and diodes. Care must be taken, because it is not 100% reliably detecting the right component type. But once it detects the expected type, the component is most likely ok. Driven by a 9V battery it's range for testing Zener diodes is limited. For that I have the DY294. Zener diodes are not the favorite components of this tester, anyway. It has trouble detecting them.

There are much improved versions of this design on Aliexpress. With color displays and a proper case plus rechargeable LiIon accumulators.

LED backlight tester

I watched a video by Shopjimmy where they used this tester to check LED backlights. This was so convincing that I had to get one to be prepared for the increasing number of backlight defects in TVs.

It can generally measure the breakthrough voltages of any single LED, but is also powerful enough to drive LED stripes or even the whole panel and that makes it a brilliant time saver. It produces over 300V if necessary. It comes with needle-pointed probes, which are able to pinch through the plastic coating of LED strips to test individual LEDs if necessary. Nice.

It is available from Aliexpress or eBay for little money. Watch out for cheaper, older versions. I have revision C.

Vellemann audio signal generator

This handy little generator is available as a kit. It produces a sine wave in four steps from 50Hz up to 20kHz. It covers all relevant frequency ranges in audio equipment. The output voltage level is tunable with a potentiometer.

DIY signal tracer & amplifier

I built this with a simple integrated amplifier chip and a DC-blocking and over voltage protection front-end. It can be used as an active speaker or signal tracer. It runs on a 9V battery.

DIY transformer ring tester

AnaTek also offers the Blue Ring Tester. This device emits a pulse and counts the damped ringing of a transformer's coil. Each count represents one LED starting with red. It can identify shorted or open transformers or inductors, respectively. I need that so rarely that I decided to build it myself hand-wired instead of buying the kit. The circuit diagram is available for free on the net.

Statron 3229 electronic load

This is one of the gadgets which are sometimes invaluable when you build or test power supplies (like I do). It can be configured to present a constant current load or a constant resistance. Electronic load devices are very expensive when they are programmable. This one isn't, yet good enough for me. You need to use a power supply or a multimeter to adjust it.

The only complaint I have is that the adjustment knobs "fine" and "coarse" are swapped in the constant R section. That's just silly. Apart from that it is quality engineering made in Germany.

Hantek DSO 1062S

This was my first digital scope. It is portable with a built-in battery, which was the primary requirement for my mobile repairs. Running on battery also has the advantage of being decoupled from ground.

The user interface is somewhat clumsy and takes getting used to. It does a good job with the measurements I do in TV power supplies. It is hackable and mine goes up to 200Mhz instead of the original 60 :-)

It has a multimeter mode, too. It is not a digital storage scope though.

Rigol DS2012A

I had a repair case where I just couldn't figure out what was going on because everything happened so quickly. That motivated me to get a true digital storage scope. For testing power up/down and glitches issues that's the only tool which helps. This thing can do way more than I will ever need or understand. For the occasional user it is actually pure luxury, but well, hobbies, what can you do? :-)

I guess I will never use up the time limit of the numerous trial features on that ting :-)

And at last: what I missed - the EDS LeakSeeker 89

EDS discontinued all their test equipment in 2014. I missed out on the last opportunity to get one of these. Impossible to find used. Everybody keeps it. Just watch the few YT videos, it is amazing. This device is second to none and it is a shame nobody builds it anymore.