Commodore Amiga A500 Repair & Overview 

Thanks =D This is one of the videos I've done that makes me cringe when I watch it now lol. So many slips of the tongue etc. My older videos tend to be poor compared to some of my newer stuff I think.

Oh crap... maybe I shoudl have asked first.. I mean I didnt notice any slip ups or anything, but I've included a refrence to this video in my latest one which i'm just about to put online any second now lol

Haha =D It's fine, I just make myself sound like a bit of an idiot because my brain is going too fast for my mouth. Thanks and looking forward to the vid =D

"Brain is going too fast for my mouth".. Story of my life! If it's a reference from my video, it'll probably make you look more sane LOL :oD

+MsMadLemon Haha :o)

I will at some point fit a CR2032 to my 500+ =D

Yes - sometimes just reseating chips can solve problems =D The Agnus is quite common for that type of issue.

Thanks =) Yes, the RetroBright on some Commodore systems doesn't work very well. I've heard of the same problems with C64's.

TheReasonForYou I don't know why you are getting so stressed about all of this. Take a look on EBAY at all the sellers who have broken A500 systems down into parts and they are selling the bits and binning the parts they cannot sell. There are so many Amiga 500's around it's ridiculous! There's a chap down south who has around 200 in storage because he cannot sell them due to lack of demand. Regards retro brite, It's not all about removing the original tint of cream, it's about removing the extreme yellow from the reaction between UV and the bromide in the plastics.

+Hovermotion The Amiga 2000 was a lovely machine - I really liked the case and the fact it was more expandable than the A500. I used to have a 2000, sold for £100 many years ago, how I wish I had kept it! =/

It still works better then my moden computer and never crashes...I get attached to sertin items and just can't sell them....e.g like the laser disc player old tech but the film box sets are amazing to look at...e.g pulp fiction. P.s my favourite amiga shooter game was alien breed...we played that over and over.....the good old days......Jim

Yeah, I love Alien Breed as well! There are quite a few follow ups you can play - Alien Breed 2, Tower Assault, Special Edition(s), and some of the newer 3D games.

dd2?

GadgetUK164 - Retro Gaming Repairs & Mods double dragon 2 used ecs version with fix/patched now works😎

Yes, and it was the really strong stuff - It was think and had that kind of foam adhesive holding the Agnus into the socket. The whole thing came off when using the PLCC extractor. I did take photos at the time, I wish I had remembered as I could have added them into the video =/ Thanks for watching and commenting =)

Maybe it was this thing called "häftkuddar" in Swedish...? In English it would be double-sided adhesive pads, I think. They are small rectangular pads with a very aggressive type of sticky material on them which makes them extremely difficult to remove once they have been sitting for a while. I have them at home, but I never use them in any kind of repair och modwork if I don't absolutely have to. I use a transparent type of double-sided tape for wire routing and bonding the wires to a PCB. Btw, I have heard you several times saying that you were in "the trade" back in the days. I'm wondering what "the trade" is/was? Some kind of electronic repair shop?

It might be the same type of pad you are talking about. It was a square / rectangle type pad which had a thickness you dont get in normal double sided tape - just as you described. It was hard separating the Agnus from the socket even after the socket detached from the pins. When I was back in the trade - I worked at a few different local computer repair companies, it was quite varied work so I didn't specialise in any particular system, but I had a tonne of exposure to the gaming machines of the 80s and 90s as well as a tonne of PC and business related stuff. Used to repair an aweful lot of Wyse dumb terminals and PCs.

I think Agnus provides some of the clocks! Check pins 34,35,36 and 41 on the diagram. There's an XCLK (not sure if that's external) coming in through a 74F04 (U33). But the main clock comes from X1 (main crystal).

If you have main clock on pin 41 of Agnus, I would suspect a dead Agnus (or socket needing replacement).

If you've tried another Agnus, I would suspect the RAM or datapath chips (74 logic).

I know =/ It seems all prices of these old systems continue to climb recently - as more people get back into collecting them.

Let me know how you get on! It could be the disks themselves rather than the machines! Especially if they were once working and now after storage they aren't. I've found around 40% of my original disk collection has picked up corruptions over the last 20 years due to the magnetic media failing (and in some cases gained mould).

Just fixed the 1200 drive, well it was my own fault actually. A few years ago I took it apart to clean and accidentally put the floppy cable in wrong way round (face palm). Anyway works like a charm now. 500 drive though is something else, I haven't really looked at that yet so I'll give the heads a clean first. I only know basic electronics, built a few guitar pedals, stuff like that so its fun learning this way. Also I've got an old snes with a video fault so i'm gonna look at that as well. Love your videos though, great to see actual faults being repaired and finding common faults with certain machines.

Thanks =) Glad you sorted your 1200 drive out! Easy to get the cable on the wrong way if you are rushing, done that myself in the past! Hope you managed to get the 500 drive working - normally a case of rubbing some alcohol on the heads with a cotton bud and clean up any dirt out of the main mechanism etc. Check for any surface mounted electrolytic caps as well.

+Gulliver Gate Could be the 12v line on your PSU, or a faulty capacitor in the floppy drive.

The green screen and flashing lights on the external RAM indicate theres a faulty DRAM chip on there! The Midget Racer is for an A1000 / A2000 I think, but it might work in an A500. It looks like it just sits in the CPU socket?

+Gulliver Gate The T splitter goes to the left and right audio outputs of the Amiga, and the other side of the T goes into the Audio In on the modulator. The 'mono' doesn't connect anywhere, that's a composite mono (black and white signal). If you still get a black screen you've likely got a fault on the motherboard.

Ignore the On-Board Mono Output, it's somewhat specialist for the A1000 Monochrome Display for 1st Generation High-Resolution Monitors... it's not compatible with Standard Composite Output; there's a list of Compatible Commodore and Sony Monitors that support it somewhere, but best to ignore it as the A500 OCS/ECS actually provides support for these via RF/AV/Composite. So first thing to make sure you have is the A520 (this >> amiga.resource.cx/exp/a520) This connects to your RGB Socket on the back of the Amiga (and is compatible with all models) On the back is an RF Out (this supports both RF Natively and Coaxial AV with an Adaptor to RNC) ... this is Region-Free (supports both NTSC and PAL), so if you have to import don't worry. On the side is Video Out (Colour Composite) and Audio In (L/F Stereo to Mono Mixer for the RF Out) Now, the best thing to do is get one of these Cables (www.amazon.co.uk/gp/product/B0000C4G9O/ref=pd_sim_23_1?ie=UTF8&psc=1&refRID=HYKG1AECJARHVQA7BX6M), which is a Basic RNC Extension Cable; Composite Colour Coded (i.e. Yellow / Video, White / Left Audio, Red / Right Audio) Plug in the Yellow (you might need to Separate it a little if it doesn't stretch far enough, a Table Knife typically works well as a separator without the risk of damaging the cable itself) in to the Side of the A520, in the 'Video Out' Port. Then the Red and White into the Audio Channels. You then have a few options: Either Natively Plug it in to SD Composite (if your TV/Monitor Supports it) A Composite to SCART Pass-Through (www.amazon.co.uk/Genuine-Official-Microsoft-Composite-packaging/dp/B0072VZ14U/ref=sr_1_1?s=videogames&ie=UTF8&qid=1474684502&sr=1-1&keywords=Xbox+Composite+Scart) - Personally I use these, mainly cause I have quite a few sitting around but also they're just high-quality with some Signal Improvements rather than just a strict pass-through box. Or alternatively a Composite to HDMI Adaptor (www.amazon.co.uk/gp/product/B01K23U298/ref=pd_sim_107_8?ie=UTF8&psc=1&refRID=JT6GVXK8KJ74NEPGEQBB) like this, which fully support the Interlace Modes as well as all of the Signal Input Types ... this makes it a very good idea for Americans who want to use a PAL Modification / European Amiga (as it supports the widest range of Software) but want to have it run Natively and on a Modern Display. Though a word of warning that Modern LCD (other than FreeSync Displays) are incapable of Immediate Mode Display, thus you will notice a 2-8ns Latency (this will come through as 'sluggish' controls) unless Games are running at Frame Perfect 25/30 FPS (50/60Hz). It often gets complicated to explain why this offers a different experience making Games "Feel" different, or Slower than they should be ... but trust me on this, you *want* to use a CRT over an LCD if possible.

Yes, I think you are right! Although I struggled to get Lotus 3 to work on this 500+ - could be due to 1Mb of chip when it needs 512Kb of fast, not sure yet until I get around to finishing this off and putting a 512Kb of fast RAM in there.

What colours screen do you get? My bet is on Agnus or the ROM if you are getting a black screen. You could try swapping the CIA chips around to see if that changes behaviour.

Hey GadgetUK. Thanks for the reply. I swapped the CIA's and no change. As for the screen colour unfortunately i can't tell you that until i get a video cable.

Hey GadgetUK. Update. The Amiga is giving a Green screen. I also noticed Gary and the Rom chip are cold, is that normal?

Maybe you have a special edition or something? I thought the A1000 had signatures from Commodore designers in the case, but wasn't aware of any of the A500 models having any signatures inside the case?

Hi, I cannot do repairs and stuff for other people - health problems, full time job, and family etc - just no time for myself. The problem you've described sounds like its just the capacitor on the audio output. There's an electrolytic capacitor for the each channel (left and right), and those caps are sat right next to the audio connectors. If you swapped those out the chances are that would solve the problem.

I need to dig out that manual at some point! I think I know where it is, it's just finding time and energy to go wading through stuff in the loft =/ Let me know how you get on with it =D

Just an update m8. I had my scope on everything thanks to finding "The Amiga Diagnostician". Its on EAB shared server and has all ic pin outs with voltages and possible signals, high low pulse etc...not perfect and more for a logic probe but enough to move along from chip to chip. Like yourself I wont be beaten and if anything this is "The Hobby", learning, sharing and with luck resurrecting a skip destined piece of gaming history. Both Denise and Paula are now hot as hell after replacing U34 and U35 but I will not rest till I get this sorted. I`m updating "The Amiga Diagnostician" as its a poor scan pdf, once done I can upload to EAB for all Amiga troubleshooters, more just a nice word document re-write with some extra pics but will make reading easier hopefully. Looking at other repairs, Jan Beta, yourself and others, Rev 5 units seem cursed, problematic and a real grind to fix!

Sometimes the actual ports break on the Amiga - check all pins in the D connector look OK! The main cause though is a faulty CIA. You can easily test by swapping the two CIA chips around. Put the odd into the even socket and vice versa. Just make sure they are put in correctly with regards to pin 1.

Just to expand my reply there - after swapping them around behaviour should change! Possibly floppy drive won't work, or colour on screen to indicate a fault, or perhaps the other joystick port will not work. The two chips are identical. New CIA chips can be bought off EBAY for a few pounds.

It's over. Patient died :( I dont know how, but now he wont even turn on now... Only a Black Screen, no Response at all. No Keyboard LED, nothing. All i did was starting it up without the Memory Expansion and instead of the gotek drive, the old disk drive. Very sad :(

Was that before or after you got chance to swap CIA around? You likely just need a new CIA. It's not a 500+ is it?

I didn't swap the CIA. Before I wanted to try this, I wanted to tried to start the Amiga (500+) without the Gotek USB drive and the real diskdrive instead. Also I removed the Expansion Memory. I think it's possible that I 1. plugged in the disk drive cable wrong (not the power cable) or 2. Plugged in the Keyboard cable wrong I'm not sure... maybe this was my fault. The only Thing that happened by turning it on the first time was the black Screen and my TV switching between 16:9 and 4:3 mode, a Grey line appearing (in the upper third of the Screen) and the disk drive "trying" to run for some seconds. No LED's or Caps Lock key working on the Amiga. Then I turned everything off, plugged all cables. I wanted to make sure now that I return everything in it's working state again. Then with the Expansion Memory, the Gotek drive and the drive and Keyboard cables plugged in (this time right, after checking it on a Website), I tried again. Now nothing happened, expect my TV switching again. I heard a noise then from the power supply unit. I think it never was there before. It's a "clicking" the whole time. Even if it's not connected to the Amiga it's clicking. Maybe the PSU is broken now, but I'm wondering how this could happen :( Why now... It's the "light" one, taken from an Amiga 600. I checked the fuse inside and it's ok. I dont have anything else to test. only 2 very old C-64 Power supplies. Someone recorded the clicking. Thats exactly the Sound it's making now: 3ehpha.by3301.livefilestore.com/y2pU83qLDYM8hAJbGfOHQvI5oGMqhb7aSGOj_BnxpvpHnzwLE3IIULE_DRffBc4ca548ge9A95km9EGBl6NTHCrwqvBH9haFha9LUdi7JbSV_g/click%20clack%20goes%20the%20A600%20PSU.mp3?download&psid=1

The one that's not booting discs - try swapping the CIA chips around. Make sure that pin 1 on each chip is still in the correct position (each chip has a notch on one side to indicate where pin 1 is). Since there are two of them, when you swap them around, if behaviour changes (eg. it boots from a disk or gives some other change in behaviour) then you know you have a fault CIA chip. If that doesnt fix the booting issue, try swapping Gary. The one with a black screen, most common cause is a dead Agnus - sometimes just re-seating the Agnus can fix it. Beyond that it could be a ROM fault, Denise, Gary, CPU etc.

@@GadgetUK164 Swapping the cia's worked 😀. I now have one working amiga. THANK YOU😄 But there still are a few issues. One i get a feedback on screen that flickers for a second an stops. Almost makes you jump. Then doesn't happen again for a bit. Could that be a faulty video cable? The other is an abnormal sound in the drive. Like a ticking/spinning when loading. (Like a ch-ch-ch sound) Is that a speed issue? I've cleaned the heads and stuff but it still does it.

Could you upload a video of the behaviour you see with the flickering? The floppy drive might need recapping - ie. swap out the electrolytic capacitors (I have a few videos on restoring Amiga disk drives - worth watching).

@@GadgetUK164 Thanks for your rely. Sorry I'm unable to upload a video for you. I've been watching a few videos to learn how to solder so I can re-cap the drive. I think the feedback might be coming from the modulator. After watching your video on the modulator repairs. The screen does get a tint, but it doesn't fully change the colour more like someone's paying with the brightness going slightly from light to dark. Then you get a single static flicker about once every 30min or so. So I might even looking into getting an rgb cable for it.

RGB cable is better! You could rule out the modulator by using the mono composite connection on the left hand rear side of the Amiga. It will be black and white, but test with that to see if the picture remains constant. If it does, chances are the A520 modulator either needs a recap or a new encoder chip.

It's 84 pin... You missed 4 pins there! I've got one in front of me and just counted the pins, 21 on each side. With regards to removing an Agnus with a jewlers screwdriver, it can be done - but it is not recommended as the sockets are brittle and break easily. A PLCC extractor is cheap as you say.

Hehe, yes they did name their chips like that. The chip was just called Agnus I think - the 'Fat' part was later added to a model that could address more RAM I think. Later people referrred to a version with even more upper address capability as "Fatter Agnus". Not sure if the "Fat" or "Fatter" parts came from Commodore or the public.

I had thought similar about chip names though some are explanatory, GARY is something to do with Gate Array , bit of both I think. I`d have stuck with Paula or Denise as I think Akiko would have been a bit of a handful, she sounds high maintenance. As for Agnus, shes a feeder and would have you well under the thumb, never mess with Agnus!

+Amy Marie Yes, solder looked a bit of a mess there on those few caps to left hand side. I tidied them up after that video. The were cracked for some reason, no idea how.

+Josè PinillosV. Thanks =D

Yes, I am sure there are instances! You get bad caps on everything in general. But I have worked on a lot of these over the last few years and it is rare.

+retronostalgic Possibly bad RAM, or a dodgy Agnus.

+GadgetUK164- or do you think i need to free up some memory by deleting files off ram disk? 99% of my 1 meg games work! i was thinking maybe these three games need that extra bit of memory to run properly

I wouldn't be booting those games whilst a RAM disk is loaded - they often make use of all of the available RAM.

+GadgetUK164 - No ram disk loaded as far as i know. just straight boot from the games. just cant understand these three not working properly when all the others work. turbo trax wont evn start, just error message 103 comes up

That's the sort of problem you get with faulty RAM. With this 500 (in the video) that's the sort of problem I had, where many games worked fine but several did not. Some had graphical problems or crashed completely. In my case I ended up swapping all of the RAM - there were minor issues with almost every chip.

Yes, that's my understanding as well! You tell people not to plug and unplug devices whilst it's on but they won't listen lol. RetroGameModz covered clamping diodes in one of his videos - with ref to Amiga RGB output and protecting the video DAC. I can't help but wonder if use of clamping diodes on some of the inputs to the CIAs might help solve the problem.

+MarkTheMorose One of the biggest issues I ran into with the Amiga and CIA chip failures was the fact that the printer port and serial port had a non standard pinouts that supplied power to devices , its easy to damage the CIA chips and other hardware if one is not careful here .

Absolutely! The C64 seems worse than the Amiga with regards to failure just from plugging / unplugging devices. I read last week that someone said even plugging an auto fire joystick in could cause the CIA to fail - that's interesting, I wonder if there's any truth to that.

Yes, they have shot up in prices at LOT! 3 or 4 years about I bought one at £60 and one at £30 (believe it or not). Both worked perfectly!!! Mine was £100 and came with a tonne of stuff including a faulty 500, spare disk drives, external disk drive, 3 x PSU etc.

bought one from an ebay auction for 180 pounds, not including shipping. I consider myself lucky compared to the prices i have seen around

At least do us a favor and sell your Amiga on Ebay so people can repair it.

+nebulawars BOTH of them were shit. Same problem with the drive not working after only a few minutes of actual running time. This is one product that was of such low quality, I am surprised it actually had a warranty. It would be in the shop longer than in your possession and became obsolete before even one task was ever completed on it. I threw mine into the Pacific ocean over 20 years ago. It is somewhere near Yokosuka Japan.

DF0: not A:> but this said typically the CIA do have a habit of causing issues with FDD, especially if they're cheap ones and the A500 did ship with a fairly renowned poor quality FDD that would fail typically just outside of the Warranty. Now sometimes it's merely because the heads get dirty, so a simple strip down and clean is enough (the dust covers were pathetic and cheap) ... but another common approach was to use a Switchable 3.5" (most Japanese FDD would come with either a Jumper or a Jumper spot to switch between Apple / Amiga and IBM / Atari compatibility). This was honestly a common problem with the A500-Series, hence why most people had External FDD as they tended to be much better quality (they also again make good replacements for the Internal Drive).

what a strange comment - most of these are still going strong after 30 years. There is no A: drive either, it's an Amiga, not a PC. Seems like Garras was on a trolling mission...

At the moment I don't - full time job, long term health issues. Just don't have the time and energy.

Such a pity is that, but what's going on, are you sick?

I have problems with my immune system that make me feel like sh£$ every day =/ Just one of the things life chose to throw at me.

Wow that sounds really bad men, but i wish you well.