be carefull at ratshack!

   / be carefull at ratshack! #41  
Besides knowing how to read resistors at a glance, a good technician/engineer can do the same with capacitors. I'm betting not many here know that one.

In the 80's I managed a full line repair center for Tandy and a computer repair center as well.
 
   / be carefull at ratshack! #42  
Besides knowing how to read resistors at a glance, a good technician/engineer can do the same with capacitors. I'm betting not many here know that one.

In the 80's I managed a full line repair center for Tandy and a computer repair center as well.

I studied caps again yesterday, and I saw the color code, and I can't do it. I just don't have a need. I know the resistor color code and I find that most times, I can't really distinguish the colors that well when I see them.

I needed a spark arresting capacitor to protect the contacts of the switching relay on a electromagnetic tooth clutch. The vendor's literature suggested a 4 uf cap, and said it MUST NOT BE ELECTROLYTIC. :confused: I have no real idea why exactly. I know most electrolytics are polar, so I suppose the current draw of the inductance of the clutch coil could amount to a reversal.

Previously, since it was a magnetic clutch using DC power, I protected the contacts using free-wheeling diodes. But when I looked, they were all in two. I asked our top guy, and he said maintenance didn't understand their purpose and cut through them with dykes. That seemed odd to me, why not just remove them? But when I inquired again yesterday, I was informed that the diodes "blew up." Hmmm.

One obvious draw back of a diode is that it will be a dead short (nearly) if maintenance reverses polarity accidentally, so I decided that I would like protection against that situation. But I was really rusty on capacitors, so I didn't know what to choose. So I wound up trying to do a quick study on capacitors yesterday and choosing a polypropylene type. I promised maintenance that if it blew up or something, I'd pick something else next time. :D

The Germans offered a capacitor in the accessories portion of their catalog, but for some odd reason, they were $250 a piece. This was for a 4uF 50V cap. I have no real idea what made that price justified, but that would have put us over our $5000 local P.O. limit, so we would have needed additional approval to add their cap to the clutch order.
 
   / be carefull at ratshack!
  • Thread Starter
#43  
ever put to EL's ack to back?
 
   / be carefull at ratshack!
  • Thread Starter
#46  
No, I never have. But thanks for reminding me, since I may need to use that technique someday.

can be usefull in a pinch.
 
   / be carefull at ratshack! #47  
Radio Shaft is about the only place where I can find thermal fuses easily. Just blew one in an electric heater and it as nice to fix if for $1.79 instead of replacing the whole thing.
 
   / be carefull at ratshack!
  • Thread Starter
#48  
i did one in a micro a few years back.. was surprised to see them on the shelf. ceramic cased fuses too...
 
   / be carefull at ratshack! #49  
Two years or so ago I had to replace the LED's in my optical mouse (I really like the mouse and didn't want to bother searching for another one as nice). I went to RS and found the place staffed by 3 cute young girls. I was wondering if the company was trying a new tactic to get guys to shop there ;)
 
   / be carefull at ratshack! #50  
My favorite was when I tried to buy something at Radio Shack with my charge card. The kid asked for my phone number and I said it was private. He said then he wouldn't take my charge card. :mad:

I needed the item, so I paid cash, but I was furious. Very rarely go there now unless I need something right away.

When they ask for my number, I say "pick one".
 

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