Need help with Atari 400, weird problem

[orsoguey]

Hi all,  I recently bought an Atari 400 that , I thought , had a problem with the membrane keyboard (a row of keys not responding).  After some tests (including changing the multiplexers) I realized that one of the keys that are directly bound (SELECT key) to the GTIA , was stuck , "pressed" permanently.

 

I bought a brand new chip and, indeed, the problem with the select key has gone, but now if you do not insert a cartridge it does not show the memo pad, so if you turn it on without a cartridge inserted you get a blue screen , no beeps , nothing.  However cartridges are loaded and run properly.

 

My original chip had this reference C014889-03 and the new one (which is new old stock) is C014889-01, does anyone has any idea what to look at?

 

 

Thanks in advance

 

[andymanone]

2 hours ago, orsoguey said:

but now if you do not insert a cartridge it does not show the memo pad, so if you turn it on without a cartridge inserted you get a blue screen , no beeps , nothing.  However cartridges are loaded and run properly.

 

My original chip had this reference C014889-03 and the new one (which is new old stock) is C014889-01, does anyone has any idea what to look at?

@Memopad: 

 

Ahh sorry, I didn´t saw " it does not show the memo pad" sorry

Thats a normal behavior ?.

My fault  ?..

 

The GTIA, you´ve swapped, is a standard PAL-GTIA, there is nothing to afraid.

 

Have you ever tried to boot up with the BASIC-cartridge?

 

Gtx.,

andY

Edited January 19, 2020 by andymanone
Typo

[+DrVenkman]

2 hours ago, orsoguey said:

bought a brand new chip and, indeed, the problem with the select key has gone, but now if you do not insert a cartridge it does not show the memo pad, so if you turn it on without a cartridge inserted you get a blue screen , no beeps , nothing.

Get some canned air and blow out the cart slot for any small bits of debris that might be shorting some of the pins when no cart is inserted, and then spray contact cleaner into the slow as well just to be thorough. Allow things to dry and then see if powering on the machine without a cart allows it to boot to Memo Pad properly again.

[orsoguey]

14 hours ago, andymanone said:

@Memopad: 

 

Ahh sorry, I didn´t saw " it does not show the memo pad" sorry

Thats a normal behavior ?.

My fault  ?..

 

The GTIA, you´ve swapped, is a standard PAL-GTIA, there is nothing to afraid.

 

Have you ever tried to boot up with the BASIC-cartridge?

 

Gtx.,

andY

Many thanks for the replay , no, I do not have the BASIC cartridge, only CHESS, and it loads and works properly, I can tell if keyboard works as I think it only works with joystick

 

Also , I put back the original GTIA chip and now  do not get the MEMO PAD neither with the original chip. Something has happened to the ROM board, I think. 

 

 I remember the vertical board next to board where the GTIA is,  received a very small impact while inserted in vertical (the mobile phone fall and hit the edge of the PCB while taking pictures), but I do not think it can be the issue was small impact. 

 

 

 

 

 

 

Edited January 20, 2020 by orsoguey

[andymanone]

1 hour ago, orsoguey said:

Many thanks for the replay , no, I do not have the BASIC cartridge, only CHESS, and it loads and works properly, I can tell if keyboard works as I think it only works with joystick

 

Also , I put back the original GTIA chip and now  do not get the MEMO PAD neither with the original chip. Something has happened to the ROM board, I think. 

 

 I remember the vertical board next to board where the GTIA is,  received a very small impact while inserted in vertical (the mobile phone fall and hit the edge of the PCB while taking pictures), but I do not think it can be the issue was small impact. 

Hmm, I guess, you mean the RAM-Card ??

 

(The ROM´s of the 400 are located on the Mainboard - except the ATARI 800, it has it´s own ROM-Card.)

So it could be a RAM issue maybe? After Power on, can you determinate one (or more) RAM chips, getting very warm/hot?

 

On the other side, have you tried out DrVenkman´s suggestions?
I think, he might be right ...?

 

Gtx.,

andY

 

[Rybags]

No memopad with stock OS seems a strange one to me.

 

It might be a Ram fault or even the OS itself.

Re key problems - the header that takes the keyboard ribbon can rust, you could move the ribbon up/down a bit to get better contact.

[orsoguey]

Thanks to all for your efforts,  I want to emphasize the fact that everything was working properly (except the always pressed SELECT key, which only happens with the original GTIA) before the change of the GTIA, but now with both GTIAs there is no MEMO PAD .

 

Also I tried what DrVenkman suggested, everything is very clear,  even checked with the tester checking continuity , the cartridge slot is ok.

 

I just get a narrower (compared with the one when I boot with the Chess game)  blue screen with just a cursor when I boot without the cartridge. See attached pics:

 

 

[Sugarland]

I had an 800 with this exact issue. Carts worked, otherwise blue screen.  I realized this stage of the lockup is where the SIO is polled for devices (SIO fart sound). That is handled by POKEY. Replaced pokey and machine worked first try.

 

See here at 31:46

 

 

 

[orsoguey]

18 hours ago, Sugarland said:

I had an 800 with this exact issue. Carts worked, otherwise blue screen.  I realized this stage of the lockup is where the SIO is polled for devices (SIO fart sound). That is handled by POKEY. Replaced pokey and machine worked first try.

 

See here at 31:46

 

 

 

Thanks, that is exactly my case, as you said.  I will buy a OKEY chip (at this rate I will end buying the full computer by parts XD )

 

Is it possible that changing the GTIA chip that had the stuck SELECT key problem for a new one caused this problem? Because it worked perfectly (except the SELECT key issue) before the swap.  The lines between POKEY and GTIA are only data right? I go not think an overvoltage could damage the POKEY now.  Or may be just a coincidence?  

 

 

[+DrVenkman]

Both are susceptible to static discharge. It’s possible you damaged POKEY accidentally while working on the machine. 

[Sugarland]

2 hours ago, orsoguey said:

Thanks, that is exactly my case, as you said.  I will buy a OKEY chip (at this rate I will end buying the full computer by parts XD )

 

Is it possible that changing the GTIA chip that had the stuck SELECT key problem for a new one caused this problem? Because it worked perfectly (except the SELECT key issue) before the swap.  The lines between POKEY and GTIA are only data right? I go not think an overvoltage could damage the POKEY now.  Or may be just a coincidence?  

 

 

 

You're welcome. To be clear, there was no game sound when playing carts. Do you have sound?  Yes, GTIA handles the function keys.   As DrVenkman said, please use an anti static setup when working on your machine. Remember, he's a scientist. His ESP shock research...

 

[orsoguey]

On 1/22/2020 at 6:47 PM, Sugarland said:

 

You're welcome. To be clear, there was no game sound when playing carts. Do you have sound?  Yes, GTIA handles the function keys.   As DrVenkman said, please use an anti static setup when working on your machine. Remember, he's a scientist. His ESP shock research...

 

 

 Errrr this very embarrassing...  I want to apologize to all of you if I made loose your time. And thanks to all for the replies.

 

 Sugarland, you hit the nail, POKEY was the issue but not damaged just.... err....  I removed for resitting all chips and put it upside down !  XD

 

 I realized while measuring Vcc to the chip, it seems that after removing it, something happened, I got distracted and by mistake I inserted it that way.  I can't understand how it happened because i am very careful with those things, I even take pictures before removing just in case the socket is wrongly assembled from factory.

 

 I turned it and runs perfect now, well, sometimes after being on a long time screen turns into red, maybe a component not working properly when it warms.

 

 Also have to get a membrane keyboard, as it is crossing keys in rows 16 and 17 , with keyboard removed (crossing the pins of the connector directly) all keys work , so if you are selling one please, let me know.

 

 

[andymanone]

23 minutes ago, orsoguey said:

Also have to get a membrane keyboard, as it is crossing keys in rows 16 and 17 , with keyboard removed (crossing the pins of the connector directly) all keys work , so if you are selling one please, let me know.

A couple of weeks ago I´ve replaced one of my 400´s with a B-Key, so the membrane Key was left over...

But an other user was very interested in, so I sold it...

But I am currently looking again for a B-KEY for another 400'er.

If I succeed, then a membrane key could be available again....

 

Gtx.,

andY

Edited January 27, 2020 by andymanone

[orsoguey]

1 hour ago, andymanone said:

A couple of weeks ago I´ve replaced one of my 400´s with a B-Key, so the membrane Key was left over...

But an other user was very interested in, so I sold it...

But I am currently looking again for a B-KEY for another 400'er.

If I succeed, then a membrane key could be available again....

 

Gtx.,

andY

 Perfect let me know if you finally get it

[Rybags]

The screen width as experienced is what is expected.

 

The Chess screen has a green background which gives the impression of "bigger" but it isn't.  The blue E: with cursor has the black border which has interference so easily distinguished from the areas that the TV would clip in the 4:3 display process.

Edited January 27, 2020 by Rybags