Trying to find a replacement relay #2

Thread Starter

mattyuk2000

Joined Sep 28, 2020
13
Thought I would join the party as I'm new to this too and failing miserably. I'm pretty sure my relay is toast as continuity readings dont change when the relay is activated. I'm desperately trying to find a replacement for a 942H-1A-12DS-T (which I can only find in China and will take a month or two to get here) but no matter how much research I do I can't find anything on Mouser or RS or similar. Can anyone help? It is described as spst but has 6 pins which seems wrong to me.

https://lcsc.com/product-detail/Relays_Hsin-Da-Precision-942H-1A-12DS_C259272.html
https://datasheetspdf.com/pdf/683874/HSINDA/942H-2C-12DS/1
 

Thread Starter

mattyuk2000

Joined Sep 28, 2020
13
Hi there I'm new to electronics pair and am trying to fix a broken treadmill power board but am failing miserably. I'm pretty sure my relay is toast as continuity readings on the non-coil pins dont change when the relay is activated. I'm desperately trying to find a replacement for a 942H-1A-12DS-T (which I can only find in China and will take a month or two to get here) but no matter how much research I do I can't find anything on Mouser or RS or similar. Can anyone help? It is described as spst but has 6 pins which seems odd to me.

https://lcsc.com/product-detail/Relays_Hsin-Da-Precision-942H-1A-12DS_C259272.html
https://datasheetspdf.com/pdf/683874/HSINDA/942H-2C-12DS/1
 

Wolframore

Joined Jan 21, 2019
1,972
Sounds like fun but Im sure you can find a pin compatible but it will take some work cross referencing footprints with the datasheets.
 

SamR

Joined Mar 19, 2019
2,789
You didn't say where you live so I assume N America? You have on the link you provided the PDF for the component that has the pinout and specs for your relay. Go to Digikey and put in signal relay, that is the type of relay you are seeking. In the seach engine ask for more filters. Select the pertinent details and it will show you what they have available. The problem you may have with eBay is where the component ships from. If from China, Taiwan, or Hong Kong it will be slow delivery. Compare the pinouts to the PDF!!! They can be different and will not mount to your board or work correctly if not identical!

This will take you right to it. Select more filters.
https://www.digikey.com/products/en/relays/signal-relays-up-to-2-amps/189?k=signal relay
 
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MaxHeadRoom

Joined Jul 18, 2013
21,629
TIP:
If the relay has a small sealing 'pip' on the top, either in the centre or corner, it pays so pop it open as it is generally intended for the de-fluxing on the board it is fitted to, opening it prevents ionization internally causing premature contact failure.
Max.
 

Thread Starter

mattyuk2000

Joined Sep 28, 2020
13
View attachment 218245
https://www.ebay.com/itm/2pcs-Hsin-Da-Relay-942H-1A-12DS-T-Coil-12V-Taiwan-/201589384452

Measure the spacing between the pins of the original relay.
Check and compare dimensions, form factor, contacts.
Hongfa HF14FW series
https://docs.rs-online.com/6f37/0900766b81663c94.pdf

RS Components UK
Thanks Mr Chips this is super helfpul. Unfortunately all the datasheets seem to refer to the same thing by different names. It's very confusing for a starter. My relay says 80VDC maximum switching voltage. The HF14FW datasheet seems to say 30VDC maximum switching voltage. Am I missing something? Sorry if this is a newbie question.
 
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Thread Starter

mattyuk2000

Joined Sep 28, 2020
13
You didn't say where you live so I assume N America? You have on the link you provided the PDF for the component that has the pinout and specs for your relay. Go to Digikey and put in signal relay, that is the type of relay you are seeking. In the seach engine ask for more filters. Select the pertinent details and it will show you what they have available. The problem you may have with eBay is where the component ships from. If from China, Taiwan, or Hong Kong it will be slow delivery. Compare the pinouts to the PDF!!! They can be different and will not mount to your board or work correctly if not identical!

This will take you right to it. Select more filters.
https://www.digikey.com/products/en/relays/signal-relays-up-to-2-amps/189?k=signal relay
Thanks SamR. I'm in the UK so still a long way from China. Which ones apart from physical fit/pins are the "pertinent" features? The same things seemed to be called different things on different datasheets. Mr Chip's photo is exactly what I have and those ratings in the top right hand corner (10A, 20A and 16A) is confusing the carp out of me. What do those figures refer to?

Sorry I'm sure it's obvious but am learning.
 

MaxHeadRoom

Joined Jul 18, 2013
21,629
The contact rating of a relay depends on whether it is switching AC or DC and whether the load is inductive or resistive.
The ratings shown on the relay reflects this. The ~ is AC and the dash with dotted line is DC.
Max.
 

Thread Starter

mattyuk2000

Joined Sep 28, 2020
13
Thanks Mr Chips this is super helfpul. Unfortunately all the datasheets seem to refer to the same thing by different names. It's very confusing for a starter. My relay says 80VDC maximum switching voltage. The HF14FW datasheet seems to say 30VDC maximum switching voltage. Am I missing something? Sorry if this is a newbie question. Also my relay says "20A 125VAC/30VDC" on it and I can't find a comparable 20A rating refernce on the HF14FW datasheet. So confusing....
 

MaxHeadRoom

Joined Jul 18, 2013
21,629
What exactly is the device being switched by this relay on the T.M? You can go by this to select a suitable contact rating sub, if neccessary.
What is the model of the T.M. power board ?
Max.
 

SamR

Joined Mar 19, 2019
2,789
The important things are Coil Voltage and Contact Rating. Other than that whether it is one or two sets of NO/NC contacts and the pin placement to ensure it will match up with your board. Lastly and not very common is latching/unlatching which apparently yours does not have.
 

Thread Starter

mattyuk2000

Joined Sep 28, 2020
13
Thanks I can see from web searches that I need to match the below, but
What exactly is the device being switched by this relay on the T.M? You can go by this to select a suitable contact rating sub, if neccessary.
What is the model of the T.M. power board ?
Max.
TM? It's a treadmill so i guess you could say either a rectifier or the dc motor is being switched on by the relay. model number on the power board is HSMD-01-05 but it's so old it doesn't existing in the world of the internet. The treadmill manufacturer says they don't have the circuit diagram either so I'm working blind.
 

Thread Starter

mattyuk2000

Joined Sep 28, 2020
13
The contact rating of a relay depends on whether it is switching AC or DC and whether the load is inductive or resistive.
The ratings shown on the relay reflects this. The ~ is AC and the dash with dotted line is DC.
Max.
Thanks Max. What's confusing me is the numbers on the actual relay - It's controlling an AC input to a rectifier that feeds a DC motor, so I guess it's contolling an AC inductive load? On the image that MrChips uploaded you will see in the top right hand corner of the relay it says "20A 125VAC/30VDC, then in the lower left hand it says 16A 30VDC. Not sure of the right terminology but am I right in thinking one is the rating for the coil part of the relay and one is the rating for the voltage/current flow that is being controlled by the relay? Confusing...
 

SamR

Joined Mar 19, 2019
2,789
They are both the AC and DC ratings for the contacts. The exact same contact has a different rating depending on if it is used for AC or for DC so it has it for both. You don't need to worry about which it uses as long as it matches the existing relay (assuming it was properly sized for the use). Edit: the contact rating can be higher for the replacement but the Coil Voltage and Pinout has to be the same.
 
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Thread Starter

mattyuk2000

Joined Sep 28, 2020
13
They are both the AC and DC ratings for the contacts. The exact same contact has a different rating depending on if it is used for AC or for DC so it has it for both. You don't need to worry about which it uses as long as it matches the existing relay (assuming it was properly sized for the use). Edit: the contact rating can be higher for the replacement but the Coil Voltage and Pinout has to be the same.
Thanks SamR but how can it be both 20A at 30VDC and 16A at 30VDC at the same time? Is that to do with inductive vs resistive loads?
Either way, my relay's datasheet says max switching voltage 80VDC and the ones being suggested to me show 30VDC maximum switching voltage. In fact having spent a looong time on RS components and elsewhere it seems to be impossible to find one that is rated at 80VDC maximum switching voltage - they seem to stop at 75VDC then jump to 125VDC, and then are generally in a different package :(

Sorry I know I should just shut up and take the advice and get the one MrChips has suggested, but I'm desperate to understand and learn so I know for next time.
 

MaxHeadRoom

Joined Jul 18, 2013
21,629
Thanks Max. What's confusing me is the numbers on the actual relay - It's controlling an AC input to a rectifier that feeds a DC motor, so I guess it's contolling an AC inductive load?
What motor is it controlling? Never seen a relay involved in the belt motor, most likely is the track raise/lower motor.
Determine the motor and see what the rating on the plate is.
Max.
 
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