Started 600XL 64K upgrade, now getting only a black screen

[+x=usr(1536)]

41464s arrived today.  Started in on the 64K upgrade by inserting two of them into the RAM sockets.  Before doing this, the machine powered on, booted to BASIC or Self-Test, and generally behaved like a 16K 600XL should.  At this point, no other changes had been made.  I decided to test the RAM by turning on the machine and got only a black screen.

 

Replaced the 41464s with the original 16K RAM.  Black screen.

 

Plugged the 1064 from the other 600XL into the PBI slot.  Black screen.

 

Checked all ICs; no seating issues.  No damage evident from removal or insertion of the RAM, which was always aligned and oriented properly.

 

Nothing is getting hot even after leaving the machine on for 30 minutes.  There's also no keypress audio or other indicators of it working blind.  Can't get into Self-Test (as far as I can tell).

 

Any ideas?  I'll break out the meter tomorrow night and see if I disturbed something, but would appreciate any pointers in the interim.

[Rybags]

So, no mods performed at all?   Just inserted the new RAM?

 

Doesn't sound right.  You should be able to insert the new RAM just fine.  I did that, all that happens is the top r/c bits aren't yet connected so it will act as a 16K system.

Are you sure you didn't put them in the wrong way around or anything?  If it's so far unmodded and not working with the original 16K back then something is definitely wrong.

[mutterminder]

The mod isn't that difficult,  it is documented elsewhere in this forum.  However,  you do have to lift a resistor, and a few IC leads as well as running a few jumper wires. If you haven't done all that yet it's not going to work as expected.   I would suggest restoring you original RAM to make sure your machine is okay before proceeding. 

[Mazzspeed]

The big question is: Are the 41464's really what they claim to be, or are they counterfeit and possibly something entirely different?

 

May I ask, where did you get the DRAM's from?

[+DrVenkman]

6 hours ago, mutterminder said:

The mod isn't that difficult,  it is documented elsewhere in this forum.  However,  you do have to lift a resistor, and a few IC leads as well as running a few jumper wires. If you haven't done all that yet it's not going to work as expected.   I would suggest restoring you original RAM to make sure your machine is okay before proceeding. 

There are several different ways to do the mod. Not all of them require lifting a resistor. 

[mutterminder]

That's true.  I've done it different ways myself. But all of them involve cutting or lifting circuit legs and soldering wires.  (Unless you use one of the plug in circuit boards I've seen.)

Edited April 15, 2021 by mutterminder
To elaborate.

[mutterminder]

Note that the 64K SRAM module offered by Lotharek still requires some soldering.

[Sinjinhawke]

Unless I am not reading it correctly he is saying he has not started the upgrade.  All he did was take out the old memory then put in the new memory then try to validate it still works but gets a black screen.  He then put the original memory back into the 600xl and still getting the black screen.  So the process of just swapping memory chips has triggered something.

[+DrVenkman]

23 minutes ago, Sinjinhawke said:

Unless I am not reading it correctly he is saying he has not started the upgrade.  All he did was take out the old memory then put in the new memory then try to validate it still works but gets a black screen.  He then put the original memory back into the 600xl and still getting the black screen.  So the process of just swapping memory chips has triggered something.

Exactly. 

 

So, I’d look for a damaged RAM socket wipe or a cold solder joint on one of them. 

[+x=usr(1536)]

9 hours ago, Rybags said:

So, no mods performed at all?   Just inserted the new RAM?

Correct.

Quote

Doesn't sound right.  You should be able to insert the new RAM just fine.  I did that, all that happens is the top r/c bits aren't yet connected so it will act as a 16K system.

Yep, which is what I was expecting to have happen.

Quote

Are you sure you didn't put them in the wrong way around or anything?  If it's so far unmodded and not working with the original 16K back then something is definitely wrong.

Nope, orientation and insertion were both correct.  Not sure what I may have otherwise disturbed, though.  Nothing that I'm aware of, but all that really means is that I just haven't found it yet

8 hours ago, mutterminder said:

I would suggest restoring you original RAM to make sure your machine is okay before proceeding. 

To clarify: the original RAM has been restored; that was the first step taken after getting the black screen with the new RAM.  The black screen persisted after that was done.  This suggests that something else changed.

2 hours ago, Mazzspeed said:

The big question is: Are the 41464's really what they claim to be, or are they counterfeit and possibly something entirely different?

That's a good question, but I have no solid reason to doubt their authenticity.  More:

Quote

May I ask, where did you get the DRAM's from?

They came from a US-based retailer of arcade game parts (name withheld) from whom I have purchased parts in the past; they are not an eBay store or similar.  Their reputation and my experience with them is excellent.  While it is possible that I may have received bad RAM from them, I have no reason to believe that these are counterfeit ICs.

35 minutes ago, Sinjinhawke said:

Unless I am not reading it correctly he is saying he has not started the upgrade.  All he did was take out the old memory then put in the new memory then try to validate it still works but gets a black screen.  He then put the original memory back into the 600xl and still getting the black screen.  So the process of just swapping memory chips has triggered something.

This is a 100% accurate summary of the situation.

11 minutes ago, DrVenkman said:

So, I’d look for a damaged RAM socket wipe or a cold solder joint on one of them.

I'll make that tonight's mission, then   The one thing that's confusing me, though, is that I still get the black screen with the 1064 plugged in.  That should bypass the on-board RAM and permit the machine to boot, IIRC.  Don't know how that might be affected if there's physical damage, though.

Edited April 15, 2021 by x=usr(1536)

[gilsaluki]

25 minutes ago, x=usr(1536) said:

 

Maybe you zapped the original RAM chips, ESD.  While I have been lucky and never ACTUALLY zapped any chips with static electricity, it is possible.  If you have some more memory chips, try those.  But, properly ground yourself first. 

[+x=usr(1536)]

Just now, gilsaluki said:

Maybe you zapped the original RAM chips, ESD.  While I have been lucky and never ACTUALLY zapped any chips with static electricity, it is possible.  If you have some more memory chips, try those.  But, properly ground yourself first. 

Agreed that it's a possibility.  It shouldn't have happened (working in the kitchen - glazed tile floor, melamine countertops, grabbed the sink tap before starting work in order to discharge static, etc.) but that doesn't mean that it didn't.

 

I'll see what other RAM I might have laying around.  It also occurred to me that removing all on-board RAM and connecting the 1064 (which is known-working) wasn't tried, so I'll add that to the troubleshooting list as well.

[Rybags]

Yeah, 1064 supposedly overrides all resident Ram so should work.

 

Also the RAM 320XL (plugs into PBI) has the option to do the same if you can get hold of one.

[bfollowell]

3 hours ago, gilsaluki said:

Maybe you zapped the original RAM chips, ESD.  While I have been lucky and never ACTUALLY zapped any chips with static electricity, it is possible.  If you have some more memory chips, try those.  But, properly ground yourself first. 

 

I'll agree that it's possible, but I don't believe it's very likely. I've worked on all sorts of retro, even when they weren't retro, and modern, even though they too are now retro systems, all the way up to my newest I7 gaming rig. This has been a major hobby of mine for 35+ years. In all that time, I've never used a static strap, and I've never once zapped any chips or boards. While I know it's a possibility, and shouldn't be ruled out, I just don't think it's all that common an issue.

 

Edited April 15, 2021 by bfollowell

[ivop]

13 hours ago, Rybags said:

If it's so far unmodded and not working with the original 16K back then something is definitely wrong.

Yes, that implies the machine was damaged with the new RAM chips plugged in. If, let's say the RAM was damaged in the first place, which ICs could it take with it? Same for when it was aligned wrong by mistake?

 

Even you think you do it right, sometimes it is not. I remember demonstrating the MIDIMuse interface with an S2 module in Herten, Germany (ABBUC meeting). Showing the S2 separately to somebody, then plugged it back in. Just before I fired up my Atari, a spectator said I misaligned the connector. Pfew

Edited April 15, 2021 by ivop

[manterola]

I agree. Even though it is possible, my bet is in the sockets. I have had problems with XL sockets a couple of times. You can try to "twist" the RAM chips a bit and see if they work. If not, check with magnifying glass whether one or many wipes of the empty socket looks weird or misaligned. You can then crosscheck the weird wipes with the chip inserted in the socket and with a multitested check electrical continuity b/w the shoulder of the Ram chip and the some corresponding point in the motherboard. The explanation to the mystery should be there, since I think it is unlikely that the old and the new RAM chips are all bad.

 

 

 

[ivop]

3 hours ago, x=usr(1536) said:

It also occurred to me that removing all on-board RAM and connecting the 1064 (which is known-working) wasn't tried, so I'll add that to the troubleshooting list as well.

If this doesn't work, the new RAM chips have probably damaged one or more of the chips on your motherboard ?

[+kheller2]

3 hours ago, Rybags said:

Yeah, 1064 supposedly overrides all resident Ram so should work.

 

Also the RAM 320XL (plugs into PBI) has the option to do the same if you can get hold of one.

 

Actually, no, according to previous discussions:  

 

 

[gilsaluki]

53 minutes ago, bfollowell said:

 

I'll agree that it's possible, but I don't believe it's very likely. I've worked on all sorts of retro, even when they weren't retro, and modern, even though they too are now retro systems, all the way up to my newest I7 gaming rig. This has been a major hobby of mine for 35+ years. In all that time, I've never used a static strap, and I've never once zapped any chips or boards. While I know it's a possibility, and shouldn't be ruled out, I just don't think it's all that common an issue.

 

Kinda what I said.

[+x=usr(1536)]

3 hours ago, ivop said:

Yes, that implies the machine was damaged with the new RAM chips plugged in. If, let's say the RAM was damaged in the first place, which ICs could it take with it? Same for when it was aligned wrong by mistake?

I'm not sure what you're referring to when you mention the ICs being misaligned.  That never happened in this case, either with the new or old RAM.  Believe me, I learned that lesson the very hard way in the past.  Everything is triple-checked before moving on to the next item or firing up the machine.

 

Won't go so for as to say it's impossible for it to happen - but I absolutely do not believe that it did in this case.

3 hours ago, manterola said:

I agree. Even though it is possible, my bet is in the sockets. I have had problems with XL sockets a couple of times. You can try to "twist" the RAM chips a bit and see if they work. If not, check with magnifying glass whether one or many wipes of the empty socket looks weird or misaligned. You can then crosscheck the weird wipes with the chip inserted in the socket and with a multitested check electrical continuity b/w the shoulder of the Ram chip and the some corresponding point in the motherboard. The explanation to the mystery should be there, since I think it is unlikely that the old and the new RAM chips are all bad.

Yep, that's all part of the plan at this point.  FWIW, I'm leaning less towards bad RAM (it's odd that both sets would be bad, particularly when one was pulled in working condition), so physical damage such as corrosion, a cold solder join, etc. is what I'm leaning towards.  Having said that, I haven't ruled out a RAM issue, so we'll see.

3 hours ago, ivop said:

If this doesn't work, the new RAM chips have probably damaged one or more of the chips on your motherboard ?

Maybe, but I really think that's a distant possibility at this point.

3 hours ago, kheller2 said:

Actually, no, according to previous discussions:

Interesting, and thanks for digging that up.  I'm curious as to how a SysCheck would compare to a 1064 in that situation with regard to the on-board RAM.

[ivop]

12 minutes ago, x=usr(1536) said:

I'm curious as to how a SysCheck would compare to a 1064 in that situation with regard to the on-board RAM.

With the jumpers in the right position, a SysCheck2 definitely replaces the on-board RAM, and even ROM if you want to.

[flashjazzcat]

Perhaps post a photo of the mod. Another observer may notice something you missed.

[Rybags]

I've not heard of Ram chips that have gone bad taking out other components.

In fact there's the common test method of piggybacking good Ram onto dead Ram.

Possibly it's just memory select logic that's gone out?

 

Really, I don't see why anyone would fake 64k x 4 ICs - they generally sell for not very much and are really common so the effort to fake them would cost more than the return.

[+x=usr(1536)]

As it turns out, the machine will not boot with any of the 41464s that were ordered, or the original RAM.  This is the best I can do for the moment in terms of RAM availability; although there are other A8s around here that I could conceivably scrounge from, I'm not keen on that idea until I've had a chance to pull the PCB and look for signs of damage.  First port of call will be the solder points on the RAM sockets.

[+DrVenkman]

34 minutes ago, x=usr(1536) said:

although there are other A8s around here that I could conceivably scrounge from,

The 600XL is the only A8 that uses that particular flavor of DRAMs, I think.