[Replacement drive belt for SF354?]

Ah that's great info guys. Thanks very much to all of you.

[Replacement drive belt for SF354?]

I would just get a PC drive and put it in there that way you have a double-sided drive. You'll have to trim the case a bit. But well worth it!

Oh ok that's great info. May I ask what type of drive you recommend? Just a standard every day PC floppy drive?

[Replacement drive belt for SF354?]

Hi all.

 

I recently acquired a great condition 520ST setup. It came with a SF354 external floppy drive. The previous owner said there was a problem with the drive, so I opened it up to take a look. The drive responds to a disk when its inserted and tries to spin up, but there is no belt connecting the motor to the disc drive mechanism flywheel. I am guessing that the belt fell off and somebody removed it from the case.

 

What's the chances of getting a replacement belt for this drive? I've searched on the net but it doesn't look too promising. Alternatively, is there another drive that I can put inside the case of this drive, if I cannot get a replacement belt?

 

The drive is a Chinon F-353AT RevA

 

Thanks guys.

[800xl Red Screen. I want to fix!]

@ SwipeCA

 

Well done the journey is a bit like the Avatar i use ( A Long and Windy Road ).

I noticed that in the second picture the red wine must have been used to congratulate yourself on a well completed project.

 

Do you really want an other one ???

 

Happy new year (2015).

 

Well done

 

Ray W

Do I really want another one???? Might have been the wine talking. lol.

[800xl Red Screen. I want to fix!]

Well thanks for all your help everyone.

 

I am running with the original SALLY, ANTIC and GTIA chips, go figure!? But, replaced overheating Ram, Capacitors, MMU and socketed everything (Ram removed and replaced twice lol).

 

It's all good!

 

.... Now I need a new broken Atari.......

 

Have a fantastic 2015 everyone!!!!!!

 

Damian.

 

[800xl Red Screen. I want to fix!]

Shame on Atari for ever producing socketless boards. And no, I don't want to hear about how they needed to save money. I say shame on them.

Yeah! But at least it's good practice swapping them out. Now I have a nice board fully socketed, that makes me sleep better at night.....

[800xl Red Screen. I want to fix!]

Just waiting on my new MMU arriving, then I will post an update.

 

In the mean time.....

 

Merry Christmas everybody, and may you have a safe, prosperous and Happy New Year.

 

Thanks for all your help!

 

Damian.

[800xl Red Screen. I want to fix!]

Looks like check ram and then mmu for the failure to init symptoms in this scenario. Red screen of death be gone!

I forgot!!! I also changed the RAM chips as a couple of them were almost too hot to touch in the beginning.

 

But yes, its looking good! Will keep you posted on the chip swaps guys.

[800xl Red Screen. I want to fix!]

Hey Everyone.

 

Sorry for the delay, I was away AGAIN with work. If we didn't need the money eh????

 

Anyway, it looks like we've cracked it! I got around to socketing the entire board - good practice with the solder sucker and the iron.

 

I started removing all the chips one by one and putting them into my good 800XL. It turns out that the only chip that 'kills' my good XL is the U3 C061618-16 8434FMM MMU.

 

I put my good C061618-16 into the bad XL and it displays the normal blue screen and READY prompt!!

 

Now, so far I have replaced with new, the U17, U7, and U8 chips. I don't know if this machine is now working because of a combination of the new chips and the good MMU U3 chip from my other machine or not. What I will do is swap back in the old suspect SALLY, ANTIC and GTIA chips one by one and see if it has any effect.

 

I now need to get my hands on a newC061618-16 8434FMM MMU chip. Where would be the best place to get one of those?

 

I have attached two images. The chip 'in socket' is the good one that works in both XL's. The chip placed on the board is the defective one. They have slightly different markings - same C061618 number though. Will I have to find the exact same 'Good' chip?

 

Question, can I use an Epprom burner to 'make' a new MMU? How does all that work?

 

I will keep you posted on the U17,U7,U8 swapping.

 

Thanks again guys. Looks like we brought another XL back from the trash can.

 

Damian.

[800xl Red Screen. I want to fix!]

Pin 11 of U18 should look just like Pin 12. There could be a short in the pin 12 net or U18 could be bad.

 

Bob

Thanks Bob. Just got back from business trip. Will look into it and post findings.

 

 

Ok. Yes Pin 11 on U18 is GREEN LOW LED Pulsing Beep Flashing Orange LED and Pin 12 is RED/GREEN LED Lit Pulsing Beep Flashing Orange LED. Different.

 

I will now begin the process of socketing the remaining chips. I will then check one by one using my working XL.

 

Thanks for your help. Will let you know.

[800xl Red Screen. I want to fix!]

Oh... GTIA 30 and ANTIC 29 are in the same net, so they should be the same. This net is the Phase 02 clock and should be a 50% signal. The signal is from U18, fed from CPU 39, which is OK.

 

Care to guess? U18 is bad? What is on pins 12 and 13 of U18? Pin 12 should be the 02 clock from CPU 39 and 13 should be tied up to +5v through a 3K resistor (R19).

 

Bob

U18 PIN 12 RED/GREEN LED Lit Pulsing Beep Flashing Orange LED - same as CPU 39.

U18 PIN 13 RED LED HIGH

[800xl Red Screen. I want to fix!]

OK - thanks.

 

What is GTIA (U17) pin 30?

 

Bob

U17 PIN 30 is GREEN LOW Pulsing beep Flashing Orange LED

 

Many thanks Bob.

[800xl Red Screen. I want to fix!]

What do pins 39 and 40 show on the CPU (U8)?

 

What is on pin 29 of ANTIC (U7)?

 

Use the TTL setting.

 

Bob

CPU 39 is both RED/GREEN LED Lit plus pulsing beep and flashing Orange LED

CPU 40 is RED HIGH

ANTIC 29 is GREEN LOW

[800xl Red Screen. I want to fix!]

Ok, here's an update for my situation, to recap:

 

- I had a dead 130XE with shows no life of sign and a red solid screen,

- Removed all RAM chips (mt4264) from the main bank and installed sockets and new RAM known to be good - NO CHANGE, still dead with red screen,

- Removed most major ICs (CPU, Antic, PIA, Pokey and ROM) installed sockets and new ICs known to be good - NO CHANGE, still dead with red screen,

- Noticed that some of the extended bank RAM chips (the 3 chips at the top of the extended RAM column) were getting extremely hot, but at first I thought they shouldn't matter and the computer should have normally booted with all new RAM chips in the main bank. Well turns out this may not always be the case. Just out of curiosity i removed the first 3 RAM chips that are getting very hot and the computer started to boot into BASIC... yay!!, but

there still seems to be some problem, sometimes when I tap on the remaining RAM chips I would see random junk/noise appearing on the screen, so I will now remove the rest of the extended bank RAMs and see where I am going from there.

 

Now, I don't know how this may help you with your problem on the 800XL but I just wanted to tell my current situation.

I now have sockets for all the chips. I am going to start the process of socketing the remaining chips on my board. Should make things a little easier on this 800XL.

[800xl Red Screen. I want to fix!]

As far as i know you need to use the TTL setting

Yes, I am using that now thanks.

 

Pretty sure you've got a CPU clock if you're getting a sync'ed screen.

 

If you're looking for something to replace next, I've seen the 74LS158's (RAM section) go bad. This is really a job for an oscilloscope at this point.

 

I have just checked all the ram chips. According to SAMS and according to my good XL all the RAM chips U9 to U16 are HI on pin3 when they should be P. Chips U9 and U10 Pin6 should be P but are 0 dead. All the chips on my good XL are as per SAMS Schematic.

 

Chip U2 looks problematic from a probing standpoint Pin4 should be P its 0 Dead. And Pins 10-15 should be P but are all HI no pulse.

 

lol @ "If you're looking for something to replace next". All fun and games.

[800xl Red Screen. I want to fix!]

Do you have a clock on pin 37 of the CPU (U8)? It should toggle 50% on your logic probe.

 

Bob

Ok. First time I have used a logic probe. I attached it to a motherboard ground and to the middle line at the power switch which showed a value of 5.4v. When I probe pin 37 it lights Low and has a pulsing beeper and flashing yellow LED. A Narrow High Pulse?

 

Ah, should I be testing using TTL or CMOS? Under TTL both high/low LED'S illuminate with the same flashing orange and pulsing beeper. I assume that both high/low indicates 50% toggle?

 

I have the SAMS schematic. I have checked all the pins on U8 All are correct EXCEPT for pin #6 should be P but is H No Pulse, pin#7 should be P but is L No Pulse and Pin# 36 should be P is H no pulse.

 

Sorry I am pretty new to this sort of thing, eager to learn the basics at least. I know that I could rapidly be venturing out of my depth.

[800xl Red Screen. I want to fix!]

Is that something translucent over the part# of the Mexican 6502C CPU(CO14608 - U8)? There is something by pin 32 that might be that or possibly cracking/discoloration.

 

Ah. What that is is a little dab of red ink from a permanent marker. I dotted all the chips from the suspect XL just in case I got them mixed up with the new ones, or the chips from the good XL. Well spotted though!

[800xl Red Screen. I want to fix!]

Peter Gabriel did Sledgehammer... not that it's quite to that point.

Ha. Now you got me thinkin'. The line comes from 'Don't give up' from Peter Gabriel's 'So' album. Just found it on my shelf - had to blow the dust off!

 

But yeah, it's not the point of this discussion. lol. But I understand that a sledgehammer may be looming on this motherboards horizon. Nah, only joking.

[800xl Red Screen. I want to fix!]

No. A missing BASIC ROM won't keep you from booting. A (really) bad ROM might, but it would have to be in the circuit.

 

Is there any noise (pops, SIO activity) when you power on?

 

Bob

Hi Bob. There is no noise, pops of any kind when I power it on.

 

you can take the BASIC ROM out. It should boot to self test.

 

I took the BASIC ROM out and still the same red screen.

 

 

 

I adjusted the color pot to go from the blue back to the red screen.

 

I have socketed all the chips marked with blue tape. I retested the XL after each socket installation as I went - no change from red screen. In the image the BASIC ROM is removed but that was also socketed and fitted for testing.

 

I swapped all the chips marked with the blue tape one by one into my socketed spare 800xl. Every one of those chips when placed into the good XL had no ill effect on the good XL. It booted to the 'Ready' prompt every time.

 

When I swapped the chips from the good XL into the bad one they had no effect on it. It still produced a red screen. EXCEPT the two chips in the centre of the mobo ( marked with the red 'x' ) when either or both were swapped from the good XL into the bad one, upon power up the screen just went black. When I swapped those two chips from the bad XL into the good one it still booted to the 'Ready' prompt - Hope that makes sense.

 

So, even with my very limited knowledge of this topic it appears that the socketed chips are functional?? And that something else is going on. If it's supposed to boot to self test without the BASIC ROM then clearly, as it's not, that's an indication of further issues I am guessing.

 

I have a logic probe and good multimeter. I can download the schematics? Is it time to start checking voltages etc? I am running the power supply that boots my good XL. Dumb question - does the keyboard have to be connected for an XL to boot? I just thought that all I have done so far, regarding test reboots, has been done without it attached.

 

 

As Peter Gabriel once wrote, "Don't give up, you still have friends"........ or was it Kate Bush... .

[800xl Red Screen. I want to fix!]

Hi Guys,

 

Ok, so I received the GTIA, ANTIC and CPU chips that I ordered.

 

I haven't had a lot of time to play yet, but after swapping the CPU no change still just red screen. After swapping ANTIC no change still just red screen. But, after swapping GTIA the screen is now a even blue. But, no 'Ready' prompt.

 

Here's a picture. I think that this particular symptom can indicate missing BASIC ROM?? I have to go out now, but I plan to socket that chip also, and I will risk swapping over this suspect BASIC ROM with that in my other working 800XL. Sound like a plan?

[800xl Red Screen. I want to fix!]

I am in the same exact boat as you are with a 130XE, dead with a red/brownish solid screen and a lot of very hot RAM chips (actually burns your finger if you keep it there long enough). I've been trying to fix that mobo for the last couple of weeks, on and off. I have all the major ICs and the main bank of RAM socketed and tried with working chips, no cigar! so far.... Next I will try to trace a fault to the OS, don't know how exactly as I don't have an oscilloscope, just a logic probe at my disposal. When I've seen your thread I was immediately interested as we live through the same experiences. I hope one of us can finally get their machine back to life and help the other to possibly figure out how to fix his. Good luck.....

 

It's nice to know there is at least two of us in the same boat lol. The help I have got so far from the guys here has been invaluable. I will keep plugging away 'till I either hit a brick wall or get it running again. I will do my best to document the proceedings so it can act as at least a path for others to follow - at least as a pointer to a possible fix. My RAM was as hot as you describe, since replacing they at least appear to be running at normal temps. As you can see I still have a few IC's to socket yet, will be completing that over the next few days. Hopefully we will get to a point where we make some headway. But I am sure there are many things that could be wrong, and not necessarily the same thing with both systems. Definitely keep in contact, lets see who succeeds or gives up first lol.

[800xl Red Screen. I want to fix!]

Not the most elegant. But it should do the job.

[800xl Red Screen. I want to fix!]

Me too. If there's enough of the leg left, it can be done where you can barely tell. If the leg breaks off at the encapsulation, you have to try to get a thin wire soldered to the little bit of exposed metal, then tack it to the PCB or to a stiff wire in the socket.

 

 

I've done that - I desoldered an Antic from an XEGS and made a meal of it. 11 legs broke off, got some donors off another chip and soldered them back on. Worked fine, not that I'd recommend it.

 

 

Yeah guys, this is what I will be tackling next....

[800xl Red Screen. I want to fix!]

Be careful when you try to plug in a chip that has been de-soldered from a board. There will be solder left on the pins, maybe a lot of solder. You don't want the old solder to contaminate the new socket or deform the connector.

 

Bob

 

 

Definitely true, but from the picture they look pretty clean. I often drag some braid down the pins to get the last of it off.

Yeah thanks that's good advice. I took my time desoldering the three chips. I used a solder sucker to remove all the solder from the pins on the underside of the board - very time consuming but in the end the chips basically fell away from the board. Cleaned up any stray solder left behind on the board surface with some solder braid and made sure that the pins were aligned before pushing them into the sockets. They went in easy and have a good firm fit. I checked for continuity from the chip pins, through the socket and into the board. They all check out perfect. So, just waiting for the replacement chips to arrive and what adventure that will bring.

 

Incidentally, anyone ever replaced a chip pin/leg? Cut one from a dead chip and soldered onto the 'stump' of a good chips missing leg? I wonder if that is possible.

[800xl Red Screen. I want to fix!]

 

The chips themselves are pretty cheap and with minimum order sizes and shipping costs, why not? It's good to have spares.

Yeah that's the way I see it.