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New to Apple II & Troubleshooting

ethump

Experienced Member
Joined
Jan 30, 2022
Messages
67
Location
Sheffield, UK
Hi all!

I hope I've found the right place. I recently picked up an Apple II Europlus. Growing up in the UK these things were pretty scarce and at the grand old age of nearly 50, I've just gotten my first one. It had apparently been stored for 20 years.

I've opened it up and cleaned it and given the PSU a full recap. All expansion cards have been taken out and I have only the power and video out connected.

When I power on, I get a screen that looks like this. There is no beep (though I'm not certain the speaker works).

1643504060977.png

I've given all the chips a bit of a wiggle. I'm actually waiting on a new can of contact cleaner to clean and reseat them all properly.

Is this screen indicative of anything? What are my troubleshooting steps?

cheers!
ecky
 
The problem is likely one (or more) of the first row (from the front of the computer) of RAM chips. This is the first bank of memory and is where page zero and the stack are located as these locations are necessary to initialize the computer (receive the beep and get the Apple prompt).

I would recommend first pulling them and then just reseating them. If that doesn't work then you may want to swap chips from the other two banks to see if it comes to life. The problem with this strategy is you don't know if the chip you're swapping in works or not. Still, if you don't have any known working replacements this will give you some level of troubleshooting.

FYI bit zero is the left most chip and bit 7 is the right most chip. Each chip stores 16 kilobits (I am assuming a 48KB configuration) thus the left most chip stores all the bit 0 values, the next stores all the bit 1 values, and so on until the right most chip which stores all of the bit 7 values. Thus the system reads / writes all eight chips for each byte being read / written.

Here are some DRAM part numbers I've seen used in Apple II Plus systems:

D416C
MK4116N
MM5290N
 
oldpcguy. Do you really think he would get a full screen of "@" if it was the row with Zero Page?

Its worth a shot cyling out the lowest bank for one of the two top banks but this seems more ROM related I think.
 
>>> I hope I've found the right place.

Of course you have! You mentioned the word Apple...

First of all, as this is your first post, welcome to VCFED.

As you are a new member, can I suggest editing your profile and adding your location to it? As you can see, I am in Worcester...

Also, you will be moderated for the first 10 posts or so. This keeps the spam off the board - and is very effective. However, it does mean that your posts will appear a bit delayed...

Same here as with your story. I always wanted a Commodore PET and an Apple - I got one of each a while ago. I had to repair both when I got them (although I bought both of mine when the prices were somewhat lower)...

If you want a good bit of bedtime reading, start here: https://vintageapple.org/apple_ii/pdf/Apple_II_Plus_IIe_Troubleshooting_&_Repair_Guide_1984.pdf

Also, I am not sure whether your specific machine has the in-built diagnostics: https://www.apple2.org.za/gswv/a2zi...chives.and.Info/YOYODUCK/YOYODUCK.INFO/P2.txt. It won't hurt to try...

Failing that, I wonder if there is something similar for your specific machine?

I ran these and found my faulty RAM chip, but that was on a IIe.

I must admit, your display looks to me to be a video-based issue. But that's purely a hunch. Have you found the schematics and technical manuals on the web?

Dave
 
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oldpcguy. Do you really think he would get a full screen of "@" if it was the row with Zero Page?

Its worth a shot cyling out the lowest bank for one of the two top banks but this seems more ROM related I think.
I am >90% confident there is a problem with at least one of the bank one RAM chips. If I were troubleshooting this system and it was sitting in front of me they would be the first thing I would check.

Here is a picture of an Apple II Plus with the DRAM chip representing bit zero of the third bank removed:

Bank 3 Bit 0.jpg

This is a picture with the DRAM chip representing bit five of the second bank removed:

Bank 2 Bit 5.jpg

And finally the same system with the DRAM chip representing bit five of the first bank removed:

Bank 1 Bit 5.jpg
 
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>>> I hope I've found the right place.

Of course you have! You mentioned the word Apple...

First of all, as this is your first post, welcome to VCFED.

As you are a new member, can I suggest editing your profile and adding your location to it? As you can see, I am in Worcester...

Also, you will be moderated for the first 10 posts or so. This keeps the spam off the board - and is very effective. However, it does mean that your posts will appear a bit delayed...

Same here as with your story. I always wanted a Commodore PET and an Apple - I got one of each a while ago. I had to repair both when I got them (although I bought both of mine when the prices were somewhat lower)...

If you want a good bit of bedtime reading, start here: https://vintageapple.org/apple_ii/pdf/Apple_II_Plus_IIe_Troubleshooting_&_Repair_Guide_1984.pdf

Also, I am not sure whether your specific machine has the in-built diagnostics: https://www.apple2.org.za/gswv/a2zi...chives.and.Info/YOYODUCK/YOYODUCK.INFO/P2.txt. It won't hurt to try...

Failing that, I wonder if there is something similar for your specific machine?

I ran these and found my faulty RAM chip, but that was on a IIe.

I must admit, your display looks to me to be a video-based issue. But that's purely a hunch. Have you found the schematics and technical manuals on the web?

Dave
As an FYI the schematics can be found in the Apple II reference manual. One great thing about these early Apple systems is Apple made so much information available about them.
 
Hi all, thanks for the pointers. I shall read through when I have time. Contact cleaner arrived so I'll switch out the RAM and see what happens. That seems the easiest place to start or at least rule out.

Should it work with just one RAM bank? Guessing it's 16Kb per horizontal bank?

Dave, I've updated my profile. Apologies, I just set the account up quickly so I could post this message.

Cheers!
 
Hi all, thanks for the pointers. I shall read through when I have time. Contact cleaner arrived so I'll switch out the RAM and see what happens. That seems the easiest place to start or at least rule out.

Should it work with just one RAM bank? Guessing it's 16Kb per horizontal bank?

Dave, I've updated my profile. Apologies, I just set the account up quickly so I could post this message.

Cheers!
It should at least beep, display the Apple ][ text, and wait at the basic prompt (assuming no expansion cards installed) with the first, the one closest to the front of the computer, bank of memory. In the images I provided in post #5 the first two had chips removed from banks two and three from the motherboard. It wasn't until I removed a chip from bank one that the system failed.

The first bank is critical to system start up. Each bank is 16KB (assuming 16k chips). One thing to note is that all eight of these chips need to be good because the bits of a byte are stored across all eight chips.
 
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Assuming its a REV 7 board you can remove all but the bottom bank. If its older as some II plus sytems go back to rev.. I dunno 4 or 5 you may need to set the jumper block for Ram like on the original Apple II. Yours looks like a rev 7 or RFI board so I doubt thats an issue.
 
'Ello 'ello...

1643738890289.png
Welded a new leg on... same issue.

I switched out the top bank of RAM for the bottom, then the second/middle row for the bottom. Still fails, pattern is different every time I power up.

1643742756963.png1643742835699.png1643742861797.png1643742882582.png1643742910320.png

etc etc
 
OK thanks all. I'll try juggle the RAM about this evening.
Be certain that you use RAM from one of the other two banks. I would recommend using a methodical approach. Perhaps pull the first chip in the second row and work from left to right replacing a single chip at a time. After doing so power on the system to see if the problem is correct. If not then move the chip to the next one over and put the original chip back in the socket. If, after replacing all eight chips, you either the chip you selected from the second row is bad so try again with another chip. Or there is another chip which is bad.

Unfortunately, without knowing the chip(s) you're using as the "test" chip(s) is/are good you could merely be testing with another bad chip. Though it has been my experience that you can find the problem by trying several chips.

I recommend pulling off the top case as it's a lot easier to access the chips. Also, you don't need to have the monitor connected as the system will beep once all the bank one chips are functional. However, you may want to have it connected as it's likely the image will change if you locate a bad chip.

Of course there's always the possibility it's not a bad RAM chip and something else is wrong but my moneys is on a bad RAM chip(s).
 
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Okay - I've switched a bunch of DRAMs out. Yes, I understand they all have to be working in that first bank. Yes, I understand that I have no way of knowing which ones are good so it's a bit of a crapshoot.

  • I've switched the other two banks of RAM in whole.
  • I've picked two other chips and swapped each one into socket 1,2,3,4 etc.
  • Switched out 4 at a time from the other banks.
  • Swapped them about.
  • Done the Hokey Cokey with them.
Each time, no joy, changing garbage on the screen, no beep.

So, either a good many DRAMs are bad, or the problem is elsewhere.

Is eBay the best source for these chips? I don't mind spending some cash on a known working set of 8. Or would I be better buying a RAM tester?
 
Do you have any other systems that you could check the DRAM chips in one at a time?

I assume they are 4116 devices?

I wouldn’t be buying them from ebay put it like that. At least with a RAM tester you have a tool for the future...

Dave
 
I have Acorn BBC/Electron kit but don't think the chips are that small. Assume it has to be like for like?

Other stuff I have is VAX, Amiga etc but i dont think they'll play with these little chips.

oldpcguy suggests these chips are compatible:

D416C
MK4116N
MM5290N
 
I would second getting the 4116 ram tester and the 74 logic tester for Apple diagnosis.

Cheap tools off ebay, and make it easy to know that the chip you have stuck in, is actually working.

I have this ram tester https://www.ebay.co.uk/itm/12472602...yTmStTbo8yrODeFs|clp:2334524|tkp:BFBMyOTn9tZf

And any 74 series logic tester, i have the battery one of these https://www.ebay.co.uk/itm/15470666...q03M6mgtNjNtwg%3D%3D|ampid:PL_CLK|clp:2047675 but there seems to be better ones for less with LCD screens these days
 
Good info Gary, thanks. I'll look into those bits.
I'm often in Manchester - never heard of this museum - will check it out!
 
'Ello 'ello...

View attachment 1238157
Welded a new leg on... same issue.

I switched out the top bank of RAM for the bottom, then the second/middle row for the bottom. Still fails, pattern is different every time I power up.



etc etc
Somehow I missed this post.

I would recommend that you first pull and reinsert every chip in the system. That ROM E0 chip looks really corroded (not to mention the damage). Do the rest of the chips exhibit this type of corrosion?

When you say the pattern is different every time can you clarify if it is different every time you power it on without making any changes (i.e. moving chips around) or if it is different only after moving chips around?
 
OldPCGuy is right. I had an Apple ii plus thst had so much corrosion alot of the sockets and card slots were green. i ended up soaking the board in vinegar then washing in the dishwasher o clean it up.. it worked. prior to that it would lose conne tions all over the board constantly.
 
Okay - I've switched a bunch of DRAMs out. Yes, I understand they all have to be working in that first bank. Yes, I understand that I have no way of knowing which ones are good so it's a bit of a crapshoot.

  • I've switched the other two banks of RAM in whole.
  • I've picked two other chips and swapped each one into socket 1,2,3,4 etc.
  • Switched out 4 at a time from the other banks.
  • Swapped them about.
  • Done the Hokey Cokey with them.
Each time, no joy, changing garbage on the screen, no beep.

So, either a good many DRAMs are bad, or the problem is elsewhere.

Is eBay the best source for these chips? I don't mind spending some cash on a known working set of 8. Or would I be better buying a RAM tester?
It appears as if you've done a very thorough job in swapping chips around. I do find the comment "changing garbage" on the screen interesting. This suggests there is a bad chip as replacing a good chip with a good chip should give you the same screen image.

All that said with the condition of the ROM chip if the rest of the system is the same way it definitely could be another issue.
 
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