Today’s board is the power supply of a Sabtronics 2000 DVM. Sabtronics is known for being one of the first, if not the first company to offer a hobby priced digital meter. They eventually expanded out into other instruments, into more specialized measurements like True RMS - also at an affordable price. Unfortunately, technology marches on and a company in the USA providing USA-made devices got their lunch eaten by the cheaper array of imports. The devices they offered still have a place today, and those bright “science blue” cases are just as attractive now as they were then.
Here’s the board:
What’s of particular note is, of course, the faint orange script “T” in the upper right hand corner. This board is more akin to the Textolite made at the GE Coshocton plant, but was made there all the same.
I always like finding a piece of home in a device. Especially one that I can use, like this meter. Stay tuned, the “T” will most certainly make an appearance again!
I did some troubleshooting on this device, checked tubes, voltages, transformers, there’s even a video about it that will show up soon and will be linked as soon as it posts. But I overlooked the obvious thing.
You see that switch in the middle of the device marked “Speaker On/Off” Good. You were probably screaming at the screen going “CHECK THE SWITCH!” I finally checked the switch. It was dirty and open. Some Deoxit later, and the tracer now works just fine.
That time was not wasted, however. I did confirm that the filters are good and that the coupling capacitors aren’t leaking, so I feel confident that I can use this device without worrying that it’s going to red-plate a tube - even though that 12CA5 output gets smoking hot.
What’s the takeaway here? Always check the little things because they tend to bite just as hard. That’s all for this device, it goes on the bench as an amp. Plenty more on the EICO 950A to come!
I picked this guy up at Dayton 2026, literally the only signal tracer I saw. This was one of two magic eye laden devices I saw, the other being one of Heathkit’s larger, upright-style R-C bridges. Test equipment of this nature was absent, probably due to the fact that what’s still working is either in collections or is being sold on eBay at the eBay tax rate.
I’ve wanted one of this style for some time, and this one was a couple of sawbucks. Vendor didn’t offer me any advice on it’s status, and I assumed that it did not work. I was correct, the device is silent and the output tube seems to be getting quite warm - much warmer quicker than a simple few minute test would indicate.
I did a bit of troubleshooting to determine if the supply was working, and it is - that will show up later in both a video and a post, as I want to get this device working.
Beyond that, there’s not much to say. Here’s the device photos:
The device is clean but dusty, and hopefully shouldn’t take much to make it talk again. Stay tuned!
More parts for the EICO 950A, this time concentrating on that center switch. This takes care of the resistors on that switch, but the two capacitors in there will still need replaced.
We’re about 3/5ths of the way done here. The power supply, and some other cleanup remains.
The EICO 150 that was on the bench had a bad speaker. Now it has noise. Lots and lots of noise.
I’m going to put a scope on the transistors to see what they look like, in particular Q3 and Q4, the output pair. This is with minimal gain, no input signal. The test is trying to determine where the noise is coming from. I made a partial determination earlier with a suggested test - unhook the base of Q4 from the circuit. If the noise stays, it’s Q4. If it goes away, it’s back further in the circuit. It went away, so something further back is bad. I’m also going to measure the voltages on each transistor for reference.
Some noise there on the collector. This will also appear on the base of Q4 since they are direct-connect.
Q4
Base
Emitter
Collector (Output)
The signal is being amplified by the output transistor. Perhaps this explains the current draw? The output transistor is doing something instead of being in it’s no output state. What’s causing this? Maybe Q3 is just noisy. Maybe one of those carbon composition resistors is noisy. It’s going to take some more work to make that determination.
Voltages
Measured:
Manual says:
You can see there are some variations here. Further work is needed.
We mostly toured the buildings, but I went away disappointed as there were no test equipment vendors present - in fact, the only real TE vendor there was Bird, but they aren’t selling to me. The guy I was with was interested, however, as he needs a commercially available handheld SpecAn that isn’t a Chinese company.
I did pick up a few things here and there, but not much. Mostly rain discount stuff.
Here’s what I saw at the show:
A meter with the Niagra Power sticker on it.
Did I photograph this already?
I took it home. Gotta have a voltmeter at a show.
One Dollar Rain Discount. It has a burning smell.
UNIX, anyone?
110VAC single phase. Unusual.
Lots of reel-to-reel players.
A very precise balance beam scale.
Stacks of stuff, why we are here.
We left probably close to 1PM, as many of the flea market vendors had started to pack up. I skipped Sunday as there wasn’t anything I wanted to see, I was aching, and I wanted to play with some of the things I bought.
Next show is Breezeshooters in Butler, PA. See you there!
Friday turned out to be a just slightly damp day at the show, we had a little rain but it cleared off quick. We toured the flea market, and saved the buildings for Saturday due to the forecast of heavy rains. The steak tips and mashed potatoes vendor wasn’t here this year, so bourbon chicken and a banana milkshake subbed in it’s place.
This year, the mobile AM CB stuff was almost all gone save a few units here and there. Hobby-level test equipment, i.e. the EICO/Knight/Heath/etc. was almost not present, save for a bunch of those crappy RF generators that no one really wants - the bridges and tracers and things are pretty much no longer for sale. At least, not at Dayton. Of course, the piles of plastic radios and old televisions are long gone, and even the big boat anchor radios are vanishing. I think I saw maybe 1 Hallicrafters S-38 unit for sale…
Things are changing, but there was still a lot to see:
A nice A-K speaker.
A basket of Apples.
Just some audio stuffs.
A nicely restored cathedral radio.
Choke the Chicken…not here please.
An old Data Precision meter.
Many DEC Rainbow computers.
New, old-stock desoldering irons.
My favorite brand of tools?
Designed for butane flow measurements.
Some tunes for the ants.
No idea what this model was.
Someone's pride and joy, dumped in a bin.
I eventually took the scope for $1.
The old way of measuring standing waves.
Just some random HP things.
Ok, if you insist.
Loudenboomer!
Some info on the Loudenboomer.
Would you like to play a game?
It's not tourist season without a thumb.
Some military equipment.
Telephone B.C. (Before Cellular)
How many of these were made?
Moto comm analyzers.
A really nice condition scope.
Some old computing horsepower.
A really old opto counter.
This scope was in bad shape elsewhere.
Parts. I took a few transistors.
High voltage?
Used to be piles of this stuff.
These are vanishing as well.
Some more radios.
And some more radios.
A scope that was part of a school course.
Even if it was good, this showed bad.
Some sort of receiver.
A tape deck. Friend wanted it, you carry it!
Lots of these, no one wants.
Some of those funky round speakers.
I took the Sabtronics unit for a sawbuck.
Semiconductor testing devices…in peach.
A Shango Special.
I have no idea.
A table full of stuff.
Hallicrafters SX-62.
It's a radio that's a table that's a radio.
Teletypes for your 110 baud needs.
A cool old terminal.
daytonf26-terminalsettings-wereboar.jpg
The only signal tracer I saw.
A giant TRF radio.
A nice looking TRF unit.
Warm soda and melted candy anyone?
Surprising, more W-J stuff this year.
Some W-J stuff.
We spent pretty much the entire day, heading out at 4:45 a few minutes before closing. We went Saturday as well, but I skipped out on Sunday.
Continuing on with the EICO 950A, the components near the power input need to be changed out, especially the capacitor used as the across-the-line component.
The orange drop is being used as the across the line cap. While this would have been acceptable way back when, it’s not acceptable now. We have specialized capacitors for this purpose, and one goes there. I’m also going to clean up the power input lead to the transformer, and it’s going to get a new line cord. The 470K resistor will go, and there’s a hidden 270K on the switch that will come off but not get replaced just yet as the parts I bought decided to hide from me.
There will be a 270K placed here, eventually.
I took the time to remove the rest of the junk from the power supply:
And the entire thing is starting to look better.
Next step is to tackle the resistors on the switch itself, as well as those two capacitors buried inside. I also need to consider where things will mount on the supply…the OEM used the tube socket as tie points for all parts, but I’m not sure I want to do that. I usually like to get the AC off on it’s own. We’ll see.
The EICO 150 signal tracer that was recently on the bench works, but it has some other problems.
Mainly: Noise.
The output is very noisy, and I want to track this down. I thought about putting this aside until later, but it has me intrigued and I want to get to the bottom of it.
This series will deal with isolating and tracking down the noise present in the unit - noise that is present on the output as popping and crackling.
The EICO 950A currently on the bench is a mess, and there’s just a lot to remove and re-wire.
The power supply area looks a little cleaner.
The leakage test lamp was mounted in a manner that required you run wire up and around. I moved that so the terminals now pointed towards their connections, and cleaned up the ground enough that it took solder as the original connection just peeled off. That took some doing with scratchy items…
The eye tube socket was equally messy, but cleaned up sort of ok.
That’s all for this round, there’s still plenty to do on the bottom, and a few parts poking up through the top that will need to be addressed. Stay tuned!
