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# Need help cross referencing and sourcing pcb relays

#### Simon Cousineau

Jan 14, 2018
5
I have a board which I am trying to fix where the relays need replacement. I have two different kinds and six in total which are all Zettler relays first one AZ942H-1C-18DT and second AZ942H-1C-24DT(205)

I just need to find suitable replacements that will not cost an arm and a leg. I have the skills to remove the component and install a new one but no skill in finding components .

#### 73's de Edd

Aug 21, 2015
3,462
Sir Simon Cousineau . . . . . .

The first one is reasonable, but if the larger quantity needed is being the second one, they are inherently costlier.
Check the units against the PDF data sheets available for mechanical sameness.
On the second part number that you gave, I think that the thrown in very end (205) numbering might NOT be relating to the part number at all , but instead is being a code date of manufacture of that unit . . . could this product be as old as an ~ 2005 date of manufacture . . . .13 years old ?

Also, do you confirm that one relay has an 18 Volt coil while the other has a 24 Volt coil ?

Check out . . . .

https://www.onlinecomponents.com/am...fferal&utm_campaign=octopart&ref=OctopartFeed

https://www.onlinecomponents.com/american-zettler-az942h1c24dt.html?p=45218020

73's de Edd

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#### Simon Cousineau

Jan 14, 2018
5
For the age it could very well be I am not certain. I do believe that you are right one would have a 18 volt coil and the other a 24 volt. Just wondering if the relay could be cross referenced. I was somewhat hoping I can give this a cheap go at trying to fix it.

#### Minder

Apr 24, 2015
3,334
As a last resort, look for a relay that has close specs and footprint, in many cases it is fairly easy to do a slight modification on the board to accommodate the replacement.
There are many suppliers of these type of cheap PCCT relays from ebay to DigiKey.
For any slight re-design of the PCCT trace, I have used drywick (solder wick) to make a suitable mod.
You just need to get a little creative.
What is the nature of the equipment they are used on.
Is that 6 on one board or total of 6 boards!!
M.

#### Minder

Apr 24, 2015
3,334
By the look of the footprint/spec in the catalogue, you should not have much problem sub'ing them if needed.
M.

#### 73's de Edd

Aug 21, 2015
3,462
O.K. . . .then . . . here ya' go.

You are looking for both 18 or 24 volt coil SPST relays, or a SPDT if one contact is being ignored.
They are in T73 physical profile cases . . .sometimes nicknamed " sugar cube " relays.
That 16 A contact current spec is sort of up in the air , as a 10A rating is a piece of cake while a 15A spec is right at the top of their current spec range.

You REALLY need to tear down the original cases and inspect how the contacts look and if there is any discoloration of the leaves feeding into the contacts. I believe that all of this series are potted and you would have to take a Dremel tool with a cutting wheel and cut/grind off all of the top 1/2's of the units for visual inspections.

Only THEN, would you REALLY be able to see which units actually passed any hefty current level and how well they have fared with their time of use.

These are all of the found " Chinee " sourced possibilities . . . . .

India is another sourcing possibility, as they make several renown relay companies products.

https://www.alibaba.com/products/F0/T73_sugar_cube_relay/2.html

73's de Edd
.....

#### Simon Cousineau

Jan 14, 2018
5
Thanks all of you for the great information you have provided. One question I have is does the voltage really matter? Or should I match the voltage and amperage?

As far as opening them up it would certainly tell me how they did. I already pulled them out of the board and lost their order which might not have been the wisest thing to do as it could of let me know maybe which one worked the hardest and maybe which one failed.

It is just a single board with a whole 6 relays on it for a furnace. At the rate of failure I am replacing these boards every 2-3 years and went through 4 of them so far and I am just fed up with it since we are talking about a simple relay issue or at least it is my conviction. The first couple I paid an HVAC tech to come and replace them at a cost of 800$CAN each time right before the holidays too which really hurts. Now I learned that this furnace has an actual problem with this component and purchasing these boards online and replacing them myself but still if I could just repair them I think it would be nice and restore a couple of my old ones for spares just in case. No point in throwing them in the garbage. If the relay fails the furnace won't start it's not complicated. #### Minder Apr 24, 2015 3,334 If these relays are of the optional vented type, maybe the small vent pip was not snapped off, This can shorten the life of the relay if left sealed, in some case where life if the relay is short, it might pay to vent them, even if of the non-vented type. Keeping them sealed when using the maximum rating can often lead to internal ionization (arcing). But IMO many of these appliance relays are drastically under rated, current-wise. M. #### Simon Cousineau Jan 14, 2018 5 There is a little stud like plastic on top of these relays and when broken you can see a needle size hole leading inside of the relay. If that is what you meant by vent pip they were all left sealed. That is a good tip which can help in the future. Not asking anyone to do my shopping for me but it would be really nice in this case if someone could give me his best educated guess in which relay I should purchase for both the 18v and the 24v replacements. I would greatly appreciate the help. #### Minder Apr 24, 2015 3,334 A couple of major sources is Omron, Potter & Brumfield etc, If requiring items fairly promptly, I usually shop Digikey, they have standard$8.00 shipping and overnight delivery to Canada, no brokerage etc.
Others take a little longer, ebay etc.
Often the vent is not removed, it is fitted to enable wash down or after production board cleaning etc.
M.

#### Attachments

• Venting_Sealed_Relays.pdf
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• Venting2.pdf
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#### 73's de Edd

Aug 21, 2015
3,462
Sir Simon Cousineau . . . . .

Pity . . .pity . . .PITY . . . . that you have already played Russian Roulette with your relays assigned positions.
Having done failure analysis so o o o o o o o o o o o o o long, that I automatically ID and differentiate between like components.
Two more considerations . . . 24volts . . . is the de facto standard for control systems supply voltages, be it AC or DC.

I very highly suspicion that if you find two relays that are rated with the 18V coils that they are going to be related to the most current / power intensive handling position(s) / functions on the board.
The logic being that the 18V coil run at 24 is going to be pressing the power handling contacts together more firmly than they would doing at 24V coil drive..

Check the boards foil traces that are related to carrying connectivity to the relays CONTACTS. They might just all be the same width, but a wider foil width would be indicative of providing a HEAVIER current carrying capability.

Thasssssit . . .

73's de Edd
.....

#### Simon Cousineau

Jan 14, 2018
5
Minder
Very interesting read about venting I will definitely vent my newly purchased board after reading this. All of the vents have remained closed on these relays. I do not need these relays quickly so ebay is a good place to purchase these? Again your help is more than appreciated and if you could point me to a product it would be appreciated.

73's de Edd
I am no expert when it comes to these things so I didn't think anything of removing these components from their assigned positions. Looking at the board there is some quite heavy traces for both 18V and 24V relays and some others really are really small for both 18V and 24V relays. The heavier ones must carry much more current than the smaller ones which would just make sense and would probably have heavier wear and tear. Although in this case I cannot tell if the 18V is actually carrying heavier current than the 24V ones.

Thanks again guys your help is greatly appreciated

#### Minder

Apr 24, 2015
3,334
There are several Zettler relays on ebay, also a email to Zettler may provide a N.A. source.
The 18v is not a common value, mostly 12v & 24v, so you may have to track down a Zettler source.
M.

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