Diagnose And Repair A Yaesu FT-7800 Ham Radio

November 11, 2013 by 26 Comments

Yaesu FT-7800 Ham Radio

[Alan Wolke] aka [w2aew] was challenged to repair a friends Yaesu FT-7800 ham radio. This radio operates on two ham bands, 2 m VHF and 70 cm UHF. The complaint was that the 2 m side was not working but the 70 cm was transmitting fine. Alan started by verifying the complaint using a Bird watt meter with a 50 watt slug and terminating the signal into a 50 W dummy load. [Allen’s] bird meter is the type that has an RF sampler that can be connected to an oscilloscope for added signal viewing and validation.

After verifying that the radio was not working as described, Alan starts by glancing over the circuit board to look for any obvious damage. He then walks us through a block diagram as well as a circuit diagram of the FT-7800 radio before stepping us through the troubleshooting and diagnostics of radio repair. Even when he realizes he might have found the problem he still steps us through the remainder of his diagnostics. The skills and knowledge that Alan shares is extremely valuable to anybody looking to repair radios.

Spoiler alert. At the end of the first video he determines that the pin diodes near the final VHF output were bad. In the second video he reveals that he could no longer source these bad components. Through some clever evaluation of a more current Yaesu radio, [Allen] was able to find suitable replacement components. Lesson two ends with some surface mount solder rework tips as well as testing that the repair was successful.

And just in case you don’t know what a pin diode is, or is used for, Alan shares a third video covering just what this component is and does in a radio. You can follow the jump to watch all three videos.

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Build Your Own Desoldering Station On The Cheap

November 11, 2013 by 34 Comments

Desoldering Station on the Cheap

[Sable Wolf] tipped us off to his DYI desoldering station for under $70. We know we have seen this conversion before, but it hasn’t been featured on Hack a Day. [Sable Wolf’s] hack is unique and has added features that make building, cleaning and the overall longevity sounder. However, some kind of sound deadening housing would have to be built around the pump as it seemed uncomfortably loud in the video.

Some Chinese made desoldering stations are getting quite cheap so maybe it’s not worth the effort unless you can salvage more components for the build. Thanks to [Sable Wolf’s] detailed blog you can browse through his BOM and scrounge up the majority of these items from your salvage bins. A cheap but reliable desoldering station would be an extremely handy tool to have on your bench.

This is much safer than desoldering with a candle or using fire as featured in the past, and is kind of a flip around on the SMD hot air pencil hack.

Follow long after the break to watch the video of the desoldering station in action.

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Hacking And Philosophy: Hacker Crackdown Part I

November 11, 2013 by 6 Comments

hnpHackerCrackdownP1

This week’s installment of Hacking & Philosophy hits the books with [Bruce Sterling’s] Hacker Crackdown. If you’re joining us for the first time, you should check out last week’s conversation over The Mentor’s “Hacker Manifesto.” Don’t stop with the article, though, or you’ll miss out on the best part!

The contributions from our community are phenomenal, and it’s worth the effort to work through the comments. There are even a few replies from [The Mentor] himself.

Unfortunately, I can’t feature all of the excellent responses for lack of room, but I will recommend a handful that I feel are uniquely important after the break. Onward for more!

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DIY CNC Rotary 4th Axis

November 11, 2013 by 31 Comments

Here’s a great CNC hack that adds a ton of functionality, a DIY rotary 4th axis!

[Jim] had started this project over a year ago when he originally ordered the gearhead off eBay, but like many good intentions, sometimes projects just get pushed to the back burner until necessity forces action. That necessity was entering our Trinket Contest, and he decided to finish it off just so he could put a HaD logo on a piece of PVC for us!

Unfortunately it took him a bit too long, and he only finished it last week — but luckily he had a fallback plan, and submitted his CNC Etch a Sketch project instead, which won him a Trinket anyway!

The 4th axis uses a 276oz-in stepper motor which is directly coupled to a Harmonic Drive Systems 11:1 planetary gearhead. It’s extremely accurate, has minimal backlash, and by using a 10 microstepping Gecko stepper drive, [Jim] is getting about 61 steps per degree of rotation. Not bad for a home-made setup!

Check out his blog for a great write up on the project, and stick around after the break to see the 4th axis in action.

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Robotic Sloth Haunts Your Dreams

November 11, 2013 by 52 Comments

robotic sloth

Have you ever seen a wet sloth? They’re pretty scary. If that’s not bad enough, how do you feel about a robotic one?

Named the X-4 “Sloth”, this is one of [222Doc’s] hardest projects to date — a highly experimental quadra-ped that can climb up and across ladders. It makes use of a Lego Mindstorms NXT controller, 8 servo motors for the joints, 4 Power Function Motors for the hands, and a whole lot of Lego. Due to the number of motors, he also had to multiplex the Power Function servos to make it all work!

Sure, it’s Lego, but it was far from an easy project, as [222Doc] estimates he spent well over a hundred hours on it, and it still isn’t complete. He says he’ll never say to himself “this will be easy…” ever again.

Stick around after the break to see it scale this ladder — we wish they sped up the video though, it appears the movement speed is modeled after a real sloth…

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Bluetooth Audio Adapter Hacked To Switch Off Amplified Speakers

November 11, 2013 by 21 Comments

bluetooth-audio-amp-auto-switch

This Bluetooth Audio Adapter is meant to connect a Bluetooth audio source (like a smartphone or tablet) to a speaker system with a plain old line-in connection. It has the ability to automatically connection when the Bluetooth device comes into range. Sounds convenient until [Andreas Pösch] points out that he still has to switch the speakers on and off manually. This hack automates the entire thing using a bit of additional hardware.

If you look closely you’ll see that the black cables have barrel jacks. This is a power pass-through rig that he whipped up. The protoboard includes a 7805 linear regulator which feeds power to the green circuit board in lieu of it’s original power adapter. A MOSFET switches outbound power headed for the speakers. All of it fits inside of the original enclosure, and he only had to add one port for the AC adapter.

This would be absolutely perfect for an antique radio retrofit. One of these adapters can be had for just over thirty bucks!

Self-Balancing Robot Keeps Getting More Features

November 10, 2013 by 18 Comments

self-balancing-robot-gets-more-features

It’s a lot of fun to see a self-balancing robot project. Rarely do they go much further than being able to keep themselves upright while being piloted remotely and annoyingly shoved by their creator as proof of their ability to remain standing on two wheels. This little anthropomorphic guy is the exception to the rule. It’s the product of [Samuel Matos] who says he didn’t have a specific purpose in mind, but just kept adding features as they came to him.

Starting with a couple of carbon fiber plates [Samuel] cut the design by hand, using stand-offs to mount the NEMA 17 stepper motors and to connect the two halves of the chassis. It looks like he used some leftover material to make a nice little stand which is nice when coding at his desk as seen above. There’s also a carbon-fiber mask which makes up the face atop an articulated neck. It has two ultrasonic range-finding sensors as eyes, and the Raspberry Pi camera module as the nose. The RPi board powerful enough to run OpenCV which has kept [Samuel] busy. He set up a course in his living room containing tags directing where the little guy should go. It can also follow a tennis ball as it rolls around the room. What we found most impressive in the clip after the break is its ability to locate the next tag after making a turn.

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