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  #11  
Old 5 Days Ago
iiAtlas iiAtlas is offline
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Quote:
Originally Posted by Tom H View Post
Loose, The problem with using a digital multimeter, is, assuming it's an original type stabilizer, is that it operates on an On/Off principle at about 2 per second, to achieve avg 10 V. This ends up reading as total random readings on a Digital.

Altas, I found your e-mail in my Junk. I'll call in a few minutes


Tom
Tom, THANK YOU so much! Your deductions with the multimeter + test lamp were quite interesting. I am hoping the technique can help me with future debugging.

For future reference: we used a test lamp to confirm the operation of the voltage stabilizer. As Tom said above, it operates by turning on/off about 2 times per second to achieve that 10v average. With the test light, you can clearly see the filament go on-off-on-off. The digital multimeter just spits out garbage. This confirmed to us that the voltage stabilizer was operating correctly, and that the new wiring was correct. It was down to gauge or sender. The gauge spat out a reading when connected inline with test light so our bet is sender. Grounding to sender top post to the case spat out an infinite reading. Sounds like that sender is shot! Maybe being hooked up to the coil did that..

Will post an update once I get the new sender ordered and installed!





EDIT: D'oh! Looks like Tom beat me to the reply. Follow his account of the events, not mine..hah! Yes a young gun...hoping to be old and wise one day!
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  #12  
Old 5 Days Ago
65beam 65beam is offline
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Series 1 & 2 use a different sending unit than series 3 thru 5. Maybe you have the wrong temp sending unit.
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  #13  
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Rootes 66 Rootes 66 is offline
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A Quick visual on the sender unit, Black insulator = Unregulated supply 12-13V Red insulator = 10V regulated and the Grey not used by Rootes was the 5V supply.
Pete
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  #14  
Old 4 Days Ago
Tom H Tom H is offline
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65Beam, the sender he has is an open circuit. It read "Open" on the 20,000 ohm range, meaning greater than 20,000 ohms. No senders have that high a cold resistance.

Pete, you said
"A Quick visual on the sender unit, Black insulator = Unregulated supply 12-13V Red insulator = 10V regulated and the Grey not used by Rootes was the 5V supply"

I'm not sure what you are describing. The temp sender on an Alpine is a simple brass fitting with one insulated terminal on it. And if you really mean the gauge voltage Regulator there are just two terminals on it :unregulated (12-13 V) in and regulated (10 V) out. (plus ground thru the housing, of course). There is no 5 v supply in any Alpine we have ever heard of. And no 5 V output on any regulator they used.

Tom
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  #15  
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iiAtlas iiAtlas is offline
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Quote:
Originally Posted by Tom H View Post
65Beam, the sender he has is an open circuit. It read "Open" on the 20,000 ohm range, meaning greater than 20,000 ohms. No senders have that high a cold resistance.

Pete, you said
"A Quick visual on the sender unit, Black insulator = Unregulated supply 12-13V Red insulator = 10V regulated and the Grey not used by Rootes was the 5V supply"

I'm not sure what you are describing. The temp sender on an Alpine is a simple brass fitting with one insulated terminal on it. And if you really mean the gauge voltage Regulator there are just two terminals on it :unregulated (12-13 V) in and regulated (10 V) out. (plus ground thru the housing, of course). There is no 5 v supply in any Alpine we have ever heard of. And no 5 V output on any regulator they used.

Tom
Thanks for all the info Tom! A new sender is on order. Looks exactly the same as the new one I ordered a few months back. Will just assume that one is defective from the source, or fried from the way it was wired. Will know more when the new unit arrives! Probably early next week.
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  #16  
Old 4 Days Ago
hartmandm hartmandm is offline
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If you are talking directly to Tom, you'll get the issue straightened out.

The original Smiths TT-4802/00 temp sender on my series V has a black colored insulator around the connector and the series V circuit is voltage regulated.

I'm a bit surprised there are some 'normal' range readings if the temp sender has such a high resistance / appears to be open when cold.

I expect Tom had you measure the resistance across the two connectors on the gauge. They should read 63 ohms.

The temp gauge circuit requires a good engine ground. Check the resistance between some point on the engine and the chassis. Should be around 1 ohm when the ignition is off. (When the car is running, a digital multi-meter will likely give bad readings due to current flow.)

When you get your new temp sender, it should read around 650 ohms at 25C/77F. A slightly higher reading at room temperature (70F). A good test is to install the new temp sender, leave it disconnected, and then continuously measure the resistance at the sender connector as the car warms up. The resistance will drop as the car warms up. It should drop to somewhere around 120 ohms at 160F. It should be 77 ohms at 185F.

Mike
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Last edited by hartmandm : 4 Days Ago at 11:31 AM. Reason: Add photo of temp sender
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  #17  
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65beam 65beam is offline
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Tom,
I'm just saying that there are two different sending units. The years tell me that the guage may work right today but may go wacky at a later date. Some of the early units now on the market won't fit. The bulb bottoms out before it seals to the housing. Some suppliers are now saying to use the later unit in all series but will they read right? Who knows. There was a reason that Rootes changed the unit when they started using the voltage stabilizer. As far as the color the black and red colors refer to the color of the bakelite or plastic material where the terminal is. Many probably never noticed this due to oil on the unit or simply the age has allowed discoloration of the material. The color code is something 99.9% would never think about.The problem now is that the black and red color doesn't hold true. I have new units in stock for series 1 & 2 that have green insulators and some of my units for later series have yellow insulators. When or where these units with these colors came from is something I don't know since they don't have a date on the box telling me when I bought them.
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  #18  
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Tom H Tom H is offline
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Beam, You are correct about the two different series of senders, but neither of them will be above 20,000 ohms when cold (or hot), so his ohms test clearly shows the sender is bad. It may well have gone bad when it was wired incorrectly. It was wired in strangely, either by the previous owner or by the shop that serviced the car after he bought it. But it was wired directly to 12 V. That may have damaged it.

I have spent many, many, hours studying and understanding the two different gauge systems in Alpines. SI, SII are very different than SIII-SV. The early series Temp Senders range from about 200 ohms at room temp (25C , 77F) to about 10 Ohms at boiling (100C, 212 F). The later Series are spec'd to go from 650 ohms at 25C to 43 ohms at 100C.

The reason Rootes changed the senders for the later Series was because they changed the whole system, using an entirely different type gauge, along with a regulator, instead of the more expensive, but less accurate, bridge type gauges used in the early Series.

I have not heard or seen any supplier suggest you could use later Series senders with early Series gauges. I would be very wary of any supplier that suggested such. They will NOT read correctly in early Series. For example, using a late Series sender with an early Series gauge will read 170F when the engine temp is actually at the boiling point.

I had not heard previously of senders bottoming out in the housing. That's certainly something to watch out for. I assume they would leak. Good to know, thanks.

Regarding the color of the insulation on the senders, I do not think there was any intention for the colors to indicate anything. There is no need for any color coding there. I am 99.9% sure it was simply a matter of using an insulator of the correct mechanical and electrical properties and taking whatever color the insulation supplier used. I have seen black, green, red, and orange (yellow?) insulation on various generations of temp senders.

Mike, I did not have Atlas measure the ohms of the gauge. I have seen very little in the way of gauge failures and we verified that the gauge and the regulator both work, and that the sender is bad. I have high confidence a new sender will solve his problem.

Tom
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  #19  
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65beam 65beam is offline
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Quote:
Originally Posted by Tom H View Post
Beam, You are correct about the two different series of senders, but neither of them will be above 20,000 ohms when cold (or hot), so his ohms test clearly shows the sender is bad. It may well have gone bad when it was wired incorrectly. It was wired in strangely, either by the previous owner or by the shop that serviced the car after he bought it. But it was wired directly to 12 V. That may have damaged it.

I have spent many, many, hours studying and understanding the two different gauge systems in Alpines. SI, SII are very different than SIII-SV. The early series Temp Senders range from about 200 ohms at room temp (25C , 77F) to about 10 Ohms at boiling (100C, 212 F). The later Series are spec'd to go from 650 ohms at 25C to 43 ohms at 100C.

The reason Rootes changed the senders for the later Series was because they changed the whole system, using an entirely different type gauge, along with a regulator, instead of the more expensive, but less accurate, bridge type gauges used in the early Series.

I have not heard or seen any supplier suggest you could use later Series senders with early Series gauges. I would be very wary of any supplier that suggested such. They will NOT read correctly in early Series. For example, using a late Series sender with an early Series gauge will read 170F when the engine temp is actually at the boiling point.

I had not heard previously of senders bottoming out in the housing. That's certainly something to watch out for. I assume they would leak. Good to know, thanks.

Regarding the color of the insulation on the senders, I do not think there was any intention for the colors to indicate anything. There is no need for any color coding there. I am 99.9% sure it was simply a matter of using an insulator of the correct mechanical and electrical properties and taking whatever color the insulation supplier used. I have seen black, green, red, and orange (yellow?) insulation on various generations of temp senders.

Mike, I did not have Atlas measure the ohms of the gauge. I have seen very little in the way of gauge failures and we verified that the gauge and the regulator both work, and that the sender is bad. I have high confidence a new sender will solve his problem.

Tom
Tom,
When I was working on the engine for the HLM I ordered a couple sending units for my stock and he told me that the supply of units for the early cars were made wrong. Now listed as NLA. I still have some new ones in stock so I won't worry about that. You know I don't rely on my gauges anyway . Other than my Beams I grew up with idiot lights . FYI, I sent the fuel sending unit for the Harrington to Nisonger today to have it refurbished. Should be interesting to see what they do.
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