The way I fried my BPPC card.

[PiR]

Listen to my very interesting story about the way I fried my BPPC card two days ago.
People willing to play with the Power can learn some from this.

Well, I have problem with power from the very beginning of my BPPC. During startup my Amy freezes before full WB getts started, at random moments. Luckilly for me after the temperature getts higher after some time it, starts working quite stable.

But this startup was getting on my nerves! :madashell:
When the mashine froze I could hear the fan getting slower. Yeah, deffinetly power problem.

I did some tests with multimeter. Strange thing - I've discovered that on 5V from the PSU to the PCB I was loosing 0,14V, while from the PCB entry to froppy connector I was loosing only 0,07V. So till floppy power connector I have over 0,2V dropping, but most of the power is somewhere inside cable + socket () BTW: I have strong PSU from Micronik, and Amy still in desktop.

On Sunday I decided - I'll connect the cables to the fan connector of BPPC! I connected GND and +5V from the main power socket. Started up. Well, it worked!  :-D

On Monday I figured that fan is not working. I got nervous. I took out my freshly bought 128MB SIMM and HOLLY COW! What a mess did I find!  :-o
Some chips exploded, covering everything with black dust, and plastic desktop case has a burned out hole in the place it sticks to BPPC. What a nightmare.  :-(

Yesterday I picked my poor card. First thing was - well, it IS working!  :-) Only fan is not moving...

Closely placed tracks looks not touched.  :-)
Only those connected to those exploded thingies...
And those thingies are surface soldered resistors, mayby hard to fix, but not a big intelligence afterall... And the only thing they seemed to be connected to is the fan.

I picked up some cables and connected the fan to the floppy power supply. The trick worked!  :-) I put everything together again.

So, I still have this trouble with power again. Till my Miggy gets warm it freezes on startup. And funny thing - I can still hear the fan getting slower at that moment. But now it is connected to floppy power supply, not to BPPC, so the drop down is global for whole Amy and I thought that this edge connector can be big trouble.

Still I have to wait until I can do anything. But I'm extremally happy my BPPC works at all. 8-) I don't understand what happend and why. The most damaged resistor is on the track closer to GND than +5V.
I won't mess around with my BPPC any more. But only the Devil knows whats happening inside my PSU cable + socket... :-(


And they lived happily ever after.

[PiR]

@Patrik

The dropping is only on Amy board I've checked the voltage inside PSU and its quite over 5V.

@lempkee

I've checked several times several things. I was not going to risk my precious! I've checked the voltage, when on-power, I've checked the resitance from one point to the other when off-power... I've checked the direct voltage (+5V and GND) and cross voltage (one pin from one point and the other from the other....)

What can I clearify more?

My checking points:

PSU (+12, GND, +5) : never under 5V

Amy Power socket on MoBo (+12, shield, GND, +5, -12) : hard to reach... Made shortcut once during tests... My PSU works tricky now after such experience ;-)

floppy power connector on Amy MoBo ( +12, sheld, GND, +5) easiest place to check; 4,8 when it's working, can drop till 4,65 on freezing...

BPPC fan connector (+5, GND): whats the difference? Its even further to PSU than floppy...

@Kronos

I could be better in present electronics, but I'd bet capacitor of valuable size should be bigger... Well, every guy with BPPC can check three thingies next to BPPC fan, on the other side.

[PiR]

Hi thanks for such a big feedback, I didn't expect it. :-)


@amigamad:
I know that sounds crazy, but I observed, that when my Amy is cold it won't work. When it gets warmer it starts working. I think that for some reason on the higher temperature either resistance or power consumption reduces.

So what is the purpose of increasing cooling, again?  :-)


@patrik:

That would be insane if just a cables had that big resistance. But what can you tell about the socket? I was trying to test it but it is too hard for me to access it (I mean internal parts of it). On the other hand this is the only thing that sounds logical to me. I've measured the voltage just at the other side of the power socket and observed the poor result, while having good values in soldering places in PSU. So either unlikely cable, or this stupid socket.
I have my original PSU. Also here I don't trust this socket, but that can be my self-sugestion, mayby I'll investigate it more deeply.


@Lemmink

Yes, it is 60. But read yourself and tell me - I'm insane and the Amiga power socket cannot be the source of the troubles... Attaching power to floppy connector is just omitting this socket.


@TheGoose

Did you blow your fan too? Do you also have 60? Mayby this is the rule - you just shouldn't do it for 60?
Am I wrong, or 60 in BPPC works under 3,3V, while 40 really uses 5V? Hmmm....

[PiR]

Hi

@Lemmink

I know, I know... But:
If you look at my first entry you'll see that I'm losing much more power (more less twice as much) on the way from PSU to MoBo (cable+socket) than really inside MoBo. Anmd belive me - I've checked it really carefully a lot of times as I couldn't belive it.

And now my fan is juiced from floppy connector and behaves EXACTLY THE SAME as when it was connected originally to BPPC. So, again also huge surprize for me - edge connector is not the main player.

To be honest - Amiga power socket was also designed for different power consumption, so 'is allowed' to cause troubles...

I have a board ver.2B, and my HD had to go off the desktop case exacly the same day my BVision arrived - unluckilly no place for both inside the case.

Luckilly for me, my Micronic PSU, appart from normal Amiga power connector has additional HD-like power conectors, so I powered HD and CD from there, not from MoBo. Frankly - this was also the most comfortable place to measure the voltage produced by PSU. And I don't have any troubles with either HD or CD.

@Brian
In my case I have a feeling that much VRAM manipulations can cause my machine to freeze (screen opening, Window moving - squares of data to copy, when machine is very cold at the beginning even text manipulations can be risky).
No, I won't add any cooling to the system... I want it to get hot and operational as soon as possible (mayby even extra heating at startup?  ;-) )

[PiR]

Hi every1 again. :-)


@patrik

I don't asume if it will help or not. I can only experiment with weaker PSU, so there is not a real point. I could try to find myself even stronger PSU, but if I am right by any chance I'll just increase my collection of Amiga PSUs with the same behaviour.
I know it shouldn't make things worse, despite decrementing my bank account.  :-D


@Tomas

Yeah, you can imagine how I do feel happy that it works. I'm affraid that working just on the edge of acceptable voltage can damage something one day.
But on the other hand I also think that if I push more power inside, my card will produce even more heat, and the heat is mayby even worse.


@x56h34 (is this alkohol or something?  ;-) )

I experimented with attaching +5V ang GND to floppy connector, while having open desktop. Had no problems with it and observed almost 200mA current... (yeeeks, and this should have the same voltage on both sides...)


@Castellen

Yes, I assume some fluctuation at startup or shutdown. I think that adding a huge capacitor in paralel (in correct direction, of cource...) could serve as the BPPC overvoltage guard.
I also know that multimeter gives me only average value, but thats enough for me to know. Even on average I can se noticable average voltage dropdown in the very moment, when my machine getts frozen.


@Chunder

Mayby that solves the riddle.
I repeat - my electronic skills are more less on the level that I know that + is over - and GND is somewhere between both, but can really capacitor be so small to look, like surface soldered resistor?

But diode... Yes, diodes are another animals, that can be as little as resistors and are also observed to have ability to explode sometimes.
Or I just mixed things up.  ;-)

Well, for me there is no more fun anyway, as those things' last action in their electric life was burnig out of my BPPC, the tracks they've been connected to...


Thanks for all

[PiR]

@Castellen

Anything is potentially repairable.

Potentially there is no reason why people aren't immortal either.  :-D
I won't fix my burnt out tracks. :-(

Sometimes there is very little physical differences.

Ok. I belive. You know what you say, so those could be capacitors.

The huge capacitor idea would not really serve as an over voltage protection. Like if you accidentally put 12V instad of 5V onto the thing

And if you connect it to 24V or directly to 220V AC it won't help either - I know. Of course I meant only for this inrush, assuming you connect correct voltage.
But i was thinkig, if this startup inrush (by any chance) happend in the opposite diretion, huge capacitor in parallel could make things even worse...

Anyway, thanks for help.

[PiR]