520STFM, no picture through RGB SCART

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galvatron1983
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520STFM, no picture through RGB SCART

Post by galvatron1983 »

Hi all,

Recently picked up a 520STFM which wont display a picture when connected any of my 3 HDTVs through RGB SCART, or the composite connection.

It turns on with a green light, and the floppy drive can be heard searching for a disc, but nothing on the screen, just an audible buzz though the TVs speaker.

Ive read here that the ST outputs a video signal that some HDTVs arent compatible with, but after trying 3 different TVs through the SCART and composite connections with no luck, Im starting to think the problem is with the ST itself. Is it common for the video hardware to fail, or is this a common symptom of as dying ST?

Or do I just happen to own 3 HDTV models that dont like ST video signals??

Thanks all!
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siriushardware
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Re: 520STFM, no picture through RGB SCART

Post by siriushardware »

Long shot, but are you sure you don't just have the 13-way monitor plug plugged into the STFM's monitor socket upside down?

It is surprisingly easy to do that despite the presence of the one offset pin and the usual symptom is no picture and a loud buzz through the sound, the latter caused by the fact that one of the video or sync signals ends up connected to the audio in of the monitor / TV when this happens.
Last edited by siriushardware on Fri Aug 03, 2018 5:05 pm, edited 1 time in total.
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galvatron1983
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Re: 520STFM, no picture through RGB SCART

Post by galvatron1983 »

Genius!

Flipped the cable around and it worked! So I do have 2 perfectly working STs which is awesome!

I feel like a dumbass though, in my defence the cable isnt marked "top" anywhere but hey-ho.
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kolli
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Re: 520STFM, no picture through RGB SCART

Post by kolli »

galvatron1983 wrote:Flipped the cable around and it worked!
I thought this was a joke! How on earth did you manage to plug a 13 pin DIN connector the wrong way round? The shielding has a Marker on the upper side and at least some pins won't find a hole when upside down. Didn't they bend / break???
siriushardware
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Re: 520STFM, no picture through RGB SCART

Post by siriushardware »

There's a recess at the opposite side of the monitor socket into which the odd pin out (pin 13) will comfortably fit if you present the plug to the socket upside down.

With the exception of pin 13, the pin layout of the 12 other pins is a perfectly symmetrical rectangle which looks exactly the same either way up, so it goes in quite easily without any force or stress applied to any of the pins.

I know... I managed to do it once myself (and have never forgotten it since). Historically speaking, we've had two or three problem posts which turned out to be down to this so I thought it was worth mentioning. Glad it turned out to be something so simple.
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