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What is this thing between the tacho and the speedo?

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What is this thing between the tacho and the speedo?
#1
dylan873 Dylan Edgar
Edinburgh, Leith, UK   GBR
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This has probably been covered many times before but I can't seem to find the right wording to search for it...

Can someone tell me what this twist switch thing with a 'P' on it does (see attached photo)? It's between the speedo and tacho on the dash.

Thanks,

Dylan


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Re: What is this thing between the tacho and the speedo?
#2
MG Cruiser Avatar
MG Cruiser Keith Delta4
Rockingham, WA, Australia   AUS
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1970 MG MGB "Moneypit"
Dimmer?

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Re: What is this thing between the tacho and the speedo?
#3
dcdci Avatar
dcdci Gold Member Dave Loechel
Kings Park, NY, USA   USA
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1966 MG MGB
Yes, it's the dimmer for the dashboard lights. Can't imagine why you'd want to dim them ... they aren't very bright to begin with. smiling bouncing smiley


Dave Loechel
66/67 roadster


"How would you like a job where, every time you make a mistake, a big red light goes on and 18,000 people boo?" - Jacques Plante

"I always shot at the goalie and let my inaccuracy score for me." - Mike Bossy

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Re: What is this thing between the tacho and the speedo?
#4
dylan873 Dylan Edgar
Edinburgh, Leith, UK   GBR
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Thanks for the response, I guess I won't be needing that then! They are surprisingly dim to begin with...

Just out of interest, does anyone know what the P stands for?

Thanks,

Dylan

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Re: What is this thing between the tacho and the speedo?
#5
dcdci Avatar
dcdci Gold Member Dave Loechel
Kings Park, NY, USA   USA
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1966 MG MGB
Panel (lights) ... I guess.


Dave Loechel
66/67 roadster


"How would you like a job where, every time you make a mistake, a big red light goes on and 18,000 people boo?" - Jacques Plante

"I always shot at the goalie and let my inaccuracy score for me." - Mike Bossy

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Re: What is this thing between the tacho and the speedo?
#6
forda2 Avatar
forda2 Brian Martin
San Antonio, TX, USA   USA
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1931 Ford Model A
1980 MG MGB
Panel?

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Re: What is this thing between the tacho and the speedo?
#7
cwru1973 Avatar
cwru1973 Lee D
Evergreen, CO, USA   USA
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1970 MG MGB
If it's British, the p stands for proper

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Re: What is this thing between the tacho and the speedo?
#8
mgjoc Avatar
mgjoc Gold Member Dennis Rainey
Crossville, TN, USA   USA
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1965 MG MGB "Roscoe"
I believe that the "P" stands for "Potentiometer" . A device an instrument for measuring an electromotive force by balancing it against the potential difference produced by passing a known current through a known variable resistance.
Avariable resistor with a third adjustable terminal. The potential at the third terminal can be adjusted to give any fraction of the potential across the ends of the resistor.

Cheers - Dennis


"Quality is long remembered after cost is forgotten" - Sir Henry Royce

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Re: What is this thing between the tacho and the speedo?
#9
DocsMG Avatar
DocsMG James Spradlin
Lakewood, CO, USA   USA
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1971 MG MGB "Tony The Fish"
1979 MG MGB
Since it is British, I would say Dennis is correct, because his answer has the most words! moon

Is dead center like that original?

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Re: What is this thing between the tacho and the speedo?
#10
riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
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1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
In reply to # 2785246 by DocsMG Is dead center like that original?

It is on a MGA as shown. The P =panel lights

B


Life's most persistent and urgent question is, "What are you doing for others?"

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Re: What is this thing between the tacho and the speedo?
#11
ErnieY Avatar
ErnieY Ernie Y
Albatera, Alicante, Spain   ESP
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1976 MG MGB GT
Actually it's a rheostat not a potentiometer but whatever you choose to call it it has to be the most useless control ever fitted to the car !

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Re: What is this thing between the tacho and the speedo?
#12
mgjoc Avatar
mgjoc Gold Member Dennis Rainey
Crossville, TN, USA   USA
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1965 MG MGB "Roscoe"
Ernie,

Along with it being at the bottom of the list of "Uselessness" is the panel light switch on the steering wheel cowl on the later models.

Cheers - Dennis


"Quality is long remembered after cost is forgotten" - Sir Henry Royce

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Re: What is this thing between the tacho and the speedo?
#13
JoeReed Avatar
JoeReed Joe Reed
Cordova, TN, USA   USA
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1978 MG MGB "Kermit"
The knob is upside down.....it's a "d" for dimmer...or maybe darker smiling bouncing smiley



Edited 1 time(s). Last edit at 2014-09-01 11:54 AM by JoeReed.

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