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Dead_Nid

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Posts posted by Dead_Nid

  1. The Oberheim OB-XA, a synth from the 80's, uses the connectors on the photos to connect voice cards to the main board. I want to replace them all and am trying to source them but I don't even know their name. thanks in advance for any help!

    ps. sorry for the crappy mobile pics, but I think anyone who is familiar with such connectors will figure it out.

    post-14286-14279144459027_thumb.jpg

    post-14286-14279144460524_thumb.jpg

    post-14286-1427914446181_thumb.jpg

  2. greetings Audioguru! Hi Ante! Glad u remember me!

    Our console's PSUs were finally relieved from their pain with some great BHC filter caps and a neat job refurbishing almost everything. A big fan (a home-use one) cools them down especially on these hot summer days that they need it so much.

    Thanx a LOT for these links, they are really very helpful! I will come back when my knowledge is stronger and am preparing to build a regulator or a balanced power transformer or both!

    Meanwhile if anyone has a suggestion, sharing it would be wonderful. Especially for DIY 230V single-phase regulation.

    thanx again! take care

  3. you're kidding me! Is it such a complicated device this power conditioner thing? No one of you electricity experts ever built or planned to build one from scratch? Apart from being very interested in building one for my needs, I am also so curious to find out why conditioners (AVR whatever they are called) are so expensive even in the low Watt range. Also all these AVR advertised UPSs do anything at all to regulate the mains voltage or is it just a "theoritical" AVR?

    Sorry if i'm putting up primitive questions and sorry that I don't have the time to investigate this thing all the way by myself. I need some guidance, somewhere to start, please. Comments, links, cheers, swears...something

    Thank you all and best regards!!! Nick

  4. Happy new year to everyone!

    Haven't tried any special diodes yet. I want to ask two very newbie things that I am curious about:
    1) My PSU uses two 4700uF smoothing caps (in parallel so total capacitance is 4700x2). I am going to replace them because they are very old. But as the opportunity arises I could replace with greater capacitance. Is that better in smoothing quality (apart from space and cost issues)? Remember, this an audio mixing desk's power supply. So...I am thinking of placing 6800uF or 10000uF and that will mean a total of 13600uF or 20000uF...Even theoritically, is there any benefit as the capacitance gets higher and higher? Is there any chance that it can cause trouble instead?

    2) What about voltage ratings? I was told (by Dan Lavry) to use caps with voltage ratings as low as possible. But in some manufacturers charts I have seen that the higher the voltage rating the lower the impedance. Any clue?

    I am between BHC, Nichicon and perhaps Black Gate caps. Any suggestions?

    Thank you! Best regards and happy,creative 2006!


  5. Hi Ante, you are right. Even though I have currently no known problems I think I am trying to accomplish the most efficient, clean energy (RF free) power supply I can make for my mixing desk. Nevertheless I've read that Hexfreds give a significant performance gain in the overall sound such as better resolution and reproduction of high frequencies and dynamics. Maybe that is another hype, that's why I am trying to get other people's opinions. Thanx a lot!

    Best regards, Nid.

  6. Hi! In the rail were caps get hot I measured 21.7VDC and 0.04VAC from the rectifiers' output whereas in other rails (where caps don't get hot) the AC voltage was max 0.02VAC. These 40millivolts can't be the cause for heat in the caps, can they? Caps are within specs. Old caps were also getting hot in the particular rail. I don't think that there should be a higher current drawn from that rail than from the others (with same outputs) but I am not sure about that. It has same design but different components though. Should I replace the diodes? (current diodes are "standard recovery")

    Thanx, Nid.

  7. thanx Ante. Is this stuff nice for cleaning reel-to-reel tape recorders' heads too?


    Interesting. I am guesing that the 0 becomes some value of resistance as you rotate the knob?


    MP, what 0 ? If you mean the 0 at my rough drawing then this is the resistance at pins 2-3 at gang-1 and 1-2 at gang-2 ONLY when the pot is at the fixed center position. If I rotate it then the resistance rises with values from 0 to approx. 88K or 82K (depending on the gang).


  8. Hi Dead,
    You didn't say exactly how much the levels were different between the channels. Ten percent voltage difference is only about 1dB which isn't noticeable to your logarithmic hearing. Maybe your speakers are out-of-phase, then one that is slightly closer sounds much louder than the other. The bass will be weird too.


    Hmmm, if you mean acoustic levels I think about 2db max. My speakers were never out of phase, I mean for several years...hey I am a damned sound engineer.


    When I visit "home entertainment equipment" stores, they always have the speakers wired out-of-phase and the bass cranked-up to try to compensate for the cancellation. I can't stand hearing their amps clipping on the over-driven bass so I quickly fix the wiring, turn down the bass and leave it sounding fine. ;D


    lol...not everyone is an audio guru.


    I use "contact cleaner" for pots and switches. I think if you use "degreaser" instead then the bearings in the pot will bind and maybe squeak.


    OK. Here I have in front of me 2 spray cans. Both Philips. One is the blue "DEGREASER CLEANER", the other is the red "CONTACT CLEANER". So, the blue should be good for cleaning e.g. connectors. The red should be good for cleaning pots. Correct?


    I don't use messy WD-40 on door hinges, It attracts dirt then evaporates leaving dirt without lubrication resulting in worse squeaking. I use dry graphite powder as a hinge lubricant. It is good in locks, too.
    WD-40 makes a very good flame-thrower. Don't try it indoors! The smoke is pitch black.


    Yeah actually I am using graphite (in powder or spray can) for hinges too. I only used WD40 in the past. However I didn't know it was that "messy".


    I agree, WD40 should not be used for this purpose. We also have another similar “drug” called 5-56 which have the same effect, collecting dirt and making things worse. As I mentioned before I use video drum cleaning spray for this with some success this leaves a non sticky, dry and clean surface.
    Yes, it makes a good flame thrower too very effective when you have too many mosquito’s around. ;D


    I'll try to find and buy a "video drum cleaning spray". Is there a particular product I should check out?

    Now I am really curious...I need to get a WD40 and do some ghost-busting...Isn't there a chance it blows in your hands? ;D ;D ;D
  9. audioguru I had done the following thing which I forgot to mention:
    I fed some line level inputs (the CD input if it matters) with a constant 1KHz sine tone from a PC pro audio interface. I measured the VAC at both channels right at the input and it was exactly the same amount of a few mVolts. Then I measured VAC at the speaker outputs and found out that there was about 500mV difference with the speaker playing lower getting the fewer volts (so I can't be wrong about my ears). Then measured the outputs of the preamp and there was a respective difference. So I am sure that the unequality comes from the preamp but I am not that good to find out where exaclty without a schematic. But I think that the pots are the first to suspect, right? There are actually four 2-gang pots in the preamp section. They control bass,treble,balance,volume. I took all of them off and measured out of circuit. All show some difference in resistance between gangs but the one for the balance control was the worst.

    I am going to post schematic soon.

    Sorry for altering the initial subject of this thread but I think we had enough interesting posts on how to clean a pot (at least a carbon pot). I will personally follow the "contact cleaner without any grease" way. Products like the blue Philips degreaser spray. Definitely not going to use the WD40!!! Though it does a great job when my doors' hinges start to squeak

  10. Hi! I am measuring out of circuit of course. Now I don't think that this pot has a wiper. In the center position there is a clearing on the carbon layer like there is no carbon there. I don't know if that is called a wiper. So here is a rough drawing to help you get the picture of what I am measuring with my multimeter: (that is on center position)

    PINS->

    post-14286-1427914254203_thumb.jpg

  11. Hi! This is a 2-gang pot metal-shaft with a center click fixed position made by ALPS. Type 100KMN. It is used for the balance control between the 2 speakers. So when it is in the center position it should measure 100K for gang-1 and 100K for gang-2. However it measures 88K and 82K respectively. As I told before, my left speaker was playing a bit lower than the right one. Is this 6KOhm difference audible or am I searching in the wrong place?

    MP, 100k sure is pretty standard but it is also a matter of dimensions and it is ALPS, rather good quality...I got a plastic pot from Piher from a local store to replace a volume pot and yikes...Raising the volume you could hear the signal swinging from one speaker to the other. Then I measured it gradually and found out that my ears were right. So, I will definitely replace the pot but not until I find a good one and that's not an easy thing to do in my country. That's why I am looking for international stores to order from.

    One last thing that just came to my mind. Let's say I don't need the balance control. I want my speakers to play equally everytime. So isn't it reasonable to put two 100K static resistors in place of the pot? (Does it matter if it is a little less or more than 100K?) But the total resistance for each channel should be equal. Common resistors are not that accurate as far as I know. Let's say that you buy 2 resistors of 47K. One might measure 45K and the other 48K...so same shit. Is there some type of resistor that is very accurate?

    Thanx!!!best regards!

  12. Hi!

    I guess when the specs of a pot have changed there is nothing more you can do to save it, right? I am trying to refurbish an old 100K stereo pot. At its fixed center position it gives about 10K difference between channels, measured on its own (not on any circuit). After some cleaning I managed to narrow the difference down to 8K...waste of time. So I guess this is why my left speaker plays at a slightly lower level than the right speaker for about a year now...(The pot is for the Balance control).

    Best regards!

  13. Hi all! Done a search on the subject in the forum and found almost no info. I thought it would be beneficial for all to gather some opinions and tips on what is the ideal way to clean an old potentiometer. Mostly refering to the ones using carbon but any info on other types is mostly welcome.
    Personally, I've heard that it is best to use a Contact Cleaner (degreaser) spray with no grease of any kind. If using one with grease then this grease may make matters worse some time later when it dries out. true? false? other?

  14. Hi! Do you know of any high grade pots and some store to order them from (in Europe preferably)? I know of ALPS but I can't find any resources to buy. Don't know if that is of any importance but I need stereo pots (both linear and logarithmic) with metal shaft and without button capabilities.

    Perhaps an idiotic question: Can one make a modification in an amplifier's volume control so that it uses a simple pot instead of a stereo pot?

    Thanx, best regards, Nid.

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