I recently bought a Kenwood KR-6400 receiver in mint condition on Ebay. However, two bulbs for the FM/AM panel display were damaged in transit. I went to a local electronics parts store and bought a bulb with a similar voltage and ampere profille, as the exact matched bulb is not available. I bought only one bulb to see whether the bulb would fit in my receiver. I did succeeded in welding the wires to the bulb and the bulb was working fine. As I was short of one bulb, I tried to re-solder one of the not-working bulbs to see whether the bulb would miraculously light up. It did not light up, and, while the receiver still turned on, I touched the soldered wire to see whether the wire was well soldered to the bulb. As soon as I touched the wire, all the bulbs and the led lights went out. Luckily tthe receiver still works fine, but none of the bulbs and led lights are working now. Does anyone know how to fix this problem and bringt back my receiver to see the "light" again? Any help and advice is appreciated. Thanks.
all bulbs and led lights stop working while changing a burned bulb
- Thread starter siyagtbg
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cademan
Lunatic Member
Sinse it was on at the time (bad move), you shorted something in the power supply, and sinse I am not familiar with that model, you need to trace the wires from the bulbs, to the power supply board or circuit, and check the fuses (and fusable links) and/or diodes and resistors with a volt/ohm meter.
71Challenger
Super Member
Oh, please never stick a soldering iron into an electronics piece when it is powered up. :tears:
Bad for the gear, could be scary bad for you.
I didn't know that Kenwood had a lamp protection fuse. Good to know.
Bad for the gear, could be scary bad for you.
I didn't know that Kenwood had a lamp protection fuse. Good to know.
dan-c
Perpetual Lurker
On my Yamaha CR640 I had the unit on and touched the blue and orange wires together. Killed a diode, resistor and a capacitor. Th fuse too.
So I gguess I can say that the Yamaha's don't have protection for the lamps
BinaryMike
Pelagic EE
Some Yamaha receivers do have lamp circuit fuses. I worked on a CR-1020 with a 1A fuse in that position recently. Someone had replaced it with a 20A fuse, in an apparent attempt to overcome the symptoms of a failing rectifier. The current owner is quite lucky to have escaped power transformer failure. Please take fuse specifications seriously. Sooner or later, you'll be very glad you did!
Hi Skippy124,
Thanks for the information. I did find a 250 v 2A fuse on a board close to the power supply. I guess this must be the fuse you referred to. This fuse seems to have nothing to do with the other fuctions of the amplifier. I removed the fuse and the receiver still works fine. I will go to the electronics parts store tomorrow to see whether they carry this kind of fuse. Thanks again.
Also, thanks a lot for the quick responses from other members. I will be more careful next time!
Chengyi
update:
I bought the 250v 2A fuse and brought back the lights partially. The FM/AM display panel is now lit up except one which was burned in transit and not yet replaced with a new bulb. The FM/AM display panel bulbs are working (except for the burned one that has not been replaced yet). When I tune to FM, the bulbs for the signal and tuning meters both work, so does the stereo led light. When I tune to AM. the bulb for the tuning meter goes off. When I turn to phono 1, phono 2, aux, and mic, the led lights do not work any longer. Does anyone know any way to make the led lights work again? Thanks in advance.
Also, does anyone know what kind of bulb KR6400 uses? There is no indication of the voltage and ampere on the original bulb. The electronics parts store simply gave me a bulb (of 14.1 volts and 0.12 ampere) that is close to the size of the original bulb. It seems to be a bit less bright than the original bulb. I bought another bulb of this. However, the led wires on the receiver are too short, making it impossible to put the bulbs in the rubber wrap. I will not try to solder the bulb until I am sure the bulb is similar in voltage and ampere to the original bulb.
Chengyi
cademan
Lunatic Member
Some receivers will turn off the tuner dial lights when phono, aux, or tape is selected.
I think the electronics parts store you visited, should have inquired about the voltage before selling you a bulb. A lot of receivers use 8 volt bulbs. This is probably why your 14 volt bulbs are dimmer.
So the phono 1, 2 lights are no longer working even when switching back to tuner and then back to phono?
My Pioneer TX9100 tuner shuts off the FM center tuning meter light bulb 'cause you don't need to have the AM stations centered, just shows the signal strength.
I think the electronics parts store you visited, should have inquired about the voltage before selling you a bulb. A lot of receivers use 8 volt bulbs. This is probably why your 14 volt bulbs are dimmer.
So the phono 1, 2 lights are no longer working even when switching back to tuner and then back to phono?
My Pioneer TX9100 tuner shuts off the FM center tuning meter light bulb 'cause you don't need to have the AM stations centered, just shows the signal strength.
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Never kerfutz with speaker wires when the unit is powered on.
Never kerfutz with interconnects when the unit is powered on.
Never, ever kerfutz with the innards of a unit when it's powered on or plugged in.
interconnects, such as control wires? i shoulda read this first before kerfutzing with the new BPC i just got.
cademan
Lunatic Member
..........such as RCA jacks that connect the CD player to the amp/receiver.
i agree. those things can be... adventurous in a negative way if properly mishandled.
The Bulbs are as follows -
Dial lights 4 off - 7V 300ma (8V 300ma would also work)
Meter lights 2 off - 7V 150ma (8 V 100ma would also work)
FM Stereo light - 7V 50ma (8V 50ma would also work)
Tuning pointer - LED
The action of the lights (as far as I can make out) is
Tuning Dial lights on all the time
FM selected - tuning and signal stength meter lights on, Stereo light when tuned in to a FM stereo station and signal strength is sufficient. Tuning dial pointer light on
AM selected - only signal strength meter light on, and tuning dial pointer light also on
Other inputs selected - neither meter is lit, and neither is tuning dial pointer light.
Hope this helps
Hi Skippy124,
Thanks for the informative response again. According to your detailed description, the bulbs and led lights of my Kenwood KR-6400 seem to work fine, except for the two burned dial lights. The seller sent me a bulb of 8V 250 ma with crimp-ons and attached lead wires when he shipped Optonica SA-5205 receiver which I won from him a couple of weeks later. As this bulb is very similar to the specifications of the original bulb, I tried it on. It was lit on. But as I was not familiar with how to use the crimp-ons, the lead wires tended to get loose. And I burned 3 fuses and all the bulbs and led lights went off again, probably because the lead wires got loose or probably because the bulb of 14.4 volts and 0.12 ampere that I bought did not fit in. I bought more fuses yesterday and removed the bulb of 14.4 volts and 0.12 ampere and connected the bulb of 8V and 250 ma. Now, everything works except for one dial light bulb. I will try to buy the 7v 300ma dial light bulb online later so that there will be no dim area in the tuning panel. Again, thank you very much for your help and for everybody else who responded to my post.
Chan