One dead amiga 500 rev5 board

[Pinball freak]

This story is getting weird.

The Amiga wich i bought yesterday, seem to have died.

As is did not get any picture either, i just wanted to see what it did with my old diskettes.

It started to load them but then the power light went out.

Tried some other disks, sometimes the machine was not responding.

So after a few times, i just shut it down, after supper i just wanted to try again, only the power supply it comes with and tested with i used, not my own.

And it just is dead, well, no, it gives me the 10 power light blinks, and then the reset blink.

 

So now i got 2 not working amiga's, if you look at the second picture the fat agnus has one pin that does not look good.

 

I will go back to the seller and he will have a look at it, as he seemed to have worked on it.

 

Ughhh.... What a nightmare.

 

 

 

[shoestring]

Well, the AGNUS socket looks a bit fucked up. Looks like the low data select pin ( if i have my orientation correct ) is damaged. Don't know how this even worked when you saw it. Get your money back

 

Edited April 3, 2022 by shoestring

[shoestring]

Also, GARY has had some work done to it with the bigger machined pin socket installed. So you probably find your broken pin somewhere there.

 

You could try applying some pressure to the chip to see if it makes a difference

 

[Daedalus2097]

On 4/3/2022 at 11:47 AM, Pinball freak said:

The question, i have an older 32'' LCD TV pal with, amiga's also pal,  if i buy online any Amiga rated rgb to scart cable > will this always work ?

Or does the tv have to be a match like monitors have to be 15hz ?

Any TV that has SCART will support a 15kHz signal so no issues there. I haven't used it myself, but many people seem to be happy with Retro Computer Shack's cables - they've a good reputation in the community: https://www.ebay.co.uk/itm/254623532468

 

On 4/3/2022 at 11:47 AM, Pinball freak said:

I found this online : http://www.pavouk.org/hw/en_rgbscart.html

That's not a particularly good schematic, so don't bother with it. There are several people these days who sell good quality Amiga SCART cables, and they will invariably be based on the diagrams you can find here: http://ianstedman.co.uk/amiga-scart-guide/

 

On 4/3/2022 at 11:47 AM, Pinball freak said:

I opened my cable at the rgb side and found out that the cable that i have found with my amiga stuff has only 5 wires going to the scart AND it seems that the audio cables are coming from the scart end and not the rgb end.

So i have no clue where i did get this cable from or if i ever used it, because as from what i can remember is that i have hooked my Amiga 500 in a amiga monitor... wich i do not have anymore.... ugh.

Yep, a SCART cable for an old 1084 or similar monitor will only have the bare minimum as the 1084 doesn't need the switching signals used by many TVs

 

16 hours ago, shoestring said:

If it has a SKART input then it should accept the Amigas video signal. Only 5 wires are needed on the 23 pin connector ( video ground, red,green,blue and csync ). 

Well, it's not as simple as that. Many TVs need additional signals to correctly configure the SCART input. Sometimes this can be done manually via the TV controls, but on many TVs there's no option. In these cases, you also need power connections from the Amiga's RGB output and some resistors at some point on the cable, otherwise the TV might not display the SCART signal, or might try to show the composite input instead. See my link above for what is the de facto standard these days for an Amiga SCART cable.

 

Additionally, there are multiple ground connections, and while you don't strictly need more than one ground connection, the quality of the signal will be improved by using proper grounding - Individual screen for the red, green and blue signals and a separate digital ground for the sync line.

 

12 hours ago, shoestring said:

Well, the AGNUS socket looks a bit fucked up. Looks like the low data select pin ( if i have my orientation correct ) is damaged. Don't know how this even worked when you saw it. Get your money back

 

It's the NTSC/PAL select pin, and it's relatively common to mod A500s to allow NTSC and PAL running. But IIRC this Agnus is too old for that mod to work, so it's pointless. Regardless, the socket doesn't look healthy all the same with the nearby pins and they could indeed be causing issues. Likewise with the Gary socket; if someone's using such inappropriate parts, they're probably not taking all that much care with the job and there's a good chance there are issues in the area.

 

[shoestring]

13 hours ago, Daedalus2097 said:

Well, it's not as simple as that. Many TVs need additional signals to correctly configure the SCART input. Sometimes this can be done manually via the TV controls, but on many TVs there's no option. In these cases, you also need power connections from the Amiga's RGB output and some resistors at some point on the cable, otherwise the TV might not display the SCART signal, or might try to show the composite input instead. See my link above for what is the de facto standard these days for an Amiga SCART cable.

 

Additionally, there are multiple ground connections, and while you don't strictly need more than one ground connection, the quality of the signal will be improved by using proper grounding - Individual screen for the red, green and blue signals and a separate digital ground for the sync line.

 

Well now I'm curious, I built my own SCART cable to use with the OSSC but didn't use independent grounds ( except for the audio ) or any other components in the schematics from the links above. But now I'm going to build another one to see if the display can get even better.

 

Quote

It's the NTSC/PAL select pin, and it's relatively common to mod A500s to allow NTSC and PAL running. But IIRC this Agnus is too old for that mod to work, so it's pointless. Regardless, the socket doesn't look healthy all the same with the nearby pins and they could indeed be causing issues. Likewise with the Gary socket; if someone's using such inappropriate parts, they're probably not taking all that much care with the job and there's a good chance there are issues in the area.

 

It's possible they had upgraded to an 8372a at some point but put the old one back in.

 

 

Edited April 5, 2022 by shoestring

[Pinball freak]

OK, i ordered some stuff online, new cable, Diagrom, and some other stuff.

I will wait first now, because without any image i shoot in the dark.

I read online that some other people also have had the white screen and solved it with another cable.

 

When i have image and have the proper color that will maybe help to point towards any fault.

If that isn't the case, i will rely on the diagrom and connect it to a pc and read it out with putty.

 

Thanks again for reply's !!!

 

[Daedalus2097]

14 hours ago, shoestring said:

Well now I'm curious, I built my own SCART cable to use with the OSSC but didn't use independent grounds ( except for the audio ) or any other components in the schematics from the links above. But now I'm going to build another one to see if the display can get even better.

Grounds being independent of each other is less important since they're mostly bound together inside the Amiga anyway (the A1200 has a separate ground for video and sync for example, but the A500 does not), and likely inside the display / OSSC too. But individual screening of the red, green and blue signals is particularly important for image clarity, especially with longer cables, and you'll see that construction in any decent quality VGA or SCART cable, even if they're all connected together at each end. Providing a separate ground (and preferably screening) for the sync will reduce or eliminate noise as a result of the digital nature of the sync signal.

 

At both the SCART and RGB ends there are individual pins provided for red, green and blue grounds, and they're located in convenient positions for making cables. That's what I do when I build a cable, even though they're connected together inside the devices.

 

It's likely the OSSC doesn't need the extra switching signals and is tolerant of the high CSync voltage because it's made specifically to cater for a wide variety of retro machines, many of which (like the Amiga) had cables back in the day that lacked them. The OSSC also has lots of configurability, so things like RGB mode and widescreen mode can easily be set manually. It's really for use on more modern TVs where they're designed to automatically adapt to whatever input with a minimum of user interaction that you'll need those extra parts.

 

14 hours ago, shoestring said:

It's possible they had upgraded to an 8372a at some point but put the old one back in.

That's my thinking too. Butchering the socket wasn't the way to do it though :/

[shoestring]

I'm get a crisp picture from the A1200, not confident I'll benefit much with such a cable but I can only try it out and see. My only complaint is the slight vertical banding I see which is likely associated with the pixel clock of the LCD which I should be able to adjust on the display or OSSC.

 

 

 

11 hours ago, Daedalus2097 said:

That's my thinking too. Butchering the socket wasn't the way to do it though ?

 

They are brittle, easy to destroy. But thankfully spare PLCCs in a variety of different sizes are still easy to source nowadays and are of good quality. As for the GARY socket, he/she could have at least trimmed it down neatly with a file so that it ends up flush with the end of the chip, that's what I'd have done after removing those extra pins had I ran short of suitable spares.

[Pinball freak]

Update,

Well i went back with the new Amiga to the guy i bought it from, it really bothered him this happened to me and he would do everything to fix it.

It was a green screen that he had. So i said, from what i saw on the internet people had or problems with ram, paula or fat agnus.

He has tested, Agnus and Paula, they worked in another machine.

So he had another solution for me, he took his own A500 rev 6 and put in an Agnus 8372a because he said the 8371 from the rev5 would not work in the rev 6???? Did not look this up yet.

 

So he came over to bring me the rebuild amiga, we tested it here and copied some disks for him, so very pleassed with that solution. He certainly did not sell me a bad machine on purpose, so Kudo's to him !

 

Also he bring with him the 520 composite box so we could test my dead board, and i do get a bright green screen and not white.

So probably this also could be a memory problem? Would that be possible or should i always have a working led lit up ?

 

Sunday i will open the new Amiga and check how it looks.

 

I was surprised to see that the diskettes i tested are still working after 25 years of storage, in their diskette box as you all know them, however safe from dust and always nice and dry though....

 

Nostalgia for the win (speedball 2 ), at least when i get my new cable, i will have a proper working A500 rev.6 now.

 

Also the extra ram expansion card from my old one isn't in a bad shape either, it has a GP battery and did not really leak. I will solder it off and replace it with a button power cell wich i also ordered.

 

Greetz... 

[shoestring]

Light green or Green ?

 

https://www.lemonamiga.com/forum/viewtopic.php?t=13978

 

 

 

[Pinball freak]

9 hours ago, shoestring said:

Light green or Green ?

 

https://www.lemonamiga.com/forum/viewtopic.php?t=13978

 

 

 

Well, as i am not familiar with the screen color codes, i would say Green. It is a deep alien snot green

So i am thinking in the direction of bad ram.

 

Problem is that i cannot recall the day it died on me, maybe it just died when i wanted to play on it.

As curious as i am, maybe i started tinkering with it and in my mind the cable that was loose at the floppy or came loose when i was busy with it that time stayed on my  mind all these years after.

 

As for the fat agnus i have a question though, i have the special tool that is needed to unplug it, i took it out and on the other side the ceramic is somewhat abused, because i can remember my mom and i have brought it in in the far past for another repair, wich is not the root of this problem because it perfectly functioned after that. But the sides where the agnus can be pried with is somewhat not chipped i would say but it has some marks.

I know from AMD cpu's in notebooks that if the core is chipped it is broken, however how does it work with an older chip ? Any thoughts about that ?

 

Thanks. 

[Pinball freak]

Very interesting link you gave me. because mine suffers from this i think:

 

When the Caps Lock key is repeatedly pressed approx. 10 times, the Caps Lock LED turning on and off each time indicates the CPU is correctly reading the CIAs. If the Caps Lock LED sticks on or off, the CPU is not servicing CIA interrupt requests.

 

If i want to figure things out, now i have 2 amiga's and i do NOT want to f#ck things up, is it best to test the CIA's in the working machhine .... or doesn't it matter and can in plug in the good ones in the dead amiga...

I do not want to blow a good working chip.  So my guess is to test the dead amiga ones in the working one ?

[Pinball freak]

Mmmm, maybe mu fat agnus is in worse condition than i hoped. It seems someone did some damage on the corners probablt with a screwdriver.

It could be me in the past, but i can't remember.

However i will upload some pics.

 

 

[shoestring]

That gouge is the least of your worries. Give those leads a good clean, there's some corrosion and oxidisation taking place on almost all pin leads. They're likely not making a good connection to the PLCC.

 

Use some rubbing alcohol or brasso and a fine toothbrush or cotton ear bud. Don't scrub accross the chip.

 

I'd consider doing this first before looking at the chip ram.

 

 

[shoestring]

16 hours ago, Pinball freak said:

Well, as i am not familiar with the screen color codes, i would say Green. It is a deep alien snot green

So i am thinking in the direction of bad ram.

 

Well it seems like a memory problem. But clean those 8371 leads and PLCC leads first before you do anything else. 

 

Don't bother swapping CIAs until you address the ram issue. 

[Pinball freak]

Well, spent some time with the 2 boards today.

I swapped over some hardware and came to these conclusions, because i am still waiting for the new RGB scart cable from england.

 

What we know is that the bad mobo has green screen, caps lock hangs over 10 presses. And the keyboard has no led lit up.

 

So i swapped the keyboard to the working amiga and there also the leds do not lit up.

So, on the dead amiga with the working keyboard from my good amiga i get the power light and it is blinking 10 times with one long.

From what i have read on the internet from people had the same issue it always came down to, Or Paula, Fat Agnus or bad ram.

 

My question, can i swap the Fat agnus 8971 wich i cleaned as mentioned in the Amiga Rev 6 to see if it works ? Or does the rev 6 have issues with that trype ?

 

I also checked my floppy drive, and in the other machine that functions properly, but it doesn's sound as good as the one that is sitting standard in the machine, so needs some cleaning i guess.

 

Should i swap Paula in the working machine to see how the working machine responds ?

 

What about the dead leds in the bad keyboard, where to look first ? ( see next post )

 

Thanks !

Edited April 11, 2022 by Pinball freak

[Pinball freak]

Ok never mind about the led lights, on the underside it has broken traces wich need to be fixed !

 

So now an hour later, i can say i fixed that problem, the power led is working again

Edited April 11, 2022 by Pinball freak

[shoestring]

Sounds like a faulty Agnus ( 10 flashes plus 1 long ). 

 

He is right when he said that you cannot put 8371 Agnus in rev 6 board. You need an additional refresh circuit which goes near the trapdoor on the motherboard. The 8371 isn't able to refresh some ram chips ( 44256 ) properly. Some early rev 6 had the 8371 but needed the refresh circuit.

 

Why not just test the 8372a in your original board ?

 

 

Edited April 11, 2022 by shoestring

[Pinball freak]

On 4/8/2022 at 10:27 PM, Pinball freak said:

Update,

Well i went back with the new Amiga to the guy i bought it from, it really bothered him this happened to me and he would do everything to fix it.

It was a green screen that he had. So i said, from what i saw on the internet people had or problems with ram, paula or fat agnus.

He has tested, Agnus and Paula, they worked in another machine.

So he had another solution for me, he took his own A500 rev 6 and put in an Agnus 8372a because he said the 8371 from the rev5 would not work in the rev 6???? Did not look this up yet.

 

 

Yeah, as i mentioned in a post before, look here above, he swapped is own mobo in this machine to get me a working one. Only it was a rev 6. 

 

But if it can't hurt and the rev 5 want's to work with the 8372a , i can tru to swap them and look what happens.

 

It is just now, when i was busy with the leds on the keyboard i noticed they feel very different from the new Amiga.

After looking the parts numer up on the internet it seems i have got the famous Chicken lips...

never knew...

 

 

[Pinball freak]

OK, swapped over the Fat Agnus and the Paula, same issue on the bad board.

 

So not much to do now than wait for the parts and the Diagrom...

[Pinball freak]

Holy crap, It's Alive, it's alive ..................... hell yes.

 

Well, here it comes, first of all thanks guys for your support and help with the reply's.

 

My even cia had some sort of mod switch , as i read that the Amiga , i think you guys mentioned it can work without it, i plugged it out of the system.

And then i saw that the soldered 40 pin ic socket had a pin in it, yep it broke off, argghhh bugger.

 

So i tried it to peel it out with a needle, but it only got deeper.
So now i had a problem, still have, so will have to solder a new one.

Hoping to get the pin out, i started tapping on the back, hoping it would fall out, did more tapping as it didn't and than , blam on the table... Hey Gary what the hell do you do there ?

Why the hell did you fall from the socket Gary, i did get all chips out about 5 times last 2 weeks, to check them and to clean them.

So I put the row of pins to the outside, that Gary got all snug in his socket.

And there it was, a steady red led, NO WAY...

So i connected my floppy, yep booting it.... Hallelujaa....

 

Damn this feels good

 

Wish i had a working cable....

 

 

btw , anybody knows if this is a mod or a fix ?

 

 

Edited April 11, 2022 by Pinball freak

[Daedalus2097]

The number of flashes of the power LED have no significance and don't point to any particular fault, and just signify that the OS has gurued. The number of flashes is hard-coded and the last long pause is the machine resetting. There are lots of guides that appear to be repeated again and again about things like the power LED flashes and the error colours that are often misleading and sometimes plain wrong.

 

Nice work on the fix, I guess there was some sort of bad connection in the Gary socket then? It's probably a candidate for a new socket to make it reliable for the future.

 

Those wires underneath appear to be just a fix - those pins are connected as they should be on the PCB, so maybe there are some scratches or damage to the top of the board between the CPU and the ROM?

[Pinball freak]

Yes, it was pure luck honestly. In the end i probably would have find it but that could really take a while....

I will order 2 new sockets, for gary and the even CIA.

Will be cleaning the keyboard and casing, and relive my youth...

[shoestring]

Happy days. So if there is a broken leg on one of the custom chips then you can solder another leg from a donor chip if it has enough metal exposed. Some people use a dremel to expose more of it if its snapped at the base of the chip.

 

http://www.ukvac.com/forum/missing-chip-pin-tips_topic350953.html

[shoestring]

15 hours ago, Pinball freak said:

Ok never mind about the led lights, on the underside it has broken traces wich need to be fixed !

 

So now an hour later, i can say i fixed that problem, the power led is working again

Yes this is a common failure point on A500 keyboards. I knew there wasn't an issue with the motherboard when you measured the signal from the status ( pin 7 )

 

Starts off as a dry joint due to constant mechanical stress from the A500 enclosure when the two slits for the LED casings are mis-aligned during reassembling. Eventually the traces on the solder side can fail.