Home » Public Forums » GMCnet » Digi-Panel Calibration?
| Digi-Panel Calibration? [message #355361] |
Tue, 02 June 2020 18:28  |
Christo
Messages: 109
Registered: April 2019
Location: Weymouth, MA
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I just replaced a broken engine temp sensor on my PO-installed Digi-Panel, and as with the old sensor (before it broke) the temp reads about 25 degrees low. My estimate is based on a reading from an IR thermometer pointed at the sensor which is attached to one of the thermostat bolts. My analog gauge reading (non-stock) is comparable to the IR reading.
Can the Digi-Panel temp reading be calibrated, or is there some other common issue that might cause this symptom? Maybe a dirty connector at the back of the Panel or something?
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
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| Re: [GMCnet] Digi-Panel Calibration? [message #355366 is a reply to message #355365] |
Tue, 02 June 2020 21:47  |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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The IR reading is also subject to emmissivity errors. All surfaces emit different amounts of IR for the same temp
________________________________
From: Gmclist on behalf of John Wright via Gmclist
Sent: Tuesday, June 2, 2020 9:23 PM
To: gmclist@list.gmcnet.org
Cc: John Wright
Subject: Re: [GMCnet] Digi-Panel Calibration?
Surface temp of the item and the actual temp at the sensor tip could vary a large amount as you are reading surface temp compared to the liquid temp.
JR Wright
> On Jun 2, 2020, at 7:28 PM, Christo Darsch via Gmclist wrote:
>
> I just replaced a broken engine temp sensor on my PO-installed Digi-Panel, and as with the old sensor (before it broke) the temp reads about 25
> degrees low. My estimate is based on a reading from an IR thermometer pointed at the sensor which is attached to one of the thermostat bolts. My
> analog gauge reading (non-stock) is comparable to the IR reading.
>
> Can the Digi-Panel temp reading be calibrated, or is there some other common issue that might cause this symptom? Maybe a dirty connector at the back
> of the Panel or something?
> --
> Christo Darsch
> GMC Nor'easters
> 1977 Eleganza II - "The Komet"
> 3.50 Power Drive, Disc Brakes, Alcoas
> Weymouth, MA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Digi-Panel Calibration? [message #355367 is a reply to message #355366] |
Tue, 02 June 2020 22:07 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Automotive gages and warning lights, buzzers, etc. are notoriously
inaccurate. They approximate a S.W.A.G of actual readings. They are
extremely voltage sensitive, something that varies a goodly amount in a 40
year old vehicle. What they do a fair job of, is changes in what is
considered normal. As in no oil pressure where there used to be plenty, or
overheating.
Jim Hupy
Salem, Oregon
On Tue, Jun 2, 2020, 7:48 PM Keith V via Gmclist
wrote:
> The IR reading is also subject to emmissivity errors. All surfaces emit
> different amounts of IR for the same temp
> ________________________________
> From: Gmclist on behalf of John Wright
> via Gmclist
> Sent: Tuesday, June 2, 2020 9:23 PM
> To: gmclist@list.gmcnet.org
> Cc: John Wright
> Subject: Re: [GMCnet] Digi-Panel Calibration?
>
> Surface temp of the item and the actual temp at the sensor tip could vary
> a large amount as you are reading surface temp compared to the liquid temp.
>
> JR Wright
>> On Jun 2, 2020, at 7:28 PM, Christo Darsch via Gmclist gmclist@list.gmcnet.org> wrote:
>>
>> I just replaced a broken engine temp sensor on my PO-installed
> Digi-Panel, and as with the old sensor (before it broke) the temp reads
> about 25
>> degrees low. My estimate is based on a reading from an IR thermometer
> pointed at the sensor which is attached to one of the thermostat bolts. My
>> analog gauge reading (non-stock) is comparable to the IR reading.
>>
>> Can the Digi-Panel temp reading be calibrated, or is there some other
> common issue that might cause this symptom? Maybe a dirty connector at the
> back
>> of the Panel or something?
>> --
>> Christo Darsch
>> GMC Nor'easters
>> 1977 Eleganza II - "The Komet"
>> 3.50 Power Drive, Disc Brakes, Alcoas
>> Weymouth, MA
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
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| Re: [GMCnet] Digi-Panel Calibration? [message #355373 is a reply to message #355365] |
Wed, 03 June 2020 05:33 |
Christo
Messages: 109
Registered: April 2019
Location: Weymouth, MA
Karma: 0
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The Digi-Panel sensor is a surface sensor, not a liquid sensor.
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
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| Re: Digi-Panel Calibration? [message #355383 is a reply to message #355374] |
Wed, 03 June 2020 11:01 |
Christo
Messages: 109
Registered: April 2019
Location: Weymouth, MA
Karma: 0
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I'm not really an electronics guy, so if there isn't a trim pot for the temp sensors and there aren't any connectors that could increase resistance (creating the low reading I'm seeing), I'm pretty much out of luck. Might just have to use it as suggested, as a guideline for what's normal. Thanks though!
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
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| Re: Digi-Panel Calibration? [message #355384 is a reply to message #355377] |
Wed, 03 June 2020 11:03 |
Christo
Messages: 109
Registered: April 2019
Location: Weymouth, MA
Karma: 0
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I have a good VOM but I don't have the curves. I suppose I could call Applied and see if they have any of that info and are willing to share it -- they bought out the mfr a few years back.
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
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| Re: Digi-Panel Calibration? [message #355461 is a reply to message #355361] |
Sun, 07 June 2020 12:34 |
Christo
Messages: 109
Registered: April 2019
Location: Weymouth, MA
Karma: 0
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I opened the case and found that there's a trim pot for all four gauges. Problem solved.
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
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| Re: [GMCnet] Digi-Panel Calibration? [message #355465 is a reply to message #355461] |
Sun, 07 June 2020 12:41 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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As a rule the calibration remains without adjustment , but it could be the
thermocouple as we change part suppliers .
Call us if you need calibration so you can send it to our ave guys .
On Sun, Jun 7, 2020 at 10:35 AM Christo Darsch via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I opened the case and found that there's a trim pot for all four gauges.
> Problem solved.
> --
> Christo Darsch
> GMC Nor'easters
> 1977 Eleganza II - "The Komet"
> 3.50 Power Drive, Disc Brakes, Alcoas
> Weymouth, MA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Digi-Panel Calibration? [message #369779 is a reply to message #355361] |
Mon, 23 May 2022 14:14 |
art woodell
Messages: 1
Registered: May 2022
Karma: 1
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Junior Member |
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Just stumbled across this forum. The Digi-Panel’s temperature sensors are a type of transistor selected specifically for their junction voltage temperature characteristics; initially, any sensor’s junction voltage is within ± 2°C at any given temperature, plus the tolerances of the internal components. The panel is then calibrated to ±1 during manufacture. There is an adjustment pot for each gauge, located behind each gauge. The current through the gauges is extremely low, so lead lengths / resistances also have little to no effect on the calibration of the unit. The junction voltages do not drift with time, so calibration remains constant. An ohmmeter reading has no value. Thermistors, however, are resistive devices and have long term drift in their values, which limits their usefulness for this type application.
If you want to have the Digi-Panel agree with some other device in your rig, you can adjust it to do so, but use extreme caution. Analog gauges are not calibrated, and the voltage variations in your rig directly affect their reading. The Dig-Panel uses a stable internal 5 volt reference so power variations have no effect on its readings.
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| Re: Digi-Panel Calibration? [message #369794 is a reply to message #355361] |
Tue, 24 May 2022 16:33 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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I treat auto gauges much like the power meterin the antenna line at my RF sites. The reflected may go up or down (depending where in the line the sample section is located), but the concern is it changed. Likewise the coach gauges - if one (other than the gas gauge) changes, why?
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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