Recent content by andy

They weren't that uncommon. It was basically a 486 that was pin compatible with the 386SX, which itself was a glorified 286. There were a lot of low end 486 boards that were basically 286 boards with one of these cut down 486 CPUs.

Most of the 5154s I've worked on have that capacitor tacked on like that.

You should scrape away as much of that brown/black glue on the board as you can. It's corrosive, and slightly conductive.

Yes, monitors from that era always under scan by a fair amount.

Wonderful! Looks like it could just use a degauss, and maybe a focus adjustment, but great to see a success. It's hard to tell if the sides are bowed out, or if that's from the camera. If the sides aren't straight, then you should be able to fix that with the pincushion control.

I think you're over analyzing this. The fact that you have high voltage means the HOT is doing its job. There isn't much that could fail to cause no horizontal deflection, but still have HV. With the horizontal yoke out of the circuit, the signal on the collector of the HOT will definitely be...

I know you can make the screen light up green, but is there any actual green video in the picture? It sounds like there isn't. Assuming that's the case, then something is interrupting the green video signal. You're not going to adjust your way out of it. Luckily, there are three identical...

Since the horizontal deflection is driven by the same circuit that drives the flyback, you can be sure most of it is working since you have high voltage. One side of the horizontal yoke winding should connect to the collector of the HOT. The other side will pass through various components on...

Don't get too caught up on making the cathode voltages match the schematic exactly. They will vary slightly depending on the condition of the CRT. An oscilloscope would be highly useful here. I would start at the green video input pin, and follow the signal until it stops. If you can't do...

It's not a critical adjustment. Just turn it up and see if you get anything on the screen. If there's no difference, put it back where it was originally. Regardless of what voltage is on the cathodes, turning up the G2 will usually produce some kind of raster. What you see could be helpful...

Have you tried turning up the G2? As said before, with only about 100v on the G2, I would expect to see no picture.

It can be a huge problem. One check I like to do is to probe various spots on the board with an ohm meter. Any reading at all means it's not clean.

There's no need to discharge the CRT unless you need to disconnect the HV cable from the CRT bell. Most monitors do self discharge due to the resistor network that creates the focus voltage, but it's always wise to assume it's charged before touching the HV connection. If it's not powering on...

Based on that, you can rule out any kind of major fault like a shorted power transistor, or bad power supply driver IC. Depending on how much capacitor leakage there was, there could be some subtle damage from that. Maybe an open resistor, or electrical leakage on the board if it wasn't...

I think people are often too critical of the 5154. I've worked on about 10 of them in recent years, and all but one were still in excellent condition as far as heat damage went. Even the worst one just needed a bunch of new caps, which isn't unusual on a heavily used monitor. I just repaired...