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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Venerable Amana RR-10 Microwave
We love our RR-10 and are the original owners (since 1979). Chromed out
with stainless interior and digital touchpad. I do have a service manual but it does not go into detail on the digital module. The digital module in this particular model was made by Essex. Last weekend, someone used it (not personally witnessed) and the digital module (Touchmatic II) went dead. I don't know what mortal code they entered on the touchpad but it is truly dead. I have a rusty old RR-10 in the garage for parts. So, I replaced the tube thermal cutout switch (which was open) and the digital module. The rusty digital module works great but has a poor Wife Acceptance Factor. Unfortunately, the original module is still dead. As a further clue, when the the connector plug for the module is plugged in, the buzzer should chirp. The original doesn't even chirp. I took it apart and found a cap that had caused the underside of the PC board to turn color so I replaced it. I also cleaned to the contacts on an unenclosed relay, too. Still dead. Since a new digital module is $170 I was hoping to get some hints as to what would be the most likely part(s) at fault. Since whatever happened took out the thermal cutout sw, I thought there may be some kind of deductive logic that could be applied here. Thanks for any and all insights, Lar |
#2
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First, check to see if there is a rectifier diode shorted which may have
caused the capacitor to burst. Next if the capacitor caused the board to change color then you have electrolyte all over the PC board causing current leakage. Try cleaning with strong alcohol, dry it and then check for corroded solder connections. If it still won't work, its likely trashed. Larry B wrote: We love our RR-10 and are the original owners (since 1979). Chromed out with stainless interior and digital touchpad. I do have a service manual but it does not go into detail on the digital module. The digital module in this particular model was made by Essex. Last weekend, someone used it (not personally witnessed) and the digital module (Touchmatic II) went dead. I don't know what mortal code they entered on the touchpad but it is truly dead. I have a rusty old RR-10 in the garage for parts. So, I replaced the tube thermal cutout switch (which was open) and the digital module. The rusty digital module works great but has a poor Wife Acceptance Factor. Unfortunately, the original module is still dead. As a further clue, when the the connector plug for the module is plugged in, the buzzer should chirp. The original doesn't even chirp. I took it apart and found a cap that had caused the underside of the PC board to turn color so I replaced it. I also cleaned to the contacts on an unenclosed relay, too. Still dead. Since a new digital module is $170 I was hoping to get some hints as to what would be the most likely part(s) at fault. Since whatever happened took out the thermal cutout sw, I thought there may be some kind of deductive logic that could be applied here. Thanks for any and all insights, Lar -- Joe Leikhim K4SAT "The RFI-EMI-GUY" The Lost Deep Thoughts By: Jack Handey Before a mad scientist goes mad, there's probably a time when he's only partially mad. And this is the time when he's going to throw his best parties. |
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On Thu, 04 Nov 2004 16:02:07 GMT, "Larry B"
wrote: Last weekend, someone used it (not personally witnessed) and the digital module (Touchmatic II) went dead. I don't know what mortal code they entered on the touchpad but it is truly dead. I have a rusty old RR-10 in the garage for parts. So, I replaced the tube thermal cutout switch (which was open) and the digital module. The rusty digital module works great but has a poor Wife Acceptance Factor. Unfortunately, the original module is still dead. As a further clue, when the the connector plug for the module is plugged in, the buzzer should chirp. The original doesn't even chirp. Why don't you swap the good electronics onto the good chrome? The glass touch panel and all the electronics come off as a single unit. Andy Cuffe |
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"Andy Cuffe" wrote in message ... On Thu, 04 Nov 2004 16:02:07 GMT, "Larry B" wrote: Last weekend, someone used it (not personally witnessed) and the digital module (Touchmatic II) went dead. I don't know what mortal code they entered on the touchpad but it is truly dead. I have a rusty old RR-10 in the garage for parts. So, I replaced the tube thermal cutout switch (which was open) and the digital module. The rusty digital module works great but has a poor Wife Acceptance Factor. Unfortunately, the original module is still dead. As a further clue, when the the connector plug for the module is plugged in, the buzzer should chirp. The original doesn't even chirp. Why don't you swap the good electronics onto the good chrome? The glass touch panel and all the electronics come off as a single unit. Andy Cuffe I was hoping to do just that except that the second unit is actually an RR-10A. Everything interfaces the same but the module is a whole different animal inside. Same basic individual parts but the layout, boards, etc are all different. The touchpad is similar ("orangier" pads), mounting holes, 9-pin connector and switches are the same but it ends there. Thanks for your thoughts. Lar |
#5
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Larry B wrote:
There appear to be 3 identical bridge rectifiers on this board. Two are side by side and the 3rd is off doing its own thing. One of the pair is directly connected to the cap in question. Should I replace just the one or both in that group? Now the question is, "with what?". The markings are : 7839, VM 08. The mfg symbol is a sylized V (kind of like \') in a circle or it could be an A if the printed markings like 7839 are not necessarily an indicator of what is right-side up. I read somewhere that they may be half-wave rectifiers. They look more like IC's than full wave rectifiers with the terminals coming out the side and down like spider legs, and somewhat rectangular. The PC board calls them BR201, 2 and 3. I have searched Google for 7839 bridge rectifier and came up empty. Sorry I am not up on my rectifier specs. Thanks, Larry - Since your oven was new in 1979, it may be that 7839 is a date code - 39th week of 1978. How many leads on this beastie? I would expect a full-wave bridge to have 4 leads, and a half-wave to have 3. Bill |
#6
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"Bill Jeffrey" wrote in message ... Larry B wrote: There appear to be 3 identical bridge rectifiers on this board. Two are side by side and the 3rd is off doing its own thing. One of the pair is directly connected to the cap in question. Should I replace just the one or both in that group? Now the question is, "with what?". The markings are : 7839, VM 08. The mfg symbol is a sylized V (kind of like \') in a circle or it could be an A if the printed markings like 7839 are not necessarily an indicator of what is right-side up. I read somewhere that they may be half-wave rectifiers. They look more like IC's than full wave rectifiers with the terminals coming out the side and down like spider legs, and somewhat rectangular. The PC board calls them BR201, 2 and 3. I have searched Google for 7839 bridge rectifier and came up empty. Sorry I am not up on my rectifier specs. Thanks, Larry - Since your oven was new in 1979, it may be that 7839 is a date code - 39th week of 1978. How many leads on this beastie? I would expect a full-wave bridge to have 4 leads, and a half-wave to have 3. Bill :Hi Bill, it has 4 so it must be full-wave. In cruising some parts websites a popular spec is DB104. Lar |
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