Fluke 187 189 (perhaps) Fault - UK Vintage Radio Repair and Restoration Discussion Forum

Racal Zonal · 6th Apr 2014, 1:21 am

Evening All

I wonder if someone can assist with a problem I am having with a Fluke meter
Part of this tale is a bit vague but please stick with me.

The subject line indicates a 187/189 but I can’t say for sure that it is this model (I did say vague) there are no identifying marks not even above the display
but it is a Fluke and matches pictures and facilities of the 187/189
I believe some government contract units were unmarked ?.
I purchased this meter Ex MOD some time ago and on initial test it was found to have had a severe insult
evidenced by a blown fuse and scorching around the diode across the output of the bridge rectifier pack.

The meter powers up ok but produces spurious readings on the volts and ohms range without any input being applied
but will zero ohms when the leads are shorted however produces no meaningful reading when checking with a few random resistors.

Having checked the high amps input this produces an accurate reading using a current limited supply.

My thoughts on this are that the afore mentioned insult has damaged part of the input protection circuit on the volts/ohms side and
this has gone partial s/c or noisy and is producing the spurious readings.
I have checked through some of this and have disconnected at various points on the protection circuit without any success.
At this stage this has been confined to the resistors, thermistors, VDR and spark gap etc. but not the current clamp.

I am rather hampered by not having a circuit for this meter but have used the diagram for an 87 for the input protection circuit
which the subject meter seems to replicate.

The plot now thickens a bit as during testing last night I lifted the top half of the case from the bench and one of the sliding fingers from the switch fell out
leaving two in situ I am now not sure what way round this should fit in the switch knob nor if there should be four such fingers I have made an exhaustive search of the work area but can’t find a fourth one, question now is three or four bearing in mind that the Amps test mentioned above was done last night.
If there is a fugitive fourth one are they available as spares ? What is their relative disposition on the quartiles of the switch .

This is a nice piece of gear that I would like to get working so has anyone any suggestions to make other than bin it ?
Any help much appreciated on any of the above, anyone brave enough.
It is I think at the top end of the range and is true RMS (if it is a 187/189).
I can post pictures later if needed.

Thanks in anticipation.

Azeem

Humber888 · 6th Apr 2014, 10:52 am

I have a Fluke 187 multimeter and the 187/189 are nice, if chubby, meters. Basic accuracy is about 0.025% on d.c. I am surprised that there is no model number and Fluke logo above the display, even for a 'special'. If you lift off the black rubber probe holder/foot on the back is there a serial number underneath?

On a.c. Volts or mV I would expect the count to wander about until you short the input, when it should then settle down to maybe 20-40 on the LSDs. On d.c. Volts or mV the display may still wander a bit but settle to maybe 1 LSD when the input is shorted. My meter reads about 12 counts on uA, better on mA or Amps. Without a lead attatched to the correct current input, it should just say 'LEADS'.

I found out from Fluke that the 187 is under 'limited lifetime warranty' until 2017, so they may be prepared to repair it if you can determine what it is and whether it has ever been registered with them (most companies never bother). That's about as much as I can help as I have never needed to take it apart or got hold of a full circuit diagram. There is, however, a calibration document floating around on the web.

Mike

mhennessy · 6th Apr 2014, 3:47 pm

It might be an 87 IV. Pictures would help.

I also have a 187 and a 189, and can check behaviour for you if that helps. I've never had to do serious repairs to a Fluke, but understand that after a "shock", the input MOVs can leak, leading to wrong readings on Ohms. They usually have a large 1k fusible resistor that can open up and upset things. Of course, the scorched part of the PCB will need cleaning with IPA.

I've never seen a schematic either, but in addition to the brains on here, there are some knowledgeable folk on eevblog.com that might be able to help.

My 187 is at work - I don't mind opening up that one to photograph the switch, as that was a tatty second-hand bargain - just remind me during the week. My 189 was bought new and I'd prefer to leave that intact.

Mark

Racal Zonal · 6th Apr 2014, 11:17 pm

Mike and Mark thank you both for your responses....

Mike
I appreciate your point re instability until the leads are shorted and that was one of my first checks. From my earlier checks the display does show "leads" when on a current range without the leads inserted.

Regarding serial number under the stand there is neither stand nor number although there is a rectangular moulding that I would expect a stand to slide into there is some tack around this area so perhaps a label was there at some stage. Defiantly no marking on the LCD bezel.

Mark
I have already checked the resistors and they look OK. I would appreciate a picture of the switch and as requested I will try to remember to send a reminder
during the week.

I am not sure if the diode insult would also effect the DC conditions.
For any further checks to be meaningful I really need to resolve the switch issue.

I have a 25 and a 75 as well as a couple of 2025s and reports in general suggest that Flukes are pretty well bomb proof it makes me wonder what this one has endured.
It would be nice have this more up to date item operational.
Still if the switch is missing an essential part I will need to try to find one that has been run over by a truck apart from the switch of course.

I will try to post some pictures later this week.

Regards

Azeem

Racal Zonal · 16th Apr 2014, 12:34 am

Mike Mark

My apologies for the delay returning, things have moved on a bit in that I now have another 189 and therefore now have a direct comparison item (if the existing one is a 189 that is). I will continue to try to repair the faulty one but possibly not in the near future due to other more pessing projects. If I find anything interesting I will keep you informed meanwhile thanks for your interest.

Azeem

Nickthedentist · 16th Apr 2014, 10:26 am

Didn't RS re-brand Fluke stuff with a sticky label where the Fluke branding would normally be?

Nick

mhennessy · 16th Apr 2014, 4:14 pm

Although the OP says ex-MOD, I'm wondering if it's a "TPWS" meter - a unit that has been certified for use with railway engineering. There were several from Fluke over the years, including a 187: http://www.eevblog.com/forum/beginners/fluke-tpws/

There's one on eBay now
My 187 has at least made its way home, so if there's anything you need, just shout.

Mark

Oldcodger · 6th Dec 2015, 5:42 pm

I realise that this post is old,possibly as ancient as some of the test gear we're discussing, but I came across it in a Google and also found this -http://exodus.poly.edu/~kurt/manuals/manuals/Fluke/FLUKE%20187_189_Calibration.pdf.

REF the mention of TPWS meters, all the ones I used had to have the word "TPWS" on the face(usually just after FLUKE). For those interested in what was measured, it was the frequency and voltage (in mV) of the signal output by the aerial grid.

6th Apr 2014, 1:21 am	#1
Racal Zonal Triode Join Date: Dec 2008 Location: Glasgow, UK. Posts: 32	Fluke 187 189 (perhaps) Fault Evening All I wonder if someone can assist with a problem I am having with a Fluke meter Part of this tale is a bit vague but please stick with me. The subject line indicates a 187/189 but I can’t say for sure that it is this model (I did say vague) there are no identifying marks not even above the display but it is a Fluke and matches pictures and facilities of the 187/189 I believe some government contract units were unmarked ?. I purchased this meter Ex MOD some time ago and on initial test it was found to have had a severe insult evidenced by a blown fuse and scorching around the diode across the output of the bridge rectifier pack. The meter powers up ok but produces spurious readings on the volts and ohms range without any input being applied but will zero ohms when the leads are shorted however produces no meaningful reading when checking with a few random resistors. Having checked the high amps input this produces an accurate reading using a current limited supply. My thoughts on this are that the afore mentioned insult has damaged part of the input protection circuit on the volts/ohms side and this has gone partial s/c or noisy and is producing the spurious readings. I have checked through some of this and have disconnected at various points on the protection circuit without any success. At this stage this has been confined to the resistors, thermistors, VDR and spark gap etc. but not the current clamp. I am rather hampered by not having a circuit for this meter but have used the diagram for an 87 for the input protection circuit which the subject meter seems to replicate. The plot now thickens a bit as during testing last night I lifted the top half of the case from the bench and one of the sliding fingers from the switch fell out leaving two in situ I am now not sure what way round this should fit in the switch knob nor if there should be four such fingers I have made an exhaustive search of the work area but can’t find a fourth one, question now is three or four bearing in mind that the Amps test mentioned above was done last night. If there is a fugitive fourth one are they available as spares ? What is their relative disposition on the quartiles of the switch . This is a nice piece of gear that I would like to get working so has anyone any suggestions to make other than bin it ? Any help much appreciated on any of the above, anyone brave enough. It is I think at the top end of the range and is true RMS (if it is a 187/189). I can post pictures later if needed. Thanks in anticipation. Azeem

6th Apr 2014, 10:52 am	#2
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Re: Fluke 187 189 (perhaps) Fault I have a Fluke 187 multimeter and the 187/189 are nice, if chubby, meters. Basic accuracy is about 0.025% on d.c. I am surprised that there is no model number and Fluke logo above the display, even for a 'special'. If you lift off the black rubber probe holder/foot on the back is there a serial number underneath? On a.c. Volts or mV I would expect the count to wander about until you short the input, when it should then settle down to maybe 20-40 on the LSDs. On d.c. Volts or mV the display may still wander a bit but settle to maybe 1 LSD when the input is shorted. My meter reads about 12 counts on uA, better on mA or Amps. Without a lead attatched to the correct current input, it should just say 'LEADS'. I found out from Fluke that the 187 is under 'limited lifetime warranty' until 2017, so they may be prepared to repair it if you can determine what it is and whether it has ever been registered with them (most companies never bother). That's about as much as I can help as I have never needed to take it apart or got hold of a full circuit diagram. There is, however, a calibration document floating around on the web. Mike

6th Apr 2014, 3:47 pm	#3
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Fluke 187 189 (perhaps) Fault It might be an 87 IV. Pictures would help. I also have a 187 and a 189, and can check behaviour for you if that helps. I've never had to do serious repairs to a Fluke, but understand that after a "shock", the input MOVs can leak, leading to wrong readings on Ohms. They usually have a large 1k fusible resistor that can open up and upset things. Of course, the scorched part of the PCB will need cleaning with IPA. I've never seen a schematic either, but in addition to the brains on here, there are some knowledgeable folk on eevblog.com that might be able to help. My 187 is at work - I don't mind opening up that one to photograph the switch, as that was a tatty second-hand bargain - just remind me during the week. My 189 was bought new and I'd prefer to leave that intact. Mark

6th Apr 2014, 11:17 pm	#4
Racal Zonal Triode Join Date: Dec 2008 Location: Glasgow, UK. Posts: 32	Re: Fluke 187 189 (perhaps) Fault Mike and Mark thank you both for your responses.... Mike I appreciate your point re instability until the leads are shorted and that was one of my first checks. From my earlier checks the display does show "leads" when on a current range without the leads inserted. Regarding serial number under the stand there is neither stand nor number although there is a rectangular moulding that I would expect a stand to slide into there is some tack around this area so perhaps a label was there at some stage. Defiantly no marking on the LCD bezel. Mark I have already checked the resistors and they look OK. I would appreciate a picture of the switch and as requested I will try to remember to send a reminder during the week. I am not sure if the diode insult would also effect the DC conditions. For any further checks to be meaningful I really need to resolve the switch issue. I have a 25 and a 75 as well as a couple of 2025s and reports in general suggest that Flukes are pretty well bomb proof it makes me wonder what this one has endured. It would be nice have this more up to date item operational. Still if the switch is missing an essential part I will need to try to find one that has been run over by a truck apart from the switch of course. I will try to post some pictures later this week. Regards Azeem

16th Apr 2014, 12:34 am	#5
Racal Zonal Triode Join Date: Dec 2008 Location: Glasgow, UK. Posts: 32	Re: Fluke 187 189 (perhaps) Fault Mike Mark My apologies for the delay returning, things have moved on a bit in that I now have another 189 and therefore now have a direct comparison item (if the existing one is a 189 that is). I will continue to try to repair the faulty one but possibly not in the near future due to other more pessing projects. If I find anything interesting I will keep you informed meanwhile thanks for your interest. Azeem

16th Apr 2014, 10:26 am	#6
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,861	Re: Fluke 187 189 (perhaps) Fault Didn't RS re-brand Fluke stuff with a sticky label where the Fluke branding would normally be? Nick

16th Apr 2014, 4:14 pm	#7
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Fluke 187 189 (perhaps) Fault Although the OP says ex-MOD, I'm wondering if it's a "TPWS" meter - a unit that has been certified for use with railway engineering. There were several from Fluke over the years, including a 187: http://www.eevblog.com/forum/beginners/fluke-tpws/ There's one on eBay now My 187 has at least made its way home, so if there's anything you need, just shout. Mark

6th Dec 2015, 5:42 pm	#8
Oldcodger Nonode Join Date: Oct 2014 Location: West Midlands, UK. Posts: 2,181	Re: Fluke 187 189 (perhaps) Fault I realise that this post is old,possibly as ancient as some of the test gear we're discussing, but I came across it in a Google and also found this -http://exodus.poly.edu/~kurt/manuals/manuals/Fluke/FLUKE%20187_189_Calibration.pdf. REF the mention of TPWS meters, all the ones I used had to have the word "TPWS" on the face(usually just after FLUKE). For those interested in what was measured, it was the frequency and voltage (in mV) of the signal output by the aerial grid.