Amiga 500 IC issues

[SuperSpork]

Hello all,

I am now the proud owner of an Amiga 500 with 512k expansion.  This is my first Amiga to date, so I don't know everything yet, but I am learning quickly.

I'm having intermittent issues, however.  Two issues plague me the most -- the flashing power light, and scrambled video.  (For reference, I'm using the mono/greyscale video port for the moment, as I don't yet have a modulator or an RGB monitor.)

Seems to me that the IC's just do not want to stay in their sockets, as pressing firmly on the CPU usually fixes a flashing power light, and pressing on the Denise chip usually fixes scrambled video. But it doesn't usually stay fixed, and that doesn't always solve the issue. So, my question is, what's the safest and most effective way of cleaning the contacts on an IC?  I've done the trick with a hard eraser to remove oxidation, but that might have made things worse to an extent.  I also know I could solder the chips into their sockets for the best reliability, but I don't really want to do that.

Also, what other things (other than the power supply -- which I can't currently test because I don't have a multimeter handy) should I check?  I know everything individually is working alright, as when it does work, it works wonderfully, just not 100% of the time.

Finally, the CPU has been replaced with a Vortex ATOnce, which is piggybacked over a stock 68k.  Can I replace this back to a regular 68000, or shouldn't I?  I don't really have any use for it.

Thanks

[SuperSpork]

Thanks everyone.  Hopefully next week I'll have a little time to sit down with the thing to do a little more thorough cleaning.

Looks like I'll need a PLCC puller as well.  The Agnus is pretty firmly seated in its socket... I'll take that as a good sign.  Might as well invest in a good DIP puller as well while I'm at it.  (I know where to get them cheap too.)

The ATOnce actually caught me off-guard at first.  There's a badge on the case of the unit that says 386dx/33, but I assumed it was on there by accident.  Then I spent a while wondering how the heck they managed to emulate a 68k on a 286 until I realized that there was a 68k underneath.  What is it actually good for, anyway?  As far as I can tell it's hardware emulation of the IBM PC, but I'm not sure why that would be important.

[SuperSpork]

As for the dips, I usually pry a little at each end with a screw driver.  If I work slow, in 5 or 6 passes the chip comes out without a bent pin.

Yeah, but the bottom RF shielding gets in the way of that, and I'd rather not remove that unless I have to.  DIP pullers can help you get IC's out with pretty much zero clearance.

Maybe the problem is with the power supply after all.  How many amps is the 5 volt rail rated for?

I'm pretty sure the power supply is still original, or at least in its original case, so it's 5V, 4.5A.

Do you intend to expand this 500?

Probably not, at least not for the moment.  This one's gonna be a gaming computer I expect, for the most part.  I might invest in an A2000 or other later model Amiga down the road sometime that I may eventually expand.

In any case, I'll start with contact cleaning before I try and moving on to anything more drastic.  Contact cleaner is generally safe on ICs, right?

[SuperSpork]

What I meant was that the RF shielding comes up around the edges of the board (to form more of a cage), and this makes it hard, nearly impossible, to get a screwdriver under one or the other end of most of the IC's.  I can get them out using just one end, but I'd rather not do that.

Although I do recall another trick: Pry one end up slightly and slip a Popsicle stick under the IC so you can pull up with even pressure under the entire chip.

I've used an eraser on some of the pins already, I just want to do a little more thorough cleaning at this point.

[SuperSpork]

Just thought I'd give an update to those interested.

I got the CPU to finally sit right, so no more flashing power light for me.  I also had a chance to check my power supply with a multimeter; at least under no load, it's outputting the correct voltage.

The Denise issues I was having were actually caused by the case.  I had noticed that there were a few cracks in the case, some especially large ones in the bottom half of it.  If I take out the motherboard from the case and let it simply sit flat on a table (on top of an anti-static mat, of course), it doesn't have any issues.  Seems that it's cracked enough to the point where the motherboard bends slightly when put into the case, accentuated by the fact that it's missing half of its screws.

So, guess I'll have to repair the case now.  I think I'll try an epoxy repair first, unless there is a better option.

[SuperSpork]

I meant to find the proper screws to secure the mobo in place, it's only being held by 2 right now, and to repair the case separately.

[SuperSpork]

Alright, this is just WAY too ironic.

I took off the screws along the ports on the back so I could remove the RF shielding and get a look at the bottom of the mobo... there was literally a (dead) bug sitting right beneath the Denise chip.  A fly, to be exact.  :roflmao:

So my system had a bug, but I think I've fixed it.