got a apco with a power supply thats doing nothing
open it up find some burnt areas around resistors on the board
as far as i can tell this is 59k ohms with my meter i see .57k ohms remove it from the board get same reading and the bands have all fallen off
green white orang brown gold is what i see
wondering if anyones got this same psu can check that resistor?
also i did test that fuse and its still good
located in northern canada
also the way u do image posting realy realy threw me for a loop never seen done this way befor on a forum
Look up the Mean Well PT-65B thread on here. That's an inexpensive and fairly easy way to get your clone running again with a brand new power supply board. I can do one for under $30 all in including shipping. I've done Apple, AE and Franklin supplies that way so far. Your ASCO would be an easy one too.
when i search for Mean Well PT-65B i just find a thread talking about going from 110 to 220V and nothing els
https://www.applefritter.com/content/apple-iigs-psu-110v-220v
had that meanwell suggested already once but they start talking about it needing to be modified?¿
also came across site that sells a drop in guts replacement kit sept they take some payment system im unable to access as it requires a cell phone number to get txt msgs witch i dont have living in northern canada nearest tower is a 4hr drive
A resistor usually can't go lower in resistance if it overheats, especially not by orders of magnitude. The normal syndrome is for a carbon resistor to drift upwards in value by 20% or sometimes more. It's more likely that you misread the brown stripe as orange.
Understanding why this resistor overheated will point to another component (or several others). To do this you will need the schematic, which considering the board being single-sided and the photos being as clear as they are, could be drawn up in an hour or so. Then based on SMPS theory, the failure mode can be guessed and tested.
As an uninformed guess, this resistor is on the primary side close to the main transformer, so it may be part of the startup circuit or the energy-recovery circuit.
Perhaps this will help:
Putting a PT-65B switchmode power module into an Apple IIe | Applefritter
Or you can try this:
PicoPSU Adaptor for Apple II, II Plus, IIe from dekuNukem on Tindie
cu
Georg
pico looks interesting sept have the wrong jack on it for plug into the mobo
that thread u linked more helpfull then anythijg i found
did stumble on this as well
https://www.reactivemicro.com/product/universal-psu-kit/
The reactivemicro PSU looks pretty good, but it is not a cheap solution when you take a look at the shipping costs. There are couple of interesting parts on thie site but I do not want to spend about 50€ for shipping.
cu
Georg
Absolutely! For Europe a much better option is the Mean Well RPT 60B, which you can get from AliExpess for only 20€ ($22 USD) and free shipping: https://www.aliexpress.com/item/1005007920070225.html
More on how to install it here: 12V Power supply conversion using a Mean Well RPT 60B