A1200+VGA adapter = no picture.

HonestFlames

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So I found the VGA adapter I've been looking for for 3-4 weeks now. Only I can't get a picture from my A1200 onto either my LCD TV, Iiyama 19" CRT or Dell 24" LCD.

I've tried two A1200's, a 1D4 and a 2B. Same result with both.

I've taken the cover off the Amiga end of the adapter to check the soldering and it all looks pristine.

This is the same VGA adapter I've had for 10+ years, ever since I had my original Amiga and it worked perfectly with a Microvitec 14" CRT, back then.

I've tried every mode and both with VGAOnly and without. Not even Multiscan Productivity produces output.

My Iiyama briefly flashes details about the detected mode and I noticed it was 31KHz horiz, but over 500Hz vert?! I doble-checked to see whether there was a decimal point, but no.

I can understand maybe the A1200 might need some work - I've not been able to test the RGB out, until now. I do have an RGB SCART, but this gives me a grey screen. I'm not surprised, as there are no resistors in the SCART adapter. For both A1200's to have the same problem - surely the VGA adapter must be suspect... but there's honestly nothing I can see physically wrong with it.

Have you had this problem? Please help :)
 
Are you sure these screen support the 15khz output from an Amiga? Most modern LCD's do not sync to that I'm afraid.

You'll probably need a flicker fixer/Scan Doubler to use those screens, unless you try the LCD TV with a RGB-Scart lead, that should work.

I use RGB Scart on my 17" LCD and it even fixes flicker in High Red Laced, the same with my 40in LCD.

However my 19" LCD does not work at all with Scart but does work with VGA converter like you are using, lucky there I guess :)

Steve.
 
No dude, I've got composite hooked up so that I can see what's what when booting to a 15KHz PAL mode.

When I switch to any of the >15KHz modes, nothing shows on VGA side of things. My Iiyama is the only device which gives me any sort of feedback on what's happening. It goes into a loop where it detects a 31KHz mode but something is wrong with the output because it never actually manages to sync.

I'm not trying to get a 15KHz mode to display through VGA, I'm trying to get a VGA mode to display :)
 
Have you tried with just the composite output to see if a picture is generated?

FYI, on the DELL 24" LCD. I am unable to display a composite signal on a 2407 model but can on a 2405.

Edit: Ok ignore the first line :)
 
Have you tried with just the composite output to see if a picture is generated?

FYI, on the DELL 24" LCD. I am unable to display a composite signal on a 2407 model but can on a 2405.

Edit: Ok ignore the first line :)

Everything is working fine on the composite side. I can even see some confirmation that the miggy is changing to a >15KHz mode because the composite output goes all screwy :)


Possible clue.... When I'm looking at the composite display on my 2405, it looks pretty good (for what it is). If I unplug the VGA adapter, the composite display goes fairly bright. Enough to make an impact on quality. Similar thing happens when I'm looking at the composite display through my LCD TV, although the picture is better there - plugging the VGA adapter in reduces the brightness of the composite output.

Weird.
 
I get the same reduction in brightness on my 2405 with composite plus another source connected. I think that's a red herring. :)

Can you test the VGA cable for continuity, might be a broken wire perhaps?
 
Have you tried with just the composite output to see if a picture is generated?

FYI, on the DELL 24" LCD. I am unable to display a composite signal on a 2407 model but can on a 2405.

Edit: Ok ignore the first line :)

Everything is working fine on the composite side. I can even see some confirmation that the miggy is changing to a >15KHz mode because the composite output goes all screwy :)


Possible clue.... When I'm looking at the composite display on my 2405, it looks pretty good (for what it is). If I unplug the VGA adapter, the composite display goes fairly bright. Enough to make an impact on quality. Similar thing happens when I'm looking at the composite display through my LCD TV, although the picture is better there - plugging the VGA adapter in reduces the brightness of the composite output.

Weird.


Dude I can swing by tomorrow and pick it up and test it at mine if you want?

Shibby!!!
 
I get the same reduction in brightness on my 2405 with composite plus another source connected. I think that's a red herring. :)

Can you test the VGA cable for continuity, might be a broken wire perhaps?

I can rule out a dodgy VGA cable. Used 2 cables which I already use regularly for other things. Thanks though ;)

---------- Post added at 16:38 ---------- Previous post was at 16:37 ----------

Khem... what time, dude? I'm like... at work and stuff until 6.
 
I get the same reduction in brightness on my 2405 with composite plus another source connected. I think that's a red herring. :)

Can you test the VGA cable for continuity, might be a broken wire perhaps?

I can rule out a dodgy VGA cable. Used 2 cables which I already use regularly for other things. Thanks though ;)

---------- Post added at 16:38 ---------- Previous post was at 16:37 ----------

Khem... what time, dude? I'm like... at work and stuff until 6.

I can come to you at lunch time ish :cool: Then I can drop it back at your house in the morning (y)

Do not know why you have not asked me anyway.:eek: Duffus!!!
 
You're a numbnutz :) .... Plus there are some really clued-up folks here and I might just have had a "you need to change the flux capacitor for one that will handle 2.1 jiggawatts" type of answer :cool:
 
OK, TheKhemist kindly tested my adapter VS his and mine is faulty. Rolling / weird video.

I'm going to check it with a meter and see what's what.
 
Get a room you two :LOL:

Jealous? :p

I've taken a soldering iron to the darned thing. Switched the HSYNC to CSYNC. I got a brief, but horizontally distorted picture on the Iiyama, but it just failed to sync (in Multiscan Productiviy mode, with VGAOnly).

I think I should just go ahead and buy the proper adapter. Mine is just a straight-through with a couple of (diodes/capacitors/resistors?), one each on HSYNC and VSYNC. All ground pins soldered to a common ground.

Worked fine, back in they day :roll:
 
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