FRQ

I have a Euro spec Pioneer radio which comes with an extra RDS LCD display not found on US models, model KEH-M9741ZT, part number 86120-50100

One of the two backlight incandescent bulbs is out and it's a longshot, but I was hoping someone here could tell me what type of bulb I need? I did some digging and found this thread for a 95+ Pioneer mentioning cel1464 8v 60mA bulbs: LINK.

At first glance, these might be identical to mine, anyone here that can confirm? I've added a picture of the bulb I need next to one of the incadescents found in the climate control backlighting to give an idea of scale. And while I'm at it, given the hassle involved with sourcing CEL1464s, could I just use 12V leds and underdrive them? If so, what would be the smarter choice to maintain backlight color accuracy, a warm white led with the original colored rubber boot from the incadescents or just go with green LEDs?

Backlight situation (left and right climate control bulbs and left RDS display bulbs are out):

YODAONE

Unsure what bulbs are user serviceable (twist-lock vs. solder), or for that matter still available from Toyota. On my 1999 LS400, purchased and replaced the radio LCD/baclighting assembly from Pioneer due to LCD segment failure. Climate control bulbs were twist lock...some had black bases, others white base...I think for different voltages . (?)

If replacing bulbs in your climate control, it might be necessary to unsolder about 40 solder pins of the LCD to gain access...very difficult unless you have professional tools.) (verify this) replaced climate control LCD in 1993 SC400 and bulb access requires unsoldering LCD) (If replacing your climate control display then simply cutting all the pins is an option...then heating each pin individually to extract. Then heating the pad, and using a safety pin to displace solder from through-hole. Repeat for each pin. When it cools then you slightly twist and remove the pin from through hole which is now open to accept new display pins.)

The other thing is some of the display bulbs may be rated 8V.

Probably postings on topic in this forum.
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FRQ

I'm 99% certain the climate control bulbs are user serviceable twistlocks (there are three twistlocks that sit right behind the panel). My uncertainty has more to do with the RDS display. I haven't found any info on the two soldered in bulbs. I think it's a fair bet that they are the 8V 60mA ones I mentioned, since Pioneer liked to use those in a bunch of their radios during that period. I'm hoping someone can confirm this though, it's quite a pain to keep assembling and disassembling the radio until I get it right.

Yamae

You are correct. The bulb's specification is 8V 60mA and is named "T3WT8V" Wheat bulb in Japan. But those bulbs were not available any more in Japan. There is a current control circuit between the +B and the bulb and an 8V bulb is used.

To use an LED is an alternative method to fix adding a current limiting device/resistor. The LED you showed is a mono-directional and it does not work well as the back light. You can't see what is displayed well especially at the centre part of the LCD. You need to choose an omnidirectional one. I once have tried to use variety of LEDs and found that the best way was to select white SMD LEDs mounting on a tiny board with a resistor and a wire to solder the board. You don't need to remove the LCD. Just remove the bulb to the side heating lead wires from the bottom side.

FRQ

Great information Yamae, thanks a lot. Now that I know the T3WT8V specification, using Google, I found other threads where you gave good advice and found the JKL CW85 incandescent bulbs, Mouser has them listed but not readily available.

I would be open to using LEDs, but I don't have the soldering skillset to add seperate resistors to the driver circuit and I can't imagine an SMD LED would be a perfect fit right out of the box. Is there a specific component you can recommend that would be a though-hole all-in-one solution? I'm sure there are several options given there's a reasonable amount of room to work on the PCB, but I'm no electronics wiz and a Google search yielded nothing so far.

The RDS display is only 40mm long, so I'm hopeful lighting it up evenly to the center won't be much of an issue regardless of the LED used.

EDIT: I'm still interested in finding a suitable through hole LED with integrated CRD or resistor, but after doing the legwork on the incandescents, I went ahead and ordered 20 pieces of the JKL CW85 as well and some matching color filters (always good to have in stock). Price was USD 1.25 per bulb for 20 pieces, USD 0.68 for 100-999 pieces. I ordered directly via JKL Components through e-mail (very prompt responses, filled out an order form PDF, the whole order took 5 minutes).

Yamae

Those SMD LEDs I used were named OSW5DLS1C1A. The detail can be found in the attached pdf file. I don't know the availability there in Europe but there must be similar ones in your part of the world.

This LED is not fully omni directional but it has -3dB angle 120 degrees and is quite OK when you mount it beaming to the centre part of the LCD. I am quite comfortable using a soldering iron as well as to design electronics circuits due to my job experience. If you are not quite comfortable doing so, it would be an idea to ask your friends who are good at it.

FRQ

Those seem to be easy enough to get in Europe Yamae, thanks. I do OK soldering, but given the rarity of a EU spec LS400 Pioneer stereo, I would've opted to take it to a professional. My SMD soldering guy charges USD40 per 15 minutes and to be fair, he gets a lot done in that time, but for the same price I just ordered 20 replacement bulbs with filters and shipping.

I've just bought this car, if I notice other bulbs start to fail, I will give some serious thought to just having them all replaced at once with LEDs.