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Repair of Aneng AN8009 meter - erroneous ohmmeter readings

Olkus 4671 34

TL;DR

  • The Aneng AN8009 multimeter showed wildly wrong ohmmeter readings, misreading a 100 ohm resistor as tens of kiloohms and even displaying nonsense with open or shorted probes.
  • Cleaning the range switch and its PCB tracks fixed the fault; oily grease had leaked from the switch onto the board, and the contacts were washed as well.
  • The meter’s original 100uF supply electrolytic was upgraded to 1000uF, one of the recommended AN8009 modifications.
  • After reassembly, the ohmmeter readings returned to correct values and the repair was completed in about half an hour at a cost of 0zł.
  • The rotary switch is a common failure point in many meters because it also handles power switching, which accelerates wear.
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  • ANENG AN8009 multimeter in ohmmeter mode with display showing OL, with red and black test leads next to it. .

    Welcome,

    Today I will give a description of a simple repair of this multimeter. The equipment is popular enough that maybe someone less familiar with the subject will find this description useful and save his instrument ;)
    The meter on the ohmmeter range indicated all sorts of silly things, e.g. a 100 ohm resistor was identified as being up to several tens of kiloohms. Without the probes plugged in, it was also able to display some nonsense, and when the probes were short-circuited, instead of zero the display could show several hundred ohms or even more.
    The first suspects were the batteries. I bought the meter in the first half of 2021 and it has been running on the same set of batteries ever since, and I use it the most out of all the meters I own. However, the cells turned out to be in pretty good shape, I even swapped them for new ones just to be sure, but it didn't do anything.
    What I observed later, normal readings could be restored (but not always) by switching between ranges a few times. So the main suspect became the switch. To get to it the meter has to be disassembled, after dismantling the casing and removing the board we have this view:
    Inside view of a disassembled multimeter showing PCB and switch tracks. .
    You can see the switch tracks, they appear to be gold plated.
    If you look closely you can see the oily ooze on the board:
    Close-up of a multimeter circuit board showing switch traces. Image of gold-plated tracks in a multimeter switch after cleaning. .
    This is probably grease that leaked from the switch and got on the PCB.
    The part with the knob on the underside:
    Close-up of the multimeter switch interior after cleaning. .
    Here the contacts look OK, however I also washed them just in case.
    The switch tracks after cleaning:
    Close-up of a PCB with visible gold-plated traces. .
    You can see a huge difference, clean was not there:
    A cotton swab with dirt on the tip against a workbench background. .
    Taking advantage of the fact that I had the meter open I also replaced the original 100uF electrolyte on the meter supply with a 1000uF:
    Electrolytic capacitor 10V 100μF lying on a grid mat. View of an open multimeter showing the interior with PCB and replaced capacitor. .
    This is one of the recommended modifications for this meter, you can read more here: https://www.elektroda.pl/rtvforum/topic3713925.html#18825243
    Well, and now the most important thing: Was the repair successful, does the meter indicate as it should? Time to check!
    ANENG AN8009 multimeter with display showing 0.004 ohms, with probes in hand. .
    It worked and the readings returned to correct :D .
    The whole repair took me ~ half an hour, cost 0zł ;) .
    The switch, by the way, is a common problem with many meters, mainly because the power switch is usually placed there as well, so the switch wears out faster because of this.
    Thank you for your attention.

    Regards,
    A.

    Cool? Ranking DIY
    About Author
    Olkus
    Level 32  
    Offline 
    Olkus wrote 3910 posts with rating 910, helped 132 times. Live in city kraków. Been with us since 2020 year.
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  • #2 21210553
    NegativeFeedback
    Level 15  
    Posts: 315
    Help: 3
    Rate: 108
    Olkus wrote:
    [url=https://
    This is probably grease that leaked from the switch and got on the PCB.
    A.


    This grease is probably silicone grease, which is used to lubricate the contact area so that the contacts do not degrade quickly, due to the poor quality of the pcb and copper plating, so I would suggest disassembling again and lubricating there.
    The grease does not degrade the contact, I sometimes grease old instruments that have deteriorated after many years of use, I have been using these for many years, I have never had a problem with the contacts because of this.
  • #3 21210559
    Olkus
    Level 32  
    Posts: 3910
    Help: 132
    Rate: 910
    NegativeFeedback wrote:
    Grease does not deteriorate the contact, I sometimes grease old instruments in this way that have deteriorated after many years of use, I have been using these for many years, I have never had a problem with the contacts because of this.
    .

    Well in this case it was making it worse. The ohmmeter was going crazy before and now it works normally, so I guess there was something not quite right with the grease?

    Greetings,
    A.
  • #4 21210879
    waldi_8601
    Level 13  
    Posts: 132
    Rate: 29
    I don't think the grease itself is the problem, I've usually seen clear grease used for such purposes, its purpose is rather to reduce friction, mechanical wear of the contacts/PCB.
    Here on the PCB you can clearly see the grease is dirty, maybe some micro filings, corrosion, so it could start to conduct current to some extent, spread it connects the contact fields and the meter in such a situation could start to malfunction.
  • #5 21210963
    Olkus
    Level 32  
    Posts: 3910
    Help: 132
    Rate: 910
    waldi_8601 wrote:
    I don't think the grease itself is the problem, I've usually seen clear grease used for such purposes, its purpose is rather to reduce friction, mechanical wear of the contacts/PCB.
    Here on the PCB you can clearly see the grease is dirty, maybe some micro filings, corrosion, so it could start to conduct current to some extent, smeared connects the contact fields and the meter in such a situation could start to malfunction.
    .

    Basically such a grease, in this case probably silicone, is an insulator. If it gets between the contacts of the switch and the copper fields on the PCB then things like this can happen.
    Well, and the aforementioned dirt certainly made things worse too.

    Regards,
    A.
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  • #6 21210978
    Krzysztof Kamienski
    Level 43  
    Posts: 21874
    Help: 2030
    Rate: 5128
    Olkus wrote:
    this is an insulator. If it gets between the contacts of the switch and the copper fields on the PCB then just such things can happen
    .
    With good contact pressure, this grease is not an insulator, and actually contributes to prolonging the life of the switch. Unless I am mistaken and the instrument was designed by a Chinese idiot.
  • #7 21211068
    E8600
    Level 41  
    Posts: 8864
    Help: 525
    Rate: 2475
    The grease should be the problem is the switch in the dial instead of a separate separate button.
  • #8 21211091
    Olkus
    Level 32  
    Posts: 3910
    Help: 132
    Rate: 910
    To dispel doubts I looked at another meter - UNI-T UT33D+, the grease is:
    Disassembled UNI-T UT33D+ multimeter showing the circuit board. Image of a multimeter interior showing a dusty printed circuit board. .
    So it looks like dirt was the culprit, or this grease was somehow left and started to conduct after some time.
    I'll have to buy silicone grease in that case, as I don't currently have any and give it a bit to this Anenga.

    E8600 wrote:
    The grease should be the problem is the switch in the dial instead of a separate separate button.


    Yes, that certainly has an impact too, as I wrote about at the end of the article.

    Regards,
    A.
  • #9 21211123
    forest1600
    Level 20  
    Posts: 612
    Help: 10
    Rate: 158
    You can always use it without grease for a test and see what condition the tracks are in after a year.
  • #10 21211496
    PPK
    Level 30  
    Posts: 1925
    Help: 94
    Rate: 421
    In my case the problem was the banana sockets. I have solid, proprietary wires, 1.5mm2 in silicone, 'gold-plated' plugs. On a DT-9935 bridge, they had a resistance of 0.1 R. Meanwhile, Aneng, (shorted), was showing a resistance of 10-20 R. The problem turned out to be the banana sockets made internally of tinned 'tinned' sheet metal, I think. After replacing them with 'gold-plated bronze' sockets (acoustic - a minor modification). The ohmmeter showed 0.3-0.4R. The 10 A load test also passed without a problem. Cost, approx. 25 PLN + 1 hour of work.
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  • #11 21211619
    kris8888
    Level 40  
    Posts: 6727
    Help: 526
    Rate: 1851
    Olkus wrote:
    I'll have to buy silicone grease in that case, because I don't currently have it, and give some to that Anenga.

    I also recently cleaned my old multimeter, it works perfectly, but I have a dilemma whether to give silicone grease to those switch contacts or better to give non-acid technical petroleum jelly? Or maybe it is better not to lubricate anything there. Maybe someone has experience and will write all the pros and cons. Does the material the contacts are made of also make a difference in terms of the choice of "lubricant"?
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  • #12 21212014
    slavo666
    Level 23  
    Posts: 724
    Help: 36
    Rate: 384
    This will neither help nor harm you. A crappy switch won't fix it, and a decent one won't hurt you either.
  • #14 21212107
    kris8888
    Level 40  
    Posts: 6727
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    Rate: 1851
    This is probably unsuitable since from the description it appears to conduct electricity. It will make "shorts" or leakage between the tracks on the switch board.
  • #15 21212112
    PPK
    Level 30  
    Posts: 1925
    Help: 94
    Rate: 421
    kris8888 wrote:
    This is probably not suitable since from the description it appears to conduct electricity. It will make "shorts" or leakage between the tracks on the switch board.
    .
    Well I had that in the 10/BCD rotary switches, because there is just such a circular plate etched into the laminate and microsteps. When I gave too much, it actually made short circuits. But when I rubbed it in with a cloth, the switch started to work properly and it's been working for 4 years now.... Another method is this spray for potentiometers - AG - Only you also have to wipe off the excess and dry.
  • #16 21212163
    Olkus
    Level 32  
    Posts: 3910
    Help: 132
    Rate: 910
    PPK wrote:
    In my case the problem was the banana sockets. I have solid, proprietary wires, 1.5mm2 in silicone, "gold plated" plugs. On a DT-9935 bridge, they had a resistance of 0.1 R. Meanwhile, Aneng, (shorted), was showing a resistance of 10-20 R. The problem turned out to be the banana sockets made internally of tinned 'tinned' sheet metal, I think. After replacing them with 'gold-plated bronze' sockets (acoustic - a minor modification). The ohmmeter showed 0.3-0.4R. The 10 A load test also passed without a problem. Cost, about 25 PLN + 1 hour of work.
    .

    The wires as well as the sockets in this case are OK. Although I have some Chinese meter where the wires themselves have 5 ohms :) .

    PPK wrote:
    Another method is this spray for potentiometers - AG - Only you also have to wipe off the excess and dry.
    .

    Maybe that would be a good solution. Or Contact 61.

    Regards,
    A.
  • #17 21212353
    fiB
    Level 14  
    Posts: 73
    Help: 3
    Rate: 20
    >>21210334 the link to the modification topic provided also contained a solution to your problem at the end. I had a similar problem a year ago. A year after cleaning and applying new grease, the multimeter works fine and the ohmmeter readings are repeatable. I used SGB grease, I suspect that the one applied from the factory is of low quality and creates problems after a while.
  • #18 21212674
    Olkus
    Level 32  
    Posts: 3910
    Help: 132
    Rate: 910
    fiB wrote:
    I suspect that the one applied at the factory is of low quality and creates problems after some time.
    .

    I also have this suspicion that there is something wrong with the factory one. I will probably buy the correct one unless Fellows can advise something else.

    Regards,
    A.
  • #19 21212707
    sq3evp
    Level 39  
    Posts: 6345
    Help: 211
    Rate: 835
    Olkus wrote:
    .
    Here the contacts look OK, however I also washed them just in case.
    Switch tracks after cleaning:

    And brag about what you cleaned so beautifully with?
    Chemistry or just a decent stick?
  • #20 21212730
    Olkus
    Level 32  
    Posts: 3910
    Help: 132
    Rate: 910
    sq3evp wrote:
    Are you bragging about what you cleaned so beautifully with?
    Chemistry or just a decent stick?
    .

    IPA :) .

    Regards,
    A.
  • #21 21214752
    398216 Usunięty
    Level 43  
    Posts: 34016
    Help: 3914
    Rate: 9190
    NegativeFeedback wrote:
    This grease is probably silicone grease, which is used to lubricate the contact area so that the contacts do not degrade quickly, due to the poor quality of the pcb and copper plating, so I would suggest there to disassemble again and lubricate.
    .
    Protect the gold-plated tracks? Unfortunately, but the Author's colleague got it right - that grease (whatever it may be; be it silicone or tow) does more harm than good. The resistance it introduces into the circuit (and modern, better class meters measure resistances with an extremely low current) falsifies the readings - not only the ohmmeter's, by the way. I myself had a similar symptom in another meter - the grease on the contacts turned out to have migrated from the "terkotki" that allows the range switch to be stabilised in the correct (for the contacts) position.
  • #22 21214775
    kris8888
    Level 40  
    Posts: 6727
    Help: 526
    Rate: 1851
    398216 Usunięty wrote:
    Protect the gold-plated tracks? Unfortunately, but the Author's colleague got it right - that grease (whatever it may be; be it silicone or towote) does more harm than good
    .
    Well that's right, it's good that you confirm. I also had an assumption that gold-plated contacts and tracks should rather not be lubricated with anything. And if they are, you should think carefully about what.
    I checked at my place in some older oscilloscope where there are also gold plated contacts of multi-turn switches, there is no grease on them and you can't see that it was ever there.

    On the other hand, I recently disassembled a rotary motorised input switch in a top-of-the-range Sony amplifier and there the contacts were clearly factory lubricated with something. The contacts looked gold-plated and the grease was unlikely to have come from the mechanism itself.
  • #23 21214825
    E8600
    Level 41  
    Posts: 8864
    Help: 525
    Rate: 2475
    I had a similar thought myself and once wiped it down, and while the contacts survived, the metal plates in the dial had become so bad that some had cracked. I then folded on what I had which was a thin layer of Vaseline with a drop of Vaseline oil.
  • #24 21214855
    Nori2
    Level 22  
    Posts: 310
    Help: 64
    Rate: 106
    kris8888 wrote:
    in some older oscilloscope where the contacts of the multi-turn switches are also gold plated, there is no grease on them and you can't see there ever was
    .
    kris8888 wrote:
    in a top of the range Sony amplifier and there the contacts were clearly factory lubricated with something. The contacts appeared to be gold plated and the grease was unlikely to have come from the mechanism itself
    .
    What conclusion can be drawn from this?

    The contacts used to be "richly" gold-plated, but now, in an age of cost-cutting, they are only "flicked" with gold.
    The lubricant is supposed to protect the gold-plated contacts from mechanical wear too quickly.
  • #25 21215530
    398216 Usunięty
    Level 43  
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    E8600 wrote:
    I once wiped it down and while the contacts survived, the plates in the dial became so bad that some cracked.
    .
    This is not a good indication of the lamellas rather than a lack of lubricant. Well-made switch plates (especially not airtight ones!!!) HAVE NO RIGHT to crack or wear out. Because (according to common sense) from what? The smooth gold-plated contacts on the laminate? Or from dust and dirt that ALWAYS gets into such (non-hermetic switches)? Meters are supposed to measure correctly and that is the most important thing. And if someone is not able to make smooth contacts, properly gild them or select metal for the switch's moving contacts, is this a reason to try to get around the problem by lubricating the contacts? Grease < and as we know, grease is extremely fond of binding dust, dirt and other nasties to itself, and I don't think anyone needs to be told how such abrasive paste behaves on the contacts....
    GREASE WAS USED IN SWITCHES WITH A SLIGHTLY DIFFERENT DESIGN AND, ABOVE ALL, DIFFERENT SWITCHING SIGNALS. And even so, such switches were capable of tripping, breaking, cracking... in audio equipment, for example.
  • #26 21215616
    Olkus
    Level 32  
    Posts: 3910
    Help: 132
    Rate: 910
    kris8888 wrote:
    398216 Usunięty wrote:
    Protect the gold-plated tracks? Unfortunately, but the Author's colleague got it right - that grease (whatever it may be; be it silicone or towote) does more harm than good
    .
    Well that's right, it's good that you confirm. I also had a conjecture that gold-plated contacts and tracks should rather not be lubricated with anything. And if they are, you have to think carefully about what.


    In that case I leave the switch without lubrication, as I thought at the beginning. We'll see if this causes any problems after a while, although I don't think it will happen quickly.

    Regards,
    A.
  • #27 21222126
    keseszel
    Level 26  
    Posts: 4087
    Help: 54
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    Often a sore point is mangy wires. I generally make my own,try to give good, expensive banks, the wire I used to give in insulation, 1.5mm sq or 1mm, secured with Distal and hot glue or butaprene. Meter wires are the last fall they add, miracle not headphone wires. But still I often get strange measurements. Gold plated contacts don't get protected, the grease is actually supposed to improve the feed rate because the fields are rubbing out, I have some older bullseye meters.
  • #28 21222170
    Olkus
    Level 32  
    Posts: 3910
    Help: 132
    Rate: 910
    keseszel wrote:
    Frequently the problem is scabby wires. I generally make my own,try to give good, expensive banks, wire I used to give in insulation, 1.5mm sq or 1mm, secured with Distal and hot glue or butaprene. Meter wires are the last fall they add, miracle not headphone wires. But still, I often get strange measurements.


    In this case it wasn't the wires that were the problem, I checked that at the outset.

    keseszel wrote:
    Golden contacts don't get protected, the grease is actually supposed to improve the feed rate, because the fields are rubbing out, I have some older bull gauges.


    So if the contacts are gold plated we don't give grease as some have written before?

    Greetings,
    A.
  • #29 21222339
    keseszel
    Level 26  
    Posts: 4087
    Help: 54
    Rate: 555
    Olkus wrote:
    So if the contacts are gold plated we don't give grease, as some have written before?
    .
    That's how I remembered it from the old days. But I remember the Isostats strewn about. I would give but would get an idea of what lubricants would be advisable these days. No matter what you do it will still be fine. You don't buy a meter for life ;-) .
  • #30 21222483
    Olkus
    Level 32  
    Posts: 3910
    Help: 132
    Rate: 910
    keseszel wrote:
    This is how I remembered from the old days. But I do remember the Isostats strewn about. I would give but would get an idea of what lubricants would be advisable these days. No matter what you do it will still be fine. You don't buy a meter for life .
    .

    Now it's probably silicone grease that would be most advisable. I leave it without for now, you are right , that you do not buy a meter for life :) Especially since the one from the topic is not very expensive, and in case of emergency I have other ;) .

    Regards,
    A.
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Topic summary

✨ The discussion revolves around the repair of the Aneng AN8009 multimeter, specifically addressing erroneous ohmmeter readings. The user initially suspected battery issues but found them to be in good condition. Subsequent troubleshooting pointed to potential problems with grease on the contacts, which may have caused erratic readings. Various participants shared insights on the use of silicone grease versus petroleum jelly, with some suggesting that grease can introduce resistance and lead to inaccurate measurements. Others noted that dirt and corrosion could exacerbate contact issues. A participant resolved their problem by replacing the banana sockets with higher quality components, resulting in improved resistance readings. The conversation concluded with considerations on whether to lubricate contacts, particularly gold-plated ones, and the implications of using different types of lubricants.
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FAQ

TL;DR: If your Aneng AN8009 shows 100 Ω as tens of kΩ, clean the rotary switch PCB first. One user fixed it in ~30 minutes for 0 zł after saying the ohmmeter was "going crazy." This FAQ helps AN8009 owners restore correct resistance readings and check whether the real fault is the switch, sockets, or leads. [#21210334]

Why it matters: Low-ohm faults in the range switch can corrupt basic continuity and resistance checks, making an otherwise usable multimeter unreliable.

Option What users observed Cost / effort Best use
Clean switch tracks with IPA Restored correct ohmmeter readings after grease and dirt removal 0 zł, ~30 min First repair step
Re-grease after cleaning Some users report 1 year of stable readings with fresh grease Extra materials, repeat teardown If the original grease was contaminated
Leave switch dry Chosen by the repair author after cleaning 0 zł When gold-plated tracks already work correctly
Replace banana sockets / improve leads Reduced shorted-probe reading from 10–20 Ω to 0.3–0.4 Ω in one case ~25 PLN + 1 hour If switch cleaning does not fix low-ohm error

Key insight: The thread points to contaminated switch grease and dirty range-switch tracks as the main cause of wildly wrong ohmmeter readings. If cleaning does not restore near-zero readings with shorted probes, check the input sockets and test leads next.

Quick Facts

  • The original repair fixed the meter after cleaning the rotary switch PCB, took about half an hour, and cost 0 zł. [#21210334]
  • The failure symptom was severe: a 100 Ω resistor could read as several tens of kΩ, and shorted probes could show several hundred ohms. [#21210334]
  • The author had used the meter since the first half of 2021 on the same batteries, but battery replacement did not solve the problem. [#21210334]
  • One user improved low-resistance performance by replacing poor banana sockets, cutting shorted-probe readings from 10–20 Ω to 0.3–0.4 Ω; the mod cost about 25 PLN and 1 hour. [#21211496]
  • A common optional AN8009 modification mentioned in the thread is increasing the power-supply capacitor from 100 µF to 1000 µF while the meter is already open. [#21210334]

How do I fix an Aneng AN8009 that shows wildly wrong resistance values on the ohmmeter range?

Start by cleaning the rotary range switch PCB and its contact area. In the reported repair, batteries were ruled out first, then the meter was opened, oily dirt was removed from the switch tracks, and correct readings returned immediately. The whole job took about 30 minutes and cost 0 zł. If the meter still shows high resistance with shorted probes after cleaning, check the banana sockets and test leads next. [#21210334]

What symptoms point to a dirty or failing rotary range switch in a digital multimeter like the Aneng AN8009?

The clearest symptom is unstable resistance readings that change with switch movement. In the thread, a 100 Ω resistor read as several tens of kΩ, open probes showed nonsense values, and shorted probes could show several hundred ohms instead of near zero. Another strong clue is that switching ranges several times can briefly restore normal operation. [#21210334]

Why can switching ranges several times temporarily restore normal ohmmeter readings in an Aneng AN8009?

Repeatedly turning the selector can momentarily improve contact between the wiper and dirty PCB tracks. The author observed that normal readings sometimes returned after moving through several ranges, which strongly implicates the rotary switch rather than the batteries. That temporary recovery usually means contamination or wear is present, not that the fault is gone. [#21210334]

What is the proper step-by-step way to disassemble, clean, and reassemble the AN8009 range switch PCB?

Use a simple 3-step process. 1. Remove the case, take out the PCB, and expose the rotary switch tracks. 2. Clean the visible grease and dirt from the PCB tracks and the underside contact part; the author used IPA. 3. Reassemble the meter and verify with a known resistor and shorted probes. In the thread, this restored correct readings without replacing parts. [#21212730]

Which cleaner works best for removing leaked grease and dirt from multimeter switch tracks: IPA, Contact 61, or potentiometer spray?

IPA is the only cleaner in the thread that clearly solved the fault. The author answered directly that the switch was cleaned with IPA, and after that the AN8009 returned to correct ohmmeter readings. Contact 61 and potentiometer spray were only proposed later as possible options, not confirmed fixes in this repair. [#21212730]

Silicone grease vs non-acid technical petroleum jelly: which is better for rotary switch contacts in a multimeter?

The thread does not show a clear winner, but it leans toward silicone grease over petroleum jelly for relubrication. Several users discussed silicone grease as the intended type, and one user reported a year of stable operation after cleaning and applying fresh SGB grease. Petroleum jelly was raised as an option, but no successful multimeter result was documented for it in the thread. [#21212353]

How much does the contact material matter when choosing a lubricant for multimeter switch contacts?

It matters a lot, because users in the thread treated gold-plated and silver contacts as different cases. Gold-plated rotary tracks were debated because grease can either protect a thin surface or raise contact resistance in low-current measurement circuits. By contrast, silver Isostat contacts were mentioned as a separate case with different aging behavior. [#21222833]

What is SGB grease, and why do some users recommend it for rotary switch contacts after cleaning?

"SGB grease" is a contact lubricant that users apply to rotary switch interfaces after cleaning, with the key characteristic that it is used in a very thin replacement layer after old grease and dirt are removed. One user recommended it because an AN8009 with similar symptoms worked correctly for a full year after cleaning and regreasing with SGB. [#21212353]

What is an Isostat switch, and how is it different from the gold-plated rotary range switch used in meters like the AN8009?

"Isostat" is a pushbutton switch family that routes signals through silver contacts, a key characteristic that differs from the gold-plated circular PCB tracks used in a multimeter’s rotary range selector. In the thread, users stressed that old Isostat experience does not transfer directly, because silver and gold contacts age and react differently. [#21222833]

Why do some users say grease protects gold-plated switch tracks, while others say it increases contact resistance and ruins low-ohm readings?

Both views came from different failure modes seen in practice. Some users said grease reduces friction and wear on thin gold plating, especially in selectors that also act as power switches. Others reported that contaminated or misplaced grease raises contact resistance, and one commenter argued this is especially harmful in modern meters that measure resistance with very low current. [#21214752]

When should I leave a multimeter range switch dry instead of relubricating it after cleaning?

Leave it dry when cleaning alone restores stable readings and the gold-plated tracks look healthy. That is exactly what the repair author decided after the discussion, choosing to run the AN8009 without new grease and monitor long-term wear. This is the safest choice when the original grease appears dirty, migrated, or electrically troublesome. [#21215616]

How can dirty grease, metal filings, or corrosion on switch tracks create leakage paths and cause false resistance measurements?

Dirty grease can spread across adjacent switch fields and stop the contact from making a clean, low-resistance connection. One user specifically pointed to grease contaminated with micro filings or corrosion, saying it can begin to conduct to some extent and bridge contact areas. In an ohmmeter circuit, that leakage distorts low-value readings and can make shorted probes read far above zero. [#21210879]

What other faults besides the range switch can make an Aneng meter read 10–20 ohms with the probes shorted, such as bad banana sockets or poor test leads?

Bad banana sockets and poor leads can cause the same symptom. One user reported an Aneng that showed 10–20 Ω with the probes shorted, then traced the fault to cheap internal sockets made from tinned sheet material. The thread also warns that some cheap test leads can add several ohms on their own, so verify leads and jacks before blaming the ADC or firmware. [#21211496]

How do upgraded banana sockets and better test leads improve low-resistance readings in Aneng multimeters?

They reduce series resistance between the meter input and the probe tip. In the thread, replacing the original sockets with gold-plated bronze types changed the shorted-probe reading from 10–20 Ω down to about 0.3–0.4 Ω, and the modified meter also passed a 10 A load test. Better leads help for the same reason: less contact loss and less conductor resistance. [#21211496]

Why do users replace the Aneng AN8009 power-supply capacitor from 100 uF to 1000 uF, and what effect does that modification have?

Users do it as a recommended AN8009 modification while the meter is already open. The repair author replaced the original 100 µF electrolytic with a 1000 µF part during the same teardown, citing an existing modification thread. This change was not presented as the cause of the ohmmeter fix, but as a separate preventive or performance-oriented upgrade. [#21210334]
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