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Ok ill look into getting one... Requested pics to follow shortly.
---------- Post added at 18:51 ---------- Previous post was at 18:49 ----------
Quote:
Originally Posted by rkauer
Oh and i'd never pull cables while its switched on but can't account for previous user.
Here we go, i presume that silver thing is the 'dsp chip'?
Some reflections are showing up in the solder which make it look discoloured in one or 2 of the pics. please look carefully while judging.
The silver "thing" is the video crystal (used only in PAL boards).
The DSP chip (video DAC) is the VP101.
lol ok thanks, as i said i'm not an electrician, stuff this deep into PCBs is pretty new to me.
Ill locate that VP101 and post another pic...
---------- Post added at 21:13 ---------- Previous post was at 21:05 ----------
Here we go...
errr.. here we are... lol
Not funny. Nothing apparently wrong with this board.
You can see the HD activity LED acting up when booting? The floppy makes its clicks? A little humming on the speakers when the Amiga is on?
I think your best bet is sending it to a skilled Amigan near you.
Quote:
Originally Posted by rkauer
No theres no HD activity light, no clicks from the floppy drive except the initial one when the power is switched on, and nothing ive noticed from speakers but havent really been focusing on that since theres no picture and the amiga doesnt make any sound normally when booting up anyways.
For symptoms please re read the first couple of pages...
---------- Post added at 11:35 ---------- Previous post was at 11:25 ----------
Oh and i was laughing because i posted without the pics, then had to post again... :lol:
Theres a quick video i posted nearer the front of the thread to show what actually happens when the power is turned on.
Ok guys ive given it some thought and I'm gonna attempt this one myself.
I've just contacted Cosmos RE: some caps and ive gone out and got a new iron (Weller 12w) and a multimeter. I've had a go at removing some caps from an old PCB I had laying around and putting them back on and I'm confident I can do it with this new iron. I will let you know how it goes...
>I've had a go at removing some caps from an old PCB I had laying around and putting them back on and I'm confident I can do it with this new iron
Amiga hardware is rare now. Maybe a better idea is to call Zetro, an UK guy
like you, for installing these new capacitors... With many beers, I'm sure he will
be ok to save your beloved A1200 ;)
I've successfully achieved it on an A600 twice with no change whatsoever to its condition. And look at it this way, if Im capable of doing it theres one more person out there capable and willing to restore these things. I'm not one to sit on my butt and pay other people to do the work if I can help it, and technology is a huge passion for me. I've learned something which can prolong a loved machine and help a community and that is priceless.
Everything is fine my friend. I'm not a total noob, just didn't have the right tools the first time... I wouldnt do it if I thought I would damage them and as per your initial advice, I've now had plenty of practice. I'm no Zetr0 but I'm perfectly capable of replacing caps now.
Do not worry, I care as much as you do. :) :thumbsup:
silly suggestion but thought throw it in anyway,have you tried connecting to a hifi then inserting a disk,then powering it on to notice would it boot and least produce a sound from a game regardless of display problem?.
well its been connected to a tv and powered speakers and left on for a full 3 minutes when i was initially testing, and nothing came out of either one speakers. Theres also definately no activity from the floppy either so i doubt it'd have loaded a game (i did try with a disk in as part of the floppy test and all you get it the initial click when the power hits the drive and then nothing).
I received caps from cosmos today. The 22uF caps on the board read (22, 25s, 29t) could anyone confirm this is standard for the revision 2B board as the 22uF caps cosmos sent read (22, 16s, 405) and i cant find any clear enough pics of a 1200 board online.
Thanks
Fear not amiga hardware has the pic-
site- http://amiga.resource.cx/mod/a1200.html
High res pic*click on "medium" pic link in the pic to shrink it*- http://amiga.resource.cx/photos/phot...res=hi&lang=en
hmm those ones are showing different 22uF caps again, at 36v. I know higher Voltage capacity is better for capacitors up to a certain extent but i need to know if the 1200 board is safe with 16v 22uF caps... :unsure:
probably no use to you but found some info here,the same site has schematics to download,all these apply to the ones made by commodore.
link with info and downloads- http://www.amiga-hardware.com/showha....cgi?HARDID=13
Quote:
Rev 2B (Both budgie Rev -01 and Rev-02 were used. Resistor 118 was changed from 470Ohm to 220Ohm)
hmm, doesnt help much im afraid, im doing a capacitor replacement and the capacitor kit i have bought from Cosmos appear to have a lower Voltage rating on the 22uF capacitors (16v as oppossed to 25v and 36v) than ive seen on other boards). I really just need to know if theyre safe to use...
@AmiNeo,
As a point of interest the Audio circuit only needs a 24v swing so 15volts (top and bottom is 30volts capacity) which should be fine (as you have -12v and +12v (total 24v swing)
Commodore had a terrible habbit of buying cheap batches of components "that will do" some overated and some (imho) underated.
On my 2B motherboard there are 2 different voltages 15v on the video feed, and 22v on the Audio - as I ran out of 15v 22uF's I had to use 2x 15v's in the Audio circuit - and these are working fine.
Had it running Project X demo (as I like the tune) and it visually tests the video with transitions and screen formats.
However if you have any problems, have a chat with Cosmo's I am sure he can help you out.
All is fine, cosmos got back to me with an explaination. Thanks for the input jack :)
ninja - sync - minute - post
Have you tried pressing firmly on each of the ROM chips? They do work themselves loose eventually and can cause the kind of problem you're looking at.
just curious,wonder would a hairline crack on the board cause any problems?
Quote:
Originally Posted by HonestFlames
Hmm, thats something i hadnt considered but i did try pressing down on the chips when i first got it on a whim incase something was loose. Once ive got these caps replaced ill give that a shot if its still not working.
---------- Post added at 20:05 ---------- Previous post was at 20:03 ----------
Hmm, just found a pad under one of the caps that was probably not making contact with the board it lifted off with the capacitor, no resistance whatsoever...
Im guessing its been corroded... looks black where the solder isnt on it...
---------- Post added at 20:34 ---------- Previous post was at 20:05 ----------
any way anyone knows of to correct this? solder to the channel etc??? I fear this may have been the problem
---------- Post added at 20:44 ---------- Previous post was at 20:34 ----------
It seems that wasnt the only pad that has loosened considerably, ive discovered a couple more that havent completely detached but have lifted on one side.
Ouch, sounds like a world of troubles. The only way I know of fixing damaged tracks is to trace the track to where it goes and bung an ugly wire between the two things it should be connecting.
Yea unfortunately the pads are a very much more technical problem. Gonna offer this board to Zetr0 afterall and look for a working replacement... :lol:
thanks AmiNeo,
I shall do a how-to track repair photo-blog here when I get some time =)
That'll be awesome. im sure many members here would appreciate it. Myself included.
Hey Zetr0
You got to do a pdf book of your repairs and mods it would make reading alot
Easer to follow when were doing one of your repairs...
Chris:bowdown::bowdown::bowdown::bowdown:
Y'know Chris,
Thats sounds like a great idea, it could be called a "Hardware Hacker Compendium" I can gather working hacks from all over the world a throw'em in an online-downloadable pdf for the Hack@Home <--- whoa.... Hack@Home and Hardware Hackers Compendium... thats two brain waves in as many minutes.... I better sit-down..
... and Zetro, thanks for the input back there too...
How do i test this amiga psu with a multimeter?
@AmiNeo: thanks for the quote for Amibay quote contest!
:lol::lol::lol::lol::lol:Quote:
thanks for the input back there too...
ROFL! :lol:
Straightens up... That was nice... :lol:
Hey Zeets, did this one ever get revived? I recall giving it to you before I trashed those 600 boards :lol:... Just wondering what became of it?
Ah my Miggy haxxor N00b days... lol.
@AmiNeo
Unforunately my friend, I made a start - with some pics to show some cool *unusual* methods of repair, but its stacked and racked at the moment, along with a lot of stuff in the office/workshop =(
Ah okay Z. Shes yours anyways now, was just curious if she ever got up and running again. :thumbsup:Quote:
Originally Posted by Zetr0
I too have an A1200 that gives no video output.
Over RF, I get black screen and no sound. Over composite (yellow/white/red to SCART cable), I get a black screen, but the sound works normally. I don't have an RGB video cable to test it. I can hear the Frontier intro music, which suggests everything is working normally except video out.
There's something odd on the motherboard, too: someone has soldered the RF modulator and the composite connector at some point. They've replaced the yellow composite jack with a white one like the audio RCA audio connector.
Any idea what this fault could be, or how to fix it? Would an RGB cable work or could it be some larger video fault? (They're ~£17 on Amigakit and that's a lot of money for something that might not work.)
Hmm... My first instinct here would be to blame the capacitors responsible for the video output. Although with you mentioning the boards outputs having been altered I'd be looking more closely for bad connections and such. It's possible that the output has been badly connected to its place.Quote:
Originally Posted by JonathanDrain
Maybe a couple of pictures may help determine what has happened to your board...
with no picture on the RF/Comp then its one of three problems
1. VIO (feed) Capacitor(s)
2. CXA1145 (RGB to Luma Croma) *feed RF and Composite
3. DAC (Digital to Analog converter)*
Recently I got smaked in the face with three boards with the latter DAC failure. since you have NO picture from either RF or Composite, I am leaning towards either a feeding capacitor to the DAC or a DAC failure itself.
While the caps are cheap and replaceable, the DAC generally isn't.... irony would have it, for an Uncommon component, its a common fault on some issue motherboards.
Sadly there are as many revisions of DAC as there are revisions of motherboard, each one needing the right version...
I wish I could bring better news.
Would an RGB to SCART cable still work if one of these faults was the case?
Some other information: My brother tested the RF on his TV, he got some signal, but it was very poor picture. On my TV, it gives a black screen and no sound. It's interesting that it gives a black screen, rather than just static. The previous owner says it worked fine over Composite with his Philips monitor. I'll try and take some photos of the motherboard.
Happy end to this story! We built an Amiga RGB SCART cable from the schematic on Ian Stedman's site, and it works fine, on CRT at least.
Quote:
Originally Posted by Zetr0
Hey Zeets! Whatever happened to the "hardware hacker compendium"? :lol: