Cool. I just bought and restored an HK930 this week. All new filters - 4 of them and it is an absolute beast. Thanks for turning me on to the HK bug Trevor. I picked up a little 340 today.
Watching you take apart and clean that multi-switch was not only a masterclass it was riveting. My 330B could certainly use a deep cleaning but for now that switch just gets a little extra fiddling.
I'm always impressed by the lengths you go to in restoring these obsolete pieces of equipment ! I'm also curious about your background and experience, clearly you are more than just a casual hobbyist and have had a lot of training, have you worked for any big companies designing new equipment or troubleshooting issues for them ? Your calm methodical approach is much more than just good practice and habits, it must have come from years of experience. If you have already talked about this in another video then I must have missed it but I'd be very interested to find out more !
I recently bought a 330B as my Pioneer SX-434 has some issues (no left channel in PHONO) so I'll have to take it out of service for awhile. I bought it off of eBay, which is risky but I've been very well pleased with it. I've been wanting to try a Harman/Kardon, and eventually a similarly low powered Sansui.
I've got a 330c on the bench right now, with a 430 up next. Parts, always parts. 330c is waiting on 820k resistors. 430 parts are in. Should be able to finish that one up. 730 got sidelined for a bit.
On one time you say "I replace the 100uF because some of them were up to 125uF" and on the other side you say "I replace the 2200uF with 8000uF and its much better now (or similar, dont remember)". So on one side, you dont like to have more uF, on the other side you like to have more uF, it is not consistent what you say sadly. Should a part in theory not be better if a 100uF cap has 125uF? Good receiver, I have bought a 630 with paperwork and ads and warranty card and receipt, looks very nice and all is working incl. all lamps. Very rare to have a never messed with, fully working unit. I just turned it on and it plays. No need to change the caps on those old Harman, the grey one (Elna) never failed for me. I did not even go to LED because it is such a nice working survivor. On the newer 80ies stuff, yes, but on the old 70ies stuff there is no need to change it. The newer ones leak their fluid but the old ones are better somehow in my experience. So good work but kinda not needed. But if it makes you happier, why not.
Hi Stefan, lets see if I can clear up the confusion. Power supply caps do just that, supply power for a amp of circuit. Oversizing power supply caps can give the unit a extra surplus of energy for periods of high demand during music, when it needs it. It provides better power stability and reserve for the amplifier. Generally, upsizing power supply caps is a good thing. The other part of your question deals with capacitor degradation. A 100uF capacitor from 50 years ago now measures 125uF. This is not because the capacitor has become "better" with age but rather has drifted out of tolerance and the internal DC leakage has fooled the meter to read 125uF. All of these high achievers will now have increased ESR. Old capacitors also drift with temperature, their value and ESR will change with temperature which may or may not affect the circuit, depending on circuit design. Those 50 year old Elnas are still working today but they also have drifted, likely more that the allowable 20% in value. Not only have they drifted but a small % of them have failed completely. Another problem with using 50 year old caps is the rubber seal on the can will leak. The heat/cold cycles of using a piece of vintage equipment can push the electrolyte out of the capacitor because the seal is compromised from age or heat. This happens regularly on the Panasonic caps from the 70's and 80's and you see lead corrosion and board damage. Once the seal fails on a electrolytic capacitor, it isn't expected to last long. They will dry out and capacitance will drop fast along with ever increasing ESR. Yes, old Elna caps are good, maybe the best there was for that era but they are still 50 years old and I expect they will not last much longer. I replace them mostly for preventive reasons. I cannot do a repair on a piece of gear and return it with 50 year old caps knowing that within the next few years it will be back on my bench because of one failed cap. The last thing I want is a boomerang. Enjoy your 630. Listen to it and get to know how it sounds. Then if and when you're ready to recap you'll have a good indication of how the sound improved. Sometimes the change is dramatic and sometimes not so much, it all depends on how far the caps have degraded and what circuit the cap is in. I've had clients tell me the change is dramatic, mostly. This is only my opinion and it's rooted by personal experience and not something I read on the internet. Cheers and thanks for your continued support
