Do you test NEW components before install?
07-15-2002, 01:05 PM
#1
Three Wheelin'
Thread Starter
Do you test NEW components before install?
Interesting...
I had the pod out for other reasons and WIWIT, tested the 68 ohm resistor for the alternator excitation circuit. It measured 74+ ohms. Even with a 5% tollerence, it should not have read more than about 71.5 ohms.
Off the the local independent electronic supply store I go. They have a new 68 ohm resistor in stock. When I got back to install it, I checked it first (a lesson learned in my business work) and found that it tested 1.8 ohms!!
I returned to the store, where they pulled out the bin of 68 ohm resistors consiting of two batches of resistors. All of the one batch tested around 1-2 ohms although marked 68. They had a few in the bin which were 68's but obviosly from another batch, they tested fine. I swapped for one, re-tested it before install (68.7ohms), and all is well. I soldered it into the sockets, as it had fit kinda loose on it's own.
Had I simply installed the first resistor without testing it, I imagine some damage would have occured. Who would think a brand new part would be defective? It just reminds me that all parts should be tested (when it is practical), before installation. How often could we be chasing a problem not solved by a defective new replacement part?
BTW, that difference of the old 74+ ohms and the new 68.7 ohms yielded a slightly higher reading on the voltmeter on the car (especially at start-up) and what appears to be less voltage drop under heavy electrical load.
Greg
I had the pod out for other reasons and WIWIT, tested the 68 ohm resistor for the alternator excitation circuit. It measured 74+ ohms. Even with a 5% tollerence, it should not have read more than about 71.5 ohms.
Off the the local independent electronic supply store I go. They have a new 68 ohm resistor in stock. When I got back to install it, I checked it first (a lesson learned in my business work) and found that it tested 1.8 ohms!!
I returned to the store, where they pulled out the bin of 68 ohm resistors consiting of two batches of resistors. All of the one batch tested around 1-2 ohms although marked 68. They had a few in the bin which were 68's but obviosly from another batch, they tested fine. I swapped for one, re-tested it before install (68.7ohms), and all is well. I soldered it into the sockets, as it had fit kinda loose on it's own.
Had I simply installed the first resistor without testing it, I imagine some damage would have occured. Who would think a brand new part would be defective? It just reminds me that all parts should be tested (when it is practical), before installation. How often could we be chasing a problem not solved by a defective new replacement part?
BTW, that difference of the old 74+ ohms and the new 68.7 ohms yielded a slightly higher reading on the voltmeter on the car (especially at start-up) and what appears to be less voltage drop under heavy electrical load.
Greg
08-09-2002, 06:08 PM
#3
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Greg-
Not being too electrically versed...I'm curious about which resistor you are refering too. Is the 68 Ohm part the white rectangular component that sticks out of the back of the instrument cluster? Mine is loose- and my voltmeter sits dead for the most part, but occasionally on longer drives suddenly comes to life...
Normy!
'85 S2 5 speed
Not being too electrically versed...I'm curious about which resistor you are refering too. Is the 68 Ohm part the white rectangular component that sticks out of the back of the instrument cluster? Mine is loose- and my voltmeter sits dead for the most part, but occasionally on longer drives suddenly comes to life...
Normy!
'85 S2 5 speed
08-09-2002, 06:28 PM
#4
Three Wheelin'
Thread Starter
Normy,
[quote]Is the 68 Ohm part the white rectangular component that sticks out of the back of the instrument cluster? <hr></blockquote>
The 68 Ohm resistor IS the white rectangular component that sticks out of the back of the instrument cluster.
As I mentioned, I soldered my new one in place.
Now that it has been in there for a while, I do believe it helped greatly. I show a good 14V reading w/no lights or A/C on, and always more than 13 under heavy electrical load (lights, A/C, etc.)
I've been chasing a 7/8 full fuel gauge, and on the email lists, there is discussion about a 100 ohm resistor for the fuel gauge. If I have any luck with that one, I'll let you know.
Greg
[quote]Is the 68 Ohm part the white rectangular component that sticks out of the back of the instrument cluster? <hr></blockquote>
The 68 Ohm resistor IS the white rectangular component that sticks out of the back of the instrument cluster.
As I mentioned, I soldered my new one in place.
Now that it has been in there for a while, I do believe it helped greatly. I show a good 14V reading w/no lights or A/C on, and always more than 13 under heavy electrical load (lights, A/C, etc.)
I've been chasing a 7/8 full fuel gauge, and on the email lists, there is discussion about a 100 ohm resistor for the fuel gauge. If I have any luck with that one, I'll let you know.
Greg