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Old 13 August 2016, 14:20   #1
Silwuff
 
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Unhappy Modern Trapdoor RAM killed my A500

Hi guys,

I'm new here so thanks for having me! I recently acquired a regular Amiga 500 from ebay - it's a B52 Rock Lobster and REV 5 motherboard.

After a lot of work I managed to reflash a Gotek virtual floppy drive, latterly deciding to splash out on a modern trapdoor RAM expansion to get me up to 1mb - http://www.ebay.co.uk/itm/NEW-Commod...gAAOSwB4NW0B1q

AVOID THESE AT ALL COSTS. Stick to the traditional A501.

My Amiga was working like a charm until I plugged this in. At first it was the dreaded green screen (apparently a sign of faulty Chip RAM) which has now become simply a black screen with a buzzing noise. I'm absolutely gutted.

I wish I'd never bought it, and would warn others to stick to the traditional A501. To all extents it seems this modern trapdoor RAM has killed my board or chips. Is it possible it's in conflict with other parts of the board? I've tried removing the offending RAM and it makes no difference, my Amiga now only shows a black screen. Just this second I've tried starting it again and it's not even green screening or buzzing anymore. No signal, it just sounds dead.

Any help would be great, but it really feels like it's beyond repair.
 
Old 13 August 2016, 15:04   #2
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Hello,
are you sure you plugged it the right way?

I am asking that because from the picture it seems that it is possible to plug the expansion card with the top of the card down faced as well.

In the ad they say:

Should be installed in the trapdoor in the way that shows the following image:


Obviously if you plug it the wrong way you can cause a severe damage to the pcb and the expansion card.
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Old 13 August 2016, 15:06   #3
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Can you check each pin on the expansion to check for shorts? Would be a good start. And was that mobo ever modded in some way? Finally check your psu voltages or try with a different one.
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Old 13 August 2016, 19:00   #4
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Also it might have nothing to do with the card, maybe just a coincidence something failed when you connected it. Years ago I loaded WinUAE and my PC died on me at the exact same time and I wanted to blame WinUAE at the time (didn't use it again for months). It turned out to be the PSU failed just at the same time I was trying Amiga emulation out.
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Old 13 August 2016, 20:04   #5
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Originally Posted by liviux76 View Post
Hello,
are you sure you plugged it the right way?

I am asking that because from the picture it seems that it is possible to plug the expansion card with the top of the card down faced as well.

In the ad they say:

Should be installed in the trapdoor in the way that shows the following image:


Obviously if you plug it the wrong way you can cause a severe damage to the pcb and the expansion card.

Hi Liviux, thanks for your reply... I installed it as the diagram shows, but when it didn't work I DID try it the other way round to see if it made any difference >.< probably a very bad move on my part. I've had other components connected wrongly and they never caused this much damage. I guess you learn these things the hard way.
 
Old 13 August 2016, 20:08   #6
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Originally Posted by dirkies View Post
Can you check each pin on the expansion to check for shorts? Would be a good start. And was that mobo ever modded in some way? Finally check your psu voltages or try with a different one.
Hi Dirkies, thanks for your reply... I'm a bit of a beginner but the seller assures me these units are all thoroughly tested; it looks brand new. The board hasn't been modded other than switching the floppy disk drive DF0 to the new Gotek drive. The seller has refunded the item on ebay so I'll be sending it back ASAP. Time for a new board by the looks of it.
 
Old 13 August 2016, 20:30   #7
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Originally Posted by -Acid- View Post
Also it might have nothing to do with the card, maybe just a coincidence something failed when you connected it. Years ago I loaded WinUAE and my PC died on me at the exact same time and I wanted to blame WinUAE at the time (didn't use it again for months). It turned out to be the PSU failed just at the same time I was trying Amiga emulation out.
Hi Acid, another Tynesider! good lad thanks for your suggestion, it could have been a coincidence, it was just a shame it was working perfectly well before I decided to try and install this new RAM. The seller has been very reasonable and rfunded me for the item and recommended a repair company, so you can't say fairer than that. It'll be hard to check every possible error so I'm looking for a new board as of now. I hope you're right!
 
Old 14 August 2016, 08:09   #8
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Quote:
Originally Posted by Silwuff View Post
Hi Liviux, thanks for your reply... I installed it as the diagram shows, but when it didn't work I DID try it the other way round to see if it made any difference >.< probably a very bad move on my part. I've had other components connected wrongly and they never caused this much damage. I guess you learn these things the hard way.
Hello mate, I can understand your "move", it's "quite normal" to try the other way since it didn't work in the right position but, "with hindsight", it has certainly been a bad move... however they should have made the expansion in a shape that it is possible to plug it only in the right way...

It is also true that when you plug something the wrong way sometimes nothing bad happens (it just doesn't work). That is what happens when the plugs are only for data but consider that some voltage goes from the mainboard to the expansion card and probably when you switched on the computer a short has burned some components.

I am sure you will be able to have a new working A500 (with expansion) soon. Good luck!

Last edited by liviux76; 15 August 2016 at 09:53.
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Old 14 August 2016, 10:13   #9
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I have two of these on two of my A500s and they work flawlessly. I am quite happy with them for they were reasonably cheap and do the job well (plus no battery, so no leaking hazard). Admittedly, though, if they do that much damage just because someone inadvertently installs them the wrong way, they should come with a flashy, very visible warning to prevent people from doing it.

Last edited by PortuguesePilot; 14 August 2016 at 11:53. Reason: typos fixed
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Old 14 August 2016, 21:39   #10
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A simple sticker on the back saying TRAPDOOR THIS SIDE should avoid such horror stories IMHO.
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Old 15 August 2016, 09:29   #11
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simple diode decoupling would solve ALL issues - tis a poor design because of it.
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Old 06 January 2021, 14:50   #12
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Sorry for resurrecting such an old thread, but exactly this happened to me too. Well, not exactly - I inserted the RAM the wrong way on the first try . The shop where I bought it had no instructions with it, and no picture of it being installed either. (But by the way, the connector is stupidly designed imho - it should be possible to insert it only one way)


Already got a new known-good motherboard I'm about to install.



What I am wondering about: do you think it is safe to install the RAM on the new board (of course installed the correct way this time ) or could it be damaged and causing issues or even short the new board too? Same question for the chips from the shorted board, is it safe to test them on another board?

Last edited by mcdope; 06 January 2021 at 15:29.
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Old 07 January 2021, 12:48   #13
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Quote:
Originally Posted by mcdope View Post
Sorry for resurrecting such an old thread, but exactly this happened to me too. Well, not exactly - I inserted the RAM the wrong way on the first try . The shop where I bought it had no instructions with it, and no picture of it being installed either. (But by the way, the connector is stupidly designed imho - it should be possible to insert it only one way)


Already got a new known-good motherboard I'm about to install.



What I am wondering about: do you think it is safe to install the RAM on the new board (of course installed the correct way this time ) or could it be damaged and causing issues or even short the new board too? Same question for the chips from the shorted board, is it safe to test them on another board?

The trapdoor RAM module can be damaged, and perform additional damages to your new motherboard.


Probably, the RAM module is still intact; but we cannot guarantee this; and due to these computers are no longer in manufacture... personally I do not take the risk.
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Old 07 January 2021, 13:13   #14
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Thought so and haven't tried so far. Had the hope that maybe someone already experienced and tested it ^^


Already ordered a new trapdoor module.


Anybody knows if it's possible to validate the module without actually installing it? Like testing points for continuity (or the lack of) etc? Not familiar with such stuff, but having a basic multimeter around.
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Old 07 January 2021, 17:50   #15
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(But by the way, the connector is stupidly designed imho - it should be possible to insert it only one way)
The connector's not the best, but it is at least offset to one side of the opening meaning original, full-sized RAM expansions could only be inserted one way. If modern expansions at least made the PCB the same width, it would only fit one way too, but I guess they're more interested in reducing costs or making them small for other reasons.

Quote:
Already got a new known-good motherboard I'm about to install.
Cool, but don't throw away the old one. It's possible that it can be repaired, or that at least some of the parts might still be useful to someone.
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Old 07 January 2021, 19:20   #16
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Cool, but don't throw away the old one. It's possible that it can be repaired, or that at least some of the parts might still be useful to someone.

The plan is to get another known-good board with chips and use it to test the chips from the shorted one. Guess the damage will be only in one IC (hoping that the damage done to that one prevented the others from being damaged). Would be a shame to rip that board only for parts, its an almost flawless rev6 from late '91, with green PCB - looking like fresh from the factory.


But burnt already quite some money on retro stuff in the last weeks, esp. with this fail (could still slap myself...) so this will have to wait.
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Old 07 January 2021, 19:42   #17
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Someone (Maybe a MOD) should update the heading on this thread as what is stated is not the case. Improper troubleshooting by the OP is the cause of the issue and while I am sympathetic, blaming the RAM module for this issue is simply wrong. And for the record, turning things around and trying them the "other way" is never a good idea with electronics. And I am not trying to be a jerk here as I KNOW this because I have tried this many years ago with an Amiga 300 floppy drive power lead and absolutely FRIED my floppy drive. Live and learn!
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Old 07 January 2021, 19:46   #18
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Someone (Maybe a MOD) should update the heading on this thread as what is stated is not the case. Improper troubleshooting by the OP is the cause of the issue and while I am sympathetic, blaming the RAM module for this issue is simply wrong.

Totally true. It's not the fault of the memory (even if its design is almost asking for it). Better title would be "Trapdoor RAM connected the wrong way fried my A500".
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Old 07 January 2021, 19:49   #19
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But the threat title IS correct - modern trapdoor RAM really killed his A500.
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Old 07 January 2021, 21:56   #20
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And I am not trying to be a jerk here as I KNOW this because I have tried this many years ago with an Amiga 300 floppy drive power lead and absolutely FRIED my floppy drive. Live and learn!
Hah, I fried an Apollo 520 accelerator in my Micronik A500 tower doing it. So then I had to replace it with a Blizzard 2060. A costly mistake!
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