Ka-5500 led?

kep1113

Member
I've got a KA-5500 amp that I rescued from the "last chance" pile at GW a while back and I've been slowly but surely bringing it back from the dead. Aside from all of its other problems, every time I turn it on from cold I have to smack the top to get the meter lamp to come on. I'm sure there's a solder joint issue or some other connection problem, but I'd like to go ahead and replace this lamp with an LED. Just wondering if anyone else has done this with a similar unit. It's a 7.5 amp lamp, not sure of the specific style.

Thanks!
 
I have one of these and it had exactly the same problem. It turns out the filament in the bulb was broken at one end and would intermittantly make contact. This was difficult to figure out and I had it apart 3 times. There is just an 8V pair of wires directly from the transformer to the bulb and no other circuit for the light. I replaced the bulb with an LED and resistor by just picking a resistor so that it runs at 20ma. It worked for a while but it has since failed. From searching around, it looks like you need to include an extra diode when running an LED direcly off of AC like this. I haven't had it apart again to try this yet though. If I could find the correct bulb I would probably just replace it instead of using an LED.

Good luck!

Dave
 
thanks for the link to the lamp supplier. That will come in handy.

... and thanks for the heads-up about the diode... I didn't even consider the AC issue. Probably just get a new incandescent bulb since I don't want to hassle with figuring out a rectifier circuit.
 
I ended up getting 300ma 8v incandescents for my KA-5500, it was formerly modded with an LED but I wanted to to take it back closer to stock. They are a little larger than I imagined...do you have only 1 bulb running in yours? That's all that was here before...I was wondering if I wanted to go with 2 bulbs, one for L and one for R, if the wire coming from the transformer would have enough power for that in theory?

Replying to this post 5 years later...how did yours turn out? Any other helpful tips you can provide on the 5500 would be great!

I thought I had a significant audio problem developing but it *may* have turned out that Deoxit magically fixed everything, based on headphones testing...fingers crossed while I get the bulb buttoned up.
 
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