Issue with fuse

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both relays from Mouser for $5, or buy a all new board for $99?
i need to check and see if the board is under warranty.
i ordered the relays, will swap them out in this board 1st to see if it will survive.
 
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but something just isnt right. the small relay (rated 10A) is the one that controls the line voltage to the blower motor !! even the way the PCB tracks run make no sense to me (bad design). with inrush of 30A not really sure how this 10A relay can survive, and to boot the blower motor runs at 14A. the board is a Source-1 board, but from what i see its not designed properly. i will call them on Monday.
 
All bets are off after the bad connections/arcing shown in your pictures.
I think you're making a mistake trying to just repair certain items on the board. Usually you are only fixing symptoms of a larger problem. I think you're "larger" problem is the board is bad and should be replaced.
For only $99 it should be done without hesitation. You could spend way more than that in just time searching for and repairing other things.

If there is anything DC involved with that board it could play havoc on everything associated because of the burnt connections.
 
Little Bill said:
All bets are off after the bad connections/arcing shown in your pictures.
I think you're making a mistake trying to just repair certain items on the board. Usually you are only fixing symptoms of a larger problem. I think you're "larger" problem is the board is bad and should be replaced.
For only $99 it should be done without hesitation. You could spend way more than that in just time searching for and repairing other things.

If there is anything DC involved with that board it could play havoc on everything associated because of the burnt connections.
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the relays are DC coils, there's a 27vac small transformer that also feeds the PCB, there is likely a bridge and one or more regulators on the PCB (havent looked for it yet).

i am almost there with ya........ i need to understand the issue before another $100 gets burned up. $5 and about 1hr of my time to remove and install the relays isnt so bad if they burn up again (which the little one just might). the pins shown are on the armature side of the relay, from the paths i see its was the the 120v passing through the 30A relay into the armature of the 10A relay. the PCB schematic (what i see visually) is odd as the output side of the 10A relay is going to the "black" wire of blower motor, but the path on PCB is not direct, there's a very thin jumper in the path. i have done PCB's in the past (yes, designed on computer then sent out to be masked and etched by machine, hundreds of boards at a time) and this PCB just looks wrong for what its controlling. not even sure why they are not using solid state relays for this stuff.

the path kinda looks like this (they are SPST relays)
lineV in on PCB --> 30A armature common --> 30A armature NO --> 10A armature common --> 10A armature NO --> very thin jumper wire (like what you see on 1/4watt resistor) --> blower motor "black" 18awg wire.

all this does not sound good for a 30A inrush and then ~14A running motor. i mean, seems like the design was done with about zero headroom. i really dont understand the use of a relay rated for 10A. the stickers on the unit for model # do lead me to find this PCB so i dont believe there is a mixup in someone matching PCB to the unit.


the one line v wire i showed in pic with red arrow of scorched wire, the strands are very black/brown and brittle. i am just wondering if my fresh new #12awg connecting in simply allowed too much amps...
 
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here's the path of the 120v
1 is lineV in to big 30A relay armature
2 is the armature of 10A relay
3 is the hair thin jumper wire
4 is out to blower motor

i have seen something like this in the past with wave solder, if the board doesnt dwell long enough the solder doesnt wick much onto the pins of the components. if they wave it with all this parts on the board at same time then they might be cutting solder time real short because of the small components, which is bad for the heavy wired items, etc. this leaves very little flux area between pin and solder/land to move the juice, etc.

melt_pins.jpg
 
yeah, this turned into me having to redesign some of the bad design of this control board. will install a Omron 40amp SSR w/ heatsink to handle the blower motor load.
 
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all i can say is, the wiring up to the unit was poor, the control board was not meant to handle 1HP motor (so UEI says), and the wiring inside the unit is for the birds.

finally fixed this mess. replaced two relays on the board, did some board mods to switch low Vdc, installed hefty SSR along with some MOV's (bottom arrow). every connector is crimped and soldered. AC feels good :)

SSR.jpg
 
I don't think you can place a 20 amp circuit on that device unless it has more than one receptacles.
 
FionaZuppa said:
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all i can say is, the wiring up to the unit was poor, the control board was not meant to handle 1HP motor (so UEI says), and the wiring inside the unit is for the birds.

finally fixed this mess. replaced two relays on the board, did some board mods to switch low Vdc, installed hefty SSR along with some MOV's (bottom arrow). every connector is crimped and soldered. AC feels good :)
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So in a nutshell you just heavily modified a listed gas fired heating unit.

That is something I would never do and think is a very bad choice.
 
iwire said:
So in a nutshell you just heavily modified a listed gas fired heating unit.

That is something I would never do and think is a very bad choice.
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I wondered all along why the OP didn't just turn the whole thing over to an HVAC tech/company. I can change some electronics but only if I know they are bad. Then the replaced parts turn out to be only a symptom of a more serious underlying problem. There is a limit to what you can do or charge a customer for something that you are throwing parts at in hopes of fixing it.

Now it looks like the equipment belongs to the OP so I don't think I can fault him for trying to fix it himself. He can't be much worse off then when he started.

Bob, I've seen some of your projects for yourself and I don't think it is beyond you to try something like this if it was your own equipment!;):p:)
 
Little Bill said:
Bob, I've seen some of your projects for yourself and I don't think it is beyond you to try something like this if it was your own equipment!
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Well thanks and I guess it would depend on how bad I wanted AC but honestly redesigning factory furnace controls would worry me if I was sleeping in the home.

Of course I did rebuild / redesign controls on some amusement park rides so maybe I am being too selective. :p
 
People from many walks of life gather around a hot-rodded car and want to see what it is, even take a ride in it, it is one of those things that gets interest in a wide variety of people. A majority of Americans anyway, have some kind of personal connection to vehicles, whether it be something they once owned or something a friend or relative had, the car they remember riding in with their parents when they were little, etc. and they do personally interact with these machines on some level. Good things and bad things happen in an automobile, all leaving us with memories. First dates (good or bad), a memorable trip (good or bad), just the daily commute to work or the supermarket, things happen when in the car. How often does one have stories to tell that involve their furnace other then it was freaking cold when it quit and it seemed to take forever for the repair guy to show up? When the thing is working it is forgotten about.

Even people that don't claim to be into cars all that much will still show some interest if you take them to a car show. But you can't take just anyone to a HVAC trade show and keep their interest, maybe some booths not quite so directly trade related may get some attention.

How many gather around a "tricked out furnace" just to look and talk about it - other then those in the HVAC trades anyway?
 
iwire said:
So in a nutshell you just heavily modified a listed gas fired heating unit.

That is something I would never do and think is a very bad choice.
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not really. the OEM board was itself a fire hazard. i simply took motor drive off of the tiny 10A relay and now the motor coils (one for now) run via the SSR. the onboard relays were switching 120Vac, now they switch low Vdc (~33Vdc). the OEM was not meant to handle 1HP motor, so i am told by Source-1 support guy. Source-1 guy tells me "i dont know why its just a 10A relay, it wasnt designed for a 1HP motor, i dont have the schematic, you should just replace the board".

mod schematic looks like this, from R1 and R2 to the right are new parts. S1 and S2 are switches inside a onboard dip IC.

hvac_switch.jpg
 

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FionaZuppa said:
not really. the OEM board was itself a fire hazard. i simply took motor drive off of the tiny 10A relay and now the motor coils (one for now) run via the SSR. the onboard relays were switching 120Vac, now they switch low Vdc (~33Vdc). the OEM was not meant to handle 1HP motor, so i am told by Source-1 support guy. Source-1 guy tells me "i dont know why its just a 10A relay, it wasnt designed for a 1HP motor, i dont have the schematic, you should just replace the board".

mod schematic looks like this, from R1 and R2 to the right are new parts. S1 and S2 are switches inside a onboard dip IC.

hvac_switch.jpg
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You did modify an already listed product.

Now just because that product is listed doesn't mean you didn't get one where they made a mistake at assembling.

Maybe they put the wrong board in it? Listed means they send certain specimen items for testing and listing to cover the entire product line, not that every item produced is examined for listing purposes. Mistakes happen and that is part of why there are recalls on products. QC is for finding such mistakes before products leave the manufacturer, but there is still things that can get by QC.

I do understand if this were your own equipment that you may make your own modifications. If you were doing this for someone else - you possibly could still modify it, but keep in mind you now have put your own warranty on it and have voided any manufacturer warranty if it is still relatively new, so you have to ask yourself just how much you are willing to stand behind should something fail? Not saying you shouldn't modify the item, just that you need to think about what liability you may be presenting yourself with before deciding to do so. A talk with customer about some of the problems encountered doesn't hurt either and remind them that you think there is a problem with the design, but if it is still under warranty that design issue should be dealt with through the manufacturer or else they are going to void the warranty.

If it is cold, a holiday weekend, and they want heat ASAP regardless of what it takes - that factors into decisions as well, but can still have later consequences if you try to resolve problem with the manufacturer.

A heavier duty fan control may not be a bad modification to make, but should you modify a high limit switch - now you have made a change that can effect other items you didn't touch. By allowing the heat exchanger to reach a higher operating temp - you may have earlier failure of the heat exchanger - should the manufacturer find out the high limit was tampered with they can reject the idea of replacing it under warranty.
 
iwire said:
Well thanks and I guess it would depend on how bad I wanted AC but honestly redesigning factory furnace controls would worry me if I was sleeping in the home.

Of course I did rebuild / redesign controls on some amusement park rides so maybe I am being too selective. :p
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its not a redesign of the controls, i only moved 120Vac off of the relays, they now switch the onboard 33Vdc out to the "cool" and "heat" terminals, which are the drive signals to the SSR's. after fixing the bad wiring the extra amps simply had a pin from each relay melt off !! melting metal pins of components simply means its a crappy design. the relays now switch 33Vdc with max 7mA (yes, 0.007A vs 30A inrush and 14A running), the contacts of the new relays will last a lifetime, and i expect no more trouble from the control board or the SSR's. in next year or two i will replace the motor with a better one.

not my 1st rodeo in mod'ing poorly designed boards.

and no, the board part # is the part # listed by York as the board for this unit. it's used across a slew of systems (not just York) where most are 3/4HP(max), this 5 burner unit has a 1HP motor. and yes, its my HVAC unit. and no, no mods made to any limit switches.
 
FionaZuppa said:
its not a redesign of the controls, i only moved 120Vac off of the relays, they now switch the onboard 33Vdc out to the "cool" and "heat" terminals, which are the drive signals to the SSR's. after fixing the bad wiring the extra amps simply had a pin from each relay melt off !! melting metal pins of components simply means its a crappy design. the relays now switch 33Vdc with max 7mA (yes, 0.007A vs 30A inrush and 14A running), the contacts of the new relays will last a lifetime, and i expect no more trouble from the control board or the SSR's. in next year or two i will replace the motor with a better one.

not my 1st rodeo in mod'ing poorly designed boards.

and no, the board part # is the part # listed by York as the board for this unit. it's used across a slew of systems (not just York) where most are 3/4HP(max), this 5 burner unit has a 1HP motor. and yes, its my HVAC unit. and no, no mods made to any limit switches.
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Again it is your furnace, you can do what you want with it, just don't expect the manufacturer to stand behind anything once you have made modifications not permitted in listing instructions. The HVAC industry in general does use light duty switching devices, but generally gets away with it. I guess they do what they can with as little as possible to pass safety testing in most instances and your seemingly undersized relay for the blower is a good example. They sell complete units at highly competitive prices, but do make a lot of $$ on the replacement parts side of things from what I can tell, but so does a lot of other industries anymore. By making an item use common replacement parts doesn't help with selling replacement parts - anyone can compete, but if you have a one of a kind component - even if it is just some common item with a little tweaking to it, you now have something that only you can provide and you can charge what you want for it rather then what the market calls for.
 
i felt the need to contact UL, they have a case open for this poorly designed board issue. will post back when i get any updates.
 
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