Dead_Nid

Thank you Ante, this is really nice info. I don't think I will go that deep and make new PCBs. The suggested maintenance and modifications should make things just fine. Can you provide a source (internet link,book) of documentation on the modification you suggest? And any source that I can study and learn more about power supplies as mine. Finally how can I build this multi-amp-meter that I mentioned before? I mean an ampmeter for each rail. Best regards,Nid.

Ante could you explain the benefit from the modification you suggest (caps across rectifier diodes)? I am of course aware that audio signal quality is greatly depending on the state of the console's internal circuits and that means hundreds of components like you said. But let's forget that and concentrate on the power supply that is of critical importance audio-wise in my opinion.It MUST provide very "clean" current. I think that is the quality I was refering to. Let me tell you another story now. The official spare parts manager in UK told me that the company is using LM338Ks in place of LT1083CKs because these are obsolete. That is definitely OFFICIAL. And so I did replace them. A few days later a

Helloooo! Forgot to ask about this: Is that some kind of extra filter that you suggest? By across you mean one cap in parallel with each diode? What kind of cap? The only hotspot is this. The PSU that has twice the +-17V rails was stupidly set to 220V input voltage. That made it work very hot all these years from approx. 1990 in the old studio without anyone noticing. Until one regulator finally died and then I bought the mixer in a really nice price

Ante, why do you consider the other end of the wires as the "load end" when there is a whole mixing desk with plenty of circuitry just beyond? This is the load I was refering to and you are right we must include the wires coming from the PSUs too.I've always been measuring right at the regs outputs when the console was on. If it is off then I measure about 0.3V higher in each rail, in other words the voltage drop is about 0.3V and I think this is natural. Now what would a medium load be in this case? Forgot to mention that one of the old regulators failed after 10 years or so in the previous owner's studio.That's why I got scared and decided to change all of them just in case. But I am always anxious that the old ones (LT1083CK) are better in terms of quality. I'm talking on specs (as far as I can understand them) and not that I've heard the difference in the sound or something. The LT1083CK is rated at 7,5A whereas the LM338K at 5A. Also the LT1083CK was twice the price of the LM338K. Now I can only get them at 60 euros each from a limited stock but that's not something I can afford (6 of them = 360 euro just for regulators!).Of course I still have 5 of the old ones but I am not so willing to use them. So you suggest changing caps and pots. What caps company would you recommend and why? Is there anything special one should consider when buying pots? Is there any online store (in Europe preferably) where I can find and order some premium quality electronic components? Thanx,best regards.

invalid topic, meant to be a reply on "How to make an audio console's power supply better" topic... Don't reply here.terribly sorry for the mess guys :'(

what the hell! ??? sorry I posted my reply as a new topic. I am sure I pressed REPLY!!! anyway,sorry :'( :'( :'(, if it was my fault it won't happen again...check the topic "schematics for my Soundcraft's PSUs" and we can carry on in this thread :'(

sorry for the delay, I've been searching for a scanner... So it's 3 pics in a zip. I'm sorry for the bad quality but they were send by fax to me by the service department... psu1_a = the +17V and -17V rail in the first psu ...note that the regulator for the +17V supply reads something like "LK068CK" but actually a LT1083CK was installed. I can't find anything in the internet as LK068CK. If anyone has a clue...or it might just be a printing error... psu1_b = the rest rails in the same psu psu2 = the second psu that supplies +17V and -17V, two times Also can someone tell when is the right time to adjust the output of the regulators, when they are under load (i.e. supplying the console) or not connected at all? Any other tip on adjusting? Does using a common, cheap multimeter mean that my adjusting is a failure or the true amount of voltage isn't that critical? Don't forget that we are talking "audio-sensitive-wise". Best regards to all P.S. Ante you chose right, Nid is how my friends call me.The "dead" portion is my way of expressing the fact of being tired. Anyway, how good are the Jamicons? If I were to replace all caps with some expensive ones what would you suggest? my_psus_schematics.zip

Hello everybody! This is my first post. I've been around electronics-lab for the last 2 years, occasionally reading some interesting threads but now it's time I join in. I am not an electronics guru so I am more of asking for help than giving but I will try my best. My point is on audio console's (audio mixing desk) power supplies, issues involved and ideas for improvements. I don't know if there has been relevant discussion on this subject in the past. If it has then please provide the link(s). So...I have a Soundcraft Sapphyre (any audio freak in here will know about). It is a rather medium to large desk with 34channels. The console is being supplied by 2 rackmounted PSUs. These provide the various needed voltage rails (+17V,-17V,24V,+7,5V,-7,5V,48V). Each PSU has a toroidal transformer, some rectifying diodes,some big smoothing caps,some filtering caps and some positive adjustable regulators. The regulators that Soundcraft put some 10 years ago when the unit was manufactured is Linear Technology LT1083CK (metallic K package). These regs are now obsolete and Soundcraft provides LM338K in their place. First of all I am suspecting that here we have an unpleasant compromise. I mean that even though I replaced all regs with LM338Ks and the console is working fine, the LT1083CKs must have certain qualities that make them better for audio applications. Does anyone have a clue? This is the page for LT1083CK: http://www.linear.com/pc/productDetail.do?navId=H0,C1,C1003,C1040,C1055,P1282 Do you know of any other "super duper fantastic" positive adjustable regulators of other companies that can provide voltages in the 7,5-24 volt range (in K package preferably)? And a second thing that matches my subject better. My PSUs are 10-14 years old. Some caps had dried out, they made random "bzzz" sounds on the speakers, so I replaced them. But I want to ask in general: Would I have any improvement by replacing all components on the pcb? I mean all caps, diodes, transistors, even resistors. The PSUs had Jamicon caps from factory. Does anyone know if these are any good? What caps would you recommend no matter the price? And the final most critical question: If you replace components that are equal to operation but have higher tolerances, does that matter? For example: The manufacturer has installed 10.000uF at 35V. You replace them with a 10.000uF at 40V or 63V. Is that OK or should you go for as low as it can get? Same thing with diodes. Of course I am talking about an audio PSU, not any application. Sorry for the long post. I feel we can extend this thread and share interesting thoughts about this subject that has its own special needs (at least for audiophiles!). Thank you all! ;) I can provide the schematics of my psus if needed.