Harman Kardon 330C: Changed to LEDs, now I see no lights at all.

[rs495]

Can't figure this out. Getting inside and plucking out the incandescent bulbs was a cinch, but after I yanked the third or fourth bulb, the remaining lights all died. There's no power or stereo light, LED or incandescent. I handled everything with kid gloves.

The unit seems to power up as I hear a faint sound each time, but not a single light is on.

Any suggestions?

 

[dshoaf]

We'll need a schematic link. Sounds like you've got some lights that are series connected - pull one and the others go out. You were not specific on which ones did and did not do this.

Also, be aware that some incandescent bulbs were part of the stereo decoding circuit (and related IC). It depends on the design. You'll need to help the arm-chair bench techs here at AK with pics, links and more details on what does and does not work. They'll help you figure it out, though.

Cheers,

David

 

[rs495]

Thanks David! Here are a few snapshots. It was about the third or fourth bulb in from the right side (facing front) that, when pulled, seemed to trigger a chain reaction. Coincidence perhaps. I'm concerned that I might have disjoined a solder connection when I pulled that bulb, though I was being pretty damn careful pulling all of them.

Thanks in advance for any suggestions!

 

[dshoaf]

Schematic is here. You'll find that there are 8 lights that are all hooked up in parallel that appear to be the backlights for the front panel. This doesn't include the selector switch lights that would be on separate circuits. Note that they're connected in parallel. This means that one of them can go out and the rest of them will continue to work. It doesn't sound like this is the problem you're reporting.

The biggest problem with those fuse-style lights is that they're typically mounted close to the metal or plastic frame of the dial. Check to see that there's no point where the snap-mounts for the lights are not gounding out. This would explain why you're having the problem with both the old and new lights.

Also, that mass of wires on the circuit board you've provided pictures for needs to be closely examined for a solder bridge. Just removing the circuit board will dislodge them sufficiently to cause a potential problem that didn't exist before. Ask me how I know this.

Nice pics, too!

Cheers,

David

 

[rs495]

Thanks again David. How do you know that? (kidding)

I checked the fuses, and sure enough, the one for the lights was blown. Put in two identical fuses (3A/250V), each blew in about a second. Lights came on for that second though. Got any other suggestions?

Many thanks!

 

[dshoaf]

Pull all the light bulbs then try a new fuse. You should be able to then add each light bulb back, testing that it comes on each time until the fuse blows or all the bulbs have been installed. Use the old light bulbs first. Then use the same technique to replace each bulb with a new one.

I'm suspecting that some of the LED replacements are not operating right.

Cheers,

David

 

[wmgwizard]

Some "drop in" LED conversion bulbs may place a higher load on the circuit than the original incandescents. A higher amperage fuse may be required, not drastic but maybe 50% higher.

 

[dshoaf]

Some "drop in" LED conversion bulbs may place a higher load on the circuit than the original incandescents. A higher amperage fuse may be required, not drastic but maybe 50% higher.

This might be a problem, then. Checking the power supply schematic, I see that there's also a voltage regulator also using the same winding as the display bulbs. If there's more current being drawn, then it may be affecting the operation of the circuits it drives.

To our OP, you'll need to confirm that the replacement bulbs are the same current draw as the originals. If you're popping fuses on that winding with the new LED bulbs, that needs to be checked.

Cheers,

David

 

[rs495]

Okay, it's working now. I think the power switch might have been the culprit. When I had the faceplate pulled out by a centimeter or so, the power button wasn't snapping into a firm on/off position. (No click feedback) When I screwed the faceplate back on, swapped out the fuse and powered it on, the lights stayed on.

Mystery solved, sorta. I'm sure there's a more technically precise explanation of what caused this problem; I'm no electrical engineer, alas.

Thanks to everyone for responding. Hope my problem/resolution was at least a little enlightening. No pun intended, I swear!

 

[rs495]

A little off topic, but this is my second vintage receiver. As many in these pages have noted, the 330C has a great warm sound. Given the number of devout HK 330C fans, I thought it might sound quite a bit better than my Sony STR-6046A. That isn't the case: On the same speakers, same room, same music, the lows on the HK sound a lot muddier and the highs less bright than on the 6046A. I find the "contour" (loudness?) button totally worthless on the 330C--just makes the lows even muddier.

I'm not complaining: It sounds great overall, but the sound out of that 40+ year old middle-of-the-line Sony is just life-changing!

 

[sKiZo]

Hey, it's your thread ... topic can be anything you want it to be! <G>

How's the light compare to the original incandescents now? Some feel the LEDs are too harsh compared to the warm campfire glow of the old bulbs, but I kinda like them on my Sansui QRX-9001. I went with 12v warm white super brights driven with 8 volts. No problems, and the light temp and intensity is REAL close to original.

 

[rs495]

I see no difference between the LEDs and incandescents. I made sure to order the 2700 kelvin LEDs ("warm white"). They're sitting behind black and green plastic, so I'm not sure it would have made a difference anyway.