Apple II

Apple II Power Supply rapid clicking

Hi All,

I'm stumped with this power supply.  Hopefully someone can help me out.

 

Symptoms

When I power it on underload, it makes a 6khz buzzing sound.  It sounds similar to the noise made when you plug in a working power supply without a load, but the click is 10x~20x faster.  Here is the waveform that is generated when plugged in under load:

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Putting a PT-65B switchmode power module into an Apple IIe

You might ask why I did not attempt to repair the original power supply (only the usual culprit, the "Rifa" capacitor had exploded / cracked open). The reason, other than the 220V issue which limits the Apple IIe to my lab, where I have a step-up transformer, is that all the electrolytic capacitors in the original power supply are 40 years old, and beyond their safe life span. Which means they all need to be replaced to have a reliable power supply which would not cause more trouble down the road. And unlike some people believe, it is neither trivial nor cheap to replace the electrolytics in a switchmode power supply. They need to be chosen carefully to be suitable for this application, and "normal" electrolytics designed for filter purposes after an AC rectifier just won't do. These are specified for 120 Hz operation only, while the typical switchmode power supply works at more than 100 x that frequency. For electrolytics in switchmode power supplies, ESR at high frequencies (up to 100 kHz or more) and ripple current ratings at higher frequencies are critical, otherwise, they might just overheat and explode. So be warned, don't attempt to replace electrolytic capacitors in switchmode power supplies unless you are competent in this field of engineering. Now, the bad news is that suitable electrolytics are special types which are so expensive that replacing all of them would cost more than a brand new PT-65B. Besides the mechanical issue that none of the modern replacements have the same footprint anymore. Even electrolytics did shrink in size in the past 40 years. This mechanical complication is worse than you might think - the issue is how to bend the leads properly without damaging the seal of the rubber plug. It can be done, but then the next issue is how to prevent them from wobbling around, they need to be glued together somehow. Same reason why "Mean Well" puts white silicon goop in their power supplies to secure larger components, like electrolytics, in place. All this conspires against replacing these old electrolytics in the old power supply PCB. IMHO, it's simply not worth the time, money, and effort.

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Upload to asimov didn't go through!

Hi!  I recently tried to e-mail the administrator at asimov.com my Smir 3, 1 text adventure and followed the instructions given and got a reply that the e-mail didn't go through after seveeral attempts.  :(  It must've worked before, as my MadLibApple program is there.  I tried to follow the instructions in the asm file there to the best of my abilities.  What could I be doing wrong?

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For Apple IIGS Fans - Zoom meeting with ALBERT CHARPENTIER - You're Invited !

If you really enjoy the amazing audio capabilities of the Apple IIGS, this might be for you.  Albert Charpentier is a co-founder of Ensoniq, which produced the wonderful sound chip inside the Apple IIGS that made the computer an audio powerhouse.

 

Please join TPUG (Toronto PET Users Group) for an interactive Zoom meeting with Mr. Charpentier on Thursday, October 19, 2023 at 7:30 PM ET.

 

Zoom details:  https://www.tpug.ca

 

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Appleslave - Arduino+SD To Gameport Backup Creator

                                                  

 

 

                                 

 What is AppleSlave? AppleSlave is an Arduino program (written by Dave Schmenk) to be able to read from an SD card directly 

 from your Apple II and write files to the Apple II disk drive! I wanted to make a quick updated guide on this project since

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Neo6502 board emulating an Apple II

https://blog.adafruit.com/2023/10/02/the-olimex-neo6502-now-can-emulate-an-apple-ii-and-oric-atmos/

 

The Neo6502 board above may be an interesting way to make kind of new build Apple II or one that could access Apple II accesories. Anyone looked into it yet?

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Have any of you tried a Gotek out on your Apple II yet?

So to my surprise there was some advancement in Apple II floppy emulation via HXC within the past few years. I havent messed around with modding a gotek since 2018.

 

I went by the instructions here and built up a cable: https://hxc2001.com/docs/gotek-floppy-emulator-hxc-firmware/pages/apple.html

 

I flashed my gotek with HXC firmware and added the Apple fimware file via the usb flash drive and gave it a try. You need to use the HXC software to convert disk images to the RAW .HFE format then copy them to a USB stick.

 

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Smir 3, 1/Apple: advertising?

Hi!  I'm pleased that people like my Smir 3, 1 text adventure even though people have reported bugs in it.  :)  Now, I'm looking for more places to post and advertise the game.  Where can I do that?

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Apple2idiot card (ESP32)

While googling I ran across this.  Apparently it was introduced at KansasFest 2022 but since that always seems to be at a time I can't go, I missed it.

 

It is an interesting and different take on interfacing an ESP32 module to an Apple II.  It uses a dual ported SRAM instead of trying to interface the ESP32 to the Apple II bus using something like 74LVC245s or through a parallel chip like a 6522 or 82C55 or through a serial chip like a 6551 or 6850.

https://github.com/equant/apple2idiot

 

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Micol Desktop Construction Set

Does anyone have any idea how to actually use Micol's Desktop Construction Set. While there is 'documentation' (attached), it is not at all clear what to do. It 'looks' like it is 'easy' to use, but I need instructions written for a 10 year old. Programmers/Developers should absolutely NEVER be allowed to write user documentation. They almost always make assumptions about the skill level of a user and while this 'documentation' contains lots of information, it is not written is a way that facilitates a first time user to create anything.

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