From tweeks@texas.net Received: from texas.net (dnet03-11.sat.texas.net [206.127.4.71]) by mail1.texas.net (8.8.5/8.8.5) with SMTP id XAA18958; Tue, 16 Sep 1997 23:23:36 -0500 (CDT) From: Thomas Weeks To: knolly CC: Thomas Weeks Date: Sun, 21 Jan 1996 21:46:35 +0500 Message-ID: In-Reply-To: <199709170244.WAA20559@ns1.tstt.net.tt> X-Mailer: YAM 1.3.4 [020] - Amiga Mailer by Marcel Beck Subject: Re: A500 Green Screen - Agnus Reseat MIME-Version: 1.0 Content-Type: text/plain X-UIDL: a0dcf1324dcc3501224e051df95adbb7 Around 17-Sep-97, knolly typed: >Hi Thomas, > Many thanks for the offer of help you are offering me >.First let me tell you where trinidad is at . We are in the Caribbean , or >the West Indies if you may . Wow.. sounds very nice... What is the weather like? Very nice I bet! Are younear the beach? > Anyway my A500 is comming on with a green screen .And that is it >nothing else happens . In my country no one knows how to fix the amiga . Not surprising... Sounds liek a chip RAM problem or Agnus problem... Do you have a 512k or 1M Agnus? Is it an 8370 or an 8372? (the latter is the 1M chip) anyway... this is the cip you want to look at first. This takes a special extraction tool called a PLCC chip puller... Do NOT , however, use the cheap plastic extraction tool that looks like this: ^ / \ / \ /| |\ / | | \ \ | | / \| |/ ` ' This extractor is BAD and can damage your chip if not used EXACTLY right and very carefully... I would use either an "Amphenol PLCC extration tool" (big expensive plue plastic pliers looking extraction tool) or just flip the motherboard over (after removing it from the case of course) and POKE the Agnus chip out from the bottom hole in the motherboard using a flat headed pen cap (or other large diameter object) (the broader the better) and a small hammer or mallet (this is probably the cheapest/fastest way for you to get the job done with limited resources.). Lightly tap the chip out of it's socket like this: X----- Hammer _ hole in mobo | | \ | | \ | | <-- Large Diamer pen or Magic Marker \| | ================================== <-mother board flipped upside down |_________| \ Agnus socket with Agnus inside the socket In this way you can carefully extract the Agnus chip... After you get it out... get yourself some radio shack spray "TV Tuner Cleaner" or some Kremolyn R5 (I think it's called) deoxidizing connector spray. Rub duwn the connectors on the agnus chip (lightly) and the socket connector pins with a pencil eraser (to get any gunk off them) and them spray them all down with whichever cleaner/deoxidizer you bought. Reseat the Agnus firmly with one short push and make sure it is seated well (minding of course the alignment of the beveled edge of the top of the chip with the side of the socket (silk screen) which denotes pin ONE) and then power up and see if the problem persists. Cleaning and reseating the agnus on these units war a common problem... one reason they went to all surface mount ont he AGA chipset machines. [Amiga Tech Secret: One of Commodore's authorized "checks" for a "mis-seated A500 agnus" was to power off a green screen machine, lift it 6-8 inches above the bench, and drop it FLAT onto the bench top, (thus using inertia) partially reseating/jostling the agnus, powering it back on and seeing if the symptom changes! THAT'S the kind of trouble shooting that goes on out of the customers sight... why do you think most tech centers do all their work in a back room behind a closed door? Scaaaary stuff eh?!?! hehehe... You should see the stuff AUDIO techs do! ;v) ] Anyway.. hope this helps you and your pee-cee weenie friend. ;v) Tom D Tek -- __________________________________________________________________________ / Thomas W. Weeks |Team AMIGA Commodore Amiga 500/030 40MHz \ | A&M EET/Telecom Grad '95 | /// Hacked Into Black Tower Case, | | Authorized Amiga Tech (7yrs) | __ /// 9M RAM, SyQuest 44M, 700M-o-SCSI | | Contact Me @ | \\\/// IBM 286 Hardware Emulator, | | o------------o | \XX/ Home Brew Audio A/D, HP48GX | | Email: tweeks@texas.net |"Amiga, The Computer for the Creative Mind"TM| |Web:lonestar.texas.net/~tweeks|"Mac, The Computer for the Rest of Us"TM | \_____________________________|____________________________________________/