HM-ES-PMSw1-PL is dead

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StefanD
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HM-ES-PMSw1-PL is dead

Beitrag von StefanD » 15.10.2020, 19:54

Hi all,

Suddenly my HM-ES-PMSw1-PL stopped working. I was using a jigsaw connected to it when suddenly the power was cut.
Even the led of the HM-ES-PMSw1-PL doesn't work anymore. It seems like a fuse has blown, however it doesn't seem to contain a fuse.
I opened it, but saw nothing that seems to be blown. To my surprise, the 12V contact of the relais measures 0 Ohm resistance. (This seems to me like a fault, but I cannot see how a faulty relais makes the entire device inoperable..)

Does this mean the device is ready for the garbage bin, or is this maybe a known issue that can easily be solved?

Best regards, Stefan.

stan23
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Re: HM-ES-PMSw1-PL is dead

Beitrag von stan23 » 15.10.2020, 20:21

Hi,
are you sure that there is no fuse?
Looking at the schematic I can see a fuse (SI1) and a "fuse-resistor" (R2) which could be blown.
Can you check both?
Viele Grüße
Marco

RaspberryMatic als VM auf einem NUC mit Proxmox und USB-Funkmodul
~80 Geräte (HM, HmIP, HMW, HBW, AskSin)

StefanD
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Re: HM-ES-PMSw1-PL is dead

Beitrag von StefanD » 15.10.2020, 22:23

Thanks for the schematic! I'll check both and post the results.

StefanD
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Re: HM-ES-PMSw1-PL is dead

Beitrag von StefanD » 16.10.2020, 18:53

I checked the fuse and the resistor. The fuse seems blown: its resistance is infinite. The resistor R2 seems OK: it still measures 1KOhm.
I do wonder why the fuse is blown. Can it be that the relais draws too much current (I measure 0 Ohm on the 12V pins)?
I have tried to desolder the relais from the print, but to my surprise my soldering iron is not able to melt the solder. Does EQ3 maybe use some sort of high-temperature solder for these boards?

stan23
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Re: HM-ES-PMSw1-PL is dead

Beitrag von stan23 » 17.10.2020, 09:27

Yes that could be the reason for the blown fuse.

Maybe the solder does not melt because your soldering iron is not able to transfer enough power to heat up the solder, the copper traces and the metal inside the relay? Have you tried a bigger tip and higher temperature, and maybe some small amount of fresh soldering tin?
Viele Grüße
Marco

RaspberryMatic als VM auf einem NUC mit Proxmox und USB-Funkmodul
~80 Geräte (HM, HmIP, HMW, HBW, AskSin)

Don Kanaille
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Re: HM-ES-PMSw1-PL is dead

Beitrag von Don Kanaille » 17.10.2020, 11:42

I do not agree that the coil of the Relay could blow the fuse. 1A at 230 V is 230 W. The relay is behind the switching power supply and only switched by a tiny BC848. Even if the relay coil has total shortcut there will never be more than 230 W. It is more reasonable that the VDR is defect. It could only absorb a limited number of over-voltage events. After that it will have low impedance and the fuse will blow.
The solder tin is not special but there is much copper in the PCB to carry the high load current and it is difficult/impossible to heat it up proper.

StefanD
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Re: HM-ES-PMSw1-PL is dead

Beitrag von StefanD » 17.10.2020, 19:58

Stan, Don,
Thanks for your replies.
I did try a bigger tip and fresh solder, but that didn't help. I don't have a variable-temperature soldering iron, just a basic Antex 25W. (I also have a big 200W Weller, but that's a bit overkill I think.)
Do you think a higher temperature iron will do the job? (It's cheaper than a new HM-ES-PMSw1-PL, so it's worth the investment)

I didnt know about the VDR, but after some reading it seems like a good suspect. Thanks for the tip!

Don Kanaille
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Re: HM-ES-PMSw1-PL is dead

Beitrag von Don Kanaille » 17.10.2020, 20:12

Are you really sure that the relay is defect and the 0 Ohm reading was not just a wrong measurement? There is no logic reason why the relay and the fuse should get defect at the same time. It is more likely that you will kill the PCB than to remove the relay. It is a very difficult job with a professional soldering equipment, with the 25 W iron it is impossible.

StefanD
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Re: HM-ES-PMSw1-PL is dead

Beitrag von StefanD » 17.10.2020, 22:36

No, I'm not sure the relais is defect. I am sure that the measurement of (about) 0 ohm is correct, but that is with the relais soldered to the print. I'm not sure if it's the relais that causes the short-circuit, or another component near to it... (That's why I wanted to remove the relais)
I measured the VDR (on the circuit board) and that measures approximately 1.2M ohm. I guess that means that the VDR is OK?
Could it be that it's just the fuse? (I am hesitant to replace a fuse without knowing the reason it blew)

Don Kanaille
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Re: HM-ES-PMSw1-PL is dead

Beitrag von Don Kanaille » 17.10.2020, 23:29

If the fuse is blown and the fusible resistor R2 is not than the defect should be in the circuit before R2, not after it. Measuring the VDR with the low voltage of a Multimeter may not bring correct results. C1 could also cause a shortcut but the VDR is much more probable. There is a reason why ELV is selling the VDRs and fuses as spare parts.

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