Author Topic: Sucker for punishment - Stern MPU-100  (Read 2097 times)

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Offline ajlaird

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Re: Sucker for punishment - Stern MPU-100
« Reply #15 on: July 30, 2009, 09:13:16 AM »
so off to one of the few real electronics stores left to buy another $15 sucker-pen...

Amen to that brother!!

Dick Smith Electronics was the last great hobbyist shop that every electronics whiz kid in the 80's wanted to work in but has now reduced itself to selling TVs & White Goods, who's next Jaycar, Altronics??
I reckon you can thank the Woolies/Coles thing about who has what and in the end we have nothing but no service and no competion . Reckon Dick Smith himself (being a True blue) would shake his head and think OMG.Try buying a set value resistor there now!!!

Unfortunately there is a simple economic reality behind this - people stopped buying components and there is very little business left in that market. Hopefully enough to sustain Jaycar et al!

These days most electronic items are relatively cheap, so putting time in to fix something broken is a low priority for most people when you can run down and get another one so easily.

pinballist

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Re: Sucker for punishment - Stern MPU-100
« Reply #16 on: July 30, 2009, 09:34:23 AM »
I agree Andrew, it's such a terrible waste of natural resources which only generates more pollution.  It's all about mass consumerism & corporate greed *.*

Offline goodolddays

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Re: Sucker for punishment - Stern MPU-100
« Reply #17 on: July 30, 2009, 10:04:53 AM »
I agree Andrew, it's such a terrible waste of natural resources which only generates more pollution.  It's all about mass consumerism & corporate greed *.*

Not just corporate greed though !! Most people are greedy don't you think ? Thats one of the main reasons why the global economy tanked over the past 12 - 18 months I suspect.
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pinballist

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Re: Sucker for punishment - Stern MPU-100
« Reply #18 on: July 30, 2009, 10:19:39 AM »
yeah, I hear what you're saying, but I would rather buy a product that lasted longer than having to upgrade every year, they just don't build things to last any more because it's not good for sales and company profits.

Offline AskJacob

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Re: Sucker for punishment - Stern MPU-100
« Reply #19 on: July 30, 2009, 10:43:24 AM »
watches the greedy corporate fat cats wringing their hands in frustration:

"what is wrong with these people? why do they keep playing games that are 10, 20 and 30+ years old?"

 :lol

Marty Machine

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Re: Sucker for punishment - Stern MPU-100
« Reply #20 on: July 31, 2009, 12:18:04 AM »
A lot of that stuff I've seen before in Mark C's coffee.....
That's what was spilled on the board in the first place hehehehe  :lol :lol :lol


That board *IS* repairable, laborous yes, but repairable.
I'd be more inclined to use solid copper (insulated-telecom) wires to bypass all the crappy pads/tracks.

I've done a lot worse cpu boards than that, and had them up & running in around 2-3 hours.
Lock the doors, phone off-hook, head down, bum up, you CAN do it !!  #@# *%* :D

MM.

Offline AskJacob

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Re: Sucker for punishment - Stern MPU-100
« Reply #21 on: July 31, 2009, 12:33:01 AM »
OK a little update, with a "How I do it" - not necessarily the best way, but it works for  me and my current tools.

Now, to remove the molex pins, remember the #1 priority is the board and the tracks, so you need to minimise the stress on the pcb. Without fancy desoldering gear, this is what I do...

With (not your best pair, this is hard on them) side cutters, cut the plastic strip base into small pieces, while they are still on the PCB. The you can easily slide the pieces up off the pins: (pic shows me 1/2 way through one). For IC sockets, you need to figure out how to remove the plastic frame and leave the pins behind. This board had 4 different types of sockets, and each one needed a different way to fiddle about to pop it off. For ICs on the PCB, just cut the legs off the body then desolder. Much easier as well as less stressful on the PCB.



Then you can use tweezers (pliers are ok but suck the heat away from the iron) grab each pin and heat the joint from the top side and slide them out, one at a time. To make this much easier, I use a paste flux I bought a small tub of from deal extreme. less than $5 and will last for years.

Once you have all the pins out, it may look like this:



The next step is to clean the pads. If they are bare copper that is tarnished like these, a fine grit sandpaper, or extremely careful scaping with a hobby blade back to shiny copper is needed. Next is to tin and flood the pads with fresh new solder:



Be quick and gentle with the heat. If the solder won't flow, then stop and re-clean the pads. More heat will not fix it, it will peel up the tracks.

Finally, you remove the excess solder with a sucker-pen. I prefer the pen over braid as you need a lot of heat to use braid. Check the back side and repeat...



In that picture you can see the left over flux on the PCB. That's ok, once we have removed all the crappy sockets, pins and components a good scrub with isopropyl and a nylon brush will have it clean and ready to re-populate.

Here are some areas that cleaned up well:





Here are some that are going to need work before components go back:





Those bad areas are in the main corrosion zone, and have had previous heavy handed work done on them...

Coming up next: Cleaning the PCB, and starting track repairs. Oh, and find out why I had to buy nail polish :D

Cheers
Jacob


Offline rads

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Re: Sucker for punishment - Stern MPU-100
« Reply #22 on: July 31, 2009, 07:40:52 AM »
I know nothing about boards and am amazed at the stuff you guys can do.  Another great thread.  Keep the updates coming

Offline Strangeways

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Re: Sucker for punishment - Stern MPU-100
« Reply #23 on: July 31, 2009, 11:46:29 AM »

Exceptional work !

I used to do this kind of work "to pass time" - and it is EASILY the hardest kind of board work you can work on. If you can fix this board, you can fix anything !

Keep the updates coming.
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Offline AskJacob

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Re: Sucker for punishment - Stern MPU-100
« Reply #24 on: July 31, 2009, 01:50:18 PM »

Exceptional work !

I used to do this kind of work "to pass time" - and it is EASILY the hardest kind of board work you can work on. If you can fix this board, you can fix anything !

Keep the updates coming.

Got it in one... it is nearly a zen meditative thing I guess. Once you are over the shock of the board, the slow process of repairing it is fiddly, tedious yet somehow satisfying and relaxing.

I wish my eyes were as good as my camera!

Cheers
Jacob

pinballist

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Re: Sucker for punishment - Stern MPU-100
« Reply #25 on: July 31, 2009, 02:50:05 PM »
Got it in one... it is nearly a zen meditative thing I guess. Once you are over the shock of the board, the slow process of repairing it is fiddly, tedious yet somehow satisfying and relaxing.

Totally!  It's like pulling apart a 4 player score motor, you know you don't wanna do it but after getting into the right frame of mind the job goes like a dream.  The trick is to do it under total silence, no music, chatter or distractions and it really works :)

Offline AskJacob

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Re: Sucker for punishment - Stern MPU-100
« Reply #26 on: August 09, 2009, 05:09:28 PM »
Before and after:

While not fooling anyone that this is an "as new" pcb now, it should be ready to go a few more years now. Just need to pop in the ICs and start testing. And probably need to get an IC or two from Ken too :)

Before:


After:



Before:


After:


Before:


After:


Before:


After:


Before:


After:



Cheers
Jacob

Offline The pinballist formally known as Dean Morgan

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Re: Sucker for punishment - Stern MPU-100
« Reply #27 on: August 11, 2009, 05:12:34 PM »
Reckon Dick Smith himself (being a True blue) would shake his head and think OMG.Try buying a set value resistor there now!!!

The huge DSE Powerhouse near us removed all the hobbyist stuff last year, lucky we've got a Jaycar about 20Kms from here.  And hey what a waste of space that Tandy Electronics is *.* it may as well be a Retravision.

Both Tandy (Radio Shack) and Dick Smith are owned by Woolworths now  !!!
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Offline Strangeways

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Re: Sucker for punishment - Stern MPU-100
« Reply #28 on: August 11, 2009, 07:51:21 PM »


Great work - you have the "hands of a surgeon".. !
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Offline MartyJ

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Re: Sucker for punishment - Stern MPU-100
« Reply #29 on: August 11, 2009, 09:33:15 PM »
Very nice work indeed.  *%*