Apple II and Atari 400/800, ports and originals.

[Apple II and Atari 400/800, ports and originals.]

As I understand it Br0derbund released their 8bit titles on the Apple first before porting to other platforms.

 

My observation was that their titles always played and felt better on the Apple. Karateka played too slow on the Commodore, perhaps they didn't take full advantage of the VIC IIs features like the smooth scrolling.

[Apple IIe dead PSU]

As for the low resistance ( 4.5 ohms ) between +5v and ground mentioned in my initial post, it turned out to be a non issue at all.

 

The 4.5 ohms was coming from the small keyboard lamp. It's connected directly to 5v and you will measure some resistance there because of it.

 

Just simply remove the keyboard ribbon connector and expansion cards from the PCB first before you trouble shoot the 5v line.

[Apple IIe dead PSU]

You have to drill rivets out. The astecs only had screws, so getting inside of those is easy.

[Apple IIe dead PSU]

After removing the screws, the lid should come off easily. Then remove the 4 leads that go to the mains power switch, then push the switch out so you can slide the PCB out once raised off its posts.

[Apple IIe dead PSU]

I investigated that link earlier for alternatives but had already committed to repairing the original power supply and wanted to keep the system as original as possible. I had already spent about $30 on capacitors and other parts, replacing those was necessary but the actual problem was with the smaller transformer ( PWN control isolator ) which failed due to a short somewhere, perhaps one of capacitors.

 

It's definitely worth considering changing those caps before your power supply suffers the same fate, if you're still using it. My original fuse in the primary was still good because the failure was obviously in the secondary,low voltage output section, so don't rely on the fuse.

[Apple IIe dead PSU]

Addressed a couple of issues with the keyboard.

 

Some keys seem to print multiple times before the key bottoms out, so that made typing difficult and frustrating.Some keys were stubborn and wouldn't respond without some effort.

 

Here's my fix in case it hasn't been covered in much detail.

 

Take the machine apart and remove the keyboard, de-solder all pads to remove the PCB from the back of all keyswitches. It's a lot of work and you need some skill to do this properly but it's well worth it. Clean the opposite side of the PCB free of dust accumulated over the years, there was a lot of dust under the keyswitches in my case. Dust can attract moisture which may cause oxidation and also may conduct, it's your computer's worst enemy.

 

Solder the keyswitches back to the PCB and put the keyboard back together. Get some isopropyl alcohol and pull the keycaps off the troublesome keys, pour drops of alcohol down each side of the keyswitch and work the key up and down, side to side. This cleans the contacts inside of the switch free of dirt and other gunk. Work the key until the problem disappears, some keys take more work than others.

 

You should now have a fully functional keyboard.

 

What an interesting project this has been so far.

 

I hope this helps someone out.

 

 

 

 

 

 

 

 

[How are the different classic computer brands holding up? (Early 80's)]

 

This is the trend. Many people are giving up (have given up) collecting anything and everything in sight. It quickly becomes unmanageable. And it consumes a hella-lotta time.

How true this is. This is the very reason I offloaded all my Amiga stuff. Amiga has a lot of chips which means more that can go wrong.

 

At one point I had an Amiga 3000, 2000 and an A500. I was tired of replacing 8520s which are a common failure.

 

If I were to get back into the Amiga hobby, it would have to be an FPGA based system.

[NOT Atari ST vs Amiga,]

You could go with an FPGA system ( fpga arcade or MIST ) rather than replacing your existing A500 if you had to.

 

8520s are a common failure nowadays & Amiga hardware is becoming more expensive than what its worth.

[NOT Atari ST vs Amiga,]

Oh no, we're not doing this again are we ?

 

Let's do x68000 vs Amiga vs ST

 

That's sounds like more fun.

[How are the different classic computer brands holding up? (Early 80's)]

 

I think Apple IIs use the same RAM but they seem to have better power supplies. But if the power dies, the RAM probably will as well.

Apple II power supplies have a voltage regulator that dies.

 

 

 

I just repaired an Apple iie power supply today and these power supplies seem to be quite advanced, better than what you'll find in micros of the same era which had to be cheap.

 

I'm no expert on the subject but Apple II power supplies ( at least the astec I worked on does ) have shutdown capability built in to them, this circuitry is also known as a crowbar which disables the power supply if there's a surge or over-voltage. It's there to protect any sensitive components downstream like your DRAMs.

[Apple IIe dead PSU]

I think I may have found the culprit.

 

The transformer T3 has a broken winding one one of the coils. It barely looks repairable

even though the break is visible at one of the pins.

 

Anybody know where I can find a suitable replacement ?

 

Edit.

 

Repaired the broken winding on T3

 

Apple iie now powers up, beeps twice and green power light is on.

[Apple IIe dead PSU]

Hi All.

 

I've just received a dead Apple IIe computer recently and I'm looking for some help from someone who has some experience with these power supplies.

 

I have the Astec AA11042C 240v version which is completely dead. Fuse tested fine.

 

So far I've replaced all the electrolytic caps including the two filter caps which can fail spectacularly and spill brown goo everywhere. The electrolytics

on the high voltage and output side were either out of spec or bulging. I also replaced the bridge rectifier which looked cooked but otherwise tested OK with the diode test on my DMM.

 

To be honest I don't know much about switching power supplies but as I understand it the astec needs to be under some load before you can can measure any voltages from the connector which connects to the Apple IIe logic board. I'm measuring around 240v across the AC inputs of the bridge rectifier but I am not sure what to look at next, any ideas ?

 

Unfortunately I can't use the IIe as a load, there is a short between 5v and gnd somewhere on the logic board and I'm pretty sure the the DRAMs are fried. The 12v lines look fine. I'll have to remove those DRAMs and test them later once I track down the short, luckily I have 4 brand new 4464s on hand.

[When and how did you discover DOOM on the PC?]

My friend and I were both avid Amiga users at the time. He purchased a PC ( I think a 486 around 1994 or 1995 ) and introduced me to doom.

 

It was then that I knew that the Amiga was approaching its last days. PCs had already caught up or surpassed it in terms of processor speed, 3D graphics and were more affordable.

 

It wasn't until Quake came out that I bothered upgrading to the PC which I built myself ( A Pentium 100 )

[What is Best text based game]

The Pawn, Guild Of Thieves feature colour graphics but are still classified as text based adventure games.

[How are the different classic computer brands holding up? (Early 80's)]

I didn't keep my original beige c64 breadbin but I acquired another one about a decade ago from the UK. At some point the kernel, character and basic mask roms were replaced with EPROMs. They did a fine job and the wiring is very clean.

 

The original MOS chips are still there.

 

It's in fair working condition but the case is a little brittle, particularly in areas were the two halves of the case snaps into place. So you can have bits coming off if you're not careful.

 

Sometimes the keys don't respond. I'm going to take the keyboard apart and address that. Could be a faulty CIA chip as well.

 

 

 

[School me on old-school monitors]

At least you know now. These unwanted Philips CRTs are hidden gems.

 

I still have my original 1084S that I used on my Amigas. It has served me well over the 20 years.

 

Nowadays I use it for arcade stuff but I try to avoid using it for the time being after having to replace the flyback and 1 capacitor. Once I recap the entire chassis I'll start using it more.

[School me on old-school monitors]

Ok! I got the monitor and it is exactly as I hoped. It has both RGB types in addition to composite.

 

I knew it didn't have s-video, but that's ok - the C64 is the only computer I have (and likely will ever have) that supports that, and I know from experience selling TV's back in the day that composite *can* look better or worse depending on the tube and comb filter, and this monitor seems to have a good comb filter. I didn't see any dot crawl or moire. (My camera did when I tried to take photos of it in action, but I didn't with my naked eye.)

 

As a bonus, it came with a C64 cable, and the monitor does work and looks great. I haven't been able to test RGB/CGA yet because I need to order the cable - I was waiting to make sure the monitor had that before I did so.

 

I think the confusion about this monitor may be because it seems like there are actually two different "Monitor 40's" - I'm pretty sure I've seen a "Color" Monitor 40 in addition to this "RGB" Monitor 40. I didn't really pay that much attention to the names, I just went by the model number of CM8505, which everything else on the internet said had both digital and analog RGB just like the 1084. Kind of a pain that it's a DIN plug but I found at least one site that has those cables for cheap.

 

Anyway, thanks for everyone's help - I wouldn't have even known this monitor existed before starting this thread, and it was a lot more reasonably priced than any 1084 I found. And all I'm missing out on is s-video.

 

Edit: to answer the Q above (or not answer, more accurately), I am not sure how it switches. Under the front door there is one switch that says "CVBS/RGB", which I assume switches between composite and RGB, but there's no obvious switch I can see for the different RGB inputs. So I'm not sure what it does. Maybe it just detects whichever is active?

Really nice score.

 

1084 monitors are priced higher because of the Commodore badging. I think most people don't realise what they really are inside.

 

I recently saw 2 x cm8833s for $50 and nobody wanted them. Meanwhile a 1084S was being bid on.

[School me on old-school monitors]

Some really good info here.

 

http://gona.mactar.hu/Commodore/monitor/Commodore_monitors_by_model_number.html

[School me on old-school monitors]

The 1084S-P1 or P2 are rebranded Philips CM8833-II. These variations ( and there were many ) were actually made by Philips for Commodore.

 

Great monitors but the Philips is slightly better, they kept the better tubes for themselves.

[What do you like about your classic computer?]

The 8 bit era is special, the machines were unique, had their own look and feel and offered something different depending on your budget and preference. Nowadays computers are so generic in every way which is not a bad thing at all, just different.

 

The old computer stores , magazines were a way to connect with the community. It's all changed now with the Internet and some modern innovations,new software that has emerged has definitely revived my interest in using 8 bits again. The SIO solutions for the Atari are wonderful and I'm using my c64 again.

 

The c64 and Apple II series were a big part of my life when growing up. On the hunt for a 2e to make this hobby a little more interesting.

[What do you think of crack intro screens?]

I believe most games on all systems, especially earlier on were programmed in isolation by one or two guys.

 

Those were often rated as the best games because the programmers put their heart and soul into it and were inventing new things/techniques for the first time. I'm not saying great games weren't achieved by larger teams but their was often a different feel to games created by one or two individuals. They had much more freedom to create so I suppose that's what makes these games so unique and interesting.

 

Fast forward 30 years later and I'm still playing Dropzone ( on an Atari these days ), Uridium, Paradroid, Mercenary Escape From Targ, Attack Of The Mutant Camels.. Etc. All created by one or two people and still fun to play today.

[Abandoned arcades, decaying arcade machines (Make Arcades GREAT Again)]

Makes me wonder if there are still any PCBs in any of those cabs.

[New to Atari 8-bit. Can anyone recommend me the must have games]

I've been spending a lot of time playing Hardball ( baseball simulation ) lately, not sure if it's been mentioned but it's a great game on the A8.

[Playing arcade boards on their own?]

The AV7000 is a great little unit, it's what I use for home. It handles RGB and composite and has an adjustable +5 line.

[What do you think of crack intro screens?]

The cracking scene was essential for pushing the system beyond its known limitations.

 

I don't know how relevant that was in the Apple's case but a lot of new techniques were discovered on the c64 & game developers would often get in contact with cracking groups and their coders to get some info. It made games better and helped push the boundaries.