|
|
I recently dug out this old VAT I built back in the 80′s just to see what components I could salvage from it.This was a combo high amp charger and loading device and would kick batteries at about 40 amps. It was polarity protected and nothing happened if it was hooked up backwards. Anybody could use it if they figured out what all the switches did. I also had a Matco charging system analyzer with amp-probe mounted in it. Pretty typical of one of my projects actually.
I tore it apart and was amazed at the quality of the old components and decided to trick the idea out a little if I could. I had a nice Wiegmann enclosure Jackster had given me and it looked like everything would fit, so I jumped in again. After considerable sawing, drilling, grinding, and cursing I ended up with this.
I’ve also made provisions to add the front panel LCD amp/volt meter and shunt when it gets here from China in a couple weeks, if I’m lucky. LOL Some things never change I guess…
Before
 
 
After
 
 
I used an old 24v printer power supply for the relays and low amperage trigger circuits. The high amp side is done with copper buss and heavy gauge wire and with the cooling should be sufficient. It’s compact and easy to handle and operate. The high current relay on the lower right makes the switch from load to charge settings anytime power is applied and it’s fused up where necessary.
I acquired a couple of pretty nice old computers from Chromedome recently and decided to have a closer look at them last night. While I was inspecting the said computers, and looking the MoBo’s over with my trusty Pelican CR123A equipped flashlight, everything suddenly went flash-bang on me. It didn’t just go “poof”, it was more on the order of a gun shot in the ear sort of thing. Fortunately it blew out the front end with the bulb and heat sink assembly rather than the tail cap that was pointing at my face. The body ended up 6 feet behind me in a box on one of the shelves and took awhile to find. One of the batteries hit the wall and was on fire when it dropped behind the bench and everything else and the other battery ended up in the computer I was checking out. It filled the place with smoke/fumes and had me ducking for awhile before I could get the exhaust fans going. Bad stuff.
Basically these batteries won’t tolerate excessive charging or discharge rates. The built in current limiting of these so called “protected batteries” can and does fail on occasion. Another issue to be considered is the fact that most of your cheap Chinese chargers for these type batteries are prone to failure and over charging/regulation issues. That puts repeated stress on the protection circuit built into the battery which then fails. If it goes “poof”, no problem, if it blows up in your face or starts a fire that’s a whole different ballgame.
It was kind of funny in a way. Until my flashlight disappeared.
Anyhow, a hat/tip goes out to Chromedome for the bit boxes!
I took some time to look into some more of the old test equipment I had on the shelf and decided to refurbish some of it. I cleaned up the cases and stripped them where necessary, and for the ones that still had a good crinkle coat, well, I spayed over them with a hammered dark bronze top coat.
Basically all that should be required to get the stuff up and running is to do a recap on the individual units. I’ve made the list of what I need and will make the order shortly and start working on re-capping the stuff. Hopefully some of it should make for some viable test gear.
From left to right:
Heathkit CT-1 Capaciti-Tester
Eico 221 VTVM
Heathkit SG-8 RF signal generator
Knight KG=650 RF signal generator
Eico 950B Comparator
RCA WR-64A Color bar/dot/crosshatch generator
I had this old piece of television test gear stored and decided to give it a closer look. The case is currently soaking in a tub of water with baking soda and 24v dc applied and should be bare metal shortly. Using electrolysis is the only way to fly when it comes to stripping metal. Anyhow, I’ll get it out of the solution and prepped for painting with a gray hammer coat of paint later.
In the mean time I cleaned up the chassis and from what I can see so far replacing the electrolytic filter caps should put it back in business. I’m not sure if I want to start relearning how to work on old TV’s again but you have to keep all your options open and hopefully preserve a piece of history in the process.
Here’s a bottom view of the chassis.
I got the cabinet repainted, installed a good leather handle and replaced the rubber feet on the bottom. The next step will be to recap it.
I purchased these two Hitachi scopes via e-bay and thought I’d run them through the paces to see if I’d made a good buy or not. The one on the left is a V-422 40 Mhz and the other one is a newer V-252 20 Mhz scope. They both locked onto the audio signal I’m feeding them here and do what they were intended to do, which is analyze wave forms. I would much rather have a good digital scope that displayed voltage and frequency along with other pertinent data and the wave form, but that’s out for now unless something happens to “fly by” on e-bay. A little math and and a VOM will do the same thing of course, but it’s still nice to be able to see what you’re doing in a visual format.
I put this together for a friend to help regulate the firebox and water temperature in the heating loop into his home. There is a similar setup controlling the draft door on the stove and this will further help throttle the water temperature. Both systems utilize Red Lion process meters mounted in stainless steel boxes on the front end, and actuators running through a 4-20 ma loop to do the heavy lifting at the other end.
The stainless is rather hard to work with, but it’s worth the effort if you want something to last longer than we do.
This is one of the better tube testers I’ve acquired in that it excepts the older 4 and 6 pin tubes commonly found in vintage gear. It worked but sometimes the meter would develop a 60 hz “buzz” at the pointer (1/16″), and do other weird stuff anytime you “clunked” a switch or made any adjustments. It did however show signs of life, so I dug into it a little further today and got it repaired.
I disassembled the 200 ohm sensitivity rheostat first and cleaned it, and then the contacts on all the other switches. It still had the same issues. So being the rational type(?), I pursued the problem and pinned it down to the selenium rectifier and a capacitor in the leakage detection circuit. Problem solved!
Here’s a bottom view of the chassis:
This is a closer look at the replaced components. I had a bunch of NOS selenium rectifiers on hand, so I decided to fix it that way rather than use a semiconductor replacement.
It was a successful project and made a nice addition to my “tool box”. In the following photo it’s warming up an old globe style 80 rectifier tube.
I’ve acquired/salvaged some pretty nice vacuum tubes recently and thought I’d give you an idea of what I’ve managed to save from ending up in a trash heap. Heh, I still have people ask me what they’re good for.
Mark Oppat over at http://www.oldradioparts.net/ mentioned that this particular chassis was rather rare and also known for having bad power transformers. I put it back on the bench to have a closer look and was pleasantly surprised with the results. I pulled the 80 rectifier tube and disconnected the filter cap as it showed obvious signs of leakage. I then powered the set up slowly with a Variac while monitoring the current on the line in and got good voltage rise on all the secondary windings. A lot of the rest will have to be re-caped and resistance values checked, but so far it looks to be one of the better sets I’ve acquired.
This is a neat old AM/FM tuner chassis I acquired recently.
What makes it unique is that it utilizes 2 6ME5 “eye tubes” for tuning indicators.I took time to clean things up a bit and then powered it up without first changing the filter caps. That’s usually a bad move, but it worked OK this time. I monitored the current inrush and the filaments lit up, so the power supply and basic circuit is intact. I patched it into an amp and got some static out of it, so there’s some hope for this one. I’ll probably just put it on the shelf for now. I’m kind of busy trying to find a real job.
|
|
