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Bad resistors from Tayda? No, cheap multimeter.

Started by AntKnee, February 03, 2017, 02:51:02 AM

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AntKnee

I was working on a build today that called for a 320k resistor, which is not very common, so I didn't have one. I decided I would measure through my 330k resistors and see if one came close, only to discover they all would not register at all on my meter. Well, they would register around half of 330 for a split second, then go to 1, indicating no measurement. I tested other resistors (from mouser) and they were fine, ruling out a bad meter. So, once again, you get what you pay for, kids. Now I will test every blasted one of them before I use them until theyre gone, then no more Tayda resistors for me.

Update: It turns out it was my cheapo multimeter. Into the bin with it!
I build, and once in a while I might sell, pedals as "Vertigo Effects".

culturejam

Quote from: AntKnee on February 03, 2017, 02:51:02 AM
Now I will test every blasted one of them before I use them until theyre gone, then no more Tayda resistors for me.

I highly recommend you just throw them away now and replace them with decent stuff. It's not worth the headache. I don't know your finances, but I can't see it being worth it. And if you are in a bad spot, PM me and I'll send you some resistors.
Partner and Product Developer at Function f(x).
My Personal Site with Effects Projects

reddesert

Were the other resistors that you tested high values, like > 200 K ?  With my cheap DVM, it can give wonky values on the highest resistance range, especially if the battery is running down. I'm not sure of a mechanism for a resistor going bad with the behavior you're describing (low value then open circuit).

IME resistors from Tayda have been fine. Do people really see failed resistors often? I understand that some of their more sensitive components may be an issue - like out of spec FETs or ICs - but I've seen a lot of threads where someone tears apart a circuit in search of faulty components and eventually finds a connection that was unsoldered all along. I've done this myself.

EBRAddict

I always test every resistor, cap, diode and transistor. It doesn't add that much time and it's so much easier to solve the problem than after it's in-circuit. With pedals, the part count is pretty small so it shouldn't take too long. I socket ICs so they can be swapped out fairly easily.

AntKnee

Quote from: reddesert on February 03, 2017, 04:35:14 AM
Were the other resistors that you tested high values, like > 200 K ?  With my cheap DVM, it can give wonky values on the highest resistance range, especially if the battery is running down. I'm not sure of a mechanism for a resistor going bad with the behavior you're describing (low value then open circuit).

Actually, the ones that tested weird were 330k and the ones I tested that worked were 100k. I just pulled out a 390k from Mouser and it tested weird, too. So I guess it is my DVM after all. Its a cheap beginner meter and I'm due for a nice one, anyway. Thanks for bringing that up. I'll retest some resistors when I get a new meter and see what happens.
I build, and once in a while I might sell, pedals as "Vertigo Effects".

cloudscapes

Yeah when it comes to dirt-cheap components like resistors and non electrolytic caps, I don't see any reason not to just buy them in the hundreds from mouser/digikey. Still only pennies (or even less), and you'll know you should be able to trust them.

stecykmi

Quote from: EBRAddict on February 03, 2017, 01:55:27 PM
I always test every resistor, cap, diode and transistor. It doesn't add that much time and it's so much easier to solve the problem than after it's in-circuit.

i never do because i'm really lazy. how often would you say that you have averted a problem by doing this?

BrianS

Quote from: stecykmi on February 03, 2017, 06:47:14 PM
Quote from: EBRAddict on February 03, 2017, 01:55:27 PM
I always test every resistor, cap, diode and transistor. It doesn't add that much time and it's so much easier to solve the problem than after it's in-circuit.

i never do because i'm really lazy. how often would you say that you have averted a problem by doing this?

I do the same thing. I test everything before I start. I use some foam strips, bend the resistors/diodes and line them up on one side and the capacitors on the other and run the lines testing.  It takes a few minutes to do it and I dont have to look at the build doc again until after all that is soldered.  I don't know how many times it has saved me from jacking something up but at least I know everything was right when placed on the board. It saved me from putting a couple of bad Tayda elec caps in.  That stopped me from buying caps from Tayda.  I still occasionally get their resistors if I am running low on a certain value and I am ordering pots/boxes. 

dbp512

What multimeter do you plan on getting? I too, only have a cheap thing that doesn't work all too well. I've been meaning to upgrade as well, but I can't tell what sets all the various models apart.
"you truly are a transistor tickler, what with the application of germanium ointment to sensitive fuzzy areas. :)" - playpunk

chordball

I've been using this multimeter for quite a while now and so far it's been great. I couldn't afford a Fluke and did some research before I settled on this one. No complaints, especially for the low cost.

https://www.amazon.com/AideTek-VC97-Multimeter-Capacitor-Frequency/dp/B008GTEZPI/ref=sr_1_6?ie=UTF8&qid=1486161905&sr=8-6&keywords=aidetek

EBRAddict

Quote from: stecykmi on February 03, 2017, 06:47:14 PM
Quote from: EBRAddict on February 03, 2017, 01:55:27 PM
I always test every resistor, cap, diode and transistor. It doesn't add that much time and it's so much easier to solve the problem than after it's in-circuit.

i never do because i'm really lazy. how often would you say that you have averted a problem by doing this?

Not often I'd say I've found at least one thing iffy or wrong out of every 10 pedals I built. Caps out of spec, a vendor shipped a MOSFET instead of a BJT, or a wrong resistor value, or a BJT with a gain too low, shit germanium diodes. For me that helps knowing the problem is likely with my soldering or wiring.

darrenw6000

please, before you say parts are faulty from certain sites please triple check things over, I'm not having a go at you it's just that it can be detrimental to some sellers of pedal parts. :-)

matmosphere

Ironically I have this thing

http://www.taydaelectronics.com/esr-meter-transistor-tester-lcd-diode-multimeter-capacitance.html

It works well for caps and resistors, not sure I totally trust it in trannies though.

stringsthings

Quote from: chordball on February 03, 2017, 10:47:23 PM
I've been using this multimeter for quite a while now and so far it's been great. I couldn't afford a Fluke and did some research before I settled on this one. No complaints, especially for the low cost.

https://www.amazon.com/AideTek-VC97-Multimeter-Capacitor-Frequency/dp/B008GTEZPI/ref=sr_1_6?ie=UTF8&qid=1486161905&sr=8-6&keywords=aidetek

Does this DMM read transistor hfe very well?  I picked up a super cheap DMM from harbor freight but it's terrible at reading hfe.
When you put the transistor in the socket, it doesn't read it unless you wiggle it a lot and get lucky.  Even then, the reading is all over the place.
All You Need Is Love

reddesert

I have a similar harbor freight DMM and the problem is that actually getting the transistor leads down to whatever the test contacts are is pretty difficult. It feels like there is not a socket there, or that getting the leads into the socket is difficult. Pre-bending the leads may help, or maybe sticking wires into the test contact and to a breadboard if you were going to test many transistors. Once it makes good contact, the h_FE number is fairly stable and agrees with specs.

On the one hand, the meter is kinda crappy in the details, and on the other, it cost $3.99!  I'm amazed at what you can get now.  The first effect I built was strictly out of parts available from Radio Shack, and I had to walk uphill both ways to get there ...