H/K T30C

New Member
Thanks to BlueGlow Electronics' wonderful video on servicing the Harman/Kardon 330c receiver, my dad and I were confident enough to buy one that needed some work.

Yesterday we started working on it and everything was going fine. We cleaned all the pieces, deoxidized all the pots, and managed to pull the glued screen part off with nothing but a hairline crack by one of the screws. We even used two spoons to get the knobs off safely. All of the lights except one were burnt out, so I ordered LED fuse style lights for it as well.

This is where we started to have some issues. The stereo logo light, the power button light, and the light behind the meter were all dead. So we managed to take off the piece holding in all the sockets for the fuse style lights, to find that it gave us access to the stereo light and the meter light too. The meter light is just a fuse-style light so we’ll just throw an additional LED fuse-style one in there and it’s good to go. The issue is when we put the one working bulb that came with it into the meter’s spot to see what it looked like lit up, we did not want to fully screw the plate back on (it was pretty hard to get off). We held it in place somewhat carefully, but when we turned it on nothing lit up. Later we realized that some of the sockets for the other faceplate lights may have been touching the metal while we did this.

Now when we turn it on, even after screwing it back on as it was, none of the light sockets get any voltage across them. We took some readings just to be safe and we know that our working bulb has continuity, the switch has continuity, and all the fuses on the inside have continuity too. When measuring the voltage through those fuses once it’s on, only the outermost one has any voltage running through it.

We have not air dusted the inside or used contact cleaner, because we didn’t have any at the time. Any clue what the issue could be? We’re lost and too stubborn to take it to a repair shop.

Also, the little bulbs for the stereo light and the power button are just 8 or 9v bulbs (I think 30-50ma too). Does anyone know where I could buy two LED equivalents to those lights (or if I should just use standard 3v LEDs scaled down using a resistor)? My dad and I looked online for awhile and we were having some trouble finding them (especially in white color). I think it would be easy to make our own because regular LEDs fit in those spots just fine based on our testing.
 
Have you looked at the schematic from the service manual at hifiengine.com and traced back from the non/lighting lamps to the source of power for them?
 
Have you looked at the schematic from the service manual at hifiengine.com and traced back from the non/lighting lamps to the source of power for them?

yeah so we tested the housing for the lamps and found that they are getting no voltage. We also checked the fuses in it and found only one was getting voltage. We did our best to read the service manual but we are having trouble figuring out what to test next exactly. We have very little experience with this stuff

all the fuses and switches have continuity. Same with our one working bulb we've been testing with
 
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No worries! You guys are doing the right thing by asking questions.

Looking at page 14 of the service manual from hifiengine, are the lamps that are out those shown in page 14?
 
If those are the non-working lamps then you should remove fuse FU1 and measure its resistance. Infinite resistance would mean a blown fuse.
 
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