In addition to the air variable capacitors, three of the parts bins contained a bunch of pre-wound antenna coils, including these that looked unused. One of them even had an instruction sheet.
Calrad CLS Loopstick.
They consist of two coils, one wound on top of the other and what seems to be a ferrite rod inside that can be tuned by turning the screwdriver or even a knob at the other end.
One was also in a box, a Miller A-5495-A with two separate coils and a capacitor. Looks like it has a tuning range of 540 – 1700 kHz, which is the AM broadcast band.
This one was tunable as well by turning the screw at the end.
Now, if I can find some Ge diodes, I wonder if I could use these in a crystal radio…
While exploring the component bins, I came across a couple of air variable capacitors, one of which was still in the box and didn’t look like it had ever been used. A Hammarlund APC-50-B air padding capacitor, complete with knob. Capacitance range is 3.9-50 pF. Looks in really good condition and turns pretty smoothly.
The other air variable capacitor I found is a little more anonymous but also looked like it hadn’t been used before. One of the rotor plates at the very back was slightly bent causing it to make contact with a stator plate. Aside from that it seems in good condition and turns pretty well.
I’ll have to see if I can straighten out that one plate. Would be cool to use it in something.
Took me a little bit longer to get to than I planned, but I finally got the capacitors replaced. The diameter of the 820 μF capacitors were a little larger than the original ones, so it was a bit of a tight fit getting the three of them in. While I was in there, I replaced two other 820 μF capacitors in the middle of the board even though they still looked in good shape. Thought about replacing the 22 μF and 47 μF capacitors, but decided not to. There were a lot of surface mount components near the 22 μF cap and I didn’t want to get the soldering iron too close or accidentally solder where I shouldn’t.
Took me a bit of time to remember how everything went back together, but I got the monitor reassembled and brought it back to the computer. Plugged it in, turned it on and was rewarded with the monitor telling me it was trying to find a signal source. Reconfigured the computer for a second display and up it came!
Monitor is fixed and now I’m back to a dual headed system.
I had the fortune of acquiring a veritable gold mine of electrical components tonight. 5 parts bins worth of resistors, capacitors, transistors, switches, ICs and other miscellaneous parts. Most everything is pretty organized so there’s really no sorting that needs to be done. Most of the components were pretty easily identifiable, but there were others that I had never seen before and have no idea what they do.
A lot of items are pretty old, but have never been used. One whole parts bin is just resistors, containing regular carbon film resistors, a few big power resistors and some carbon composition resistors, which you don’t see a whole lot of these days.
The next bin contains transistors and a few other miscellaneous parts. Some of the are unidentifiable other than their form factor and others have never been used.
The third bin is kind of a mish-mash of parts – pre-wound coils, resistors, things that looked like variable capacitors. Quite a few components in this bin that I have never seen before.
The capacitors bin contains some interesting capacitors. Lots of electrolytic caps, and some really big caps in the mF range that I guess could be used for power filtering.
The fifth bin contained all sorts of ICs and EEPROMS. I’m not sure how much of what’s in here will be useful, but I’ll need to try to identify them first. There are even a bunch of Z80 CPU chips in here. I wonder if I could do anything with them.
It was off to the operating tableworkbench with the dead monitor. In case you haven’t been following along, the Samsung 226BW monitor I picked up a while ago from EBay died a couple days ago.
Following this very helpful disassembly/repair guide, I got the covers off and the display panel separated from the chassis. In the process I discovered evidence of either a previous repair attempt, rough handling or just fragility from old age, since holes for two of the three screws holding the case on were broken.
After disconnecting the wires and separating the display panel, I made it to the circuit boards.
Right away, I could see four bulgy capacitors. My board must be a different revision than what was posted in the guide because that board had three caps. They are very bulgy indeed. It’s a good thing they didn’t explode or anything.
Note the very domed looking tops of the capacitors. The other brown thing in the middle of the capacitors is an inductor.
Fortunately the back of the circuit board has the capacitor positions labeled, so there’s no need to guess which joints need to be unsoldered. I’ve outlined them here in the yellow boxes.
Inspecting the other capacitors suggested they were all still good with no signs of bulging. There are a couple others that I could probably replace, but some of the others, like the big black 100μF 450V capacitor, are glued to the board or other components and I don’t want to risk damaging the board just to replace them. So now it’s off to do some shopping to find some replacement caps.
Two of the 820 μF and the 22 and 47 μF still seem to be in good shape, but I figured since I’m replacing capacitors, I might as well replace those too. I’ll probably order at least two sets of each so that I’ll have them on hand in the event my other monitor (which is even older than this one) dies in the same manner.
Parts are on order from Mouser and should be here in a few days. Stay tuned for part 2 (or maybe 3), in which the capacitors are replaced.
