Amiga 500 Plus Repair - Take 2

Подписаться 1,8 тыс.

Просмотров 2,1 тыс.

50% 1

This Amiga does't boot: it just has a black screen and a flashing drive light. Check out www.pcbway.com for great PCBs, 3D printing and other services from just $5.
From the initial look I suspected the 2MB Agnus was dead ( a very expensive IC), but maybe there are problems with the RAM support logic? and there's always the old standby... battery damage.
Also viewers suggested checking out this video • Amiga 500 Plus motherb... for what looks to be a similar problem. So let's do that.
🔴 Subscribe for more retro stuff: ru-vid.com...
🔴 Buy me a coffee or make a one-time donation: www.paypal.com/donate/?hosted...
🔴 Blog: timsretrocorner.com
Music: Arpanauts by Eric Skiff - ericskiff.com/music
Chapters
00:00 - Introduction
02:52 - Sponsor Message
03:40 - First Test
06:32 - Scope it Out
10:17 - Desoldering Montage
13:30 - Chips tested
15:18 - Beeping the PCB
16:34 - Green Goo
20:02 - Bodge Wire
20:58 - New Chip, Crystal
22:39 - After all that… Does it work?
23:48 - Vanilla A500 Comparison
25:22 - Clean the PLCC Socket
26:56 - A New Agnus
29:05 - Trying the New Agnus
30:45 - Another Desoldering Montage. Oh joy!
34:53 - Epilogue

Наука

Опубликовано:

8 июл 2024

Ссылка:

Скачать:

Готовим ссылку...

Добавить в:

Мой плейлист

Посмотреть позже

Комментарии : 19

@ralfr.5974 Год назад

Hope You get it fixed🤞🏻 Good Luck🍀

@Crashedfiesta Год назад

Not sure if you've looked at the CPU yet. Black screen and no output from diagROM screams a CPU issue to me since it's about the first thing that diagROM checks. Also, with all the A500+ repairs shenanigans I've had it's NEVER been a RAM fault. It's been broken traces, dodgy sockets or busted logic chips adjacent to the battery. Your broken chip is mighty unusual. I have an A500+ board that will normally refuse to start until I poke hard at the 68000. Basically, the socket is bad. So check all your sockets. Also, subscribed. 😁

@TimsRetroCorner Год назад

I’ve since desoldered the RAM and checked it in a straight A500, and they’re all fine. The CPU, CIAs & other chips (except the Agnus, obvs) have all been pulled and checked in the straight A500 and are working. I have sprayed the sockets with contact cleaner, but yeah they could still be dodgy ( the Agnus socket definitely was). Thanks for the sub :)

@eukat3ch Год назад

Hi Tim, new sub. Love the channel !

@TimsRetroCorner Год назад

Cheers! and welcome aboard

@andymaher13 Год назад

Hi, I was wondering did you make any headway on this? My 500 seems to have the same issue, no output from diagROM and a blank screen. Thank you

@TimsRetroCorner Год назад

No I've got no further with it. I'm halfway convinced that the Agnus is dead and that the replacement Agnus is also dead. But without a second, working machine to try them in I've got no way to prove (or disprove) that. And with 2M Agnus chips costing £60+ each, they're too expensive to just buy more. Every other major chip has checked out fine in a regular A500. The other possibility is a board fault, but I've followed every trace between Agnus and RAM & the surrounding area multiple times and the connections all appear good. So I'm kinda stuck waiting on new inspiration (or a lotto win!)...

@andymaher13 Год назад

@@TimsRetroCorner Thanks for the reply and good luck with the lotto

@steveb1912 Месяц назад

Check CPU clock & reset pins

@emilianopepa8678 Год назад

Hi ... RAM Chips are usually the First culprit. I suggest you to replace them. By the way ... Can you check of debug ROM can work with only fast RAM ... In this case Will Be enough to fit 1 Meg of Fast RAM ( totally under 68000 control) in the expansion slot

@TimsRetroCorner Год назад

RAM chips have since been replaced, although it made no difference to the result.

@thomask7144 Год назад

Have you checked the reset circuit? Hope that helps. Best regards

@TimsRetroCorner Год назад

Yes, the reset is operating normally :)

@JVHShack Год назад

Just for a sanity check, I suggest ruling out the RAM itself as the cause of this machine's woes. If That checks out, then I would go for the A500++ board.

@TimsRetroCorner Год назад

Thanks. Will do...

@TimsRetroCorner Год назад

I've pulled the DRAMs and they check out fine in a plain A500. And I socketed up the Plus & put in fresh ICs for completeness. No difference. So I guess that's ruled out.