Interesting one about multi-meters in a BL service instruction booklet.

To set the TPS (throttle position sensor) as fitted to early (1980) Rover
V8 Lucas injection.

It is a large carbon pot sitting across 5v (nearly) and provides a
variable voltage out by throttle position. Quite a chunky device with twin
wipers, so a lot more butch than the average volume control.

It is adjustable, and the original way to set was to use a BL special
tool. You set it to null a couple of LEDs. No doubt cost a fortune.

The later Land Rover guide gives a method using a volt meter. Pic shows a
DVM - rather than an AVO 8, etc. You connect to output and ground and set
it to 0.325v +/-0.025v.

It's the note below which is interesting:-
CAUTION: The following adjustment must be made using a voltmeter set to a
maximum scale of not more than 10v. If a voltmeter of more than 10 volt
scale is used the potentiometer will be irreparably damaged.

Try as I might, I ain't got a fooking clue what they're on about. ;-)

--
*The hardness of the butter is proportional to the softness of the bread *

Dave Plowman London SW
To e-mail, change noise into sound.

On Sat, 22 Aug 2020 13:27:08 +0100, Dave Plowman (News) wrote:

Interesting one about multi-meters in a BL service instruction booklet.

To set the TPS (throttle position sensor) as fitted to early (1980)
Rover V8 Lucas injection.

It is a large carbon pot sitting across 5v (nearly) and provides a
variable voltage out by throttle position. Quite a chunky device with
twin wipers, so a lot more butch than the average volume control.

It is adjustable, and the original way to set was to use a BL special
tool. You set it to null a couple of LEDs. No doubt cost a fortune.

The later Land Rover guide gives a method using a volt meter. Pic shows
a DVM - rather than an AVO 8, etc. You connect to output and ground and
set it to 0.325v +/-0.025v.

It's the note below which is interesting:-
CAUTION: The following adjustment must be made using a voltmeter set to
a maximum scale of not more than 10v. If a voltmeter of more than 10
volt scale is used the potentiometer will be irreparably damaged.

Try as I might, I ain't got a fooking clue what they're on about. ;-)

Almost a Rheostat.

On 22/08/2020 13:49, jon wrote:

Almost a Rheostat.


Someone in this group gave me two enormous rheostats years ago. They are
really useful for acting as dummy loads when testing PSUs.

Bill

On 22/08/2020 13:27:08, Dave Plowman (News) wrote:
Interesting one about multi-meters in a BL service instruction booklet.

To set the TPS (throttle position sensor) as fitted to early (1980) Rover
V8 Lucas injection.

It is a large carbon pot sitting across 5v (nearly) and provides a
variable voltage out by throttle position. Quite a chunky device with twin
wipers, so a lot more butch than the average volume control.

It is adjustable, and the original way to set was to use a BL special
tool. You set it to null a couple of LEDs. No doubt cost a fortune.

The later Land Rover guide gives a method using a volt meter. Pic shows a
DVM - rather than an AVO 8, etc. You connect to output and ground and set
it to 0.325v +/-0.025v.

It's the note below which is interesting:-
CAUTION: The following adjustment must be made using a voltmeter set to a
maximum scale of not more than 10v. If a voltmeter of more than 10 volt
scale is used the potentiometer will be irreparably damaged.

Try as I might, I ain't got a fooking clue what they're on about. ;-)

Whoever wrote that was a technical writer who didn't have a clue.

I suspect the intention was to prevent anyone from applying 10V to the
potentiometer but somehow lost in the translation.

On 22/08/2020 13:27, Dave Plowman (News) wrote:

The later Land Rover guide gives a method using a volt meter. Pic shows a
DVM - rather than an AVO 8, etc. You connect to output and ground and set
it to 0.325v +/-0.025v.

It's the note below which is interesting:-
CAUTION: The following adjustment must be made using a voltmeter set to a
maximum scale of not more than 10v. If a voltmeter of more than 10 volt
scale is used the potentiometer will be irreparably damaged.

Try as I might, I ain't got a fooking clue what they're on about. ;-)


My take.

A typical DVM will be 3.5 digits.

On the 10V scale, the display has the possibility of showing between
0.00 to 10.00

So you can see the allowed limits
low - 0.300
high - 0.350

On a higher scale, say 30V

the display will show just 0.00 to 30.0. You lose a digit of display,
they can't do anything with the leading 1 digit.

So you can see the allowed limits displayed as
low - 0.30
high - 0.35

If your component is set above 0.35 (say 0.358), you won't be aware of
it until you see the smoke.


--
Adrian C

On 22/08/2020 19:03, Adrian Caspersz wrote:


If your component is set above 0.35 (say 0.358), you won't be aware of
it until you see the smoke.


Erm. Rereading that, I think I may have written some ******** there.


Somebody correct it.

(By a similar logic(?) the 0-3V range would not work)

--
Adrian C

In article ,
Adrian Caspersz wrote:
On 22/08/2020 13:27, Dave Plowman (News) wrote:

The later Land Rover guide gives a method using a volt meter. Pic shows a
DVM - rather than an AVO 8, etc. You connect to output and ground and set
it to 0.325v +/-0.025v.

It's the note below which is interesting:-
CAUTION: The following adjustment must be made using a voltmeter set to a
maximum scale of not more than 10v. If a voltmeter of more than 10 volt
scale is used the potentiometer will be irreparably damaged.

Try as I might, I ain't got a fooking clue what they're on about. ;-)


My take.

A typical DVM will be 3.5 digits.

On the 10V scale, the display has the possibility of showing between
0.00 to 10.00

So you can see the allowed limits
low - 0.300
high - 0.350

On a higher scale, say 30V

the display will show just 0.00 to 30.0. You lose a digit of display,
they can't do anything with the leading 1 digit.

So you can see the allowed limits displayed as
low - 0.30
high - 0.35

If your component is set above 0.35 (say 0.358), you won't be aware of
it until you see the smoke.

It only has a very limited range of adjustment - fixing holes are slotted.

But just how would any setting cause smoke? The track is wired across 5v.
The output is 0-5v, depending on throttle position.

Perhaps it was written for the average garage mechanic. Who doesn't know
what a decimal point is. And tries to force it round to get 35 volts out
of it. ;-)

--
*If you don't pay your exorcist you get repossessed.*

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Adrian Caspersz wrote:
On 22/08/2020 19:03, Adrian Caspersz wrote:


If your component is set above 0.35 (say 0.358), you won't be aware of
it until you see the smoke.


Erm. Rereading that, I think I may have written some ******** there.

I must admit to not quite following it. ;-)

Somebody correct it.

(By a similar logic(?) the 0-3V range would not work)

I did wonder if it was to do with the current taken by a 'mechanical' volt
meter. The vast ancient units from the 1920s.

--
*I have never hated a man enough to give his diamonds back.

Dave Plowman London SW
To e-mail, change noise into sound.

On 22/08/2020 13:27, Dave Plowman (News) wrote:
Interesting one about multi-meters in a BL service instruction booklet.

To set the TPS (throttle position sensor) as fitted to early (1980) Rover
V8 Lucas injection.

It is a large carbon pot sitting across 5v (nearly) and provides a
variable voltage out by throttle position. Quite a chunky device with twin
wipers, so a lot more butch than the average volume control.

It is adjustable, and the original way to set was to use a BL special
tool. You set it to null a couple of LEDs. No doubt cost a fortune.

The later Land Rover guide gives a method using a volt meter. Pic shows a
DVM - rather than an AVO 8, etc. You connect to output and ground and set
it to 0.325v +/-0.025v.

It's the note below which is interesting:-
CAUTION: The following adjustment must be made using a voltmeter set to a
maximum scale of not more than 10v. If a voltmeter of more than 10 volt
scale is used the potentiometer will be irreparably damaged.

Try as I might, I ain't got a fooking clue what they're on about. ;-)

just wondering why you started a new thread?

Dave Plowman (News) submitted this idea :
I did wonder if it was to do with the current taken by a 'mechanical' volt
meter. The vast ancient units from the 1920s.

The higher the set voltage range, the lower the current absorbed by the
meter.

On 23/08/2020 16:07, Harry Bloomfield wrote:
Dave Plowman (News) submitted this idea :
I did wonder if it was to do with the current taken by a 'mechanical'
volt
meter. The vast ancient units from the 1920s.

The higher the set voltage range, the lower the current absorbed by the
meter.
The higher the voltagee range, the same is the current absorbed by te
meter for the same percentage of full scale deflection


--
Renewable energy: Expensive solutions that don't work to a problem that
doesn't exist instituted by self legalising protection rackets that
don't protect, masquerading as public servants who don't serve the public.

In article ,
Harry Bloomfield wrote:
Dave Plowman (News) submitted this idea :
I did wonder if it was to do with the current taken by a 'mechanical' volt
meter. The vast ancient units from the 1920s.

The higher the set voltage range, the lower the current absorbed by the
meter.

Quite. Although a massive old mechanical voltmeter might draw more current
than a newer one of the same.

--
*The sooner you fall behind, the more time you'll have to catch up *

Dave Plowman London SW
To e-mail, change noise into sound.