After my own holy war with this center console problem on my 2004 TSX, I think it's a good idea to document my findings and solution for future users. This is especially true since new PCBs are no longer available for purchase, and the refurbished ones are "quirky" at best. I'd like to clarify that there are usually two separate but related problems (or symptoms). The first issue involves what I call the "button backlights". These backlights illuminate the buttons for the center console; i.e. the controls for both the radio and HVAC system. Under normal operation, they only get illuminated when your twist the headlight switch to either the 2nd or 3rd position. The second issue is what I call the "display backlights". These backlights illuminate the 3 LCD displays; one each for the clock, radio, and HVAC. The display backlights should always be on, but will change intensity when the headlight switch is into position 2 or 3 based on how the intensity knob (next to your fuel gauge) is set. From what I gather, if the display backlights go out so do the button backlights. However, it's a more common problem if just the button backlights go out.
---
My history with this problem (feel free to skip this part) begins maybe about 10 years ago (roughly 2012-ish) when the button backlights would not work for about the first 30 minutes within activating them. After the ~30 minutes, they would eventually come on. Eventually within the year, they stopped coming on completely. It didn't really bother me that much since my display backlights still functioned and I got pretty good at stabbing at the correct buttons during nighttime driving. Then in 2020, my CD changer, which I still use a lot (don't judge me!), jammed up and was no longer functioning. This prompted me to purchase a full radio off the used market and put it in myself. I knew it would be a gamble that the button backlights would work on a used unit, but it turned out I got lucky and all the backlights and CD changer worked. Well...not too lucky because the CD changer in that unit jammed 2 months later. I bought another used unit and when summer came around again (working on cars in Chicago winter is no bueno), I swapped just the CD changer section since I knew my current PCB had working backlights and didn't want to gamble that part again. Well.......that CD changer jammed on me after only a couple weeks. I was starting to get sick of pulling the radio out so frequently and breaking off clips in the process, so I gave up on testing my luck at used radios. I eventually found a new-old-stock 2005 TSX radio, and transplanted that CD changer into my 2004 radio. It ended up working great and I was super happy. Then...a couple weeks ago the display backlights and button backlights all went dead. I bought a flashlight I could shine into the displays to see if the heat was on and what track of what CD I was currently playing. I was kind bummed out because I didn't want to have to spend the whole Chicago winter using that stupid flashlight all the time.
---
Anyway, when I was constantly swapping parts, I noticed the heat damage on the PCB and in the back of my head I would always think that eventually this will need to be fixed properly. Well...this was finally the time for that. I got lucky with a 55°F day coming up in the forecast. I dug out the PCB for my OG stock radio (I held onto it) which had the button backlights burned out and began ordering parts for a "throw the kitchen sink at" type of fix for it. Based on other users on this thread and other similar threads, I started by looking for a non-obsolete replacement for "the transistor". This is Q705 on the PCB and it's supposed to be a Panasonic 2SB13980PA PNP transistor. I found the onsemi KSB1151YS to be a suitable replacement. It's a little taller but still would clear the CD changer above it. It also has more surface area which facilitates installing a small heatsink on it. I did a similar replacement for the NPN transistor also in the heat damaged area; Q766 (Panasonic 2SD22490QA) replaced with the onsemi KSD1691GS. Because the heatsinks can make contact with the steel plate nearby, I also added for each transistor some ARCTIC MX-4 thermal paste to the side of the heatsink which makes contact with the plate (see photo below).
I was skeptical of the 4 large semiconductors which make contact with the big screw-on aluminum heatsink, so I looked them up. The two smaller ones are voltage regulators (BA41W12ST and BA61W12ST) and have internal protections for overcurrent, overvoltage, and thermal shutdown so I think those are fine. The two giant ones (Q761 and Q763) are Panasonic 2SD17050P NPN transistors. Since they have no internal protections, I wanted to replace them just in case. They are obsolete, but I was able to find a bag of new-old-stock on eBay (at the time). Regardless, I added some of the same ARCTIC MX-4 thermal paste to the faces of all 4 of these semiconductors which make contact with the big aluminum heatsink (see photo below).
I had a few ideas on what to do with the resistors. I first thought of double-stacking 1206 size resistors but it was hard to find the resistors in stock at double the value (you need 2x the value when doing parallel resistor stacking). I saw others hack-in axial through-hole resistors instead of the chip resistors, but I didn't like this idea as it gets cluttered easily and a car is a high vibration environment. I didn't want to use a glue/epoxy to secure those. So I went with using high-wattage "anti-surge" 1206 resistors from Vishay. I replaced all 1206 sized resistors within the heat-damaged area; 24 on top and 4 on bottom for a total of 28 resistors. I did one extra quirk too. R702 is a zero ohm jumper and the copper around it looked kinda heat damaged. R703 is normally unpopulated and it runs parallel to R702 so I decided to stuff R703 with its own zero ohm jumper. This allows the copper around R703 to be used for high current, helping alleviate the original path for R702. So if you count that, then it's 29 total resistors installed.
The official replacement PCBs from Honda for the service bulletin and the 2005 TSX radio both include a thermal gap filler pad on the bottom of the PCB to kiss off heat to the steel chassis. To duplicate their solution, I measured a 55mm x 30mm rectangular area for the heat damage and experimented with 3 different thicknesses of Laird Tflex B200: 0.150", 0.180", and 0.200". The 0.200" is too thick and makes assembly a little difficult, but can be used if necessary. The 0.150" is not thick enough and doesn't apply enough pressure to the chassis in my opinion. The 0.180" was juuuuust right. Check the photos below for proper placement. You need to stay clear of the hatched keepout area for the nearby screw-hole. I don't recommend purchasing pre-cut smaller pieces from other manufacturers and just stacking them next to each other. It's better if it's a single piece.
---
When the 55°F day rolled around I swapped in this PCB for what I hope is the final time. The button backlights work perfectly now. I also did the same fixes to the unit that got swapped out. This is the unit which had both the display and button backlights go out. One interesting thing about this unit is it looks like it has been reworked in the past (the soldering looks horrible). Also, R702 was stuffed with a 2.3A surface mount fuse which was blown and I'm guessing that's what caused the backlights to go out.Anyway, I'm hoping I can ship this to someone who can try it in their car. I don't want any money and can ship it for free (USA or Canada only). It is a full unit with the anti-theft code, but it has a jammed CD changer inside. You can just use the whole unit as-is or can swap out the PCB into whatever you already have (FYI: the code follows the PCB). I just want feedback if it worked or not, so we can finally put this issue to rest for any current and future 2004 TSX users. I guess send me a message with your address if anyone's interested??? (UPDATE: offer already taken)
---
Based on my experience with this issue, the other posts on this forum, and my engineering intuition...I speculate the following to be true. The resistors overheating and failing is what's causing the button backlights to go out. I believe when the display backlight goes out, some kind of semiconductor (or R702/R703) switching/controlling current into those resistors gets fried. For what it's worth, none of the transistors I changed out for the two boards I reworked measured shorted or open (all PN junctions were functional). With overheating damage, it's hard to exactly pinpoint the problem so I still recommend changing as much out as possible. So the "throw the kitchen sink at" approach summary is below, listed it in order of what I believe is most critical.
1.) Replace resistors with high-wattage equivalents:
Here is the BOM (bill of materials) for the resistors. I provided links to both the 5% and 1% tolerance versions purely for stocking reasons. The tolerance doesn't matter so either can be used. Feel free to use Octopart to see other distributors' stock.
0Ω x 2: R702, R703
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12060000Z0EAHP/2222404
4.7Ω x 12: R823, R824, R825, R818, R819, R820, R760, R762, [R821, R822, R826, R827] (bottom side of PCB)
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12064R70JNEAHP/2222462
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12064R70FKEAHP/2227497
5.6Ω x 1: R761
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12065R60JNEAHP/2228096
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12065R60FKEAHP/2227506
6.8Ω x 6: R763, R767, R764, R772, R773, R774
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12066R80JNEAHP/2228098
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12066R80FKEAHP/2227516
10Ω x 1: R756
https://www.digikey.com/en/products/detail/vishay-dale/CRCW120610R0JNEAHP/2222464
https://www.digikey.com/en/products/detail/vishay-dale/CRCW120610R0FKEAHP/2222408
12Ω x 2: R757, R758
https://www.digikey.com/en/products/detail/vishay-dale/CRCW120612R0JNEAHP/2228103
https://www.digikey.com/en/products/detail/vishay-dale/CRCW120612R0FKEAHP/2227542
680Ω x 1: R775
https://www.digikey.com/en/products/detail/vishay-dale/CRCW1206680RJNEAHP/2228140
https://www.digikey.com/en/products/detail/vishay-dale/CRCW1206680RFKEAHP/2222426
1.5kΩ x 4: R750, R751, R752, R753
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12061K50JNEAHP/2228147
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12061K50FKEAHP/2222436
I whipped up a quick assembly drawing in MSPaint to show where everything goes on the top side of the board. The bottom is pretty straightforward since it's only the four 4.7Ω resistors.
Here are some photos of the board both before and after replacement. Unfortunately, resistor manufacturers have recently started to remove resistor code markings from the top so it's hard to see which is which.
2.) Add thermal gap filler pad:
The recommended pad material is the Laird Tflex B200 with a thickness of 0.180". It only comes in full sheets of 228.6mm x 228.6mm, so you have to buy the full sheet and cut out the required 55mm x 30mm section. The part number for the sheet is A17916-18.
For cost savings, you can try cutting up two pieces of this alternate part to cover the entire 55mm x 30mm area. It won't be as effective as using a single piece, but likely good enough and a much better option than not using anything.
Here are photos showing the proper placement of the pad. You need to stay clear of the hatched keepout area for the nearby screw-hole.
3.) Replace Q705 & Q766 and add small heatsinks:
Q705 PNP transistor KSB1151YS
https://www.digikey.com/en/products/detail/onsemi/KSB1151YS/1052006
Q766 NPN Transistor KSD1691GS
https://www.digikey.com/en/products/detail/onsemi/KSD1691GS/1051421
I used these 8.8mm x 8.8mm x 5.0mm heatsinks with a built-in thermal pad from Amazon.
https://www.amazon.com/gp/product/B08ZMTN8CH/
And the ARCTIC MX-4 thermal paste I also got from Amazon.
https://www.amazon.com/gp/product/B08VN345D4
Photo of transistors and heatsinks installed below. Notice the thermal paste between the heatsinks and steel plate.
4.) Add thermal paste to the 4 big semiconductors
Same link for the ARCTIC MX-4 thermal paste as above
https://www.amazon.com/gp/product/B08VN345D4
Photo of thermal paste applied before installing big aluminum heatsink.
5.) Replace Q761 & Q763
Both are Panasonic 2SD17050P NPN Transistors. This is the least critical item and likely not necessary, especially since they are difficult to find now:
https://www.digikey.com/en/products/detail/panasonic-electronic-components/2SD17050P/972165
---
My history with this problem (feel free to skip this part) begins maybe about 10 years ago (roughly 2012-ish) when the button backlights would not work for about the first 30 minutes within activating them. After the ~30 minutes, they would eventually come on. Eventually within the year, they stopped coming on completely. It didn't really bother me that much since my display backlights still functioned and I got pretty good at stabbing at the correct buttons during nighttime driving. Then in 2020, my CD changer, which I still use a lot (don't judge me!), jammed up and was no longer functioning. This prompted me to purchase a full radio off the used market and put it in myself. I knew it would be a gamble that the button backlights would work on a used unit, but it turned out I got lucky and all the backlights and CD changer worked. Well...not too lucky because the CD changer in that unit jammed 2 months later. I bought another used unit and when summer came around again (working on cars in Chicago winter is no bueno), I swapped just the CD changer section since I knew my current PCB had working backlights and didn't want to gamble that part again. Well.......that CD changer jammed on me after only a couple weeks. I was starting to get sick of pulling the radio out so frequently and breaking off clips in the process, so I gave up on testing my luck at used radios. I eventually found a new-old-stock 2005 TSX radio, and transplanted that CD changer into my 2004 radio. It ended up working great and I was super happy. Then...a couple weeks ago the display backlights and button backlights all went dead. I bought a flashlight I could shine into the displays to see if the heat was on and what track of what CD I was currently playing. I was kind bummed out because I didn't want to have to spend the whole Chicago winter using that stupid flashlight all the time.
---
Anyway, when I was constantly swapping parts, I noticed the heat damage on the PCB and in the back of my head I would always think that eventually this will need to be fixed properly. Well...this was finally the time for that. I got lucky with a 55°F day coming up in the forecast. I dug out the PCB for my OG stock radio (I held onto it) which had the button backlights burned out and began ordering parts for a "throw the kitchen sink at" type of fix for it. Based on other users on this thread and other similar threads, I started by looking for a non-obsolete replacement for "the transistor". This is Q705 on the PCB and it's supposed to be a Panasonic 2SB13980PA PNP transistor. I found the onsemi KSB1151YS to be a suitable replacement. It's a little taller but still would clear the CD changer above it. It also has more surface area which facilitates installing a small heatsink on it. I did a similar replacement for the NPN transistor also in the heat damaged area; Q766 (Panasonic 2SD22490QA) replaced with the onsemi KSD1691GS. Because the heatsinks can make contact with the steel plate nearby, I also added for each transistor some ARCTIC MX-4 thermal paste to the side of the heatsink which makes contact with the plate (see photo below).
I was skeptical of the 4 large semiconductors which make contact with the big screw-on aluminum heatsink, so I looked them up. The two smaller ones are voltage regulators (BA41W12ST and BA61W12ST) and have internal protections for overcurrent, overvoltage, and thermal shutdown so I think those are fine. The two giant ones (Q761 and Q763) are Panasonic 2SD17050P NPN transistors. Since they have no internal protections, I wanted to replace them just in case. They are obsolete, but I was able to find a bag of new-old-stock on eBay (at the time). Regardless, I added some of the same ARCTIC MX-4 thermal paste to the faces of all 4 of these semiconductors which make contact with the big aluminum heatsink (see photo below).
I had a few ideas on what to do with the resistors. I first thought of double-stacking 1206 size resistors but it was hard to find the resistors in stock at double the value (you need 2x the value when doing parallel resistor stacking). I saw others hack-in axial through-hole resistors instead of the chip resistors, but I didn't like this idea as it gets cluttered easily and a car is a high vibration environment. I didn't want to use a glue/epoxy to secure those. So I went with using high-wattage "anti-surge" 1206 resistors from Vishay. I replaced all 1206 sized resistors within the heat-damaged area; 24 on top and 4 on bottom for a total of 28 resistors. I did one extra quirk too. R702 is a zero ohm jumper and the copper around it looked kinda heat damaged. R703 is normally unpopulated and it runs parallel to R702 so I decided to stuff R703 with its own zero ohm jumper. This allows the copper around R703 to be used for high current, helping alleviate the original path for R702. So if you count that, then it's 29 total resistors installed.
The official replacement PCBs from Honda for the service bulletin and the 2005 TSX radio both include a thermal gap filler pad on the bottom of the PCB to kiss off heat to the steel chassis. To duplicate their solution, I measured a 55mm x 30mm rectangular area for the heat damage and experimented with 3 different thicknesses of Laird Tflex B200: 0.150", 0.180", and 0.200". The 0.200" is too thick and makes assembly a little difficult, but can be used if necessary. The 0.150" is not thick enough and doesn't apply enough pressure to the chassis in my opinion. The 0.180" was juuuuust right. Check the photos below for proper placement. You need to stay clear of the hatched keepout area for the nearby screw-hole. I don't recommend purchasing pre-cut smaller pieces from other manufacturers and just stacking them next to each other. It's better if it's a single piece.
---
When the 55°F day rolled around I swapped in this PCB for what I hope is the final time. The button backlights work perfectly now. I also did the same fixes to the unit that got swapped out. This is the unit which had both the display and button backlights go out. One interesting thing about this unit is it looks like it has been reworked in the past (the soldering looks horrible). Also, R702 was stuffed with a 2.3A surface mount fuse which was blown and I'm guessing that's what caused the backlights to go out.
---
Based on my experience with this issue, the other posts on this forum, and my engineering intuition...I speculate the following to be true. The resistors overheating and failing is what's causing the button backlights to go out. I believe when the display backlight goes out, some kind of semiconductor (or R702/R703) switching/controlling current into those resistors gets fried. For what it's worth, none of the transistors I changed out for the two boards I reworked measured shorted or open (all PN junctions were functional). With overheating damage, it's hard to exactly pinpoint the problem so I still recommend changing as much out as possible. So the "throw the kitchen sink at" approach summary is below, listed it in order of what I believe is most critical.
1.) Replace resistors with high-wattage equivalents:
Here is the BOM (bill of materials) for the resistors. I provided links to both the 5% and 1% tolerance versions purely for stocking reasons. The tolerance doesn't matter so either can be used. Feel free to use Octopart to see other distributors' stock.
0Ω x 2: R702, R703
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12060000Z0EAHP/2222404
4.7Ω x 12: R823, R824, R825, R818, R819, R820, R760, R762, [R821, R822, R826, R827] (bottom side of PCB)
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12064R70JNEAHP/2222462
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12064R70FKEAHP/2227497
5.6Ω x 1: R761
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12065R60JNEAHP/2228096
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12065R60FKEAHP/2227506
6.8Ω x 6: R763, R767, R764, R772, R773, R774
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12066R80JNEAHP/2228098
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12066R80FKEAHP/2227516
10Ω x 1: R756
https://www.digikey.com/en/products/detail/vishay-dale/CRCW120610R0JNEAHP/2222464
https://www.digikey.com/en/products/detail/vishay-dale/CRCW120610R0FKEAHP/2222408
12Ω x 2: R757, R758
https://www.digikey.com/en/products/detail/vishay-dale/CRCW120612R0JNEAHP/2228103
https://www.digikey.com/en/products/detail/vishay-dale/CRCW120612R0FKEAHP/2227542
680Ω x 1: R775
https://www.digikey.com/en/products/detail/vishay-dale/CRCW1206680RJNEAHP/2228140
https://www.digikey.com/en/products/detail/vishay-dale/CRCW1206680RFKEAHP/2222426
1.5kΩ x 4: R750, R751, R752, R753
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12061K50JNEAHP/2228147
https://www.digikey.com/en/products/detail/vishay-dale/CRCW12061K50FKEAHP/2222436
I whipped up a quick assembly drawing in MSPaint to show where everything goes on the top side of the board. The bottom is pretty straightforward since it's only the four 4.7Ω resistors.
Here are some photos of the board both before and after replacement. Unfortunately, resistor manufacturers have recently started to remove resistor code markings from the top so it's hard to see which is which.
2.) Add thermal gap filler pad:
The recommended pad material is the Laird Tflex B200 with a thickness of 0.180". It only comes in full sheets of 228.6mm x 228.6mm, so you have to buy the full sheet and cut out the required 55mm x 30mm section. The part number for the sheet is A17916-18.
For cost savings, you can try cutting up two pieces of this alternate part to cover the entire 55mm x 30mm area. It won't be as effective as using a single piece, but likely good enough and a much better option than not using anything.
Here are photos showing the proper placement of the pad. You need to stay clear of the hatched keepout area for the nearby screw-hole.
3.) Replace Q705 & Q766 and add small heatsinks:
Q705 PNP transistor KSB1151YS
https://www.digikey.com/en/products/detail/onsemi/KSB1151YS/1052006
Q766 NPN Transistor KSD1691GS
https://www.digikey.com/en/products/detail/onsemi/KSD1691GS/1051421
I used these 8.8mm x 8.8mm x 5.0mm heatsinks with a built-in thermal pad from Amazon.
https://www.amazon.com/gp/product/B08ZMTN8CH/
And the ARCTIC MX-4 thermal paste I also got from Amazon.
https://www.amazon.com/gp/product/B08VN345D4
Photo of transistors and heatsinks installed below. Notice the thermal paste between the heatsinks and steel plate.
4.) Add thermal paste to the 4 big semiconductors
Same link for the ARCTIC MX-4 thermal paste as above
https://www.amazon.com/gp/product/B08VN345D4
Photo of thermal paste applied before installing big aluminum heatsink.
5.) Replace Q761 & Q763
Both are Panasonic 2SD17050P NPN Transistors. This is the least critical item and likely not necessary, especially since they are difficult to find now:
https://www.digikey.com/en/products/detail/panasonic-electronic-components/2SD17050P/972165