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Jaf
Joined: 08 Jun 2006
Posts: 194
Location: Oria. Spain
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 Posted: Tue Jul 04, 2006 3:33 am Post subject: Grrr, stupid digital meters |
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Ok, so I'm finally getting round to sorting out my car. One of the headlamps wasn't working on dipped beam. Normally it's a bulb right? So I swap the bulbs over. Still doesn't work. Check the fuse with a digital meter. It's fine, so I checked the voltage at the bulb. It's 12volts. At this point I gave up and called my dad out. He double-checked that there's voltage and the bulb and also checks the earth. Both are fine according to the meter. He then had a brainwave and wouldn't tell me what it was. He went and poked the fuses with a wooden lolly stick. Bloody bulb worked!
Turns out that digital meters don't put a load on the voltage. So you get false readings. Dad says always check the voltage on the bulb with the bulb plugged in.
Rant over!
Jaf
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1978 924na |
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John Brown
Joined: 07 Nov 2002
Posts: 903
Location: Leesburg VA
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| Posted: Tue Jul 04, 2006 3:50 am Post subject: |
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Yes, but ....
No voltmeter made in the last 50 years is going to pull enough load to show the loaded condition of the circuit. Digital or not. Even the old style were in the neighborhood of 5k/volt which also would not have shown anything.
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John
80 931 - #931 44Cup
99 Escalade - tows track cars
gone but not forgotten: original 924.org car - 82 |
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Paul
Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin
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| Posted: Tue Jul 04, 2006 10:12 am Post subject: |
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That's why an old fashioned 12 volt test light still has a place in my tool box....
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
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Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy. |
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Lizard
Joined: 03 Nov 2002
Posts: 9364
Location: Abbotsford BC. Canada
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| Posted: Tue Jul 04, 2006 11:08 am Post subject: |
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agreed Paul, however from all the issues that you list it sounds like you have ALOT of corrosion on or around your fusebox area.
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D Hook
Joined: 02 Nov 2002
Posts: 3158
Location: Omaha, NE
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| Posted: Tue Jul 04, 2006 8:52 pm Post subject: Re: Grrr, stupid digital meters |
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| Jaf wrote: | Ok, so I'm finally getting round to sorting out my car. One of the headlamps wasn't working on dipped beam. Normally it's a bulb right? So I swap the bulbs over. Still doesn't work. Check the fuse with a digital meter. It's fine, so I checked the voltage at the bulb. It's 12volts. At this point I gave up and called my dad out. He double-checked that there's voltage and the bulb and also checks the earth. Both are fine according to the meter. He then had a brainwave and wouldn't tell me what it was. He went and poked the fuses with a wooden lolly stick. Bloody bulb worked!
Turns out that digital meters don't put a load on the voltage. So you get false readings. Dad says always check the voltage on the bulb with the bulb plugged in.
Rant over!
Jaf |
What he may have done was simply knock some corrosion off one of the connections. Take all the fuses out one and a time and clean the contacts, both on the fuse and the fuse holders in the fuse box. Then do the relays one at a time. You'll be amazed.
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'80 924 n/a SOLD |
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