EEVblog 1562 - THE 1980's Boombox TEARDOWN - Sharp GF-7600

The beat switch is for tweaking the AC bias frequency slightly for times when harmonics of the bias oscillator interfere with AM radio stations. If you're trying to record your favourite station but get an annoying whine but only when you're recording - try a different position of the 'beat' switch. I got through all my life not knowing this but it was @vwestlife's video that told me a while back. Cheers Dave!

14:10 that switch is to select between record & play. Parts of the circuitry were switched over to share componnets

I believe the little compartment with the small gear for the eject mechanism is intended to contain some grease that slows down the opening of the compartment, effectively providing the soft eject you were looking for.

At 18:01 there is a "soft touch" door opening mechanism. Usually filled with silicone damping fluid, which has probably migrated out. The "beat cut" switch changes the frequency of the bias oscillator to minimize a beat frequency when recording from AM radio stations (particularly weak ones). Thanks Dave!

This teardown reminds me of all the old electronics that I used to tear down as a child in the mid nineties (some without parents' permission)! All those SIL ICs, old school AM frontends etc. The reason for getting into EE is due to the fascinating insides of this type of gear. Thanks Dave!

at 6:49 there is a plastic spacer for the tuning knob that fell on the floor not sure if you noticed it or not. Cool BoomBox By the way.

The tape door does have a slow eject gear. I bet it just needs some love

I have approx 50 boomboxes so I know what is inside but great show to see all of the design inside. The good thing about "Made inJapan" is that you know it is easy to open and made very service friendly. I have a few Sharp devices and still going strong, also the 90s versions. Sony, JVC, Sanyo, Silver, Panasonic, all made in Japan. But I also have some Philips devices and that is a real different story. They made very nice units but man problem is always the same: Cheese gears. Use of flimsy connectors or not a connector at all, a spagetti of wires. I think the model you showed is really nice piece, you can see the effort they put into it. Simple, but build quality wise very good. Your unit can run for decades after decades.

In Christchurch, New Zealand in the mid 70's to late 80's we knew these as ghetto-blasters. Boombox still sounds very strange to me today all these years later!

In Sweden they were often called "bergsprängare", the Swedish word for rock blaster (the profession), which for once works pretty well when translated to English. The term seems to have been coined by Hitachi marketing but caught on and was then used for just any system with just a passing resemblance of a Boombox.

In Spain those were call "loros", parrots. Because some people used to carry them on their shoulders (like a parrot) very loud, while walking on the street, on the beach... Like a walkman but with the capacity of disturbing everybody 1km around.

No one does enthusiasm in electronics like Dave!

Great teardown. Take that, @Techmoan! :) We had a few domestic made models of "radiomagnetofon" (radio cassette recorder) here in Poland-not-Portland, and the common name was "jamnik" (dachshund) and later on, boombox. "Ghetto blaster" would never pick up given up the tragic memories of WWII and Holocaust, still fresh among anyone over 40 back then.

I'd love a second-channel video where you actually test the speaker frequency response and compare it to the graphic.

Great idea with the trace fill on the top, you can see the circuit without taking out the board. We called it cassetophone. And the VHS machines were just "video".

It was nice of them to print the frequency response on both speakers to prevent neck strain (perhaps exacerbated by holding it above one's head for extended periods)

I bought my mother a GF7200 (smaller model with similar styling) in the early 80s, to use in her kitchen. When she passed away in 2011 it was still there, being used every day, and working like new. FM radio worked so poorly in her North London kitchen that I added an FM aerial socket when it was new, and used a large aerial in the loft, that also fed the Hi-Fi in the lounge. That was the only time the case ever needed to be opened. It wasn't cheap, but it was great value for money.

Wow, mechanics with servo-assisted movements, and at that time a recorder like that was practically junk for us. Instead, having it today is like getting a space saw.

I don't know if it was a London thing but they were often referred to as wog box or ghetto blasters, boom box seems to be a name used posthumously but not really a name of the time.

Huge fan of these teardowns, absolutely terrific!