Amiga 500 plus with boot problem

[jdupuis]

Hi all,

i need help to boot my amiga. I cleaned all chips and replaced the faulty battery with a CR2032 one ( i found a guide for this).

It boot with showing a white screen, but the game get loaded, with video glitches, only if i insert the floppy before power on the amiga but with video.

Hi!

Like Mike said, remove expansion. Check for Insert Disk Screen.
If you removed any of the chips, check that they are oriented and seated in socket correctly. If you removed Agnus, check that all pins are making contact in socket (none bent over). Check that Denise has no bent pins and is seated. Sounds like it might be Denise and/or Agnus is not seated. Double check your work.

Cheers!!

[jdupuis]

Hello again!

This may help others as it has helped me over the years: From my Amiga World Magazine. Issue Oct. 1994 page 4 "Denny on DOS"

The screen flash at first power up is actually a series of colors. Fist color is Dark Gray. If it stops here you need to open up and press all chips down firmly in place. Second color is Light Gray. If re-seating chips does not help you have serious problems. Third color is Red. Indicates problem with Kickstart ROM, faulty expansion cards and loose Agnus chips. Try pressing down Agnus. If still no good, try removing expansion cards. Replace one card at a time until you find the problem. Fourth color is Green. Chip RAM problem. Bad memory chip. Fifth color is Blue. Indicates problem with Custom Chips. Again, re-seat or there is a faulty Custom Chip.
On A3000 Desktop. Stops at Yellow. Check Fast RAM Zips. One may not be seated or faulty.

Hope this helps.
Cheers!!

[jdupuis]

hi again,

@Oldsmobile_Mike
the model is amiga 500 plus with no expansion card
I don't get the "insert disk" screen, just white.
I'll try a wb disk tomorrow, but games boot.
Caps lock doesn't blink.
Rarely on boot up, just a black screen and video signal lost.

@jdupuis
I'll check all tomorrow. However i got the white screen before i removed them.

PS: i attached a "video glitch" example

Check that the braided grounding strap isn't shorting on the keyboard circuit board.
The picture you included looks like it might be Denise. I would not think the Video Hybrid Chip. 500 plus should be rev. 6A. Look over all to see obvious first. Check for mis-cut trace for 2 Meg Chip RAM Mod. Remove 501 Memory Module if you have it.
Cheers!!

[jdupuis]

Above information is incorrect. 500 Plus is Rev. 8A motherboard. Has 1MB chip built into the motherboard, optional 1MB chip in the trapdoor slot. No chip ram mod necessary, and doesn't use a 501 (a 501 is for the regular 500 - only adds 512K - 500 Plus generally uses a different board to reach it's full 2MB of chip).

I would think Denise, too, but it's on the far side of the motherboard - not likely to be affected by battery damage. Still, worth a good cleaning of it's socket.

Hope for OP's sake it's not bad ram on the motherboard...

https://en.wikipedia.org/wiki/Amiga_500_Plus

Thank you Mike! 23 years - I did not know there was an 8A. I guess when I made the move to my A3000 goofin' around trying to make the A3640 work and OS 3.9, I lost touch with the A500 stuff. Now I'm on to the X1000. Appreciate the heads up!! My A500 Plus was bought from Air Force Base Exchange. "Refurb" yeah! They installed Rev. 6A MB. Guess I was had way back then. $499.00 OUCH!!  :lol:

[jdupuis]

"Yikes! I remember going to the PX with my dad way back in the day. First time I ever saw an Amiga, it was love at first sight. Those were the days! "

Yes they were. Commodore falling apart and pumping last stock out. I think that's how I got the 500 Plus. 1 meg Agnus 512 on board chip and 501 on rev. 6A. (NTSC) That's how they got away with calling it "Plus". A590 with 2 meg RAM coverted to SCSI HD makes it fun. Still love it though. The only Amiga I can turn on a play my boxed games no tinkering!  
Amazing how floppies kept in box - in house, have outlasted expectations as with alot of SCSI HD's. They don't make 'em like that anymore.

[jdupuis]

Yes, that was me that mentioned the possibility of faulty ram.  

I've never heard of a case where you could turn on a system and boot off a game disk and play the game with just a little bit of graphics corruption (and presumably sound), yet when you turn the machine on without a disk in the drive it just gives a white screen, no "Insert disk" screen.  .......LOL, maybe he's got a malfunctioning floppy drive that's throwing some crazy error?  Could be anything at this point.  :lol:

What kind of monitor is this hooked up to?  Can you confirm the monitor displays correctly with any other system?  PAL and NTSC modes both display correctly?  (if I remember most A500 Plus's were PAL, is it possible your monitor is NTSC only, that's why you're not seeing the "Insert disk" screen?)

Non-ECS Denise? Agnus failing? PAL/NTSC Jumper pad not soldered correctly or not at all? Leaking cap? Corroded traces on back of MB? SCART cable not makin good connection? Cold or loose soldered joints? 2.04 ROM bad? ....the list goes on, etc.

Cheers!!

[jdupuis]

If you have a spare single chip rom just try it, no matter if it is 1,2,3.x.
If you don't and need to buy then go for a v2 or if you want to expand it without an aca500 then try v3.

I'm with vince, just try something else. I agree with Mike. Use anything but Cloanto ROMS. I found 2.04 to run nicely on the 500. Hopefully you will find Denise, Agnus or 68000 loose or something.

Cheers!!