Atari STE - no monitor output, RF fine

[Hellraiseruk]

Already tried that to no avail. Will get the desolder station ordered - been toying with the idea of getting one for ages but manually desoldering a TIA chip for a VCS made my mind up, just not got round to it yet :)

Still can't see how the socket could fail as pin 2 and 13 are nowhere near each other and the design of the socket I can't see how it would fail but it seems to be where the problem lies from what I'm seeing. Get it off the board then have another look I guess, thanks for your help!

[russellnash]

I de-soldered a monitor socket very quickly and cleanly using a normal hot air gun, the type you use for stripping paint. In general I am terrible at de-soldering, Most things, where possible, I de-solder by cutting pins leaving enough so that you can grab hold of whats left with pliers, heat them with the soldering iron and pull. It is very effective at protecting the board, which is in most cases more important than the component.

[Hellraiseruk]

That's not a bad idea, problem is the hot air gun I have is a simple, two-setting thing which would probably melt the board. Whilst I've done quite a bit of desoldering over the years, it seems that either my soldering iron is useless or the STE boards are awkward to work with, had major issues trying to get a couple of jumper blocks in the place of w102 and w104, so a little wary of going in all guns blazing with a hot air gun, cheers for the idea though. Might invest in a new soldering iron with hot air at the same time, damn PayPal credit 🤔

[1024MAK]

Some time ago (okay, a long time ago, about 20 years :shock: ), I used a normal iron (but a good quality one) to desolder the floppy drive socket on a STFM520. That took rather a lot of time and effort because the 0V/GND pins being connected to the large ground tracks.

I've not known "round" PCB DIN sockets (I describe it like this because there are other DIN standards) to go short circuit except on the rear when they have been physically damaged. Which is of course visible.

The 13 pin DIN socket for the video has the smaller pins rather closer together compared to a standard size 'round' PCB DIN socket. So there is the possibility of a short due to solder on the top side under the socket.

There most definitely should not be short between pins 2 and 13. As I said in my PM on the other forum, I will do the test you requested when I get a chance.

Mark

[Hellraiseruk]

Excellent, thanks for your help Mark. I think I am going to wait for my desoldering station to arrive rather than risk breaking a 99%functional STE, especially as I was lucky enough to get one already expanded to 4MB. I look forward to hearing from you!

[Hellraiseruk]

Problem solved!

OK, so the desoldering station arrived, first thing I did was to remove the 13 pin monitor socket, tested that all fine. So, checked the board, and still shorted between pin 2 and ground. No sign of any solder trails or anything under the socket, so I followed the trace back - it went to the end of resistor R439, but I noticed the track continued under the modulator and then there was what looked like the leg of a component soldered under there. Desoldered and it turned out to just be a through-hole, but miraculously once this was removed I was no longer reading a short to earth; looks like the solder blob on the through hole was actually shorting across to the groundplane next to it.

Assembled the ST, fired it up and lo and behold a perfect image via RGB SCART :)

So, I would imagine this has been like this since manufacture and the previous owner must have used it solely via RF, or maybe in high res mode. Either way it might be worth others being aware of this should they find themselves in possession of an STE which won't produce a composite signal from pin 2, and therefore nothing over RGB SCART either.

[stephen_usher]

Could it have been contacting the modulator can and that has recently bent slightly as you've been handling it and touched the solder ball?

Anyway, I'm lad it's fixed!

[Hellraiseruk]

Don't think so, as it was like this from the start - it wasn't a ball, more like a large whisker which looked like the remnants of a component leg sticking through the board - I was quite surprised when the desolder gun left me with just the through hole and nothing else, but a win is a win!