How many people have Dash Needles that don't work ?
03-24-03, 08:43 PM
#16
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I have a 92 sc 300 and noe of the needle lights work . I bought a used cluster that had working needles ( out of a es 300) but whe I put the new needles in my clustrer they did not work. I think the needles are not getting any power since none of them work at . However the gauages do show correct info - they just don,t light up.
03-24-03, 08:50 PM
#18
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Well, i feel there are enough people to share this info with. I have recieved the schematic for the sc400 speedo cluster and traced the circut as well as spoken to a lexus certified tech (i am not certified, just a tech) and we have determined that over 70% of the problems are NOT led related. After sitting down with him over the last weekend we have sucessfully repaired both his and my guages from non working back to full on. his flickered and half lit up, mine were totally out. Apperantly two heads are better than one.
Now, there are LED's that do go out, but this problem may be related to the OPAMP. The reason why a lot of people see guages failing due to having the needles full on is not overheating the led's, rather it is because of certain parts inside the unit dry out and/or become brittle and split.
(found some more info to include)
Now, there are LED's that do go out, but this problem may be related to the OPAMP. The reason why a lot of people see guages failing due to having the needles full on is not overheating the led's, rather it is because of certain parts inside the unit dry out and/or become brittle and split.
(found some more info to include)
Last edited by O. L. T.; 12-02-03 at 07:38 PM.
03-24-03, 08:59 PM
#19
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Further notes from my weekend with Jeff.
Statistics show the earlier model SC's cluster needles last longer than some newer models. When Lexus first designed the us models they were using only the best components inside the clusters. As production costs were on the rise and demand was overwhelming Lexus was getting electronic parts from anywhere they could get them to keep up with supply and demand after '93. these parts went inside every model of vehicle so there were PLENTY being used. Around the mid 90's Lexus used a lot of parts from a supplier that went bankrupt and those years are prone to failure even before the older models due to the substandard parts used to keep up with production and lower cost. everything about the older models sc's from the beefy larger Nak amps to the components used to build the speedo's and climates were better overall.
Statistics show the earlier model SC's cluster needles last longer than some newer models. When Lexus first designed the us models they were using only the best components inside the clusters. As production costs were on the rise and demand was overwhelming Lexus was getting electronic parts from anywhere they could get them to keep up with supply and demand after '93. these parts went inside every model of vehicle so there were PLENTY being used. Around the mid 90's Lexus used a lot of parts from a supplier that went bankrupt and those years are prone to failure even before the older models due to the substandard parts used to keep up with production and lower cost. everything about the older models sc's from the beefy larger Nak amps to the components used to build the speedo's and climates were better overall.
03-24-03, 10:09 PM
#20
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The reason why a lot of people see guages failing due to having the needles full on is not overheating the led's, rather it is because of certain parts inside the unit dry out and/or become brittle and split.
It sounds more reasonable that what you said is true based on how electronic components, especially caps, can dry out. I see where you circled, but what components in particular are you talking about? The xformers, coils, or caps? Have you narrowed it down to 2 specific components?
I saw somewhere once before where a guy had done his dash repair and replaced 2 components (I think they were transistors) on his board. Wish I could remember where that was.
Tim
03-24-03, 10:20 PM
#21
this is great stuff - - onelasttry, you are becoming the Club Lexus Instrument God! If you are right about those needles, you are gonna be getting clusters in the mail! Mine still work - but yes, I still plan to send you my climate control panel for relamping SOON - -
It'a also nice to hear that the older models are better
It'a also nice to hear that the older models are better
03-24-03, 10:24 PM
#22
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i have read the same thing, but i thought that doesn't work on our car. it only works on JDM cars.
but if it does work, did you replace caps or did you just resauder them??
but if it does work, did you replace caps or did you just resauder them??
03-24-03, 10:26 PM
#23
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first of all, is is not the diodes. when a diode fails it 90% of the time fuses closed. when this happens it allows reverse voltage which can destroy a circut , but more importantly it raises the voltage in the circut because the diode drops voltage .6 volt when working properly. when this happens, things start to burn. so no, diodes are not the problem. if they were you'd be frying a lot of things to charcoal. in almost every circut when a diode goes bad it pops fuses and if it cant pop fuses it starts burning things because of reverse voltage and increased voltage.
caps are your main concern, bad conections are your main concern. the solder tends to get cold spots over time. there are also resistors in line that must be checked. which is why i basically circled the entire area. the two TO-220 style transistors are regulators that run the main power on the board and are more directly related to other things.
My opinions differ from lexdash for a number of reasons. If i have any opinions on lexdash' views i care to voice, the one that comes to mind is how it can be suggested that the led's recieve too much voltage and overheat .... yet they last for 9 years or better. When something does go wrong, it is usually a board component and not the needle at all.
Ever sent too much voltage to something? wouldnt last 9 seconds, much less 9 years. LED's are made of silicon, it is a conductor that is either on or off. flickering indicates a board component that is failing, and it is a non silicon component.
caps are your main concern, bad conections are your main concern. the solder tends to get cold spots over time. there are also resistors in line that must be checked. which is why i basically circled the entire area. the two TO-220 style transistors are regulators that run the main power on the board and are more directly related to other things.
My opinions differ from lexdash for a number of reasons. If i have any opinions on lexdash' views i care to voice, the one that comes to mind is how it can be suggested that the led's recieve too much voltage and overheat .... yet they last for 9 years or better. When something does go wrong, it is usually a board component and not the needle at all.
Ever sent too much voltage to something? wouldnt last 9 seconds, much less 9 years. LED's are made of silicon, it is a conductor that is either on or off. flickering indicates a board component that is failing, and it is a non silicon component.
Last edited by O. L. T.; 08-16-03 at 08:12 AM.
03-24-03, 10:29 PM
#24
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Originally posted by onelasttry
Ever sent too much voltage to something? wouldnt last 9 seconds, much less 9 years. LED's are made of silicon, it is a conductor that is either on or off. flickering indicates a board component that is failing, and it is a non silicon component.
Ever sent too much voltage to something? wouldnt last 9 seconds, much less 9 years. LED's are made of silicon, it is a conductor that is either on or off. flickering indicates a board component that is failing, and it is a non silicon component.
03-25-03, 12:28 AM
#25
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As you can see from my less than wonderful drawing I whipped together, the top in red indicates a healthy voltage with a full on cycle of 1 second. The second in blue indicates a struggling voltage of only a half second on time. When components get older they only feed voltage for about 60% of the time they did when they were new. This is critical to things most especially related to lighting because there are only two components running that specific circuit. While one is on, the other is off, and they alternate. When the power output is only submitted for .6 tenths of the full second it is supposed to be on, the voltage drop turns the load (in this case the load is the led) completely off for the remaining .4 tenths of a second before it comes back on when it alternates to the other component. Guess what that looks like while you are waiting for .4 tenths of a second for the other component to turn on? FLICKER. As the condition worsens, the time difference becomes even more far apart as the component fails. Eventually, the component will completely fail and then *poof* nothing. There is not a silicone product in the entire world that does this. As I stated before silicon is either on, or off. Good or bad. When it goes, it’s gone, quickly. There is no dragging out over an extended period of time for silicon. Short and sweet, one big poof and you smell it burning.
I hope this helps everyone understand why the needles flicker over time and then cease to function eventually. I could sit up here and sell you on the idea that the deathly expensive needles are shot all to heck and your only way out is to strip everything out and redo it, but for every action there is a reason, for every reason there is a cure, and a simple basic course in electronics will teach you that the load in a circuit either fails or doesn’t fail. If the load in a circuit only works half the time, the load is good and what’s controlling it is bad.
It all seems clear now, doesn't it?
I hope this helps everyone understand why the needles flicker over time and then cease to function eventually. I could sit up here and sell you on the idea that the deathly expensive needles are shot all to heck and your only way out is to strip everything out and redo it, but for every action there is a reason, for every reason there is a cure, and a simple basic course in electronics will teach you that the load in a circuit either fails or doesn’t fail. If the load in a circuit only works half the time, the load is good and what’s controlling it is bad.
It all seems clear now, doesn't it?
Last edited by O. L. T.; 07-31-03 at 02:01 PM.
03-25-03, 12:45 AM
#27
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i changed the drawing just now, if you refresh you can see the new one. a bit better detailed. it shows the longer pause in the off voltage that displays itself to you as a flicker.
since the circut is old in these, replacing them with just one or two new high powered fresh units wil only cause problems, more failure from overpowering weak components is sure to follow, so personally i rebuild the entire circut that is within the red circles. it also means that once the repair is done, burning at full blast is not recommended.
since the circut is old in these, replacing them with just one or two new high powered fresh units wil only cause problems, more failure from overpowering weak components is sure to follow, so personally i rebuild the entire circut that is within the red circles. it also means that once the repair is done, burning at full blast is not recommended.
03-25-03, 01:18 AM
#28
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BEFORE I FORGET, i wanted to tell you NOT to handle the board without special static discarge tools. Most of the chips on the board are mosfet gated and simply touching the board can ruin it if you do not have the tools. Where you work must also be static free. laying the board down in an area such as a laminated surface or glass, as well as cloth can discharge the static and ruin the processor chips inside the unit. Nothing will work if the chips are damaged by the static electricity of your body. If you don't have the tools to do this, DON'T. You will only be setting yourself up for a major expense if you do.
