Dead 130XE - Any advice?

[TroyQ]

Greetings,

 

Just got back into A8 after a long hiatus. Got a 130XE a few weeks ago. Had some bad trace on the keyboard mylar, but I fixed that. Otherwise was working fine.

 

Turned it on and got a solid brown/red screen, no booting "clicks". Sometimes the screen is solid dark green.

 

I've reseated and swapped with a known good CPU - mainly because that is the only chip socketed on this board (rev 5). It has 15 pieces of micron memory and 1 nec (based on what I've read in other posts, this was a likely factory fix?).

 

i have a multimeter but not any logic probes, so I'm resigned to swapping components blindly until I get it fixed or no longer fund the endeavor (or break the board is also a possibility I suppose).

 

Is this a logical order to tackle this? :

- memory

- mmu / emmu

- freddy

- gtia

- antic

 

I'm scouring the existing AtariAge posts for help, but would appreciate any advice. I saw a reference to swapping the banks by changing to resistors (R110 & R111 ?). Any specific components I can measure with a multimeter that will point me in a direction?

 

What is a good current source for the RAM? There are a lot of dead ebay links in the forums.

 

Thanks!

Edited November 22, 2017 by TroyQ

[hunter44102]

The first thing to do is start from the power source. Make sure your power supply is producing a good 5V.

[Guest]

i'd say this is a good order

 

>>Leave system running and check if any chips get hot (twenty mins) should be long enough REPLACE ANYTHING HOT. Nothing getting hot?
>>Look at swapping in/out Basic Rom with known good part.
>>If no change, then next try; CPU, MMU, OS Rom and finally Ram chips
>>a red screen means that GTIA is (at least) working at a very fundamental level) - but can still be faulty. Replace.
>>Is your display steady or does it flip/roll? If steady, then again Antic is managing to issue VSYNC commands - but may still be faulty. Replace.

[Level42]

i'd say this is a good order

 

>>Leave system running and check if any chips get hot (twenty mins) should be long enough REPLACE ANYTHING HOT. Nothing getting hot?

>>Look at swapping in/out Basic Rom with known good part.

>>If no change, then next try; CPU, MMU, OS Rom and finally Ram chips

>>a red screen means that GTIA is (at least) working at a very fundamental level) - but can still be faulty. Replace.

>>Is your display steady or does it flip/roll? If steady, then again Antic is managing to issue VSYNC commands - but may still be faulty. Replace.

 

 

I don't agree.

 

Leaving a dead system running can make things worse.

 

My step by step:

1) Check power supply voltage to be +5V

2) Are there mT RAM's => Feel for hot ones. Replace. Even better, replace them all.

 

This will fix the VAST majority of XE's.

If not:

3) FREDDIE

4) MMU

 

5)GTIA

6)Anything else.

 

And once again, my list of possible replacement RAMs. Search on the numbers followed by the word "RAM" on ebay/google etc.

 

4164 RAM equivalents:

HM4864(A) (Hitachi)

µPD4164 (NEC)

M5K4164 (Mitsubishi)

MK4564 (Mostek)

MSM3764 (OKI)

MN4164 (Matsushita)

KM4164B-15 (Samsung)

HYB4164 (Siemens)

LH2164 (Sharp)

TMM4164(A) (Toshiba)

TMS4164 (Texas Instruments)

MB8264(A) (Fujitsu)

MT4264 (Micron) (DO NOT BUY)

MHB4164 (TESLA)

KR565RU5 (Russian)

[TroyQ]

Additional info:

 

Checked voltage = 5.16v. P/S runs fine on 800XL.

No chips are hot. The CPU gets a little warmer than cold. Touching all 16 ram chips and none of them had a discernible temperature difference. I only had it on like this for 3-4 mins max. Wait longer?

 

Video is stable. Just a single color, always darkish (dark green, dark brown/red). there are vertical stripes but those were there when everything was working. I'm using chroma/luma into a svideo->vga box. This setup (PS, A/V path, A/V Cable) was working fine before & still works great on an 800XL.

 

I've seen a number of posts that indicate "130xe with micron memory = replace it all, its crap". Also, seemed like the most likely component to decide to work and then crap out; possible after having not been used for years (before I got the system).

 

Since everything was working fine (and the power supply does not look like its a culprit), I'm thinking that this probably a single component failure... probably.

Edited November 22, 2017 by TroyQ

[TroyQ]

 

I don't agree.

 

Leaving a dead system running can make things worse.

 

My step by step:

1) Check power supply voltage to be +5V

2) Are there mT RAM's => Feel for hot ones. Replace. Even better, replace them all.

 

This will fix the VAST majority of XE's.

If not:

3) FREDDIE

4) MMU

 

5)GTIA

6)Anything else.

 

And once again, my list of possible replacement RAMs. Search on the numbers followed by the word "RAM" on ebay/google etc.

 

4164 RAM equivalents:

HM4864(A) (Hitachi)

µPD4164 (NEC)

M5K4164 (Mitsubishi)

MK4564 (Mostek)

MSM3764 (OKI)

MN4164 (Matsushita)

KM4164B-15 (Samsung)

HYB4164 (Siemens)

LH2164 (Sharp)

TMM4164(A) (Toshiba)

TMS4164 (Texas Instruments)

MB8264(A) (Fujitsu)

MT4264 (Micron) (DO NOT BUY)

MHB4164 (TESLA)

KR565RU5 (Russian)

 

Thanks Level42!

 

Yes, 15 of the 16 are Mt chips. I got your list from another thread already open and have been doing the ebay searches. LIke everything on ebay, its been a mixed bag of results...

 

I suppose this is part of my penance for having gotten rid of all my original A8 stuff back in the 90s... lol

[Level42]

It could be anything between 1 single RAM chip or all of them. I've seen both and between....

 

If you're confident with soldering, I'd replace all of them. They're probably going to die all of them sooner or later...

 

The "hot detection" method could be useful if none of the other chips get hot instantly.

 

In that case leave it running for a while...this is a nice trick from Flashjazcat in this video, spraying some alcohol to detect which ones get hot......fingers aren't too reliable/quick in finding which ones get hot(ter) soon....

 

Edited November 22, 2017 by Level42

[Level42]

 

Thanks Level42!

 

Yes, 15 of the 16 are Mt chips. I got your list from another thread already open and have been doing the ebay searches. LIke everything on ebay, its been a mixed bag of results...

 

I suppose this is part of my penance for having gotten rid of all my original A8 stuff back in the 90s... lol

 

There's also sources outside of eBay.....

 

Oh and welcome back, it's never too late to return

 

If you're in Europe I could do the job for you...

Edited November 22, 2017 by Level42

[1050]

Additional info:

 

Checked voltage = 5.16v. P/S runs fine on 800XL.

No chips are hot. The CPU gets a little warmer than cold. Touching all 16 ram chips and none of them had a discernible temperature difference. I only had it on like this for 3-4 mins max. Wait longer?

No need to wait longer, if it's shorted ram they will

show up rather quickly. It could be just plain dead

ram where one can piggyback good working ram chips

on top of the current ram line up and 'fix' the

machine or at least temporarily have it working

fine as a go/nogo test for the memory aspect.

 

I've seen a number of posts that indicate "130xe with micron memory = replace it all, its crap". Also, seemed like the most likely component to decide to work and then crap out; possible after having not been used for years (before I got the system).

Replace it all would be the advice of some but not

me. I just change the bad ones. I also don't use

synthetic oil in my car thinking I'll ever recover

the cost over and above plain ol good stuff in

there.

 

I object to the consensus that MT ram is bad,

my experience shows no issues what so ever.

BUT I don't recall many cases where the ram has

up and quit working entirely here. Your symptoms

seem to suggest this is the case because simply

ram always is at least warm or hot to the touch

and you state this is not so with this case.

 

It may well be that when MT ram experiences a

brief over voltage event that it's internal gold

wires that connect the die to the legs act as a

fuse and blow apart rendering the ram non-functional

entirely. If all of them were blown and I had four

machines of these to do I might also call them junk

and they certainly would be if the following plays out.

Because in blowing instead of shorting the power

supply down to safe levels of voltage the MT

rams (if this is the actual case) would not be the

ram I would ever use to replace with. I WANT a

safety device that shorts to ground in order to

protect the rest of the machine.

 

 

I also do not concur with the consensus of the

'factory fix' of one NEC ram chip. They were ALL

tested prior to being inserted and wave soldered

all at once. How stupid would it have been to install

bad ram at the factory? Didn't happen, so it's

just an unexplainable side effect of some aspect

of the assembly line we can only guess at now.

Certainly not worth pages written about it.

Similar to starting another thread about Steve

not answering email in a timely manner over at

ATARIMAX.

 

Piggybacking good ram onto the current line up

would be my next step.

 

It would be quite interesting to note how many

good ram are actually needed to revive this one

if in fact this is the issue. If the NEC chip

still works while only some of the MT work that

would move me in the direction of never use MT

for replacement ram.

 

They may indeed be the source of opened ram and

none of us really want that because it's not

protecting the rest of the machine.

[Level42]

That.................was probably one of the most confusing and incorrect posts I have ever read on this forum.

 

I have no time to go into the separate parts of incorrect stuff in there now, but I will a bit later.

[Guest]

 

I don't agree.

 

Leaving a dead system running can make things worse.

 

My step by step:

1) Check power supply voltage to be +5V

2) Are there mT RAM's => Feel for hot ones. Replace. Even better, replace them all.

 

This will fix the VAST majority of XE's.

If not:

3) FREDDIE

4) MMU

 

5)GTIA

6)Anything else.

 

And once again, my list of possible replacement RAMs. Search on the numbers followed by the word "RAM" on ebay/google etc.

i'd disagree with you on this. a Red Screen is not a dead system. therefore, powering it up for the hot detection is a good starting point.

you may have misunderstood what i was saying. by saying "twenty mins is long enough" - i'm saying DON'T leave it powered up any longer.

ie - if chips aren't hot in that time - then it's NOT a hot chip problem.

i also disagree with you regarding the ram - if they're not hot, why change them at this stage? that's a job for later - once you've got a functioning machine. again this is why hot test first - change anything hot, and then the components in the order i suggest is the most efficient.

once you have a working machine (of sorts) then any ram failure(s) will surely take you to self-test screen?

my checklist works fine and failures are easy to identify this way - if done in that order.

seems little point trying to offer any help on this site, when someone shouts you down.

Edited November 23, 2017 by Guest

[flashjazzcat]

Level42 is right to focus on power and DRAMs first, and to be fair he only suggests replacing all the MT DRAMs as the "ideal" solution. Personally, I'd only replace two faulty DRAMs if that's all it takes to get the machine working, unless the customer wants to pay eight times as much to get all sixteen replaced.

 

I was helpfully informed that certain factors (IC location, the fact FREDDIE is CMOS) make some chips more likely to be dead following a power spike or visit from 9V AC. FREDDIE and MMU are therefore the next ports of call after the RAM, although OS ROMs are sometimes dead too.

 

It usually takes no more than 5-10 minutes for bad RAM to get hot to the touch or warm enough to burn off alcohol. Be aware that DRAMs can sometimes get hot and appear shorted because of FREDDIE itself being dead. I believe that was the case with one of Martin's 65XEN machines.

[+DrVenkman]

Here's my tuppence, for what it's worth:

 

You have a system that boots to a red screen; I have some experience dealing with symptoms like this. That indicates to me that the system is TRYING to boot. ANTIC is generating a display and feeding it to GTIA but the system OS isn't loading. That could be a problem with the CPU or even PIA, but just as likely to be an OS ROM or BASIC issue. I didn't see it in the topic replies yet - if I missed it, apologies. Did you try booting with OPTION pressed to see if the system boots to the self-test screen?

 

 

[flashjazzcat]

The red screen is certainly an indication that the OS locked up before it got a chance to initialise the graphics hardware. I would expect the system to hang on a blue GR.0 screen if BASIC was bad. But yes: it could be a bad OS ROM or PIA. The key is to eliminate the most likely stuff first, and the red screen is very frequently caused by bad DRAMs or the kind of damage typically caused by power spikes or C64 PSUs (dead FREDDIE, MMU, etc).

[TroyQ]

Thanks everyone for your advice and input! Even with differing opinions, its good to get different points of view - it is all appreciated! Even though I've spent most of my life maintaining servers & workstations, I guess I've gotten a little spoiled by just replacing defective boards and not worrying about which component on the boards had failed.

 

@Level42: Thanks for the offer but I'm in the US. My work has a large-ish site in the Netherlands, so maybe someday I'll get sent there...

 

Tried a few things based on above suggestions:

 

- Holding OPTION during power on did not change anything - still dark colored screen

 

- Left system on for about 20 mins and checked for heat. Some chips were warm (in descending temp order):

- CPU, uncomfortably hot after touching for about 20 seconds

- Antic, warm, not as hot as CPU

- GTIA, warm, not as warm as Antic

- OS ROM, slightly warm

 

all other chips (PIA, Pokey, Basic ROM, Freddie, RAM, MMU) were cold/room temp.

 

Sniffed all around the board and no odd burn smells. No bulging or leaking caps. No home modifications, stock board with what looks like a couple of factory reworks (pink & purple wires I've seen in pix on other 130s).

 

The only PS I've used is the Atari one that I have for my 800XL. Definitely no C64 9VAC.

 

I've ordered RAM and sockets, so will wait for those to arrive and see what I find. I am hopeful this is the problem. Wish my 800xl had socketed mem chips I could borrow to quickly test. While waiting, I am pondering doing the bank swap just to see what happens ( Worth it? Maybe interesting side note, all the pix I've seen (and my board also) that has a single non Mt RAM chip is always in that first position (towards the rear, left edge).

 

I have done due diligence and watched pretty much every YouTube from Flashcatjazz, GadgetUK164 & JaysVintageJunk (probably forgetting a few) and reading all the old posts here that might be related.

 

 

Completely unrelated: If anyone has run across an 800XL with Rambo and 4 momentary round push buttons (2 red, 2 black - standard radio shack) wired to do the 1200XL function keys - let me know. That's my childhood A8 that I stupidly let go of in the 90s.... Along with an MIO, USD 1050, Happy 1050 & screaming 2400bps modem.

Edited November 23, 2017 by TroyQ

[1050]

I'll suggest a dead Freddie then based on your diligent

efforts at temperature measurements, ram always run a

bit warm when it's working so I'm assuming here it's

not getting /RAS or /CAS signals at all. But I don't

know that symptom is valid for lack of dead Freddie

experience.

 

Any chance you can lay hands on a scope to look for

such signals? 120$ with probes.

https://www.picotech.com/oscilloscope/2000/picoscope-2000-overview

[Level42]

TroyQ:

 

The temperatures you describe about fit the regular profile. The fact that you cant hold your finger on the CPU longer than 20 seconds is not per sé an indication of it being bad. As you probably know from your work chips run a lot hotter than the temperatures of human skin so its natural to feel some heat and the temps as you describe are like I experience them with a fine working system.

 

I recognise the board swapping issue, my education was in electronics but in my work too I used to simply replace entire units, there was no time (=money) for doing component repair, in fact in many jobs we werent even allowed to mod anything on a PCB because it would fall out of certain safety certifications.

 

Wonder what company you work for, you can PM me if you dont want to name it here.

 

About bank swapping: you could try, but I dont think it will work, not even if all the mTs on the right bank are OK. As you noticed, the upper left RAM not an mT and this IS for a reason, despite what 1050 claims. In have experimented a lot with swapping RAMs and never got the 130XE board I was working on running with a GOOD mT RAM in the lop left position. I dont think we fully understand why this is but it is. It is also NOT just a random thing, else there would be more different brands on different positions, but after seeing lots of 130XE in person and on lots of pictures on the net it is clear twat it is always only the top left position where they put a different brand (which was probably a more expensive RAM). Actually wouldnt be surprised that mT KNEW about the issue and made a deal with Atari to dump their inferior RAMs at Atari for a very interesting price.......but at LEAST Atari knew about the issue and solved it this way.

 

Now...suppose your right bank is completely fine and you swapped it, then youd still have an mT on the top position an the machine likely will not work. However, if you feel like it, by all means try it, it cannot harm anything and you could even leave the banks switched for good after the repair. But I would be curious about your findings, if they confirm what I found or maybe the opposite.

 

Could you post a picture of all the RAMs now in your machine ? Id like to see if we can find some kind of structure in what mT RAMs are bad. It might well be just one certain run or between certain date cases that the problem existed, because my main 130XE had mT RAM too and works just fine.

 

Once the RAMs arrive, I would try the piggy back method, first one chip at a time, starting at the top left position (even thought the NEC is likely still OK).

 

The reason we mention C64 supplies is that you got this XE used and dont know what happened to it in the past. Many stupid people have hooked up a C64 PSU to try power up an A8 because it fits and killed them instantly.

 

Im pretty sure that that was what has happened to my spare 130XE board since it had ALL 16 RAMs dead. Even the NEC which seemed still OK first turned out to be faulty.

 

You dont need an oscilloscope to fix 90% of A8 defects because just like most electronics devices, they developed their typical issues which happen most of the time. I have a nice brand new digital scope but never use it for these typical issue.

 

IIRC JFC mentioned he doesnt have an oscilloscope, yet he fixed many A8s. Im not saying all, because he also has some boards as unrepairable but Im pretty sure those are exceptions.

Edited November 24, 2017 by Level42

[flashjazzcat]

IIRC JFC mentioned he doesnt have an oscilloscope, yet he fixed many A8s. Im not saying all, because he also has some boards as unrepairable but Im pretty sure those are exceptions.

Yep: I gave up on two boards (IIRC) but eventually repaired one of the no-hopers after returning to it later on. That's out of about a dozen repairs of dead machines in 2017.

[+DrVenkman]

I agree with Level42 and flashjazzcat - no, you don't need a 'scope to fix an A8 machine. Nearly everything - everything! - that commonly goes wrong with them can be diagnosed and fixed by careful, methodical chip/component swapping. If you add in use of a multimeter to check voltages and measure continuity, you can fix just about anything. If you're willing to spend $20 on a logic probe and watch a few YouTube videos on how to use one, you can use it to narrow down where to start swapping components and sometimes it reveals problems that appear at first like bad chips - for instance, if you realize POKEY isn't working properly, a logic probe can instead show you that you have an issue with a broken trace or a perhaps a bad socket wipe, not the chip itself.

[1050]

I offered a link to a 120 dollar scope - peanuts

compared to most other new scopes. Picoscope in case you

didn't know has some fabulous free software to run

without purchase of hardware, just in case you want to

try that part out first - just for grins. You don't get

any different software no matter if you've purchased or

not. That same free software covers the entire line if

I understand it correctly, it's only demo mode when you

don't have the scope attached.

I've seen them at work on You Tube and they are highly

desirable in the automotive repair field but at a much

higher price point due to more channels and features.

This one is entry level only. I will be getting this one

myself as soon as some cows are sold. I would also get

DrVenkman's 20 dollar logic probe if he would just

promote it with a model number more often, I keep

forgetting to order that one.

 

Level42 doesn't seem to understand that my posts in this

and other threads on the general topic are my thoughts

aloud and even evolving such that he and I could very

well be running around beating the same bush but just

in different directions.

 

For example - IF open, dead ram = MT ram in large

percentage then we can assume they have very fine gold

wires connecting the die to the legs and these are prone

to opening up upon exposure to over voltage. Atari would

know this much by actually testing for this function.

 

And they may indeed have placed the more sturdily built

and more costly single NEC ram chip in slot #1 so it

could be easily spotted to be a corrected system for

this very issue where MT ram opens up and they needed

at least one robust ram chip to short out and sink an Atari

power supply's current to lower the voltage in order to

protect the rest of the more expensive chips.

 

This would cut down on customer repair expense while

allowing dealers to fix the non working machine in

house rather than bother with a return and replacement

of the entire machine without Atari's involvement for

the most part.

 

And that leaves me wondering if they learned to do this

from the 800XL assembly line where this NEC ram pattern

doesn't exist? I do remember having difficulties keeping

track of the types and speeds in the 800XL line up,

not a problem if it's always the top chip that is of

interest.

 

Hey - I've gone 180 here and it's all because Level42

talked me into it. Right?

 

I'll withdraw this thought the moment I find that NEC is

no more robust than any other ram and/or MT isn't

prone to opening up in over voltage failure mode with

Atari power supplies providing the current. Since this

isn't on my to do list, I'll not be the one to actually

prove the above most likely - I just don't care enough

to start with and I had other plans for my work bench

along with a decided lack of handy chips for this kind

of sacrifice.

 

Commodore power supplies are quite likely to provide more than

enough current to open the one NEC ram too and then take

out the rest of the machine. It does appear that this

might be a possible cause for this particular case.

 

Won't be an update, won't be an admission of any sort

either if the MT = weak sauce equation fails. Will never

retract the observation that nobody I know

of actually replaces working ram. MT or otherwise.

I can not then stand by quiet and let 'replace all MT'

go unchallenged as if it's the only approved, universal

mantra. It reminds me too much of overreaction knee

jerk solution to a problem that isn't really THE problem

that gets economically fixed. My MT ram woks perfectly fine

here. BUT - I won't be using it for replacement ram

anytime soon if ever again and if I ever did in the past,

I'm now sorry I did that. I also don't expect that Level42

will adhere to my 'MT is OK' suggestion or that he'll even

slow down in the slightest on yanking it all out and

throwing it away. I'm good with that too.

 

Level42 has the proper passion for Atari, no doubt about

that. But we all do and that's why we are here in this

very healthy forum.

[+DrVenkman]

I would also get

DrVenkman's 20 dollar logic probe if he would just

promote it with a model number more often, I keep

forgetting to order that one.

 

This is the one I have - it was a godsend tracking down the socket issues with my Ugly Duckling 1200XL restoration project:

 

Elenco Electronics LP-560 Logic Probe

 

When you point this at an address or data pin and you get a solid tone or none at all, something ain't right! Ditto for the clock signals. Makes it very easy to figure out where to start troubleshooting, if somewhat tedious for 40-pin IC's. On the other hand, it sure as hell beats screaming in frustration after the first couple obvious chip-swapping tries have failed.

[Level42]

1050:

 

Maybe you should learn to READ.

 

1) I have stated MANY times on a few threads about 130XE and RAM issues that my 130XE has mT RAM and it is still working fine and I have no desire whatsoever to fiddle with it....as long as it works.

 

2) I have also stated several times that by my experimenting with RAMs all over the sockets on the 2nd 130XE board I have that an 130XE,WILL NOT OPERATE WITH A mT RAM IN THE TOP LEFT POSITION, no matter if that same RAM chip will work on any other position. There is something about timing or maybe voltage levels, I dont know what it is but a GOOD mT RAM on the top left position will render a non working 130XE.

 

3) mT RAMs do not only die because of over voltage, they just die (of age) on systems that have never been exposed to over voltages. Who says its the wires ? It can just as well be defects on the chip itself. Whatever they did, they screwed up in the factory.

There have been many different brands of RAM on Atari machines, and ONLY mTs are known to die often.

 

4) I have bought mT RAMs in the past during my arcade collecting years. I was unaware of their issues then. I stored them in an ESD safe box. Only recently, when repairing my 2nd 130xe board, I tried them. They were dead. All of them. They had done nothing for 25 years or so and they were dead. IMHO this is an induction that probably some gas or other substance got inside during production that corroded or otherwise deteriate these chips.

 

So....to sum it up, mT RAMs have TWO issues : 1) they had timing issues that Atari KNEW about. 2) they did not last very long, which I guess Atari never knew because they stopped existing in 1992 and the problem only became clear much later than that.

 

Issue 1) is very likely true for ALL mT 4164s.

Issue 2) simply happens often but NOT always, as our working machines prove.

 

There...I hope that was clear

 

 

I dont care about fine gold wires or whatever might be inside them. What are you telling us, you like mT RAM because they act like fuses ? (Which they dont....Bering up,RAMs are a sign of something shorting instead of opening up)

 

I just dont get it. I am posting tips here for someone who asked for some practical advice to solve his issue and from my experiences and knowledge I gave him some answers that I am convinced of are the most likely causes for his issue.

 

Now, the decision to replace ALL mT on a board is for the owner. Myself, I would just replace only the dead ones. Because the others could last for maybe the rest of my life.

But some people dont like having to open up the system each time a RAM dies, and replacing the single dead one. Some want to be sure it will run fine all,the time from now on and will choose to replace them all.

 

Its exacly the same as people who do cap-kits on arcade monitors. They replace all of them, while probably only a few are really bad. But they dont want to go over the entire monitor again and again for the coming decade. Myself, I only replaced the bad ones, but for caps I have a very reliable tester. Theres no such tester for RAMs but even so, Id leave in the good ones...sadly.....with my second 130XE board, ALL RAMS were dead.....I desoldered each and every one of them and tested them one by one in a 800XL. They were ALL gone, even the NEC although that one tried to play hide and seek as it first seemed to be OK.

 

The internal XL self test has its limitations. It really depends on where the bad RAM is positioned if it will show up or not. Sometimes a bad RAM on the second bank of the XE will take down the entire system, sometimes it will just pass the entire test (and I mean the XL version of this test which doesnt test the second bank).

Putting a bad RAM on position 7 or 8 of bank 1 usually makes it pass the test, which is weird....but it does...

 

Something else:

 

Do you seriously expect that Atari tested the XEs in over voltage situation ? It was the Tramiels running the show then....their only goal was to get the machine to run just long enough to make it past the warranty period.

Edited November 25, 2017 by Level42

[Guest]

Now, the decision to replace ALL mT on a board is for the owner. Myself, I would just replace only the dead ones.

 

My step by step:

1) Check power supply voltage to be +5V

2) Are there mT RAM's => Feel for hot ones. Replace. Even better, replace them all.

 

seriously?

don't want to fall out with you - but if you are going to give advice, at least be consistent.

 

you can't tell people to "replace them all" and three days later say "i would just replace the dead ones"

people will point to your advice - and will you then say

"do as i say" - "and not as i do" ?

 

that kind of advice consfuses

Edited November 25, 2017 by Guest

[haightc]

I am not an expert on atari systems like most of the guys here, but I'll though out some suggestions. Put a small amount of alcohol is a good way to see if some RAM chips might have shorts. RAM modules can fails in ways that don't produce heat, this is the most common critical failure phenotype. I would recommend you give the board with cleaning as well and inspect all the solider joints. I have brought a few electronics back to like with nothing more than a cleaning and quick spray of DeOxit. The one thing I wonder about replacing only bad DRAM is how it does effect system time. From what I understand the Atari is not nearly as sensitive to timings as some other platforms. Don't some of the 4164 versions have time and response varieties?

[Level42]

 

 

seriously?

don't want to fall out with you - but if you are going to give advice, at least be consistent.

 

you can't tell people to "replace them all" and three days later say "i would just replace the dead ones"

people will point to your advice - and will you then say

"do as i say" - "and not as i do" ?

 

that kind of advice consfuses

 

Damn....I hope I don't get sued.....

 

I clearly explained WHY _I_ would do something else than others MAY do at their own decision....but you forgot to quote that part of the posting....

 

Oh, and I'm not paid to do this stuf.....