That explains why I haven't been able to PM. We are currently experiencing a postal strike here so mailing it right now would be pointless. Can i check back with you once this strike is over? Maybe I'll be able to PM by then too. Thanks Caution!
New Member SCR8 issues.
- Thread starter Lino
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- scr-8; 14-778
R164 does test bad. .97 K Ohm. Now to figure out the replacement. Should I just buy a variety pack? I’m seeing different wattages and I’m afraid I have no idea what I need. The coloured bands will tell me that I assume?
No, the bands tell value, not wattage. Typically if the resistor is comparable in size to the majority of other resistors, it will be 1/4 watts. 1/2 watt resistors are significantly more beefy and unmistakably larger. Also fusible resistors are not “standard” resistors. They are rare in modern equipment because there are better ways to design a circuit these days than rely on resistors that blow up so you may have to find NOS offerings. Alternatively if you can’t locate true fusible resistors, at least use flameproof ones. That way if it burns up, at least it won’t catch on fire.
Ok. good thing I asked. There are so many options available. Glad I didn’t go ahead and order a bunch. I’ll research and see what I can find. Really appreciate the insight. Thanks so much.
L
I'm researching and hoping to find NOS or anyone who has a stock pile from days gone by. I assume there is no work around outside of fire proof ones?
These by their nature, will run hot. Very hot. You can use regular ones but if an overcurrent condition occurs, they might ignite and either there’s going to be scorching or worse case is everything goes up in flames.
I won’t risk it. I’ll hold off until I find the right ones. No point putting all the work in only to have it go up in flames.
Thanks. Both test bad. R164 reading .97 k ohms and R 264 reading 300 K ohms. Keep in mind I'm super new to this so I'm not sure how accurate these readings are. I have a new meter that defaults to Auto and I'm not sure I trust it entirely. Just a cheapo I got from Amazon.....
Tinman
Member (SA)
I was in my box of resistors last night and found some flameproof 2.2, 4.7 and 10 ohms.
They were "normal" size so I'm assuming they're 1/4 watt.
I may have bought the 2.2 and 4.7 resistors for some of the SCR-8s I've had in the past.
Unfortunately, I can't remember where I bought them from.
I've used manual ones in the past but only ever bought auto ranging meters so I'm not sure how yours works.
Maybe you can find and watch a tutorial on the model you have or even a similar one.
They were "normal" size so I'm assuming they're 1/4 watt.
I may have bought the 2.2 and 4.7 resistors for some of the SCR-8s I've had in the past.
Unfortunately, I can't remember where I bought them from.
I've used manual ones in the past but only ever bought auto ranging meters so I'm not sure how yours works.
Maybe you can find and watch a tutorial on the model you have or even a similar one.
I just tested a bunch of resistors that I pulled off a sacrifice board I'm using to learn on. Meter checks out fine. So I'm assuming the resistors are in fact bad and will figure out replacements.
It is my experience that while there might be some inaccuracies in a meter, especially with respect to very low resistance measurements, we are generally speaking of small percentage tolerances. The greatest factor that gives me pause and reservations on my measurements is always seemingly fluctuating readings that are hard to pin down. But the reason is very simple.... all metal eventually develops an oxide coating that is invisible but affects readings. If you've found you get one reading when you initially place a probe that is suspect, but you press harder and you get a different more stable reading, this is almost surely the reason. This happens on even very expensive meters such as Fluke. While the probe tips has chrome tips that looks beautiful, the oxide coating is real, even if invisible. Basically, I just clean them every so often with plastic polish compound and then the oxide coating is wiped away and I get very stable readings. I also clean them before using them if they've been sitting around for any appreciable amount of time. Of course the component leads are also prone to this oxidation too, so the components under test will need to be cleaned for precise measurements. This could be done with some isopropyl and fiberglass tipped brush, or whatever you have since fiberglass tipped brushes are not common in most folks tool arsenal.
Great advice! Thanks. I’ll put that into practice. I’ve also been wondering what I can use on the PCB as far as a brush is concerned. Is the concern the isopropyl? I’ve been cleaning up after soldering with a cotton swab. Not doing the job and gets snagged and is just slow and inefficient. I also tried a tiny piece of a gentle scouring pad and tweezers but again super inefficient. I’ll try to track down a fibreglass brush. Thanks for the tips. Appreciate it!