I felt sorry for an old 1957 4-tube AM portable radio chassis lying on the shelf.
The thing was designed for either 115v AC, or batteries (7.5v + 90v).
After some "tinkering" (I rally hate that word since I'm a professional) I got the chassis to run on AC - and the reception was loud and clear on a lot of channels!
I even picked up stations from Chicago and New York the other night here in Philly.
So......
Today, out in the garage, I started up the table saw and began making a wood cabinet for the old girl. - table radio style of my own design.
I love the smell of fresh cut wood in the afternoon.
I'll post photos later on.
The thing was designed for either 115v AC, or batteries (7.5v + 90v).
After some "tinkering" (I rally hate that word since I'm a professional) I got the chassis to run on AC - and the reception was loud and clear on a lot of channels!
I even picked up stations from Chicago and New York the other night here in Philly.
So......
Today, out in the garage, I started up the table saw and began making a wood cabinet for the old girl. - table radio style of my own design.
I love the smell of fresh cut wood in the afternoon.
I'll post photos later on.
Yesterday I did (probably temporary) repairs to 2 instruments, in 2 different locations, with the same problem: Various random, intermittent symptoms, most of which involving LOUD, obnoxious popping & cracking noises.
These are typical digital/analog audio circuits, with typical +5, +-15VDC supply feeding several boards via the usual Molex MTA156 connectors. 5V on the boards was down around 4.5 and fluctuating - well yeah, that'll cause some pretty loud bitching! A quick wiggle of the Molex power plug, and 5V was immediately restored.
Here's where I made a disappointing discovery: The male headers on the boards are the standard tin-plated type, while the female cable connectors are gold! I know dissimilar metals are a pretty bad idea, especially in a higher-current application like this. What I didn't realize until some further research last night is that this gold/tin pairing is actually in the red zone on all the galvanic action/corrosion charts - as in, "Yeah, don't do that."
I won't name names, but this is a reputable company that should know better.
I did a temp fix by soaking everything with Gold Guard, but I'll also be submitting quotes for replacing all these connectors with matching parts, because it's just a matter of time. But first I have to do a bit more studying. I'm pretty sure gold plating is actually not recommended for hi-current connections, right? Maybe better off sticking with tin for both parts in this case.
Into the data sheets we go...
These are typical digital/analog audio circuits, with typical +5, +-15VDC supply feeding several boards via the usual Molex MTA156 connectors. 5V on the boards was down around 4.5 and fluctuating - well yeah, that'll cause some pretty loud bitching! A quick wiggle of the Molex power plug, and 5V was immediately restored.
Here's where I made a disappointing discovery: The male headers on the boards are the standard tin-plated type, while the female cable connectors are gold! I know dissimilar metals are a pretty bad idea, especially in a higher-current application like this. What I didn't realize until some further research last night is that this gold/tin pairing is actually in the red zone on all the galvanic action/corrosion charts - as in, "Yeah, don't do that."
I won't name names, but this is a reputable company that should know better.
I did a temp fix by soaking everything with Gold Guard, but I'll also be submitting quotes for replacing all these connectors with matching parts, because it's just a matter of time. But first I have to do a bit more studying. I'm pretty sure gold plating is actually not recommended for hi-current connections, right? Maybe better off sticking with tin for both parts in this case.Into the data sheets we go...
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Back in the early 70's I ran the service department in an Olson's electronics store. We had a lot of issues in Fisher solid state receivers with the tin plated connectors. The heat and humidity in south Florida caused some of the connectors to turn green and corrode. A thorough cleaning with a toothbrush and WD-40 would usually fix them.
Sometimes the corrosion was bad enough to cause the connector terminal to wire crimp connection to go open or intermittent. My own 500TX had this disease. That's why I got it cheap from a UM student when it was less than 2 years old. It did live in a frat house, but other than dust it looked OK inside.....no beer!
Sometimes the corrosion was bad enough to cause the connector terminal to wire crimp connection to go open or intermittent. My own 500TX had this disease. That's why I got it cheap from a UM student when it was less than 2 years old. It did live in a frat house, but other than dust it looked OK inside.....no beer!
Thank goodness you are still around. I guess you become wiser with safety. The flash bulb is a excellent prank, shame I cannot buy them anymore.
I used to play around steelo wool and connect a 30V power supply and goes like a flash bulb but in slow motion.
Someone sent me a repair job, a heavy duty telecom P/S. There are burnt stuff inside and no wonder why, the fuse was a solid piece of brass, nicely lathed into a 3AG size. Kept the brass fuse as a souvenir and fixed the P/S.
Someone taught me, once you repair something with high power, put one hand in your pocket & step back before you switch the unit on. I'm still here and with no scars.
Yes, thermocouples can generate a millivolts junction.
Once I found the company bought thousands of cheap mini jumpers, the audio/video eurocards were becoming intermittent. Thus all incoming repairs, first thing was to replace all the cheap ones with quality jumpers and work from there.
I used to call these "No-Blo" fuses. In the 70's someone (Mallory maybe? I remember a blue and red box) made a replacement volume control with a scored hollow aluminum shaft which could be broken to one of several common lengths. One of the left over pieces of aluminum was just the right size to fit in most fuseholders.
They worked better in situations where a "strong" fuse was needed, far better than the usual aluminum foil wrap. I used one of these to find the intermittent short in my 1965 Pontiac's AC system.
I like to think of any Pdmax spec for SS parts to be under cooling with LN2. Unlike a vacuum tube where the spec is actually obtainable in an oven
I agree.
The trouble is..
Almost nobody wants to do the tedious, dirty work, they just want to jump right in and play Mister Technician.
By that I mean learning and becoming familier with the fundamentals, the theory involved with electronics, along with the "oh-so-many" facets, some which are critical to success, and without them can lead to failure.
I'm sure you've all heard the saying: "A guy buys a radio shack multimeter and a soldering iron and thinks he's now a technician".
Granted, a hobby is just that, nothing more.
But with the potential dangers involved in servicing or designing anything that runs off electricity, there is no leeway or room for mistakes.
The previous comments of people jumping fuses is a very dangerous thing to do, yet some people are clueless of the repercussions and dangers that can arise from such acts.
A guy brought in a flatscreen TV to my shop a couple years ago.
Screws missing from the rear panel... telltale sign of tinkering.
Later, when I opened up the set, the main AC fuse was wrapped in several layers of tinfoil.
Along with that, board traces were fried beyond repair, blackend boards, parts blown to bits, a real mess that I didn't give more than 5 minutes of my time to.
It was now worthless junk for the scrap heap.
And yet, when I discussed this with the guy later, he had the nerve to critisize my competence!
Naturally, he was added to my "black list" in case he brought anything else in.
I don't need that aggravation.
>Transistor junction temperature is not transistor case temperature.
Well, I had to go to college, become employed by a then leading computer company and work in chip component hardware to understand that. It was only then that I learned about the basic thermal resistances all encapsulated silicon fabrication is presented with.
When I was in college, I remember looking at an opened up PDP-11 and wondering "what are all the fans for?"
I cant imagine "more people" having such experiences, than less people.
Well, I had to go to college, become employed by a then leading computer company and work in chip component hardware to understand that. It was only then that I learned about the basic thermal resistances all encapsulated silicon fabrication is presented with.
When I was in college, I remember looking at an opened up PDP-11 and wondering "what are all the fans for?"
I cant imagine "more people" having such experiences, than less people.
I fixed my internet connection. Wasnt even getting the minuscule speed we pay for...
I own my own router. DOCSIS 3, Motorola Arris - got it at a yard sale years ago. Decided to power it using a 12V brick with a 3 wire cord, whose connector happened to fit, was the right polarity and current was adequate. Lost the original wall-wart somewhere along the way.
Located it out in the garage corner, next to the breaker panel. No excess microwave emitters in anyones bedroom. Finally called c-cast and worked with the rep, begging them to send someone out to re-cable the thing to the street. Worked on the cabling myself from their pipe into the garage, drilling a hole in the wall. Still abysmal performance...
Seemed worse in the morning. They had some ground wire coming from what looks like a rod in the ground, which may be shared with the breaker panel. This wire went to the bracket holding a female-to-female threaded piece allowing extension of the their street coax into the house. Naturally I left it in place when I replaced the modem cable connection.
I removed it. Now I'm getting my whopping 3.5 Mbs, whereas with that ground connected, 0.8 to 1.2. So there's a ground loop; breaker panel to wall outlet, to power supply, to modem, to coax cable, to connector-thingy, to ground rod, and back into breaker panel.
Now I have to leave it disconnected, or get a different power supply for the cable modem with a floating secondary. I wonder what's going to actually happen? It's raining this morning and my speed measures 2.9, with a 10T cable connected directly to the modem. At least The JazzGroove now streams w/o interruption...in the morning.
c-cast's speed test says that's good enough for email - nothing else. Guess they want us to pay them more.
I own my own router. DOCSIS 3, Motorola Arris - got it at a yard sale years ago. Decided to power it using a 12V brick with a 3 wire cord, whose connector happened to fit, was the right polarity and current was adequate. Lost the original wall-wart somewhere along the way.
Located it out in the garage corner, next to the breaker panel. No excess microwave emitters in anyones bedroom. Finally called c-cast and worked with the rep, begging them to send someone out to re-cable the thing to the street. Worked on the cabling myself from their pipe into the garage, drilling a hole in the wall. Still abysmal performance...
Seemed worse in the morning. They had some ground wire coming from what looks like a rod in the ground, which may be shared with the breaker panel. This wire went to the bracket holding a female-to-female threaded piece allowing extension of the their street coax into the house. Naturally I left it in place when I replaced the modem cable connection.
I removed it. Now I'm getting my whopping 3.5 Mbs, whereas with that ground connected, 0.8 to 1.2. So there's a ground loop; breaker panel to wall outlet, to power supply, to modem, to coax cable, to connector-thingy, to ground rod, and back into breaker panel.
Now I have to leave it disconnected, or get a different power supply for the cable modem with a floating secondary. I wonder what's going to actually happen? It's raining this morning and my speed measures 2.9, with a 10T cable connected directly to the modem. At least The JazzGroove now streams w/o interruption...in the morning.
c-cast's speed test says that's good enough for email - nothing else. Guess they want us to pay them more.
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I don't have any worries about ground loops in my phone/internet lines.
Verizon Fios is optical.
Amazing technology it is...
Two different colors of lazer light - one for phone calls, another for internet.
And the actual "fiber optic conductor" or "light pipe" is tiny! - imagine a single bristle of a toothbrush - that's how thin the thing is, but wrapped in a sturdy "cable like" sheath.
Verizon Fios is optical.
Amazing technology it is...
Two different colors of lazer light - one for phone calls, another for internet.
And the actual "fiber optic conductor" or "light pipe" is tiny! - imagine a single bristle of a toothbrush - that's how thin the thing is, but wrapped in a sturdy "cable like" sheath.
Our fibre is all IR, and the box (Home Hub 3000 - support, help and troubleshooting from Bell Internet) that has the router and wi-fi also has the Voip for a POTS telephone. It only provides 48V for ring though so my oldest telephone won't ring (it wants 90V). I don't even have a phone connected to it anymore. I only have it because they tell me it saves me a few dollars a month.