iFixit - Answers With Device "Test Equipment"

Multimeter: Multimeter continuous beeping in continuity mode

Sun, 04 Jan 2026 08:12:24 -0700

continuous beeping even with test leads removed.

checked battery and opened it up with no showing of corrosion or something shorting anything. Fuse still intact also did not work with high voltages.

Was checking some dead phone batteries at the time and when got back to it it kept beeping.

does not want to work in any other mode at all.

⟐ Commented January 04, 2026 at 8:12 MST

MCH-108 Digital Multimeter: What is the accuracy of the device?

Tue, 29 Aug 2023 14:51:36 -0700

Hey all!
I've been eyeing the market for a digital multimeter and I'm definitely interested in this model, but unfortunately there aren't any technical specifications listed on the store page for the product. I just wanted to know if anyone knew what the accuracy of this model is? (i.e. To how many decimal places can this model measure confidently)

Thank you for your help!

⟐ Answered August 29, 2023 at 14:51 MST

Multimeter: Meter displays OL in voltage continuity mode with or without probes?

Mon, 19 Jan 2026 09:56:38 -0700

Quite an expensive Voltmeter device , did this from day one

OL means ‘over load’ but it isn’t even connected to anything

i suspect it is faulty but wanted to find out if anyone else has experienced this and maybe it’s simple

⟐ Commented January 19, 2026 at 9:56 MST

Fluke 77 Series III: Could somone please do a repair tutorial on the continuity buzzer

Wed, 28 May 2025 18:25:42 -0700

My Fluke doesnt beep when i measure for continutiy but unfortunatly i dont know where to start with the troubleshooting. Regards, Thomas

⟐ Answer accepted May 28, 2025 at 18:25 MST

RadioShack 22-510 Switching Power Supply: Acurite Digital Readout Power Supply

Fri, 30 Dec 2022 06:28:47 -0700

Hope someone can help.

I could not find a listed device even close.

The primary windings of the transformer have gone (open circuit). I am trying to find the secondary voltage so I can purchase a new transformer. There are no markings on the transformer. One of the first components after the rectifier on the pcb is an LM340T5780P+ voltage regulator (wired as fixed output). Is it possible to work out it’s supply voltage and hence input voltage from other components from the pcb?

Spec sheet says Vout - 5,12,15. Vin - 10,19,23. Are these just test voltages for the specs or are they the only 3 operating voltages?

It is connected to 2 capacitors with markings - K5R 334K & 105 +25K.

The transformer connects to the two pins.

There is no model number - Acurite Millmate.

The only numbers on the board are; 387575-6033 (printed) and 7-19 570702 1-29-90 (hand written) and ACU-RITE 387575-6034 ASSM. REV A (printed).

There does not appear to be a thermal fuse within the transformer. It has 4 primary windings and a single secondary winding.

The transformer is connected to the two pins shown in photos 1 and 3.

Is it possible to workout the supply voltage from the voltage regulator and the components around it - capacitors and resistors?

Do you mean the tiny capacitors near the regulator that I gave the numbers for, or the electrolytic capacitors?

The main transformer is connected directly to a RMS401L rectifier (Max 35V). The rectifier is connected directly to some electrolytic capacitors, the LM340T5 voltage regulator, an IC - TL494 and the small capacitors associated with the LM340T5 as listed above. The electrolytic capacitors are rated at 16V, the IC is rated at 7-40Vand the regulator is rated at 5V out and 5 to 18V in.

If I had to take a guess, it would be 12V supply to the board. Would that be correct? Could I damage anything with 12V - Would 10V be better?

Can anyone help

Kind Regards

Jeremy

⟐ Commented December 30, 2022 at 6:28 MST

Fluke VoltAlert: How to extract PCB from chassis of Fluke VoltAlert 1AC-A II?

Sun, 03 Jul 2022 03:27:21 -0700

This is a Fluke VoltAlert 1AC-A II. I have to extract the PCB from the chassis of the same in order to re-heat some components. The circuit moves, but it stops even 1 mm. I tried to see where the block was, but I could not see it. Is there anyone who has already extracted the circuit and knows how?

The acid output from the batteries has corroded some welds that have to be redone, but to access them I have to be able to pull the printed circuit strip out of the wrapper that contains it. I need to know where to unlock to allow the exit as it flows though for a very short ride (less than 1 mm)

⟐ Commented July 03, 2022 at 3:27 MST

MCH-108 Digital Multimeter: Am I testing continuity correctly?

Mon, 09 Dec 2024 03:18:18 -0700

I recently bought a ifixit multimeter and I tested it out to see if it was working properly. I tried out the different modes and they worked until i tried out continuity. I took a battery that i knew was charged and tried to test it out my multimeter. I turned continuity testing mode on and touched both probes together to see if it would beep and it did. I then took the red probe and held it on positive terminal and put the black probe on negative but the multimeter didnt beep. I was very confused. I then got the idea to put the red probe on the negative terminal and the black probe on the positive terminal and guess what, it beeped.

My question is when testing continuity in a battery am i supposed to put red probe to positive and black probe to negative or am i supposed to do red probe to negative and black probe to positive.

⟐ Answer edited December 09, 2024 at 3:18 MST

Power Supply: Dell EP071350 power supply out pins

Tue, 17 Feb 2026 08:35:36 -0700

Hi,

I have Dell EP071350 server power supplies I would like to use as a lab power supply, but I couldn't find the out pins of this model anywhere on the web.

Does somebody know this?

⟐ Edited February 17, 2026 at 8:35 MST

Multimeter: Can I use a multi meter to discharge residual charge on capacitor

Sat, 11 Jan 2020 14:14:14 -0700

I want to remove an appaently faulty capacitor from a 1980’s Metz flashgun. It is likely to be holding some charge at maybe up to 300 v, DC, so i do not want to injure myself or cause an explosion.

Can i use a multimeter to discharge this capacitor before I remove it from the gun and if so what settings do I set on the multi meter.

⟐ Answer accepted January 11, 2020 at 14:14 MST

HP power supply D13-180N1A 180 w power supply: What is the cause of the electric shock

Wed, 15 Nov 2023 00:50:10 -0700

What is the cause of electric shock in power supply

⟐ Answered November 15, 2023 at 0:50 MST

Power Supply: My TSC printer power supply 24v 2.5a is dead, how to repair?

Sat, 18 Dec 2021 07:11:03 -0700

This power adaptor was powering TSC ttp 244 plus label printer. Power cable is ok, green LED not working, how to go about checking whats wrong.

⟐ Answered December 18, 2021 at 7:11 MST

Etekcity Lasergrip 1080: Why won't the device turn on?

Tue, 13 Oct 2015 06:00:04 -0700

I keep pressing the buttons but the device won't turn on.

⟐ Commented October 13, 2015 at 6:00 MST

Power Supply: APW7-12-1800 12V Power supply for Antminer ASIC Machine

Mon, 10 Feb 2025 11:42:58 -0700

Hello! I have a Power supply for antminer Bitcoin mining ASIC. model apw7-12-1800. Made by Shenzhen Century Cloud Core Technology, Ltd. Model subtype A3, Looking for repair information. any help? Thanks! Dave

⟐ Commented February 10, 2025 at 11:42 MST

Power supply: Service maual, wiring diagram needed - PULS SL20.110

Fri, 29 Jul 2016 06:00:15 -0700

Hello, does anyone have repair manual for this type of power supply from

PULS - SL20.110 ?

Thanks

⟐ Commented July 29, 2016 at 6:00 MST

Multimeter: MastTech MS8229 beeps all the time

Thu, 04 Jul 2024 19:19:13 -0700

Hi I own a MS8229 multimeter for a few years now. It works fairly well except the one (super annoying) thing it does is it beeps whenever it is turned to a current/voltage/resistance measurement. It doesn't matter if the probes are plugged in or not. The beep differs (deeper beep) if the probes aren't plugged in but then it's a high pitched beep when they are removed. The beep goes away if I change it measure lux/audio, etc…

So wondering how/if this can be debugged. I'm also thinking to disconnect the speaker as it's terribly loud. Is there a suggestion one what I can do to fix this? I'm thinking of clipping the speaker but that seems like a worst-case scenario. I'd hate to throw this device away.

⟐ Answered July 04, 2024 at 19:19 MST

UK-830LN: Black lead has shorted how do I fix lead

Sun, 14 Dec 2025 20:14:59 -0700

Black lead has shorted how do I fix lead

⟐ Answered December 14, 2025 at 20:14 MST

RadioShack 22-510 Switching Power Supply: Getting hash from 22-510

Sat, 10 May 2025 16:08:40 -0700

My Radio Shack 22-510 power supply is generating hash in my receiver. Need solution.

⟐ Answer edited May 10, 2025 at 16:08 MST

Multimeter: Klein tools MM700 multimeter resistance reading false.

Sun, 19 Jan 2025 10:33:32 -0700

I got this Klein tools MM700 True RMS multimeter, when testing resistence or continuity, by touching test leads together it should reads less than 1 Ohm, but the reading is 3-4 Ohms now.

I have purchase new Klein tools OE replacement test leads, verify they are good with other known good meters, test both fuses, replace batteries, etc.

I tried everything I could, and even went to Klein tools website looking for repair portal, oddly there is none.

Klein tools simply provides 2 yrs warranty return window and no links for repair, feels like that their meters are basically consumables, and when warranty expires, just toss it away and get new one, wtf is that?

So now I have a faulty meter which cost me $150+ bought new, a known brand, not no name cheap amazon junk, but acting like one.

Should I try something else to fix it? or just get a Fluke?

⟐ Answered January 19, 2025 at 10:33 MST

Klein Tools NCVT1P: New Klein NCVT1P no test sound

Tue, 23 Apr 2024 04:19:04 -0700

My new Klein NCVT1P responds correctly to turning on and off with lights and beeps but makes no sound when testing a known good circuit.(the red led illuminates but no sound) Is there a switch to change it from silent to audible notification of voltage?

⟐ Commented April 23, 2024 at 4:19 MST

Multimeter: My multimeter won't turn on after high voltage spike

Sun, 09 Oct 2022 23:53:19 -0700

I was measuring the voltage of a small fly swatter racket so I could modify it and make a lantern bug zapper thing, so I barely tapped the button to attempt to produce a smaller voltage, and I expected it to be around 280 to 400v, but my meter just shut off and now it won't turn back on. It is a barn star DT9205A from Tractor supply with a CAT ll 600v rating on the bottom left. Note it looks NOTHING like the picture I selected. It is a big 10 inch long meter with resistance test, ac and DC voltage up to 600v, capacitance test up to 200 μF, and an ac and DC current test up to 10A. Please help soon as this is my only multimeter!

⟐ Edited October 09, 2022 at 23:53 MST