Kenwood KR-9600 LED question

Hi All. I have a Kr-9600 that i'm in the middle of restoring. I had a question regarding adding LEDs to this amp..

I'm electronically inclined as far as most solid state and soldering. However I've never messed with LEDs and want to make sure I do it correctly. Some of the bulbs are burned out and figure while im restoring this I might as well switch it over to LEDs.

Was curious if somebody can tell me how to go about doing it. I know you need a resistor for a LED and I know about the R=v1-v2/I formula. I just wasnt sure if I can go about adding a LED and resistor to each of the bulbs or if their hooked up in series or is each bulb in this unit running independently?

I'll use the 4 meters in this amp as an example. If I were to add 4 LEDs, do I need 4 resistors? I was looking at LEDs that are 3.8V 20ma, if I follow that formula, it's 8V for V1(supply voltage) 3.8V for V2(LED voltage) and my formula would be 8-3.8/.02 which would require a 210ohm resistor per led?

And then the same logic for all the indicators? Sorry for my lack of knowledge regarding LEDs, I was hoping somebody could give me a better insight on how to add LEDs to this amp and what I need to do to.

Thanks,
Frank

Have not changed to LED's on my KR9600, stayed with the factory look.
This link is pretty easy to work with;

http://led.linear1.org/led.wiz

It seems that with LED lighting it is a bit hard to determine the color tone beforehand, to harsh, to bright etc.

Kenwood wizard EchoWars has posted a lot of upgrades, mods and tired component tips in the AK forums. AK member Dgwojo has the bulb (LEDs ?) thing down; http://www.dgwojo.com/. Good luck.

I just installed some white LEDs in a KA 9100, They were way too blue, didn't come close to matching the 8300 tuner. I recommend using the "warm" white bulbs. If this was a Marantz I'd say use the regular white. I used 220 ohm resistors a 1n4004 and a 10mm led. not sure of the specs of the led anymore.

Did you use 1 resistor per led? I assume you have to. I got the schematic and seen its 8volts on the rail to each of the current bulbs. Some of the stock bulbs are burned out and some you have to tap the front of the unit for them to work. Leds would be a cool upgrade. Ill have to try it. I agree white is prob the way to go.

The tuner backlight and the meters need something larger than the standard 5mm LED. They also need an LED with maximum dispersion.

At Superbrightleds.com, the 8mm 360° LED works well for the meters and the tuner backlights. Part number RL8-W110-360. These lamps run off of 8Vrms AC. Use about 240 ohms total (two 1/2W 120Ω resistors, one on each lead) for each LED on the meter LED's, and 200 ohms total (two 100 ohm resistors) on the tuner backlights. Digikey has some amazingly small 1/2W resistors by Vishay BC Components. 100 ohm would be PPC100XCT-ND, and 121 ohm would be PPC121XCT-ND.

The indicator lamps are run from a DC supply, so orientation is important (install one of these backwards and it won't work...flip it around and you're OK). First off, the 'Stereo' indicator looks best if it's red. I use a 5mm water clear red LED for the stereo indicator, part number 67-1612-ND. For current limiting on this one, just change Rk10 on the Power Supply (A) board (X00-1830-10) from the stock 39 ohm 1/4W to a 1.2K 1/2W. The leads on these LED's are too hard to bend around like the thin wires on the original incandescent lamps, so I clip them off and solder on thin leads from some 1/4W resistors.

The rest of the indicator lamps should all be white. In the past, I've been getting these LED's from eBay seller 'whsh94a' (he'll also sell you an entire kit for a 9600 if you don't want to fool with all of this resistor nonsense yourself). For these lamps, white LED's are appropriate. Use the RL5-W15120 from Superbrightleds.com. These have a good dispersion angle, but I don't know a good resistor value. Too bright will wash out the lettering and look bad. I'd suspect that a starting point might be about 750 ohms (6mA, using a supply voltage of 8V and a Vf of the LED of 3.3V).

The same DC supply also actuates the protection relay. On power-down, the current draw from the indicator lamps is used to kill the protection relay. The reduced current draw of the LED's will cause the relay to remain closed on power-down for too long. The solution is to add a 220 ohm 1/2W resistor in the unused capacitor space next to Cq2 on the Relay Board (X13-2400-10).

Again, the easiest way to deal with all of this is to simply contact the eBay seller mentioned above and order the necessary parts. Beyond that, I've pretty much told you all I know about adding LED's to the 9600.

Perfect! Thanks echo! I appreciate it.

Just an update to this thread. I have upgraded my 9600 to the LEDS as mentioned by Echo. Came out great. Photos below. I still have to add the resistor to the replay board as mentioned, there is a 1-2 second delay before the amp clicks off. But this restoration project is pretty much done.

Picture below of the leds. I still may replace the glass piece with the dial numbers on it. Theres a couple scratches on it and the LEDs illuminate the flaws more.

But it's more or less complete now. Thanks to Glenn, the guys on ebay I dealt with in restoring this thing and to the guy who made the LEDs. Appreciate all the help, works and sounds awesome!