I really didn’t go to this show expecting to buy much, and I didn’t - I spent $30 and brought home these two items:
The audio generator on the left works, but has a messy sinewave output. I’m not sure if this is normal, but knowing some of the other equipment I’ve had from this era - it may be. There are some capacitors in the unit with high ESR, so I may play with it a bit before making further judgement.
The RF generator on the right has an absolutely miserable output, the entire bottom half of the output waveform is clipped off - which I thought was bad. Nope, they apparently overdrove the final amp to the point where that’s the way it worked. It also is overmodulated with internal audio, so this thing was a turd when it was new. I found some suggested fixes, so I may play with it a bit when time allows.
The RF generator was a “Offer I can’t refuse” thing - the guy said take it for $5? Ok, sure!
That’s all - I did want the capacitor checker in my show post, but I restrained myself and someone else picked it up for the low price of $40. Thank you rando for saving me!
I did it again. Too much stuff, but I’m going to blame some of the sellers for being so congenial about negotiating on prices! (Yah right!)
So, what did I bring home this year?
Fuses.
This vendor had a lot of different values, including a lot of fractionals that will cost you a small fortune if you buy them new, so I picked up some 1/3, 1/4, 15mA, and 1A varieties. What’s kind of cool about these things is Seneca Fuse used to be a Columbus, OH corporation, and one of the boxes is marked as such. The company was purchased by an entity called Russell Enterprises, which appears to have long since gone out of business.
This is a cool little device that didn’t cost much. It’s a primitive hypot-type device that can test for leakage in a circuit. While primarily designed for appliances and other large current consuming things of yesterday, it still works great as a bench voltage monitor. It also performs it’s other functions without issue, so it was a good find - and it had the manual with it. I’m not sure what the leads were for, this device used EICO’s pin plugs. No worries, another set of leads on the bench is always a good thing!
I actually only wanted the AC Voltmeter in this lot, but the seller was really good on the price for all three, so I came home with the AC Voltmeter, a current meter, and the oddball Sanwa transistor checker. The meters are nice dampened movements and work well, but I haven’t installed batteries in the tester to see if it works. Not sure I will, those little handheld device checkers do an excellent job of sorting parts and identifying things for you.
This little meter in a case was probably part of some course offered by NRI Schools, an early “distance learning” company. (Started in 1914 as National Radio Schools, ended in 1999 as NRI - changing tides on the electronics landscape did them in.) While it’s not really of much use, the real Mueller copper clips and other test leads were well worth the price of $3. The device itself sat in a basement for some time, and it smells like it - if I can get the smell to fade, perhaps I’ll find a use for it.
Here’s the odds ‘n ends portion of the program. An apparently new Ford AM radio that I got for a put-in-the-rack project, a B&K Precision LED voltmeter that matches my capacitor checker, and a surprisingly well written TAB book about early microprocessors. I say “well written” because TAB would publish almost anything. Some books were pretty good, but some were literally nothing more than a guy who wrote a book about taping LEDs to various things and called it “101 electronics projects.”
I don’t need more of these, but they were a good price for functional units, and they’re starting to get outrageously priced. These were checked for operation, and will go into storage as parts donors - or perhaps as resale units once cleaned up and re-capped. Who knows?
In all, it was a good show. I didn’t need to drag home some of that stuff, but I did. I’ll see you at the next show this weekend!
It’s not really important to operation, but having clean knobs and lenses on indicators is always nice. Since I have an ultrasonic bath, I’m going to use it.
The knobs on this guy are pretty cruddy, and the power indicator has a spritz of bronze paint across it.
While I’m removing the knobs from the volume and function selector, they get a shot of deoxit to clean and lube them.
Everything goes in the bath for 20 minutes.
In the end, they all come out nice and clean and ready to re-install!
Parts have been ordered, we’ll go through those next.
The Scott Antique Market has closed for the season in Columbus, with the next show happening in November. There weren’t enough things to make a post for each of the past few months, so I’ve consolidated everything from this year into this one post.
The normal assortment of radios, televisions, and other electrical oddities showed up, with a number of just interesting or other neat things.
I did pick up one item that will be the subject of it’s own post, but until then - here are all of the things I found interesting from the last three shows.
An unusal Ideal toy from the 1970s?
A “Bandmaster Senior” radio. This image ended up on radiomuseum.
The Bandmaster's back.
A closeup of the VFO on the Bandmaster.
The bike everyone wanted in the 1970s.
An optician's cabinet full of test lenses.
8 tracks cartridges and Pink Panther valentines cards.
This Humble Oil tiger really doesn't care about your problems.
No longer a blue light special.
When a snake dragon T-Rex stands on your rocket, it's time to stop drinking.
A couple of radios and “I believe in believe.” Sure thing?
Some nice radios and a Sears clone pong game.
A rather worn radio.
Right off the boat from Hong Kong and deaf as a post.
A couple of table radios from the late 60s.
Your new Sega System awaits.
A small Sony television.
A small battery power early Sony B&W set with frog that's so high he sees the faces.
A small Aiwa reel to reel pocket tape player with mic.
I sat down with an Eico 145 Signal tracer this weekend, evaluating what it would need to put it back into daily service. The answer? Pretty much everything. Leaky wax capacitors, carbon comp resistors that are 50% off of their marked value, and a few “doesn’t appear to ever have been installed” parts complete the list of this thing’s issues. It’s amazing that it’s still working, but I would bet that continued operation would destroy the tubes in short order.
The large 470Ω resistor in the foreground was of interest. A quick shout out to a friend confirmed that this was a 2W part, not a high-voltage device. This makes sense, as the resistor could potentially dissipate 600mW at maximum plate current. It’s also interesting because there’s supposed to be a 10uF bypass capacitor across that part, but it looks like it was never installed!
Right under that, of course, is the across the line capacitor. That ’splodey boi gets replaced first.
A quick trip to mouser for components is in my future.
I picked this unusual device up from an antique store in rural Pennsylvania, near where the groundhog works one day a year. It’s a fairly large place and prices vary, but it’s worth a couple hours of your time if you’re into that sort of thing, see the link below.
(The place seems to only have a facebook presence, and I’m not going to post one of those dirty links here - but here is the local chamber’s page for Yoder’s Antique Mall in Punxsutawney: https://punxsutawney … 73c05f142052452104c6.)
It’s a toolbox! Yeah, right on! Well…no, unless you’re interested in old toolboxes. It’s a fairly nice example of something from when Sears used to make things worth more than the metal it was stamped from. It’s what’s inside that I was interested in.
It’s a demand meter! Yeah, right on! Well…yes, but there’s something unusual about this one. It’s a 2-wire, 115VAC unit. While this is similar to what you would have on your house (or would have had before the electronic switchover,) those are usually wired for 230VAC instead.
This one appears to have been meant for sub-branch metering at some point, as evidenced by the easy-to-remove wiring compartment at the bottom of the meter’s housing. Whomever had this before me took advantage of that in that they wired a plug and outlet in line with the device - perhaps as a jobsite meter to pay the site owner for power consumed? Not really sure here save that all of the cable is pretty stiff and in need of replacement if it was going to be used.
Overall age of the device is in question as well - it looks to be 1930s, but Westinghouse probably made these things for decades. I suppose I could try and track it down by serial number, but who knows if those records still exist?
I tried it out by hooking it to a kitchen appliance with a heating element. It works as expected.
I’d like to get it out of it’s silicone covered metal box for a good cleaning, but that’s a project for another day.
SO…here’s another one of these piece of crap meters. Why? This one was cheap, and was purchased non-working - primarily for parts, as in the NIXIE tubes. ZM1000 tubes aren’t exactly common these days, so having a few spares laying around seems to be a good idea.
I decided to at least take a look inside to see what’s broken. It doesn’t power up because the fuse is blown. That never bodes well, so I jumpered the fuse temporarily and turned it on quickly.
Yep, it’s got some problems. All segments of the tubes are lit, and the tab on the +5 regulator transistor got pretty warm being on for 5 seconds. Turned it on again to get some quick voltage measurements:
+5V Output (Emitter) = +0.8V
+6V (Base) = +2.6V
Measuring the resistance to ground:
E = 2.8 Ohms.
That’s not good.
A good unit measures (to ground):
E = 1.4MOhms.
+5 primarily powers chips, so I pulled all the ICs to start. Things changed, but not necessarily completely back to normal.
Good unit:
E = 1.4M
B = > 8.5k (charging)
C = Open
Bad unit:
E = 2.5k
B = 1.9k
C = Open
I started putting chips back in, the very first one I replaced (IC5) took the Emitter of the regulator transistor down to 3 Ohms. So that chip is bad.
However, there’s something else wrong. With all the chips gone, the +5 load should be negligible. I did a quick scrape on the transistors to see if one was shorted but didn’t find anything obvious. That leaves old capacitors that could be leaky. This thing is full of Tantalum drops and cheap-ass film caps, any one of those could be partially shorted and there’s no real way to know except to start lifting parts.
Since this is just a parts unit, and the tubes and driver ICs appear good, I think it’s just going in the parts bin as intended. Maybe if I have some snowy Saturday, I’ll pull it out and start lifting parts to see what’s going on. But for now - parts is parts, and parts is what it is.
I’d never attended this show, but was pleasantly pleased with the turnout. There were perhaps a few dozen vendors and a packed house of visitors in the old gymnasium of the converted school. Quite a bit to look at, and prices were really good. I managed to bring home some good things for a total of $10, almost spending more on drinks and snacks on the way home! I didn’t think the weather was going to cooperate, but it turned out to be just a bit slushy, cold, and windy.
We wandered the aisles for about an hour, taking some time to stop and look at the old photos on the walls from the building’s time as a school, talking to some of the vendors, and digging through boxes of stuff. Since this is so close and easy to get to, I’ll probably attend next year as well - weather permitting of course!
A bunch of books. The ECG manual went home with a friend.
Some rat shack remainders. I picked up the cable.
Lots of AM CB showing up right now, including these old phone-style units.
Parts, and some rat shack 300 ohm clip on connectors. Got these for the nostolgia factor.
A friend pulls a microcassette unit from a dollar bin.
Some test equipment. The (working) signal tracer went home for $2.
More random equipment.
Even more equipment. The power supply was unique enough to go home with me for $2.
And I have to say it was a pretty good little show. The weather wasn’t planning on agreeing on the ride down, but it turned out to be just a skiff of snow and cold, windy weather. There were maybe a couple dozen vendors, and a packed house full of guests to the point where cars had to shuffle so others could leave.
While I only spent an hour there, I walked out with some good stuff as did my fellow show-goer. I’m working on processing pictures, and will post those soon.
One of the issues with the IM-1212 and it’s clones is that it drifts all over the place, and part of that is the oscillator that actually does the counting for the display. This is an attempt to replace that section with better parts to see if it’s any more stable. I started this with this previous post, and present my findings here.
We start by identifying the components of interest and removing the board:
In the oscillator circuit, other than the transistors, are the following passives:
We’re not going to replace the pot, but all of the other components are going to be replaced by film and/or temperature stable to 25ppm components.
The sharper-eyed among you will have already seen an issue. There’s no 15k resistor identified here, and I’ll talk about this a bit later in the process.
Before taking the board out, I let it warm up and preset the oscillator to it’s suggested 85 count.
Getting the board out isn’t too bad. There are 6 screws, three solders, and a clamp.
The screws are the ground lug for the power cord on the back panel, the two screws that hold the transformer down, and one screw each in the remaining corners. One of the screws is under the switch assembly and can just be seen by the red input jack, so you’ll need something relatively thin and long for this one. They all appear to be the same size.
Next are the three jacks on the input. I unsoldered these at the front panel itself, but the white wire was long and flopped around and broke because it is solid wire. Not a big deal there.
Last, is the clamp for the power cord on the back panel. This is just squeeze it with pliers and work it out. I left the power cord attached to the unit and just pulled it through the bottom case so I had enough room to work, and used the ground lug screw and nut to temporarily hold the transformer down as not to break the relatively fragile connections to the PCB.
Before getting started, I did an inspection of the board. There were a number of bad solders on some of the components - mostly things with thick leads like the potentiometers. I took a minute to clean those up before getting started.
Removing the parts is relatively easy, this being a single sided board. A soldapult and some wick made short work of the old solder, and that’s when I noticed the 15k resistor wasn’t.
The schematic indicates 15k, as does the board - and another unit I have has the correct 15k part in it. I have to wonder why this was there - did the original builder not get the correct part, or was it broken during assembly? Who knows - but it didn’t really matter as the device worked.
Interesting.
The rest of the parts are replaced without issue, and the correct 15k is placed where indicated.
There’s not a lot of current or voltage here, so I wasn’t particularly concerned with the size of the resistors.
After doing a precursory check of parts, solders, and whatnot, I powered the device up on the bench. The oscillator count was quite different, so my replacements had some effect.
Some warmup time later and I adjusted the oscillator to the correct value:
Putting it back together and:
It’s already drifting. I set it back to 85 and let it set until the next day.
It didn’t do a thing. I will say, however, that it seems easier to adjust it back - there’s not as much play in the overall adjustment - you can set it and it generally stays there until the temperature changes.
So, my conclusions? This whole thing probably would need rebuilt with modern components in order to maintain any stability in measurement. For now, it’s just going to be sitting in a rack on all the time measuring the 12V rail of a power supply so … it is what it is, I guess.
