Jump to content
ortencia

SE/30 - blown ADP ports

Recommended Posts

Mobo = Motherboard (otherwise known as the main logic board). The ADB Fuse is located on the motherboard...I'm unaware of the exact location, or how easy it is to replace - we have a few people on here who know the SE/30 extremely well, they might be able to help you out :)

Share this post


Link to post
Share on other sites

thanks. i found the site again; it tells of a IIfx in a similiar situation. different motherboards obviously. shouldn't i be able to find this out with a copy of the schematics of the SE/30 ? anyone have access to that ?

Share this post


Link to post
Share on other sites

Ortencia,

 

You'll need to open up the case and remove the "mobo", aka Logic Board in Apple Computer terms. This is the circuit board on the very bottom of the SE/30. Once the logic board is removed, hold the board top side up. Look in the top right-hand corner of the logic board. You'll see a silver colored part near the numbers 12 and 13. That part is labeled "F1". That should be the fuse for the ADB ports. You can get replacements from http://www.mouser.com or http://www.digikey.com .

 

I'm not sure if they are "fast-acting" or "slow-blow", but the type you want to look for is "surface mount" (SMT) and has a rating of .500 mA (milliamps). I think the voltage going through the ADB ports is around 5 Vdc (Volts DC).

 

I hope this helps.

 

73s de Phreakout.

 

PS: If you need pics, I'll provide them to you via email, as I have an SE/30 logic board to reference from.

Share this post


Link to post
Share on other sites

phreakout -

 

thanks for your reply. based on the article i mentioned earlier (re: mac II in same situation) i was thinking it could be F1 or F2. I have located these on the logic board. F1 it is....

 

i have two of these SE/30 machines, as you do. the one with blown ADP ports also has no sound, which doesn't bother me much, but i know it's a sign of bad capacitors. i have emailed trag@io.com to place an order for these. i've decided to get two sets, and just do both boards at the same time. maybe this will take of things for a good while ;)

 

still not totally sure about doing the soldering myself. the current cylindric capacitors are seated in a little piece of black plastic. when removing the old capacitors, does the black plastic part come off as well? if you have any pics of that process, that's what i'd like to see.

 

thanks a bunch,

ortencia

Share this post


Link to post
Share on other sites
..."still not totally sure about doing the soldering myself. the current cylindric capacitors are seated in a little piece of black plastic. when removing the old capacitors, does the black plastic part come off as well? if you have any pics of that process, that's what i'd like to see."

 

thanks a bunch,

ortencia

 

The black plastic is part of the component. They are called "SMT Chip Capacitors". The one way to quickly remove the base from the canister in a destructive way would be to overheat the part so that it bursts and spews out the dielectric while you are extracting it from the board, as I have done in the past. Don't worry, though, it's unavoidable. By the way, if you don't have the proper desoldering tool tip for removal of these caps, I'd go the other route and use two pencil soldering irons of 15 Watt rating to remove the caps. It really does work.

 

73s de Phreakout. :rambo:

Share this post


Link to post
Share on other sites

The IIfx has a 1A fuse between the SWIM chip and the RFI filter, the SE and SE30 do not.

 

There is a 470 Ohm resister in line with the 5VDC line powering the ADB signal line, that could be blown or you burned a track, blown the RFI filter (Tokin D16-C), or the ADB transiever chip itself.

 

ADB bus signals are:

 

Pin 1 : ADB

2: n.c.

3: +5V

4: GND

 

So with a meter check to see if you have +5V (used to power ADB devices) between pins 3 and 4, and then check for ADB signal (will be a lower voltage because of the resistor ) between pins 1 and 4.

 

Referenced Chapter 8 Apple Desktop Bus page 293, Guide to Macintosh Family Hardware : Second Edition.

Share this post


Link to post
Share on other sites

Page 293 in the normally authoritative source differs with reality. 8-o

Two actual SE/30 boards before me have a current limiting device, F1 in the ADB power net. In one instance it is a fuse in the form of an axial lead orange plastic cylinder similar in size with a 1/4 watt resistor, in the other case it is a self resetting solid state circuit breaker device that looks like two overlapping metal plates.

 

Add Q3 to the list of things that can blow, it is a SMT 2N3904.

 

I have read (Larry Pina) that the Tokin filter can develop an inter-signal short inside the filter itself, and thus an unwanted connection between any of +5, the ADB net, and ground. So check for shorts also. This kind of short may be due to aging of wire insulation, or possibly from an inductive voltage spike associated with hot unplugging / re-plugging devices that draw considerable DC current.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×