When those of us who are into “gadget porn” look at the latest state-of-the-art home entertainment gear, and then check its prices against our dwindling bank accounts, we can’t help but feel embittered. Our techno-lust is bust.
But we want that US$1500 DVD player; we crave the best audio and video that money can buy. Lucky for us, much of the good stuff in the top end components has trickled down into very affordable equipment. Digital processing chips, which are the brains of audio and video players, are relatively inexpensive and universally available. But if a DVD player is selling for $150, the manufacturer’s costs were probably not much more than $30, and that cost includes labor. So manufacturers skimp wherever they can: on the cases, the capacitors and resistors, and connectors—common components that they can purchase for pennies.
Free of their mass-marketing imperatives, you can spend dollars, rather than pennies—and hear and see the difference. That’s the basic strategy of a thriving if somewhat esoteric group of hobbyists who take such affordable electronic equipment and modify, or tweak, it to perform at levels that reach far beyond its meager beginnings. These upgrades replace cheap components with better-quality and lower-tolerance parts, and the results are often startling. Take a $150 DVD player. Add less than $100 in boutique parts, perform a bit of simple soldering, and the resulting sound and video can compete with that from DVD players costing hundreds of dollars more in retail stores.
Some have made a business out of such upgrades—charging three to five times the cost of the added parts for labor, knowledge, and experience. But if you can read a schematic, are willing to tinker a bit, have basic soldering skills, and are willing to spend about $250 altogether, you can cut out the middleman and get a disk player that will be the envy of all your gadget-lusting friends.
The Toshiba SD4960, also sold as the Samsung DVD-HD841, is the inexpensive universal disk player I chose to modify. It has received good, if not spectacular, reviews in video and audio magazines and e-zines. It uses the same digital processing chips found in considerably more expensive players and its laser mechanism is well regarded, though packaged in a flimsy plastic support. Best of all, it will handle almost all disk formats: DVD Video, DVD-R, DVD-RW, CD-R, CD-RW, SACD (Super Audio CD), DVD-A (DVD Audio), MP3, and digital picture CDs with JPEG. Toshiba licenses the design from Samsung, but most of the parts in the two models are identical. To my eye, the Samsung unit is more pleasing; it also has an HDMI video output connection that the Toshiba lacks. The Toshiba’s street price is about $100, while the Samsung sells for about $120 (but prices may be even lower by the time you read this).
The first time I listened to a CD on the unmodified Toshiba player I noticed some distortion affecting the high-pitched sounds like cymbals, bells, and harmonica. Also, there was not a lot of life to the sound. It was a little congested; complex passages in the music were not entirely clear to the ear. Tonally, however, the Toshiba player does well, making instruments sound like instruments, not plastic facsimiles.
The player’s video capabilities were similarly solid. Images were free from obvious grain. Colors seemed correct and contrasts were distinct and without shadows, but in the video as well as the audio, there was room for improvement.
To perform an upgrade, you’ll need a few things. One of them is the service (not owner’s) manual from the manufacturer, which contains the schematic. You can get a copy for $22 plus $7.95 shipping and handling from J&J International at +1 800 627 4368; ask for the Samsung DVD-HD841 service manual. Another thing you’ll need is a 25- or 30-watt soldering iron and some rosin core solder.
If it’s been a while since you had a soldering iron in your hand, spend a little while practicing the art of making a good, swift solder connection. To avoid damaging delicate microelectronics, touch the tip of the hot soldering iron for a second or two to one of the leads that connects the component to the board, then touch the tip of the solder to the now-heated connection point. The solder should flow freely to the component lead and the board connection. Pull the solder away from the joint, then the iron, leaving a shiny, rounded connection. Before you start, tin the iron’s tip and keep it shiny and clean—wipe it with a damp sponge between tasks.
The instructions below are written for the Toshiba and Samsung players, but you can apply them to just about any of the vast array of universal disk players priced under $200. If you’re willing to spend a little more, the Marantz CD5400, with a street price of about $300, is a good choice. Just be sure to plan your upgrade carefully before ordering parts.
The three places where tweaks to an inexpensive player can make the most difference are the power supply, the power supply, and the power supply. Okay, that may be a slight overstatement, but it’s a fact that the power in your home is often corrupted by air conditioners, dimmer switches, halogen lights, and other noisy appliances—yours and your neighbors’. Cleaning up and filtering out this noise on the line will help any player perform better.
Essentially all low-cost DVD players these days use a switching power supply. It converts the line’s ac voltage to dc, at, for instance, the 3.3, 5, and 12 volts needed by chips, motors, and other internal components. Switching power supplies use switching transistors and other devices to, in effect, chop the 50- or 60-hertz line frequency into an ac signal at tens or hundreds of kilohertz. The advantage of this higher frequency signal is that it can be filtered, and its voltage changed, with small and light capacitors and transformers. The high-frequency transformer also easily provides multiple output voltages and isolates the dc from the input voltage.
The supply consists of a power-input receptacle, a bridge rectifier to convert ac to dc, capacitors for smoothing the resulting pulsed dc waveform and for storing the energy needed by the other sections, MOSFET transistors to chop up the dc into the high-frequency ac, and the high-frequency transformer with multiple secondaries to produce the various desired voltages. For each secondary coil, there are rectifiers and filter capacitors to yield the desired dc output. Besides being smaller and lighter, switching power supplies are typically more efficient than other types. The tradeoff is that they tend to generate more high-frequency noise on the power line. Sufficient filtering becomes important—especially in audio circuits.
Before you begin, a few words of caution. You will be playing with a system that runs on real ac current, so make sure the unit is unplugged while you are working on it. If you are new to the world of building and troubleshooting electronics, read this excellent guide before proceeding: http://repairfaq.ece.drexel.edu/REPAIR/F_appfaq2.html. Be careful and patient. Oh, yeah, this will definitely void your warranty, too.
To open the Toshiba SD4960, remove the three screws on the back panel; then slide off the lid. Snap off the front panel, being careful not to break the fragile plastic clips that hold it in place. Unplug the ribbon cables where they attach to the main printed-circuit board and unplug the wire running from the electrical cord to the board. Unscrew the board, and lift it gently out of the case.
On the board (See photo, “Inside the Toshiba SD4960”), you will notice lots of insect-like components, their bent leads splayed like little legs on the surface of the board. You will be leaving these surface-mount parts alone. They are too small to fuss with, and their would-be replacement parts too big to fit in their place. Also, they have been machine-soldered to the top of the board and would be hard for you to remove and replace without damaging other circuitry.
Starting with the power supply section (indicated in yellow), first identify all of its capacitors and their values. You should replace all of these capacitors with higher-quality capacitors with the same voltage value but about 20 percent more capacitance. (See table, “Replacement Parts Selection.”) There are various measures of a capacitor’s quality; one is ESR, or Equivalent Series Resistance. A low ESR means low resistive losses inside the device, and therefore better ability to deliver power to the sort of fast-changing loads presented by the clock and other high-frequency digital circuitry. There will also be one relatively large capacitor just after the rectifier or diode bridge (indicated in pink); you can double the capacitance value of this one, from 82 microfarads (µF) to about 180 µF, or whatever you can fit in the available space.
Basically, by using better-quality parts, like Sanyo Oscon, Panasonic FC, or Nichicon UHE or FG/KZ capacitors, and increasing their values, you will improve the power delivery to the other circuits. That in turn will increase the dynamic range and enhance the all-important bass performance. Besides low ESR, such high-end capacitors have tighter tolerances and use better materials (the Nichicon leads, for example, are copper, not steel).
The one constraint you’ll face in replacing capacitors is the space on the board—capacitors with larger values are bigger, so make sure you have enough real estate for them. And don’t forget to note the polarity of the capacitors you are removing so you know which way to solder in the new ones. Polarity is usually indicated on the board, but go slow and be cautious.
To take your upgrade a step further, replace the diode rectifier bridge with “soft” recovery FREDs (fast recovery epitaxial diodes) or Schottky diodes. These fast-action diodes have what is known as soft recovery. What that means is that when the voltage across them changes polarity, causing them to go from forward- to reverse-biased, the plot of current versus time slopes smoothly back toward zero current, rather than overshooting the zero axis and wobbling briefly around it, or “ringing.” Basically, the lack of ringing means less noise.
Buy replacement diodes with higher amperage ratings than the original ones. The original diodes are designed to tolerate high-peak surge currents, which occur when the power-supply capacitors are charging (and don’t forget, you added more capacitance!). Chances are, your replacement diodes aren’t designed for high current surges; in my case, replacing the specced 1-ampere 600-volt diodes with the same value FREDs smoked them. So I used 4-A 600-V diodes and they worked fine.
You may have to be a bit creative with the installation of these replacements, because diodes with this increased rating are usually only available in a TO-220 type package instead of the original DO-41 package. Note that the TO-220 package has a metal tab at the top; this tab is generally connected to the cathode and should therefore be insulated with heat-shrink tubing to avoid any shock hazard.
Again, be very, very careful of the orientation of these diodes. By putting a faster, soft-recovery rectifier in the power supply, you will allow the power supply to respond more rapidly to the demands of the downstream circuitry with less switching noise.
Taking the modification yet further, you can also replace both of the X-rated capacitors (indicated in orange)around the transformer with 0.47 µF 600-V Auricaps. These will set you back about $13 apiece. X-rated capacitors are standard components that meet Underwriters Laboratories Inc. (UL) standards for use on ac mains lines. These capacitors are designed to be self-extinguishing in the event of a big surge on the power line. They’re potted in fire-retardant compositions, and are designed to fail open, rather than closed, so components up- and downstream will be protected. Auricap capacitors, a brand of high-end capacitor favored by audiophiles, are not rated against UL standards for ac current.
While this tweak is widely used in audio modification circles and no problems have ever been reported on the audio tweak Web sites (as far as I know), it could potentially lead to damage in other parts of the system, so you might say it’s risky. But, to my ears anyway, it does noticeably improve audio quality. If you’re squeamish about replacing the X-rated capacitors, you might try a compromise, such as replacing the stock X-rated capacitors with a good-quality safety-rated polypropylene capacitor, such as the MKP series from Illinois Capacitor (part number 474MKP275K).
In the digital- and video-processing sections (indicated in red), there are lots of surface-mount components. Leave them alone, along with the various chips that are soldered to the board. The capacitors, however, are all fair game. You can again use the Sanyo Oscon, Panasonic FCs, or Nichikon UHE or FG/KZ series. The Sanyo Oscon capacitors are harder to find, but you can buy them from Capacitors Plus Inc., +1 800 422 7758. The Panasonic parts listed in the sidebar