Therapy and electronics

I'm starting to see a therapist for EMDR work for trauma recovery. Danae has been doing that for a while and has found it to be the most effective form of therapy she's ever had, and she's had a lot of therapy. I'm giving it a try on her advice and suggestion. Tonight, I've spent a lot of time going through old LJ posts to find events and dates, and it's been taxing. To be expected, when I'm specifically looking for dates of things that are traumatic events and triggers, but rough. I was also reminded of how much happier, confident, and outgoing I have been at various times in the past, and that's reassuring. It's a reminder that this is something I can be and do.

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I have a draft done of my preservation final, and now I need to do a bunch of work on the database final. I can do this.

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Tinkering is a wonderful distraction for me. When I'm able to fix something, it just makes me feel *so* good about myself! I think taking a little time away from finals to do some of that was worth it.

And I did fix that TV! The Y-sustain and Y-buffer boards arrived on the first. I installed them and still got no picture, but the clicking noise wasn't happening either. After trying permutations of parts, it's working correctly with the new Y-main board and the old Y-buffer board. I think they may have sent me a bad Y-buffer? Either way, it's working now. I played games on it for several hours to make sure it wasn't going to die again and have now posted it for sale on Kijiji.

While I was on Kijiji, I found someone selling a Heathkit multimeter for $25. I now own my first piece of Heathkit gear! It expects an 8.4 volt mercury cell battery that is no longer made as a power supply, but it looks like 9 volts will work in a pinch. I'm going to built a power supply for it eventually. For now, I need to figure out why the needle pegs high when turned on in any settings. Probably a short? So I have ordered a cheap multimeter to fix my multimeter with!

Heathkit Troubleshooting

My multimeter showed up today! I paid about $18 Canadian including shipping, and you definitely get what you pay for. But it works, basically. The rotary switch is a little...special. So I dug into troubleshooting the Heathkit!

It has 700 microamps across the meter when turned on with no probe connections. The meter reads full scale at 20, so of course it pegs. I'm pretty sure the problem is a bad transistor, either Q1 or Q2. Q1's source is connected with Q2's base and they read more than 8 volts to ground. The schematic suggests that measurement there should be about 5 volts. So either Q2 is bad, or it's running full on all the time because Q1 is bad. I think? I guess I'll order some transistors and find out!

Also the resistor measurements are all way low of spec! Not sure if it's a flaky multimeter, or measurements in-circuit are off, or if the resistors have just drifted after 60 years or so. Once I get a power supply for the soldering iron that Mark gave me as a birthday present (*so awesome!*), I'll take one off the board and check it out.

Heathkit Tinkering

So Q1, a 2N4304 FET is no longer available and I need to either buy some from Ebay or find a replacement. Trying to find replacement transistors is a new and special kind of hell, isn't it? Especially when I don't have enough of a grasp on theory to fully know what I'm looking at.

I do have a datasheet, but I don't know how to figure out which values are critical to match and which are less so.