SinclairSoftware
New member
Watching this project slowly come together is very inspiring!
Schrockwell's S3/30 Reloaded build
- Thread starter schrockwell
- Start date
schrockwell
Active member
Well, that was short-lived. A little later I plugged in a keyboard and mouse, and now it won't boot. The failure was gradual. The screen and audio started wigging out, and now the display won't come on at all, and certainly no startup chime. There was some high-pitched squealing that might have been coming from the flyback transformer.
I suspect the power supply needs a recap, which I will tackle next. I just hope it didn't take damage anything else.
I suspect the power supply needs a recap, which I will tackle next. I just hope it didn't take damage anything else.
schrockwell
Active member
I recapped the CR-44 power supply with the kit from Console5. All went well. Thank god for the Hakko; I got it done in just 90 minutes.
Here are the output voltages, unloaded. No major changes.
After reassembly, the problem persists. I managed to capture a short video:
View attachment IMG_0415.MOV
Sometimes it plays a complete chime and shows the cursor, but then freezes. Other times it just shows garbage on the display, or the display is blank. Definitely feels like an intermittent failure of an analog component.
I also got an error code once:
I checked the voltages on the floppy connector:
Note that there is NO voltage on pin 5, where -12V is expected.
Could that be the culprit? Maybe a bad voltage regulator in the PSU?
Here are the output voltages, unloaded. No major changes.
| Color | Before Recap (V) | After Recap (V) |
|---|---|---|
| Green | -8.11 | -8.22 |
| Red | 13.48 | 13.51 |
| Orange | 5.33 | 5.32 |
| Yellow | 14.01 | 14.02 |
After reassembly, the problem persists. I managed to capture a short video:
View attachment IMG_0415.MOV
Sometimes it plays a complete chime and shows the cursor, but then freezes. Other times it just shows garbage on the display, or the display is blank. Definitely feels like an intermittent failure of an analog component.
I also got an error code once:
0000000F 00002802.I checked the voltages on the floppy connector:
| Pin | Expected (V) | Measured (V) |
|---|---|---|
| 5 | -12 | 0.0 (!!!) |
| 6 | 5 | 5.00 |
| 7 | 12 | 12.72 |
| 8 | 12 | 12.72 |
Note that there is NO voltage on pin 5, where -12V is expected.
Could that be the culprit? Maybe a bad voltage regulator in the PSU?
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schrockwell
Active member
I measured the -12V line at -11.7V at the power supply connector in-circuit. So the power supply is working, but the bad reading at the floppy connector still might be a clue.
schrockwell
Active member
Actually, pin 5 on the floppy connector is N/C, so that was a red herring.
Currently, there is startup chime or display at all. I did find and repair a couple cold solder joints on the analog board, but no improvement there.
I'm pretty stuck at this point.
Currently, there is startup chime or display at all. I did find and repair a couple cold solder joints on the analog board, but no improvement there.
I'm pretty stuck at this point.
schrockwell
Active member
Yup, that is what I found as well.
I realized that I did not recap the analog board yet, so that is the next step.
I realized that I did not recap the analog board yet, so that is the next step.
SinclairSoftware
New member
The analog board was pretty easy peasy from what I recall from working on mine. Even used hot glue on the caps so they wouldnt move around and break solder joints. Felt super professional and fancy afteword lol.
@schrockwell if you get to the point of selling any completed board builds, I think you'll have some buyers! I'd like to get in line 
schrockwell
Active member
That would be quite the undertaking. It would be really difficult to price them low enough to make it worth the cost of parts and time. I think it would have to be a labor of love for someone with ample free time.@schrockwell if you get to the point of selling any completed board builds, I think you'll have some buyers! I'd like to get in line
croissantking
Well-known member
I’ve had an issue like this. Couple of things to check - solder work around the GLUE chip (possible poor connection), and sagging 5V line (possibly causing a twitching reset line).
When you come to recap the analog board, check all the sockets for dry joints on their pins.
Great work so far - you’re very close to solving it.
schrockwell
Active member
Thanks, I checked both of these things. I even asked my wife, who has experience with electronics QA, to look it over. No improvement, unfortunately.
And the analog board recap went smoothly but did not change anything.
I dusted off the scope and began poking around, starting with the oscillator output. The frequency is good, but I was surprised to find a jaggy triangle waveform with a DC offset. I was expecting a sine wave or square wave centered at 0V. Does this look normal?
I also probed the reset line at the switch, and after power-on it goes high and is never pulled low.
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schrockwell
Active member
It sure seems like 1.120V is not low enough to trigger a logic low, since the specified threshold is 0.8V.
schrockwell
Active member
Here's the C32M line, measured from the output of UH7 at R28. It's pretty sad-looking.
schrockwell
Active member
I desoldered Y2 from the board and tested it directly with a 5V bench supply. The results are very similar to the in-circuit plot from before.
The leads were too short to stick in a breadboard, so I couldn't set up a proper test circuit. But connecting 5V, ground, and the output directly should be good enough, right?
Anyway, I think this oscillator is cooked. I may have overheated it when removing it from the donor board. Will have to source a new one.
The leads were too short to stick in a breadboard, so I couldn't set up a proper test circuit. But connecting 5V, ground, and the output directly should be good enough, right?
Anyway, I think this oscillator is cooked. I may have overheated it when removing it from the donor board. Will have to source a new one.
codevonlux
Well-known member
I think I have a few spares of the oscillator (new), DM me if you need any.
