modern maid gas range


  #1  
Old 02-19-05, 10:13 PM
TimB
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Question Modern Maid PHU-185

Hey Quickvan,

Did the new oven igniter resolve your problem? I just read this old post and wanted to see if the igniter fixed the problem in your case as I am having the same problem with my oven and have looked at it for some time now.

IMO, the "bake" ignitor on my stove is getting hot enough and is just as bright as my broiler igniter, but the oven is not getting enough gas flow at the oven (bake) burner for the igniter to start the flame.

As quickvan pointed out, the broiler works fine and ignites after approxmately 50-60 seconds of turning the oven switches. The igniter itself is hot enough IMO after about 20-30 seconds, then a few seconds later you can hear the gas open and the flame ignites.

However, on the oven (bake) side of things the igniter comes on in about the same amount of time, but the gas doesn't come on as fast and not as pronounced as it does in broiler operation. At this time, I also get a strong order of gas buildup coming through the upper vent and burners on the stovetop.

I have played a bit with the position of the igniter to see if getting it closer to the burner tube would make a difference, but these ceramic igniters don't have alot of play room and no noticable difference was noted. I have also started the burner manually using a hand spark lighter and notice the gas ignites, but the flame is small, much smaller than the broiler (though correct in flame adjustment). Sometimes this flame goes out, sometimes it stays lit until the oven reaches the high-limit temperature, then shuts off. Problem is, then it doesn't re-ignite to maintain the temperature and the oder of gas returns.

Removing the lower storage drawer to access the oven from underneath, I notice the two ports where the gas enters the stove. The straight connection goes to the burner assemblies and the other one with the small shutoff valve goes to the oven (both bake and broiler igniters). However, from there I can't see where the gas tubing goes as it passes out of site on the left of the stove.

I have played with the small brass shutoff valve and notice that by moving the valve stem from open to close and back again, it will allow enough gas to shoot through the line to ignite the burner assembly. The gas sound is noticable, similar to the broiler ignition, but then the gas dies off slowly and I'm back to square one.

My question concerns the gas valve itself. On the schematic, it shows where the igniters are connected to this gas valve via wires (violet for bake) and I need to know where this valve is physically located without disconnecting my stove and removing it from the mountings if at all possible? My train of thought now is that the gas valve for the bake side of operation is not functioning. Either the wire connections are bad or the valve needs to be readjusted or replaced.

Any thoughts?
Tim
 
  #2  
Old 02-20-05, 08:52 AM
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Hello Tim. Welcome to my Gas Appliances topic and our Do-It-Yourself Web Site.

I seperated (split) your question from the one it was posted into. The condition you describe is like or similar to the problem your question was posted to but it is always best to post your own question seperately. That ensures you get the attention you deserve for the appliance in question and we can focus attention to yur aplliances problem specifically.

Based on the problem description you described:
the "bake" ignitor on my stove is getting hot enough and is just as bright as my broiler igniter, but the oven is not getting enough gas flow at the oven (bake) burner for the igniter to start the flame....the broiler works fine and ignites after approxmately 50-60 seconds of turning the oven switches. The igniter itself is hot enough IMO after about 20-30 seconds, then a few seconds later you can hear the gas open and the flame ignites.

However, on the oven (bake) side of things the igniter comes on in about the same amount of time, but the gas doesn't come on as fast and not as pronounced as it does in broiler operation. At this time, I also get a strong order of gas buildup coming through the upper vent and burners on the stovetop.
The broiler is used less than an oven, so the ignitor is in better working condition than the ignitor in the oven. Thus, the broiler works and the oven does not. A common cause for the problem you are describing, in the second paragraph, is often related to a weak hot surface glow ignitor (HSI)

First attempt to fix the problem is to replace the ignitor, regardless of the color of the ignitors glow. If replacing the ignitor does not resolve the condition, than replace the burners gas valve.

Or, best practice, is to replace them both at the same time. Replacing them both, HSI & gas valve, at the same time is a common appliance repair practice for the condition described.

The tiny gas valve you described, with the lever, is an isolation valve. That valve only controls the volume and flow of gas into the gas control valves. Fully opened is the position it must be at all times.

Opened fully, allows all the gas volume to flow into the burners gas control valve. That tiny isolation valve, opened fully is not the cause of the smaller flames to the oven burner. Either or both the HSI and/or the burner gas control valve (the part the wires are connected to) is the cause.

Additional Suggestions:
Read the manufacturers online web site for product information, problem possibilities, causes, solving methods, part locations, disassembly, reassembly methods, repair procedures, pictorials, schematics, repair and or owners manuals which may be available online.

Advertisers & Sponsors Web Sites:
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Kitchen Appliance Parts:
http://www.parts-depot.online.com

Cautionary Notes:
Before attempting any repairs, be sure to unplug the appliance from the wall receptacle power source first. Turn off the tiny isolation gas valve before removing the gas control valve.

Help Link: Range-Stove-Oven-Broiler Basic Help Information & Manufacturers Web Site Links: http://forum.doityourself.com/showthread.php?t=159808

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  #3  
Old 02-20-05, 03:31 PM
TimB
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Thanks,

Yes, I understand the small brass valve is a oven shutoff/isolation valve and not the root source of the problem; only making an observation that by closing and reopening the valve, it allows enough gas flow to ignite the oven burner assembly, leading me to believe that the igniter is hot enough to ignite the gas.

I have tried going online to Modern Maid, but didn't see any specific info on this particular stove. Will try the other websites you provided links to. I really need to see where this gas valve is physically located so I can inspect that and see if it's repairable or need to replace.

Thanks again.
Tim
 
  #4  
Old 02-20-05, 06:15 PM
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Tim

The gas control valve I am referring to is located at the end of the burner tube. The part is rectangular and has the two wires attached to it. Burner tube has to be removed from the orifice on the gas control valve.

The gas control valve, the supplies gas to the burner, is NOT a repairable part. Replace it only. Likely to need the brass or bronze orifice on it. While replacing that part, replace the HSI also.

TIP:
When removing the orifice, first, count the number of turns DOWN it takes to bottom out. Write that number down on the control valve. Than remove the orifice. When installing the orifice onto the new valve, thread it until it bottoms out, then open it to the number of turns it took to bottom it out on the removed old valve. Doing this helps to ensure a reasonably accurate burner flame size like the current valve is presently set at.
 
  #5  
Old 02-20-05, 10:36 PM
TimB
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Wink

Hey, thanks again!

Just a follow-up here as its Sunday. I browsed the links that you provided and one of them shows an illustrated parts breakdown (IPB) of sorts for a Maytag oven. It must be the same model (PHU-185) stove only with a different name on it.

Anyway, I was able to use that and locate my "dual gas valve" after taking the top portion of the stove off. Got thinking after seeing it and took some voltage checks at the electrical connections before and after the switches were turned selecting each respective igniter. Now, I'm thinking that the problem has to be either the gas valve not opening enough or the electrical side not sending the signal to open the valve, so...

A continuity checked showed the wiring to be sound between the igniters and the gas valve. Noting the circuit schematic, I see that the 120vac 60hz is stepped down at transformer (T1) on the circuit card. Though the schematic doesn't show it, I believe the stepped down voltage is approximately 3.0vac.

I noted the following: With the oven set to "off", I was reading zero volts at both igniter outputs, measuring these points at the gas valve connectors. That's a violet wire for the 'bake' and a brown wire for the 'broiler'.

Trying the broiler operation first as I know that works, I turned the switch to broiler and the other one to either broiler or any temperature and the voltage increased to 2.9vac and eventually went up to 3.15vac once the igniter came up to full burn. Keep it mind the igniter is nothing more than a big resistor in the circuit. The gas came on (through the dual gas valve) and ignited the broiler burner. Once I turned it off, or it reaches a preset temperature, the circuit opens and the gas stops and the voltage goes back to zero.

On the 'bake' cycle however, the voltage increased from zero to 2.7vac and even after being on for a few minutes only increased slowly to 2.92vac max. The oder of gas is noticable after a couple of minutes, so my thinking is that the gas valve must be opening at least a bit.

Now, comes the idea that "if" the bake igniter is bad (the resistor's circuit resistance has increased and is now dropping more voltage across the igniter) and not allowing enough voltage through to fully open the gas valve, then it could explain why the gas flow is not enough to ignite the burner initially, but just enough to leak enough gas by to give the smell. Not sure what these gas valves are rated at and if the tolerances would be that close, but if the valve is rated for 3.0vac minimum to open the valve, then at 2.9vac, the valve may be starting or trying to open but there just isn't enough voltage to fully actuate the valve???

I guess I could pull and isolate the bake igniter and do an ohm check to see how much resistance I get, but it may be just as easy to replace it as you suggest and go from there. For the meantime, based on what I see this afternoon and considering the cost of a new gas valve, I will hold off for now and try the igniter assembly first. I actually have a better feeling that the gas valve may be okay after seeing the voltage differences.

Any additional comments, specs on these valves, or suggestions appreciated! Thanks so much for the links and the time.
Tim
 
  #6  
Old 02-22-05, 05:58 PM
TimB
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Thumbs up Status Update/Topic Closed Out

Just closing this out. The ignitor fixed the problem.

FYI, anybody following this thread or coming across it in the future; The dual gas valve discussed above requires 3.0 amps to open for either bake or broil cycles. Mine was showing only 2.68 amps after the heating element was hot, and though close, was not enough to fully open the gas valve as suspected above.

On the cycling of the small isolation/shutoff valve below that was giving me a momentary jet of gas enough to ignite the burner but not enough to maintain or re-ignite the burner again; this was due to the pressure differential in the gas valve assembly and mattered not for this problem, but might help in diagnosing a bad valve for someone else.

**SAFETY NOTE** If you check the amps (AC), make sure your meter has that capability as some only check (DC) amperage. You also have to put the meter in series in case you forgot, so just undo one end of the ignitor wire (wirenut) and clamp your meter on the two ends in case somebody didn't know this.

Also, the ignitor tip is VERY fragile, so don't touch it or bang it into anything like the little metal shield or you'll be buying another one!! Also, check into the smaller (and much cheaper) igniters that are only a couple of inches long. They are supposed to work in place of these longer ones and might save you $20.00+ a pop. Also, parts for Amana/Maytag/Modern Maid are pretty much the same provided the model number is the same.

Thanks again to those that helped on this.
Tim
 
 

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