ARCANE RADIO TRIVIA: Electric Banana

February 13, 2016 1 comment

Arcane Radio Trivia found a really cool banana-inspired portable record player, allegedly from the Andy Warhol era.

Banana

Plays in any position…even upside down! I’d love to see one of these in person. I wonder how many were ever manufactured in the first place.

I recently found this… Supposedly it was inspired by the work of an Andy Warhol. It’s based on his painting of a banana that served as album art for the Velvet Underground. The Warhol Foundation has reported that it was not officially licensed.  They are rare as you might imagine, but they do have one at the International Banana Museum in Mecca, CA.  The image above comes from an old issue of  the Speigel catalog. Regardless.. one of the strangest record players I’ve ever seen.

via ARCANE RADIO TRIVIA: Electric Banana.

Categories: Uncategorized

Google’s Picasa is Shutting Down

February 12, 2016 1 comment

Bad news! Google is shutting down their Picasa service and forcing everyone into Google Photos, built into their Google+ platform. Google Photos has been available for a long time, but I’ve always resisted using it because it has an overly minimalist UI which is hard to use – but also because Picasa offered the ability to get a specific URL for a photo, to use it as embedded image hosting. Google Photos only offers links to the social network photo page for the photo you’ve selected.

Given that nearly 100% of the photos on Retrovoltage are hosted on Picasa, it remains to be seen if the URLs embedded in the past 5 or so years of posts will stay active, or if every image I’ve ever posted will become a broken link.

Either way, it’s time for a transition apparently. My options:

  1. Find another free or paid photo hosting service.
  2. Use the storage space built into raincityaudio.us.
  3. Run my own simple hosting server. (I have a bunch of public static IPs available, which makes it easy.)

I’m not a big fan of IT projects these days, so (3) is probably a non-starter. What does everyone think of 1 or 2?

Moving on from Picasa
Friday, February 12, 2016 10:00 AM
Since the launch of Google Photos, we’ve had a lot of questions around what this means for the future of Picasa. After much thought and consideration, we’ve decided to retire Picasa over the coming months in order to focus entirely on a single photo service in Google Photos. We believe we can create a much better experience by focusing on one service that provides more functionality and works across mobile and desktop, rather than divide our efforts across two different products.

We know for many of you, a great deal of care has gone into managing your photos and videos using Picasa—including the hours you’ve invested and the most precious moments you’ve trusted us with. So we will take some time in order to do this right and provide you with options and easy ways to access your content. We’ve outlined below some of the changes you can expect.

Picasa Web Albums
If you have photos or videos in a Picasa Web Album today, the easiest way to still access, modify and share most of that content is to log in to Google Photos, and all your photos and videos will already be there. Using Google Photos, you can continue to upload and organize your memories, as well as enjoy other great benefits like better ways to search and share your images.

via Picasa Blog.

Categories: Uncategorized

Like Classic Receivers? Check Out This Blog

February 3, 2016 2 comments

If you’re reading this, you’re probably at least somewhat interested in vintage stereo gear, since that’s a huge amount of what I work on. There’s a lot of it out there! I just discovered a great new blog that showcases a different vintage receiver every few days, with a quick photo summary and some links to more information or to find some on eBay.

ClassicReceivers.com

They’re showcasing a Harman Kardon 330B right now.

Worth checking out!

 

HH Scott HHS-20 “Scotsman” Receiver Overhaul

January 27, 2016 1 comment

A local repeat customer recently brought in his old HH Scott HHS-20 receiver for an overhaul. It worked a few years ago when he put it away, although not without a few issues of its own, and when he dug it out it was right to the shop for an overhaul.

The HHS-20 was a very entry-level receiver, and not much information turned during research other than some speculation about it sharing an FM section with a bigger sibling. Inside, it used construction that would have been at home in a late-’60s early solid state receiver with a couple of odd exceptions, there’s a single PDIP-14 op-amp chip, and an assortment of TO-39-style op-amp chips in the FM IF strip.

It’s a cute little receiver with an FM MPX tuner, a tape loop, a single aux and phono input. I’d more accurately describe it as a self-propelled FM radio, more or less, because the -20 in the model number “HHS-20” represents the total power output: a maximum of 10W per channel, as measured after the repair was complete. Sensitivity measured at 150 mV LINE and 4 mV PHONO for maximum output.

Inside, it’s built on a pretty simple chassis, with separate boards and jumpers connecting everything.

Component replacement was entirely uneventful. There were several styles of electrolytic capacitors, but no real challenges.

Time for a power-up! It did great, given the low power, on the AUX input and Phono settings, but the FM tuner was dead. The Germanium output transistors gave this one a very warm, tube-like sound. Time to investigate the FM IF strip.

This radio checks out much like any other. Starting at the detector and working my way back, I injected a modulated 10.7 MHz signal into the circuit and listened for the tone.

Good injecting into the discriminator, but injecting into the input of the 4th IF Amplifier IC gave no output. However, when bypassed with a cap, the tone came in loud and clear. A bad IC!

According to Internet research, these UA703 IC amplifiers are a common failure item. I obtained some new Fairchild UA703HC chips in a more reliable metal case (date code 7603!) and replaced the defective amplifier.

Better! The new IC passed a signal, but the IF chain was still broken. Additional tracing revealed that the problem was the 2nd IF transformer, between the 2nd and 3rd IF Amplifier ICs – so, this receiver had both a dead transformer and a dead chip in the IF chain. Another jumper fixed the problem. Unfortunately these IF transformers aren’t exactly easy to obtain, however, it was easy to bypass entirely with a small capacitor out of the way and no real significant change in operation.

With the jumper in place on the bottom of the IF board, the receiver picked up stations immediately, and indeed the dial tracking was very close to correct. Time for an IF alignment. Received FM distortion started out about 3.1%, but adjusted to <1%.

With that adjustment, the FM sounded very good over the air, but there was a lingering issue with the FM MPX circuit failing to fire the Stereo lamp even with a good bulb. Unfortunately, the service manual provided no instructions for an MPX alignment and the MPX design in this receiver was an unfamiliar one, and since stereo decoding appeared to be working even without the light firing, so other than a quick adjustment of the stereo separation no additional work was done on the MPX decoder.

The factory service manual came with quite a few hand-written notations from a previous shop or tech, including a hand-written FM IF alignment procedure (involving a no-modulation test signal, 100K resistor, and DC voltmeter) but the distortion alignment was an even more precise adjustment, and none of the extra notes provided any insight to the MPX, unfortunately.

Like many budget receivers of the era, this one used RCA jacks for speaker connections.

Time to put the amp through its paces!

All told, this amplifier delivered 10W per channel into an 8 Ohm load, all channels driven, 50 Hz – 20 kHz +0 / -3 dB, with THD < 0.5% / THD+N < 2.2% at 1 kHz. The channels are ever so slightly imbalanced, about 0.5 dB – not perfect but not enough to worry about.

Not too bad, considering! There’s a few tricks which could bring those distortion figures down a little bit, including replacing a number of extra resistors and some of the coupling capacitors, but the labor on such extra work quickly becomes uneconomical.

Quite a few replaced parts! Caps, and one IC.

This receiver had its share of issues, but they were easy to track down and resolve. With new, top quality parts installed, this little receiver should keep singing for a long time to come!

Idea Poll: A tutorial on buying parts online?

January 26, 2016 Leave a comment

Once again, I’ve been asked “Where do you buy your parts?” and that’s a question that comes up very regularly. (My answer? Mouser.com, of course.)

I’ve heard from quite a few people over the years that Mouser.com can be intimidating for new hobbyists to navigate, though, and I can understand it. They sell everything under the sun for electronics and it’s designed primarily for professionals. The ecosystem of smaller vendors selling curated selections of common capacitors, resistors, etc. with simple, friendly websites (and a somewhat higher price) serves as further support for this position.

Really, though, for many if not most types of parts you’ll buy for common radio and stereo repairs there’s not much to it and once you’ve seen it once or twice it’s second nature.

If I went through and wrote a tutorial on how to navigate Mouser.com and find common parts, is that something anyone would find useful? I imagine that of the people reading this blog, there’s a mix of advanced hobbyists and professionals who already know the drill alongside casual hobbyists and beginners who might not have taken the time to explore it just yet.

What do you think?

How to Read Capacitor Codes

January 24, 2016 1 comment

I ended up with a massive stash of mil-spec CDE Mica caps recently, and was searching for a refresher on decoding their military part numbers like “CM05FD221GP3”, since the caps came marked for their values but not their voltage ratings.

I stumbled on the Xtronics Wiki page about reading capacitor codes, which has all the info I needed, and more. It has instructions on reading EIA and Miiltary codes, and tables of the tolerance, delectric materials, temperature coefficients and ranges, and working voltage codes.

Turns out, those are 500V CDE Mica caps, 2%, and with a +/- 0.05%+0.1pF capacitance drift over temperature. Not bad!

If you need a quick reference for all these different codes, definitely check out the Xtronics wiki.

Categories: Commentary, DIY, Electronics Tags: ,

Bose® 901 Series IV Active Equalizer #501554 Overhaul and Upgrade

January 20, 2016 Leave a comment

From the Rain City Audio Repair Blog:

This Bose® 901 Series IV Active Equalizer, serial #501554, came into the shop with the owner reporting that it loses output on one channel and the sound degrades the longer it is powered on. Definitely time for an overhaul!

There were a couple of things which were interesting about this particular Active Equalizer. For one, the voltage marking was covered in residue. Inside were a different style of capacitors with European markings:

And finally, the power supply links had been added:

This unit was originally used on 220V in Europe, but was converted to U.S. operation at some point in the past.

Interestingly, this one also came from the factory with sockets for the op-amp chips, and the same National LF353 op-amps which were the subject of a January 1983 service bulletin recommending their replacement.

In this case, the owner requested an upgrade to TI precision low-noise op-amps which offer much improved performance over the originals, along with the standard capacitor overhaul and performance verification.

All set! This Active Equalizer sounds fantastic and works perfectly, just like it should.

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