Hot and bothered? - UK Vintage Radio Repair and Restoration Discussion Forum

medge799 · 21st Nov 2010, 6:48 pm

Hi all,

My daughter works as a research biologist and has recently given me an infrared temperature measurement gun. This thing has a pistol grip with a trigger switch which turns on a strong beam of laser light from the front of the device. If you point the beam at something, a display on the back tells you the temperature in degrees-C or F, at a distance, without actually touching the thing being measured. I'm reliably informed that it is *the* way of measuring the temperature of bacteria cultures; but what about old radios?

I tried it on an old valve radio which had not yet been otherwise assessed. The tool quickly showed that some of the old paper-wax capacitors were running above ambient (35 C in an ambient 20 C). The rest were at ambient. Sure enough, these were indeed leaking when measured out of circuit. This was by far the quickest way to assess those hot components without getting fingers burned (literally) or shocked, and may save a fair bit of time...

You can get these things from Amazon; a quick web search will find one for you. Mine is a Digitron, the attached picture is for a Silverline 633726 Infrared Thermometer at £22.25, but I'm sure there are others.

Hope this is useful....

Mark

By the way; the cat has great fun chasing the beam around, and the cooker and fridge have been recalibrated too

Darren-UK · 21st Nov 2010, 7:05 pm

As I see it, this wouldn't be reliable on old radios. Let's say I was checking the temperature of 'that' cap; how would I know the reading wasn't being affected by heat from the o/p valve, mains dropper or whatever?

Perhaps the laser beam is so focussed that the reading wouldn't be confused by heat from other nearby sources?

But reliable or not, to me this gadget whitewashes over the traditional skills involved in suspecting/tracing and replacing dodgy components and thus rather removes much of the interest from the hobby.

Sorry to poo poo. Others may not agree though.

evingar · 21st Nov 2010, 7:18 pm

My understanding is that the measurement is done in a very selective area, so would probably be fine for the purpose suggested.

As I see it, it could be a very useful extra tool in the repair arsenal - also good for solid state stuff - Who hasn't ever "barbecued" their finger on a hot IC or tranny when trying to isolate "that hot smell" ?

Framer Dave · 21st Nov 2010, 7:22 pm

Quote:

Originally Posted by Darren-UK

how would I know the reading wasn't being affected by heat from the o/p valve, mains dropper or whatever?

In the same way that you would know if you put a finger on it!

I think it's an excellent suggestion. Just because our wirelesses are museum pieces, doesn't mean our diagnostic methods should be antediluvean too.

Regards,

TuningIndicator · 21st Nov 2010, 7:31 pm

We've got some of these at work, and I sometimes bring one home when the need arises.
Very useful for measuring heatsinks and transistor temperatures.
The ones at work are FLUKE branded.
Very accurate, and not affected by background temperature.

I agree with Dave above.
I often think of the way Ed China repairs classic cars on Wheeler Dealers, he uses modern tools and equipment to repair old cars.
I may be repairing a 50-year old radio, but I have no qualms in using modern tools and equipment to get it going again.

medge799 · 21st Nov 2010, 7:31 pm

Quote:

Originally Posted by Darren-UK

...Perhaps the laser beam is so focussed that the reading wouldn't be confused by heat from other nearby sources?...

The beam focus is not as pin-point as the laser; it varies with distance, but its pretty sharp when close. On mine the ratio is 1:8 (eg a 1 inch beam at 8 inches, or 1 cm at 8cm if you prefer).

For me its a safety thing; I can find out whether that transformer is hot *before* it starts to smell hot, and I don't have to touch anything. The caps are almost always on the other side of the chassisto the valves, and so are relatively easy to assess.

Ta,
Mark

Richard · 21st Nov 2010, 7:32 pm

Hi

I have used these for diagnostics, mainly in big commercial catering equipment, very handy, quickly show overheating terminals, relays, even bearings on motors etc.

Like all tools, they have their uses, and quicker and safer than sticking you finger in

Richard

mhennessy · 21st Nov 2010, 7:35 pm

Darren,

The laser is nothing to do with it; it's just a pointer to give you a clue where the focus of the centre of the IR optics are...

These things are absolutely great - I've had mine for about 6 years now and wouldn't be without it. Like any tool you need to learn how to get the best from it, and you obviously need to interpret the readings.

One critical thing to understand is the spot size. For the cheaper ones it tends to be 6:1, which means from 6 inches away, it will be sampling a circle 1 inch in diameter. You can obviously get much closer, and by moving it around when sampling you can easily find "hot spots" in components as small as a BC108. The more expensive ones give you smaller spots - IIRC my Fluke is 8:1.

Another factor is the emissivity of the material, and the basic ones are fixed in this regard (IIRC, it's 0.95). More expensive models let you alter this, so accounting for different materials and surface finishes. Funnily enough, copper doesn't emit IR at the same rate as most metals (even chromed fittings), so using it for checking your central heating means that you need to wrap black tape around bare copper pipes. Once you've done that, it's really handy.

I've even used it to measure the temperature of walls in the cellar to prove that the damp walls were a victim of condensation rather than "rising damp".

In short: buy one. Even the very cheapest ones are worth considering

JimMac53 · 21st Nov 2010, 8:45 pm

Sorry, Darren, I couldn't disagree with you more. I don't know why you think it replaces traditional methods. It doesn't replace traditional methods, it adds another weapon in the arsenal. I think it's a great idea.

Mark, thanks for a great suggestion.

Tim · 21st Nov 2010, 11:02 pm

I never thought one of these could be so inexpensive. I'll put it on my Santa list.

KeithsTV · 21st Nov 2010, 11:13 pm

We have these at work but they have 2 lasers and give the most accurate reading when the 2 beams coincide, as in the dambusters. As has been said the emissivity of the surface will affect the reading, we tend to put a spot of tippex on the part under investigation and use the lasers to focus on the spot to get a more accurate reading.

We also have a thermal camera which when pointed at a processor with a spot of tippex on shows very clearly the effect of the different emissivity. I don't thing I'd be able to borrow the camera as it cost around £30,000 when new.

Keith

David G4EBT · 21st Nov 2010, 11:54 pm

I bought one some months ago for balancing the radiators after our CH boiler had been replaced. Maplin had them reduced from £44 to £20 so it was an impulse buy. Although I bought mine for that purpose, they're certainly handy for checking thermal runaway or to see if the temperature of a transformer has stabilised, and so on. Maplin have since discontinued the model that I bought, (which doesn't have a maker's logo on it) and the replacement is actually cheaper. The range is from -35 C to +230C. the display can be in degrees C or F.

http://www.maplin.co.uk/module.aspx?moduleno=220790.

As has been said, the laser is only for aiming purposes - the actual infra red beam is from a 2cm diameter lens. It follows that the closer to the object, the narrower will be the beam, just as with say a torch. A google search turned up several makes and models from a range of suppliers cheap enough to be a 'stocking filler'!

David

threeseven · 22nd Nov 2010, 3:38 pm

I'm always intending to buy one of these, this thread has convinced me to do it !

Has anyone done any valve operating temp work with one ?

G8HQP Dave · 23rd Nov 2010, 5:09 pm

Quote:

the actual infra red beam is from a 2cm diameter lens

To or from?

I have sometimes wished I could measure component temperature. I did have a thermocouple range on an old DVM but I could never be certain that the junction was at the temperature I was trying to measure. I didn't realise these IR guns were so cheap. I want one too!

Phil G4SPZ · 25th Nov 2010, 12:14 am

A brilliant suggestion. However whilst it will identify leaking decoupling capacitors it would probably not identify "that" capacitor, which is unlikely to dissipate significant power even when leaky - but we all replace "that" capacitor on sight before applying any power, don't we?!

Jonster · 25th Nov 2010, 10:35 am

I have a Fluke one and would not be without it. Useful for finding short circuits on PCBs as well when debugging new equipment, connectors with high resistance (volt drop causes heat and you can identify the actual pin concerned), and for automotive use pinpointing blockage in car radiators due to uneven temperature gradients. An essential part of the modern toolkit.

21st Nov 2010, 6:48 pm	#1
medge799 Pentode Join Date: Feb 2009 Location: Saffron Walden, Essex, UK. Posts: 100	Hot and bothered? Hi all, My daughter works as a research biologist and has recently given me an infrared temperature measurement gun. This thing has a pistol grip with a trigger switch which turns on a strong beam of laser light from the front of the device. If you point the beam at something, a display on the back tells you the temperature in degrees-C or F, at a distance, without actually touching the thing being measured. I'm reliably informed that it is the way of measuring the temperature of bacteria cultures; but what about old radios? I tried it on an old valve radio which had not yet been otherwise assessed. The tool quickly showed that some of the old paper-wax capacitors were running above ambient (35 C in an ambient 20 C). The rest were at ambient. Sure enough, these were indeed leaking when measured out of circuit. This was by far the quickest way to assess those hot components without getting fingers burned (literally) or shocked, and may save a fair bit of time... You can get these things from Amazon; a quick web search will find one for you. Mine is a Digitron, the attached picture is for a Silverline 633726 Infrared Thermometer at £22.25, but I'm sure there are others. Hope this is useful.... Mark By the way; the cat has great fun chasing the beam around, and the cooker and fridge have been recalibrated too Attached Thumbnails __________________ Mark Edgeworth ____________________________________________ BVWS Member

21st Nov 2010, 7:05 pm	#2
Darren-UK Retired Dormant Member Join Date: Apr 2003 Location: Blackpool, Lancashire, UK. Posts: 4,061	Re: Hot and bothered? As I see it, this wouldn't be reliable on old radios. Let's say I was checking the temperature of 'that' cap; how would I know the reading wasn't being affected by heat from the o/p valve, mains dropper or whatever? Perhaps the laser beam is so focussed that the reading wouldn't be confused by heat from other nearby sources? But reliable or not, to me this gadget whitewashes over the traditional skills involved in suspecting/tracing and replacing dodgy components and thus rather removes much of the interest from the hobby. Sorry to poo poo. Others may not agree though.

21st Nov 2010, 7:18 pm	#3
evingar Octode Join Date: Oct 2003 Location: Newbury, Berkshire, UK. Posts: 1,770	Re: Hot and bothered? My understanding is that the measurement is done in a very selective area, so would probably be fine for the purpose suggested. As I see it, it could be a very useful extra tool in the repair arsenal - also good for solid state stuff - Who hasn't ever "barbecued" their finger on a hot IC or tranny when trying to isolate "that hot smell" ? __________________ Chris

21st Nov 2010, 7:31 pm	#5
TuningIndicator Retired Dormant Member Join Date: Aug 2010 Location: Sussex, UK. Posts: 161	Re: Hot and bothered? We've got some of these at work, and I sometimes bring one home when the need arises. Very useful for measuring heatsinks and transistor temperatures. The ones at work are FLUKE branded. Very accurate, and not affected by background temperature. I agree with Dave above. I often think of the way Ed China repairs classic cars on Wheeler Dealers, he uses modern tools and equipment to repair old cars. I may be repairing a 50-year old radio, but I have no qualms in using modern tools and equipment to get it going again.

21st Nov 2010, 7:32 pm	#7
Richard Heptode Join Date: Feb 2003 Location: Garnant, near Ammanford, South Wales, UK. Posts: 657	Re: Hot and bothered? Hi I have used these for diagnostics, mainly in big commercial catering equipment, very handy, quickly show overheating terminals, relays, even bearings on motors etc. Like all tools, they have their uses, and quicker and safer than sticking you finger in Richard __________________ BVWS member.

21st Nov 2010, 7:35 pm	#8
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Hot and bothered? Darren, The laser is nothing to do with it; it's just a pointer to give you a clue where the focus of the centre of the IR optics are... These things are absolutely great - I've had mine for about 6 years now and wouldn't be without it. Like any tool you need to learn how to get the best from it, and you obviously need to interpret the readings. One critical thing to understand is the spot size. For the cheaper ones it tends to be 6:1, which means from 6 inches away, it will be sampling a circle 1 inch in diameter. You can obviously get much closer, and by moving it around when sampling you can easily find "hot spots" in components as small as a BC108. The more expensive ones give you smaller spots - IIRC my Fluke is 8:1. Another factor is the emissivity of the material, and the basic ones are fixed in this regard (IIRC, it's 0.95). More expensive models let you alter this, so accounting for different materials and surface finishes. Funnily enough, copper doesn't emit IR at the same rate as most metals (even chromed fittings), so using it for checking your central heating means that you need to wrap black tape around bare copper pipes. Once you've done that, it's really handy. I've even used it to measure the temperature of walls in the cellar to prove that the damp walls were a victim of condensation rather than "rising damp". In short: buy one. Even the very cheapest ones are worth considering

21st Nov 2010, 8:45 pm	#9
JimMac53 Hexode Join Date: Apr 2009 Location: Naples, Florida, USA Posts: 255	Re: Hot and bothered? Sorry, Darren, I couldn't disagree with you more. I don't know why you think it replaces traditional methods. It doesn't replace traditional methods, it adds another weapon in the arsenal. I think it's a great idea. Mark, thanks for a great suggestion. __________________ Jim Mac

21st Nov 2010, 11:02 pm	#10
Tim Dekatron Join Date: Jan 2003 Location: Bradford on Avon, Wiltshire, UK. Posts: 3,310	Re: Hot and bothered? I never thought one of these could be so inexpensive. I'll put it on my Santa list. __________________ "Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly."

21st Nov 2010, 11:13 pm	#11
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,573	Re: Hot and bothered? We have these at work but they have 2 lasers and give the most accurate reading when the 2 beams coincide, as in the dambusters. As has been said the emissivity of the surface will affect the reading, we tend to put a spot of tippex on the part under investigation and use the lasers to focus on the spot to get a more accurate reading. We also have a thermal camera which when pointed at a processor with a spot of tippex on shows very clearly the effect of the different emissivity. I don't thing I'd be able to borrow the camera as it cost around £30,000 when new. Keith

21st Nov 2010, 11:54 pm	#12
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,761	Re: Hot and bothered? I bought one some months ago for balancing the radiators after our CH boiler had been replaced. Maplin had them reduced from £44 to £20 so it was an impulse buy. Although I bought mine for that purpose, they're certainly handy for checking thermal runaway or to see if the temperature of a transformer has stabilised, and so on. Maplin have since discontinued the model that I bought, (which doesn't have a maker's logo on it) and the replacement is actually cheaper. The range is from -35 C to +230C. the display can be in degrees C or F. http://www.maplin.co.uk/module.aspx?moduleno=220790. As has been said, the laser is only for aiming purposes - the actual infra red beam is from a 2cm diameter lens. It follows that the closer to the object, the narrower will be the beam, just as with say a torch. A google search turned up several makes and models from a range of suppliers cheap enough to be a 'stocking filler'! David

22nd Nov 2010, 3:38 pm	#13
threeseven Octode Join Date: May 2010 Location: Worcestershire, UK. Posts: 1,880	Re: Hot and bothered? I'm always intending to buy one of these, this thread has convinced me to do it ! Has anyone done any valve operating temp work with one ?

25th Nov 2010, 12:14 am	#15
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Re: Hot and bothered? A brilliant suggestion. However whilst it will identify leaking decoupling capacitors it would probably not identify "that" capacitor, which is unlikely to dissipate significant power even when leaky - but we all replace "that" capacitor on sight before applying any power, don't we?! __________________ Phil Optimist [n]: One who is not in possession of the full facts

25th Nov 2010, 10:35 am	#16
Jonster Heptode Join Date: Apr 2008 Location: Eastbourne, East Sussex, UK. Posts: 671	Re: Hot and bothered? I have a Fluke one and would not be without it. Useful for finding short circuits on PCBs as well when debugging new equipment, connectors with high resistance (volt drop causes heat and you can identify the actual pin concerned), and for automotive use pinpointing blockage in car radiators due to uneven temperature gradients. An essential part of the modern toolkit.