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Keurig 2.0 Hack: Make Any Coffee You Want

December 20, 2014 Leave a comment

I’m a bit late to the game for this particular trend on the Internet, but it’s definitely worth sharing. If you drink coffee in the mornings, you’ve probably heard of Keurig and their single-serving K-Cup style of brewing coffee. Pop a pod into the machine, push a button, and out comes an amount of coffee. The original version of these machines would happily brew anything you put into it, as long as it was the right size. Keurig also sold officially-branded coffee pods to use in their machines, but other companies made them too.

Enter the Keurig 2.0. Under the guise of delivering a better coffee experience, somehow, Keurig developed a special kind of ink to use on their K symbol on the lids of these new cups. A complex optical reflectivity measurement system ensures that you’re using an authentic Keurig coffee serving, or the coffee maker will refuse to brew your coffee. I assume they didn’t enjoy losing out on the revenue stream of providing the pods and thought this would be a good way to ensure they controlled the supply of coffee you could purchase.

Unfortunately for them, it turns out people really did enjoy the hundreds of unique varieties of coffee which Keurig didn’t authorize and provided a diverse selection of products which would work in the system. And it also turns out that, when you take away people’s choices in the name of greed, people will find a way around it.

But now, we have the Keurig Hack:

Simply peel off the lid of a “legitimate” Keurig-branded coffee pod, and scotch tape it to the optical sensor. Now, your coffee maker which was artificially crippled by the greed of the manufacturer will continue to brew any of the alternative coffee products dozens of other companies have produced.

I’ve been looking at buying a Keurig machine for a while – making coffee in the mornings is a bit of a pain, and this system really takes the hassle out, but I don’t care for most of the generic selections they offer. Now that this hack is out in the wild, I’ll probably pull the trigger in the next few months, since now I can use any kind of coffee I want. It’s a little expensive, but break-even point is about 3 months of Starbucks drip coffee on the way to work, so it’s easy to justify.

Happy brewing!

[Hack-a-Day] and [Lifars]

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Sony TA-5650 VFET Integrated Stereo Amplifier Overhaul

December 18, 2014 Leave a comment

Cross-posted from the Rain City Audio Repair Blog:

I recently got to work on a very interesting piece of vintage stereo gear from the golden age of hi-fi in the ’70s, the Sony TA-5650 VFET Integrated Stereo Amplifier.

It’s a little rough, and while the power amp section works great the pre-amp doesn’t produce any output, this is a rare and interesting amplifier. In the output stage, the finals are Sony VFETs – a new and experimental type of vertically oriented FET which was being pioneered around this time. Sony used them in a small handful of receivers from the same year and never again in any other models or years; Yamaha produced a couple of models which used them as well, and oddly enough they turned up in a handful of 1990s MTX car audio power amplifiers – but overwhelmingly, it’s a rare and esoteric output device.

It’s also missing a knob.

It’s a well laid out amplifier inside: Towards the front, the final module with large bottom-mounted heat sinks and chimneys to the top-side vents for good airflow. The pre-amp controls, power supply, and rectifier are along the front and there’s a large power transformer.

A shot of the regulated power supply. As a part of the process, all the electrolytic capacitors get replaced. At this point in the process, the underlying cause of the pre-amp failure isn’t known, but that doesn’t change the procedure. The most likely cause of failures is often a failed electrolytic capacitor which leaks and damages near-by components. With the front face and knobs removed, the boards can be removed.

Overwhelmingly the capacitors were all replaced with Nichicon Fine Gold capacitors, although a handful in power supply circuits in high-ripple locations were replaced with other models with a better current capacity to ensure reliable operation. Unfortunately, however, this didn’t fix the problem: it turns out the 2SK76 small-signal VFETs were defective. That does mean this integrated amplifier will never have a functional pre-amp again, but it’s still a fantastic power amp stage.

The chimneys clip into the board supports, with the VFETs along the bottom. Removing it exposes the board to view.

One major reliability problem with these Sony VFET amplifiers, which has sent many of them to an early grave, is the varactor diodes used in the bias circuitry. They’re used to provide a stable, temperature-invariant voltage reference but unfortunately over age (aided by leaky capacitors) they tend to start to avalanche and fail to prove bias, instantly destroying the VFET output devices. They’re unobtanium, so if this happens, really the only source of new parts is another one that’s died for some other reason.

It’s not pretty, but it works: these VD-1221 varactor diodes can be replaced with a pair of 1N4148 in series.

One other issue with the Sony VFET series of amplifiers is the rectifier board. Sony used screw-in capacitors with a 10mm lead spacing; these are no longer manufactured. It was necessary to extend the leads and mount the board slightly on an offset. Again – not pretty, but completely functional.

After mounting everything back together, adjusting the power supply’s voltage reference, and adjusting the bias on both channels it was time for a burn-in test. This one plays very well with exceptionally low distortion, crisp and clear highs and a very triode-like midrange owing to the VFETs.

Quite a few parts were replaced during this repair – and I found a “new” chickenhead knob as requested by the owner to replace the missing knob (on the far right.) Fully reconditioned like this, it’s going to sound fantastic for a long time! These are pretty uncommon to find these days, so even with a bad pre-amp section it’s definitely worth the effort to repair – and with the low distortion and unique VFET sound it’s great for an audio enthusiast. This particular one belongs to a Grammy® Award-winning record producer if that gives you any idea of the quality and performance.

If you have a Sony VFET amplifier that needs a preventive overhaul to ensure it doesn’t meet an early demise, Rain City Audio can help!

Philco 42-365 Antique Radio Repair

December 15, 2014 Leave a comment

Cross-posted from the Rain City Audio Repair Blog:

This Philco 42-365 came to the shop in need of major repairs. It was missing its dial string, lamps, and the power transformer had melted down due to a failure in the main electrolytic capacitors.

It’s melted and run everywhere, and left quite a bit of smoke residue. Fortunately, the power transformer on this model was also used on a few models spanning several years, so it was fairly readily available.

Transformer leads back then weren’t always labeled with standard conventions, so it’s always important to test them.

The replacement has a bit of surface rust but otherwise works perfectly.

The dial cord on this model is two separate strings wrapped around 5 pulleys, but it went back together okay.

It all went back together! The dial scale on this model is attached to the cabinet, and the owner brought the chassis and speaker alone, so I aligned the IFs but wasn’t able to align the dial tracking.

Back in its cabinet, though, it looks great!

Rain City Audio can fix your vintage radio, too.


Bose® 901 Series IV Active Equalizer #116907 Overhaul

December 12, 2014 Leave a comment

Cross-posted from the Rain City Audio Repair Blog:

Another Bose® 901 Series IV Active Equalizer came through the shop recently. It’s owner shipped it in without the wooden cover for security. This is a bad idea on the Series I/II, but for the III and later which have a rigid metal shell it’s a fine way to ensure the wood case isn’t damaged.

This one was sounding muddy and distorted, and it was time for an overhaul to keep it sounding like new. It has plenty of original electrolytic capacitors, along with old style vintage op-amp chips.  The bridge rectifier is also made up of discrete diodes in this model; later used an integrated bridge package.

Interestingly, this is an earlier board revision with U101 in a different orientation than on later boards. It also shows evidence of having been replaced before – the stock filter capacitors were both 470 uF units; at some point in the past they’d been replaced with a 330 uF and a 1000 uF.

The op-amps had been replaced once before as well. This was a common factory repair on the earliest Series IV models, the chips occasionally suffered reliability problems. I doubt these were repaired by the factory, though, as Bose® factory service back in the day would never have used the wrong parts and damaged the PCB this much while soldering.

Pads were badly damaged, but I was able to repair them to make a good physical and electrical connection with the new chips.

With new electrolytic capacitors, new op-amp chips, and repaired traces on the bottom of the board this equalizer is back up to full performance and it should stay that way for a long time to come.

Rain City Audio Bose® Equalizer Repair Service

Bose® 901 Series I Active Equalizer #33133 Overhaul and Upgrade by Rain City Audio

December 8, 2014 Leave a comment

Cross-posted from the Rain City Audio Repair Blog:

Another Bose® 901 Series I Active Equalizer was through the shop lately, serial #33133. It came in working well enough on its original components for an overhaul and upgrade to ensure it lasts for a long time. It’s pretty unusual for these to still be running on original components so this was a bit of a surprise.

This one got all new parts. The electrolytic capacitors are all Nichicon Fine Gold audiophile electrolytic caps, with an even bigger upgrade on the output capacitors to high-end film capacitors with an ultra-low dissipation factor. It also got a new set of gold-plated RCA jacks to accommodate today’s thicker and more heavily shielded audio cables.

This equalizer is going to be a great focal point of a vintage stereo system for many years to come.

Rain City Audio Bose® Equalizer Repair Service

Bose 901 Series IV #244005 Repair by Rain City Audio

December 4, 2014 Leave a comment

Cross-posted from the Rain City Audio Repair Blog:

Bose® 901 Series IV equalizers are coming through the shop more regularly in the past year. It’s expected as these are definitely getting up there in years. This one was sounding muddy and not like it used to, so it came in for a full overhaul.

Manufacturing technology has reached the point by the Series IV that most of the film capacitors are reliable and don’t need to be replaced, but there are plenty of electrolytic capacitors, plus the original op-amps get noisy over the years and should be replaced as a matter of course.

This one received all new Nichicon Fine Gold electrolytic capacitors, and new TI TL072P op-amps.

If your Bose® Series IV Active Equalizer isn’t performing like it used to, Rain City Audio can help. Bose® Equalizer Repair Service

How Speakers Make Sound

December 3, 2014 Leave a comment

If you’re looking for a great visual primer on how speakers convert electricity into the music you hear, check out this fantastic animated infographic by Jacob O’Neil at Animagraffs 

12-3-2014 9-55-37 AM

How Speakers Make Sound


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