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HK 630 Receiver - FM Issues and Amp Adjustments

Go ahead and replace the MC1307P, but leave Q301 uninstalled for the first test. The stereo lamp will not operate that way, but you should get audio through - both mono and stereo. I like the idea of the socket.
 
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Ylli said:
Go ahead and replace the MC1307P, but leave Q301 uninstalled for the first test. The stereo lamp will not operate that way, but you should get audio through - both mono and stereo. I like the idea of the socket.
Click to expand...
We have success! :) I have audio on FM and FM stereo settings, and the reception is definitely in stereo. Q301 is still disconnected, as instructed above. Is there anything I should test or check before connecting it back up?

Top IC Side.jpg
 
It still concerns me a bit that you had +19 volts on the base of Q301, so..... Remove the new IC from the socket, and install the new transistor. (I assume you got a new one, if not, then reinstall the old) Use caution to get the right transistor leads into the right holes . The flat on Q301 should be as shown.

Power up and measure the voltage on pin 14 at the IC socket. It should show <0.5 volts. If it does NOT, STOP and get back to me. If it does measure <0.5, then reinstall the IC in to the socket and everything should be good to go.
Screenshot 2022-08-15 191212.jpg
 
Ylli said:
It still concerns me a bit that you had +19 volts on the base of Q301, so..... Remove the new IC from the socket, and install the new transistor. (I assume you got a new one, if not, then reinstall the old) Use caution to get the right transistor leads into the right holes . The flat on Q301 should be as shown.

Power up and measure the voltage on pin 14 at the IC socket. It should show <0.5 volts. If it does NOT, STOP and get back to me. If it does measure <0.5, then reinstall the IC in to the socket and everything should be good to go.
View attachment 2640132
Click to expand...
I did not order a replacement for Q301, since it tested good. I certainly can, and I'll get it quickly from Amazon. Getting this one back in correctly is gonna be tough; the leads were not inline with the transistor initially, and it's hard to tell where they went from my pics. I'll see what I can figure out!
 
Go ahead and try the old one, but be sure to check things with the IC removed from the socket as above - don't want you to blow out your new decoder.

Looking at your picture, the leads of Q302 (which you did not remove) look correct. It appears the base of Q301 is still soldered to the board - OK. The center lead of the transistor goes in the hole adjacent to the base and the lead of the transistor 'flying high' goes in the hole closest to the IC pin 1. The holes are in the same sequence as the transistor leads, no criss-crossing needed.
 
Ylli said:
Go ahead and try the old one, but be sure to check things with the IC removed from the socket as above - don't want you to blow out your new decoder.

Looking at your picture, the leads of Q302 (which you did not remove) look correct. It appears the base of Q301 is still soldered to the board - OK. The center lead of the transistor goes in the hole adjacent to the base and the lead of the transistor 'flying high' goes in the hole closest to the IC pin 1. The holes are in the same sequence as the transistor leads, no criss-crossing needed.
Click to expand...
We're def on the same page. I pulled Q301, straightened the leads out (how / why were they so mangled?), and reinstalled it. Voltage is less than 1mV on pin 14. I also measured Q301 with the IC removed:
Values are listed in volts as E - C - B:
Previously: 0 - 19.7V - 19.7V
Now: .1mV - 19.7V - 0
I guess it's time to install the IC, power it on, and... hold my breath. I always do, after working on electronics (and plumbing)!
 
And... we have success!
Stereo.jpg
Thanks so much for your help. This is an example of the best thing about AK - the members who take time to help others, even when it involves a bit of handholding! Next up, recapping the power supply boards, phono stage, and finally amp and preamp boards!
 
I wanted to add that I needed to replace the MC1307P on a HK930 and was relieved to find Consolidated Electronics (https://www.ceitron.com/howto.html).
The website is primitive, but they sell on ebay as ceitron (https://www.ebay.com/itm/291174309313) and are willing to ship small quantities.
I called them and got someone right away that steered me to the Zenith equivalent (221-79-01). I had 3 shipped to me for ~$35 and the first one I put in works great.
I will start future searches for parts like this with Consolidated Electronics.. :cool:
 
Oh, I think I need to confirm that I have no affiliation with the fine folks at Consolidated Electronics...
Just a grateful shopper.
 
Ylli said:
MC1307P or equivalent. Two options here - ebay has some listing, but they would all be coming from overseas. Shipping could take a long time, and some of the products shipped from China are of dubious quality. The NTE722 is an equivalent. NTE parts can sometimes be problematic, but most of the reports I have seen indicate this one works well to replace the MC1307P. I found:

https://www.ntepartsdirect.com/ENG/PRODUCT/NTE722
https://vetco.net/products/nte722-ic-fm-stereo-demodulator
https://www.electronicsurplus.com/nte-electronics-nte722-ic-fm-stereo-multiplex-demodulator
I am sure there are other sources too.
Click to expand...

Expanding on research by @Ylli :

All of the following IC chips should be functionally identical and interchangeable with the LM1307N in the HK 630 (and other units using this IC chip):

ECG722 - 27 listings on ebay right now​
MC1307P - 32 listings on ebay right now​
LM1307N - 3 listings on ebay right now​
ULN2128N - 1 listing on ebay right now​
UA767PC - 7 listings on ebay right now​

(showing number of eBay auctions to demonstrate availability and popularity of specific chip numbers)​

More equivalents and the datasheet PDF here: https://audiokarma.org/forums/index...128-ua767-ecg722-nte722-all-the-same.1070587/
 
Thomas Ryan said:
I wanted to add that I needed to replace the MC1307P on a HK930 and was relieved to find Consolidated Electronics (https://www.ceitron.com/howto.html).
The website is primitive, but they sell on ebay as ceitron (https://www.ebay.com/itm/291174309313) and are willing to ship small quantities.
I called them and got someone right away that steered me to the Zenith equivalent (221-79-01). I had 3 shipped to me for ~$35 and the first one I put in works great.
I will start future searches for parts like this with Consolidated Electronics.. :cool:
Click to expand...
Hi , i was able to grab one of these chips to repalce the MC1307P in my HK 630. I recapped the mpx board and still no stereo so bought the zenith equivalent.
Question is how does this chip orient on the board compared to the MC chip? Two images included. Original on the board and the new Zenith chip.
Does the printed text represent the correct way to place the chip. Or keeping the little half indented circle on the chip to the left?

Thanks!
 

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Ok, i'm stoked stereo is back but i will say the stereo separation is no where near my Sony 7065. I believe the previous owner cranked the VR301 and VR302 pots all the way CW (right) to maybe temporarily fix this when it broke. I had to adjust V302 CCW a bit to make the Stereo light come on and get separation. It's there but it's just not very wide. What does VR301 do? It's all the way CW. And it doesn't appear any of the L pots were touched but maybe they were. I don't have any instruments to test 19kHz tones.
Again, there is separation but when I compare it to my STR-7065 it's like standard definition vs HD.

Any tips?
 
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FYI, I decided to tackle this myself. Hooked up my Luxman FM receiver to the AUX port, tuned both to the same station. Marked all the pots on the MPX board and started slowly adjusting the 19Khz pots in increments listening through headphones. I would switch back and forth between the Luxman and the HK to compare the stereo fields.
Both 19Khz and the 38Khz pot needed slight adjustments to match the Luxman's stereo field. Sounds great now.
 
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