No red coming from RGB port

[waltermixxx]

Hi there i was wondering if anyone has come across this before...
This particular A600 according to the seller, has great colour from the RF and from the composite output ( it's a pal unit so i cannot use these connections as I am in Canada...)

According to the schematic, Pin 23 is the red output of the cxa1145 encoder chip. there are only a hand full of components from there to the RGB connector... R231a, q231a, R232a, R233a, R234a

I guess if there is some kind of signal coming out of pin23 i just go from there?

At any rate, what frequency should I set my little DS0 to (seeedstudio's little oscilloscope...it's all i have...) in order to test for a signal?

has anyone ever fixed this sort of thing before?

cheers and thanks in advance for any help at all...


http://www.ianstedman.co.uk/download...schematics.pdf

last page of this particular document covers the video portion of the Amiga 600...

[kipper2k]

Originally Posted by waltermixxx

Hi there i was wondering if anyone has come across this before...
This particular A600 according to the seller, has great colour from the RF and from the composite output ( it's a pal unit so i cannot use these connections as I am in Canada...)

According to the schematic, Pin 23 is the red output of the cxa1145 encoder chip. there are only a hand full of components from there to the RGB connector... R231a, q231a, R232a, R233a, R234a

I guess if there is some kind of signal coming out of pin23 i just go from there?

At any rate, what frequency should I set my little DS0 to (seeedstudio's little oscilloscope...it's all i have...) in order to test for a signal?

has anyone ever fixed this sort of thing before?

cheers and thanks in advance for any help at all...


http://www.ianstedman.co.uk/download...schematics.pdf

last page of this particular document covers the video portion of the Amiga 600...

If you have red coming out of the cxa1145 (which you do) then the problem for the RGB output lies in the input to the RGB connector. I'd have to check the schematic. back track from Pin 3 of the RGB connector and check the resistance values. Pin 4 and 5 control the other 2 colours so you should be able to use their values as reference

Just looked at the schematic, it is possible that pin 23 from the CXA1145 is dead as that supplies only the Analog red signal to the 23 pin RGB. The red for composite is mixe internally and fed to the composite through pin 20

[waltermixxx]

yup the first thing i have to do is check pin 23 on the cxa1145... fingers crossed...

cheers and thanks for the reply...

[pandy71]

line time is approx 64us thus somewhere in this area - but perhaps it will be easier to observe whole field/frame then time 20/40ms .

You can trig scope to CSync/CVBS signal.

[waltermixxx]

thank you ...
i will give it a shot...

cheers.

[waltermixxx]

hmmm if I am not able to get this to work, is converting the Amiga 600 to NTSC as "easy" as doing the Amiga 1200, ( I guess this is aimed at Kipper2K, as he posted instructions on converting the 1200 from pal to ntsc )... if I can convert it, i think i would be ok not using the RGB port...

[kipper2k]

Originally Posted by waltermixxx

hmmm if I am not able to get this to work, is converting the Amiga 600 to NTSC as "easy" as doing the Amiga 1200, ( I guess this is aimed at Kipper2K, as he posted instructions on converting the 1200 from pal to ntsc )... if I can convert it, i think i would be ok not using the RGB port...

You still need to fix the red issue otherwise you would only be able to use composite which is fuzzy at best. Agnus and the master clock needs to be changed in order to do a full conversion to NTSC so its not that simple. My Svideo adapters require the RGB port in order to convert the signals to produce Svideo.

I think at worst your problem would be the cxa1145. See what you can do with it, if you want me to look at it for you, you can send it to me. but look at the schematic (last page) to see what components to check/compare (R234a is a good place to check for 75ohms across it)

[waltermixxx]

Okie doke Kipper2k i will see what I can do.
thanks again for the advise, and the offer.
i will keep you posted

i keep having to go back and edit to remove excessive smiley faces...

[waltermixxx]

Well good news folks...

it looks like a capacitor or something leaked onto q231
i cleaned it and resoldered it, ( the transister leads where almost all eaten away...
but managed to get a connection... and now it's working fine...

i know i will need to recap this one. but at least i have proper video now

cheers I think i got off lucky...

[waltermixxx]

pictures...

http://www.flickr.com/photos/66577016@N00/9425195036/

if you can see here, the transister leads are a bit fuzzy with corrosion.
after a bit of a clean and some liquid solder flux, got the transister to make the connection and colour red popped up on the screen...

http://www.flickr.com/photos/66577016@N00/9422567275/

on the monitor it looks great... just this picture is not the best...

now to try and get my 4 gig kingston card working with it.

at least to keep me busy while i wait for my cap replacement kit from france...

not ordered yet, so if anyone sells these things let me know
rather do it here than on ebay...

Cheers.

[gnujon]

Originally Posted by waltermixxx

Hi there i was wondering if anyone has come across this before...
This particular A600 according to the seller, has great colour from the RF and from the composite output ( it's a pal unit so i cannot use these connections as I am in Canada...)

Are most TVs and monitors in North American still NTSC only? Modern equipment in every country I've lived in seems to be multi-system these days (can handle PAL or NTSC into their composite or s-video inputs).

Isn't there a lot less NTSC software in existence for the Amiga?

[kipper2k]

Originally Posted by waltermixxx

pictures...

http://www.flickr.com/photos/66577016@N00/9425195036/

if you can see here, the transister leads are a bit fuzzy with corrosion.
after a bit of a clean and some liquid solder flux, got the transister to make the connection and colour red popped up on the screen...

http://www.flickr.com/photos/66577016@N00/9422567275/

on the monitor it looks great... just this picture is not the best...

now to try and get my 4 gig kingston card working with it.

at least to keep me busy while i wait for my cap replacement kit from france...

not ordered yet, so if anyone sells these things let me know
rather do it here than on ebay...

Cheers.

Good to hear I have the caps, i always keep a stock

[alenppc]

Originally Posted by gnujon

Are most TVs and monitors in North American still NTSC only? Modern equipment in every country I've lived in seems to be multi-system these days (can handle PAL or NTSC into their composite or s-video inputs).

Short answer: yes. Long answer, see my post here.

[waltermixxx]

Well here's an update... I was putting in a piggyback 2meg chip ram hack, and turned on my Amiga only to find i had no red again... so I Poked and prodded and nothing... so then i checked my Aged cable, and sure enough the red wire inside was disconnected as i tried it on my A1200 and no red again... so it had to be the cable, so I took apart the cable re-soldered the red connection and my 1200 worked fine... all colours...

I went back to my Amiga 600 and still no red... in the process of poking and proding i loosened Q231, much to my horror it came off completely ....

I have never soldered anything that small before... so I picked it up with my tweezers, put it aside... cleaned up the motherboard with flux and copper wick...(very tight little space...) cleaned up the transistor (as tiny as it was...) and painstakingly re-soldered it to the mother board... tested and back in business... with 2 megs of chip ram

[Blaqua]

Here is how i fixed my a600 red and green missing in rgb:

exact part names:
2x SMD RESISTOR 1206: 33 kohm
2x SMD RESISTOR 1206: 1 kohm
2x MMBT3904 SMD

[hese]

Ok, good job. Thanks for the info.