HARMAN KARDON 330C - No Stereo Light or Sound?

[JB8]

HK Experts!

Very nice looking unit here, sounds excellent, very clean, quiet, FM alignment is fantastic but I'm only getting mono from the FM section - no light or stereo separation even with strong signal and antenna attached. Here's what I've done thus far:

• Controls cleaned and exercised
• VR302 replaced
• VR301 removed, tested, reinstalled
• Q302 & Q301 removed, tested and reinstalled
• C302 & C323 replaced
• No change in sound when engaging the mono button

Are there voltages I can check on IC301 to help determine if it's working properly? There are very few threads out there - or at least none I could locate - specific to this issue, so any assistance is certainly appreciated!

 

[milo63]

The VRs are adjusted with special sauce tuner equipment and once moved will probably need a pro to get back into alignment.

You can check the bulb by grounding R304 (when IC301 sees the correct inputs it gives a ground to the bulb).
Here's the deets:

 

[JB8]

That damned special sauce tuner equipment... Thanks for the deets, I'll jump in and check the bulb and voltages. I wish I could just mix up some relish, ketchup and mayo but I imagine that won't work, and there are zero pro's here on the southern Oregon coast. Thankfully, I likes to tinker, so I'll tinker, and fiddle with it and report back my findings.

Thanks @milo63 , I always appreciate the support!

 

[JB8]

Bulb worked like a champ when grounded, excellent, thanks for the hack.

Voltages, not so much, definitely some wonkiness. I associated the pins with the schematic - when looking at the IC from the top, mark notch on left, I worked the bottom row left to right, #'s 1-7, back row working right to left, 8-14. Tuned to a known stereo station, signal meter working roughly 75% of the meter. I double checked these readings as well. Also, both of the VR's, 301 & 302 are set roughly to center.

1. 11.58V
2. 4.08V
3. 6.04V
4. 8.29V
5. 8.37V
6. 12.46V
7. 0V
8. 2.74V (!)
9. 2.79V (!)
10. .08V (!)
11. 2.75V
12. 2.78V
13. 2.80V
14. .04V (!)

 

[JB8]

I swapped out C305, 306 and 307 since they were associated with pins 8, 9 and 10. No change, voltages tested the same as my last post. I then tested R305 and R307, both tested fine as well. Are any of the voltages listed in the schematic for the IC based on being on a stereo station or should these be static voltages?

Any other suggestions would be awesome, would love to rule out as much as possible before changing out the IC. And I'm convinced I can dial in the VR's even without the secret sauce tuner gear, I guess we'll see!

 

[dlucy]

Are there voltages I can check on IC301 to help determine if it's working properly? There are very few threads out there - or at least none I could locate - specific to this issue, so any assistance is certainly appreciated!

That IC often goes bad, there are a bunch of variations or compatible chips, and the data sheets are not hard to find.

You can start here: https://www.audiokarma.org/forums/i...310-lm1310-nte801-ecg801-all-the-same.785294/

 

[JB8]

Thank you, Doug, I appreciate the assist!

 

[JB8]

Just popped the new IC in, easy peasy! Powered up the unit and amazingly enough there was no secret sauce tuner equipment needed to get VR301/302 dialed, ha! Got lucky I guess! Stereo light came on as soon as I powered up the unit, nice separation, couldn't be happier.

Thanks again for helping get me to the solution quicker, you're the man!

 

[JB8]

Quick Saturday afternoon update. Putting this dude back together, just polished the face "glass" with Novus 3-stage, looking much better. But what's up with the knobs, JB8? Well, when I picked this one up it only had three of the original knobs. I remembered having this set of Cambridge Audio (?) knobs and I'm curious what your thoughts are? I like them, and I'm surprised how well they match the original knob vibe. The vibe, not the look of course.

Anyhow, fun stuff, love all the 330's!! This is my 23rd ish 330C and first IC chip failure, always learning.

 

[mea2112]

I think they look great for not being original!
If you happen to find a set of original knobs great, but if not those definitely work.
I picked up an immaculate 330C a while back for $50. Hooked it up and could not believe my ears!
If I had to get rid of all the 20 or so receivers/amplifiers in my collection with the exception of the 330C, I really wouldn't be all that upset!

 

[CT Jim]

The knobs look fine! They match each other, don’t know if they are the split type but who cares? Only one who will possibly know it is someone who owns another 330. I have a 330B but its tucked away waiting to be worked on, and I can’t tell you what knobs are on it!