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Old 1st May 2019
  #31
Gear Maniac
Thanks for sharing, Brian. The the yellow ceramic
Caps replace the opamps on the other side, or they are on there as well?

Quote:
Originally Posted by Brian M. Boykin View Post
Here are some pics of .1 mono ceramic caps from the v+ and v- pins of op amps to ground. That’s 2 per op amp. It lowers power supply noise and gives the op amp more available power since upgrading op amps usually means they require more power. Not always though. I use Panasonic FM and FC electro’s because they’re readily available and sound good to my ears. I bypass the electro’s in the audio path with .01/250 WIMA’s for the reasons described above. I’m in the process of swapping all the carbon film resistors in my console with dale metal films. Jim Williams says he hasn’t measured any difference in distortion but I agree with him that they sound better. Transistors can be swapped also. All to more modern lower noise and lower distortion parts. It does make a difference but can also change the sound of the gear so it’s a trade off. I prefer clean transparent audio so it doesn’t concern me much. I have yet to mod a piece of gear and be unhappy with it. Here the pics.
Old 1st May 2019
  #32
Lives for gear
 
Brian M. Boykin's Avatar
Quote:
Originally Posted by shortyboyboy View Post
Thanks for sharing, Brian. The the yellow ceramic
Caps replace the opamps on the other side, or they are on there as well?
The yellow caps are for decoupling the op amp. They are there because the original design did not have them. Some designs do and some don’t.
Old 1st May 2019
  #33
Gear Maniac
Awesome. Do you have any pictures of the channels you worked on? That would be rad to see. Did you build the power supply yourself, or did you give them the specs and have them build it?

Quote:
Originally Posted by Brian M. Boykin View Post
My console is a Soundcraft 400b. No transformers and was loaded with tl072’s and tl071’s. I put opa2134’s in the input stage, opa2134’s in both the EQ stages, and lme49710 for the fader buffer. I recapped with Panasonic FM and bypassed all the electrolytic caps in the audio path with .01/250 WIMA’s. It made a considerable difference. I had several channels in different stages and can say the recap made the biggest difference, however, swapping the op amps made a huge difference as I began mixing and summing channels. All the EQ caps were swapped from the box films to WIMA’s. I did value for value. Again, made a difference. I just finished switching all the carbon films to Dale metal films in 8 channels. Again, made a sonic difference. What I’ve found is it’s easier to get everything to sit in the mix and requires less EQ. I mostly use subtractive in the mids and boost the highs and lows just a hair. Sometimes no EQ is required at all. One of the biggest improvements was building a new power supply from Power One modules. I can push the levels much farther into the red and it doesn’t fall on its face. I learned all this from this sub forum. Mostly Jim Williams, John Roberts, Nosebleed, Audiospecific, Recordruff, Brian Roth, Radardog, Richard Crowley, Matt Syson, Gyraf and many others I’m probably forgetting. These guys know their **** and have test equipment to prove they know their ****. They can be a little rough from time to time but most of the time that’s what you need. A smack upside the head. I say, pick a piece of gear you can stand to mess up and search mods for it. Organize the mods on paper. Maybe do it in stages. You do it all at once and it goes bad you’ll have a harder time finding where you messed up. I’d start with recapping. Makes a big difference and it’s pretty easy if you stay with value for value. This requires piping the top and writing down values. Mouser is where I do most of my purchasing. They’re in Tx and I’ve ordered before like 3:00 on a Monday and had it on my doorstep the following morning. Digikey, Parts Express, Allparts, and EBay if you can find a trusted seller. EBay is last resort for me.
Old 1st May 2019
  #34
Gear Maniac
You are amazing. I’m going to
Message you right now

Quote:
Originally Posted by Blackandwhite View Post
@ shortyboyboy : fixing electronics isn't hard, it's a great and fun hobby. I can suggest you to read some books about electronics, especially if you're a beginner. I can recommend you the following books:


For beginners/novice:
- Make Electronics by Charles Platt
- Electronic Gadgets For The Evil Genius (2nd Edition) by Dave Cutcher
- Practical Electronics for Inventors (4th Edition) by Paul Scherz

Fixing electronics:
- How to Diagnose and Fix Everything Electronic by Michael Jay Geier
- Electronic and Electrical Servicing by Ian Sinclair

MUST HAVE:
- Electronic Projects for Musicians by Craig Anderton (you def must own this book if you're into fixing audio equipment)
- Encyclopedia of Electronic Components Volume 1, 2, 3 by Charles Platt

Tools you should have:
Solderstation: Get a Weller WS 81, it's one of the best solderstations out there. A friend of mine bought this one back in the 80ties and has been using it every single day and it never broke. He is still using it now. A de-solderpump is a must have.

Solder wire: Soldering is very easy, you can get these experimental PCB boards they have these holes in them. You can use them for small projects which will also increase your soldering skills. Avoid lead free tin, it's horrible AVOID IT LIKE A DISEASE. Go for the Sn60Pb40 type, preferably 0.5mm so it's easier to control the amount of the solder you're applying. Multicore solder is very good, it flows good. I can recommend you that. Stannol is also a good brand.

Multimeter: Go for a Fluke if you're serious about this hobby. They produce some of the finest multimeters.

Oscilloscope: IMHO a must have if you're going to fix audio equipment. I can recommend the Rigol DS1054Z, get the 400USD model. Some of the features will be unlocked and you have to pay for them buy entering a license key, but there is a hack for this which unlocks all the features on this scope. Once you unlock it it will be the same scope as the expensive model. (spend the rest on a synth lol).

Components: it's always to have components laying around, they're dirt cheap. You should get the E24 resistor series kit, capacitor kit, tactile switches, IEC connectors, insulated wire, 1N4XXX diode kit, a bunch of IC sockets, a bunch of voltage regulators (+5v, -5v, +12v, -12v, +15v, -15v), heatshrink tubes.

There is an Asian equivalent of Mouser, they supply components from top Asian brands which are very cheap. Dave Jones from the EEVBlog has reviewed this website and they seem to be legit: Electronic Components Distributor | EasyEDA Parts Online Store - LCSC

Here is a fun fact: I've seen people selling these tactile switched for the Juno 106 for a ridiculous price on eBay. On the site I provided they sell exact the same component for just 1 cent. Go figure.

Component tester: also a must have, with this device you can test out components like transistors, diodes, capacitors, voltage regulators. Sometimes a capacitor looks normal, but it's broken internally. With an ESR meter you can be sure of this. Most component testers have an ESR meter. They're pretty cheap.

Learn to use a 3D CAD program
Learn how to make custom components in a 3D cad program. For an example you're working on some kind of equipment and the buttons are all messed up. What do you do? You'll either over pay some greedy guy on eBay or you recreate the component in a 3D CAD program and send off the model to some 3D CNC milling company in China after which you'll receive a brand new component for less the price. This is good for buttons, slides caps, knobs and heatsinks. You're going to need a good digital caliper to measure everything. You don't need to be an expert in a CAD program, there are so many tutorials on YouTube. Also you can find these CNC milling companies on Alibaba.

Fixing audio equipment
The very first thing you need to do is to open up the gear and check the PCB's and components, in many cases if a component has burned out you'll see it (it's literally burned) often it will damage the surrounding components or the traces on the PCB. In a case like this you'll need to fix the traces, you do this by soldering thin solid wires to the traces, so the signal can continue. You'll also need to replace the component. Or one of the caps is leaking, in this case you need to remove the cap, clean the board, replace the cap with a better one just like the Panasonic caps mentioned by the other poster.

Usually when fixing a synth for an example if one of the keys doesn't work, in most cases it's a case of a bad contact. You can open it up and clean the contacts. If doesn't turn on, usually there is a problem with the power supply in most cases it's a bad capacitor or the fuse has broke, I would also check and test the power switch with a multi meter, if it gets the power but doesn't deliver the output on it's rails then it's probably a voltage regulator. You can use a multimeter to test these regulators.

If it doesn't produce any sound the problem might be a dead voice. For this you need to get the schematic and use the scope to follow the trace right from the sound generator. Like IC1 produces the sound, the IC has a voltage input and audio output. You'll need to check out the datasheet of the IC, the next step would be probing, so you'll see if it gets an input and output. If it doesn't get a voltage input, you'll go one step back, whats the source of the voltage output for this IC. If it the source is putting out the voltage, in this case the IC is dead. If for an example the IC doesn't have an audio output then it's broke. If it's fine you'll check the next component which receives the audio signal of the IC. Rinse and repeat. You can literally see the audio waves on your scope thats why a previous poster also recommend to have a scope.

If a button doesn't work in most cases the button needs to be replaced but it also can be cleaned as you can open up some buttons (for an example like the ones in vintage drum machines like the Drumulator). If it's one of those small tactile switches you can easily replace them since they're very cheap. If it's a custom switch you can either look for the original part or you can make an adapter with a tactile switch and a custom button (thats why I recommend you to learn some CAD program). But for this you need how to make PCB's which is also damn easy.

With 7 segment displays, if it doesn't work it's either the led driver, the resistors on the led drivers output or the display itself that has died. But also in a case like this you can use the previous troubleshooting method I mentioned. There are two kind of 7 segment displays, common anode and common cathode. If your vintage synth uses a common cathode display, a common anode display won't work.

In some cases a LCD display doesn't get the proper voltage for operation, in this case you'll need to check out the voltage regulator thats responsible for providing the voltage to the LCD display. You can find this in the schematic. If it's dim , the chance is big that the voltage regulator doesn't provide enough juice. In a case like this you must replace the regulator.

Sometimes you can save something on a device like a synthesizer, in most cases the battery needs to be replaced because it has no juice or it's leaking. There is a nice trick, get one of those AA battery holders and remove the old battery holder. Solder the new battery holder and glue it somewhere with hotglue. Now you can use those special batteries they use in smoke detectors etc. They will last you way longer.

An another reason why a scope is so important is when you've been swapping out components on a voice card of a synth you'll need to re calibrate it. You can always find these steps in the service manuals. Usually you'll have a point you need to probe, while playing on a certain key the signal should be a fixed variable, you can see this on the scope. If it doesn't match there is some kind of trimmer you can turn, you'll turn this till you get the required signal. It's the same with some power supplies, in that case you'll need to use the voltmeter, for an example you replaced the voltage regulator and now you need to calibrate the powersupply. You just put the probe on the output of the power supply rail and see which trimmer you must use to increase or decrease the output voltage. You'll turn it till you get the required output. If you changed lets say a 5v regulator, the output should be 5v.

Troubleshooting goes like this, whats the problem, find the area where the problem is, start probing till you find the dead signal. It's like fixing a puzzle. If you're interested in those books just send me a PM. And good luck on your journey.
Old 1st May 2019
  #35
Lives for gear
 
Brian M. Boykin's Avatar
Built the power supply using power One modules. Three modules. 2 for the bipolar rails and one for the 48v phantom power. There may be pictures of it on my build thread. Search Soundcraft 400b. I married two consoles together into one.
Old 2nd May 2019
  #36
Quote:
Originally Posted by shortyboyboy View Post
Thanks for this useful information. I am having a bit of him from a few pieces of outboard gear when insert them into channels of the console. I read that you should ground external gear to the console. Does that mean run a line from the casing of the gear to the casing of the console? Also, have you had experience grounding a
Console into the earth with a stake ? I hope I’m saying this correctly. Ha!
What kind of console? What kind of gear?
How is it being connected? By two-conductor wire, like a guitar cable?
Or by 3-conductor, like a mic cable?
Can you find which piece if gear is causing the hum by disconnecting them one by one?
It might help to look at the manuals for the outboard gear, or the mixer. Sometimes they have recommendations for how to deal with grounding.
In my experience, you disconnect the ground from one end of the cabling. Either at the rack box or at the console.
If the internal grounding in the mixer is not correct, it will always be a problem.
I am working on a DDA mixer at the moment, and it seems to be very well designed and has no problems with grounding on any of the many FX units I have connected to it. This was not so with a Studiomaster mixer I was using before it, and the problem was the way the grounding was done inside the mixer.
Ground connections in the mixer were made by pressing the wires into a loom, and over time, the grounds had become loose, and needed to be soldered.
I think you should not have to "earth" the ground connection if the power in your studio is done correctly, but perhaps smarter folks than I will have something to say about this.
Old 4 weeks ago
  #37
Gear Maniac
 
drsaamah's Avatar
Reviving the thread for my own selfish purposes :P
So I am in the process of patchbay-ing my equipment. Just got done soldering the DSUB ends of the snakes I am building. The other end was going to be a combination of TRS and XLR connectors until I remembered I have a few pieces of gear that have unbalanced outputs. I just got done reading through Rane Notes 110 (http://www.rane.com/note110.html), and I need something clarified, if one of the more experienced members of this thread would be so kind...
I am under the impression that I have two viable options to deal with this. 1) I can solder a TS connector connecting the tip to the hot wire, the ring to the cold, and soldering the ground wire from the DSUB end to the copper shielding, or 2) Build a box to balance the signal. Is this accurate? And if so, is one of these two preferable in terms of avoiding excessive noise and/or signal deterioration? I am assuming the answer is option 2, and if so, is it as simple as the "schematic" in Figure 2 in the Rane Notes? Just TS-jack to transformer to TRS jack?
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