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#1 2016-03-14 03:59:54

Dnal
Member
Registered: 2015-01-03
Posts: 58

Q605 death chord

Not a good Mac day for me.  After the 9600 dead end, I decided to recap a Q605 board I got.  It would not boot and had a garbled Chime of Doom, and leaky caps.  I did the recap (ceramic caps... Wow are those small).  Now the sound is nice and clear--- it is very distinctly the Chimes of Doom/Death right after the startup bong. 

There was cap goo under one Ram chip, but no rotted traces anywhere.  Not sure where to start... Should I clean it again?

H

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#2 2016-03-14 05:15:09

ClassicHasClass
Member
From: Electron Alley
Registered: 2014-05-26
Posts: 1,105
Website

Re: Q605 death chord

Can't hurt. Also, PRAM battery? While a bad PRAM battery wouldn't cause CoD, it would certainly impair booting.

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#3 2016-03-14 06:05:20

macdrone
Member
From: Rainier, Or
Registered: 2014-05-25
Posts: 237

Re: Q605 death chord

clean and clean ram and vram contacts in slots before reseating.

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#4 2016-03-17 02:45:22

Dnal
Member
Registered: 2015-01-03
Posts: 58

Re: Q605 death chord

Well, that didn't work.  Starting to suspect a burned trace under a chip or something.  Or maybe just a bad chip altogether.

Sucks, cause I always thought the Q605 was cool.  Guess I will try to refurb my old LCII board instead.

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#5 2016-04-04 03:47:29

Dnal
Member
Registered: 2015-01-03
Posts: 58

Re: Q605 death chord

I wasted an hour tracing things around and think I might have some bad traces under a RAM chip.  Although, I'm suspicious since there are 4 vias that go to the next RAM chip down and I can't get a continuity reading for them.  Seems odd that all 4 are bad, but it is also hard to get a good reading off a via. 

Question is, how to get the RAM off of there?  I could make flyover wires but am worried there may be other bad traces.

I know hot air rework is best, but I don't have one.  I would like to put the RAM back so maybe this is an excuse to order it.

Last edited by Dnal (2016-04-04 03:49:19)

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#6 2016-04-04 17:19:15

mcdermd
Member
From: Corvallis, OR
Registered: 2014-05-12
Posts: 970
Website

Re: Q605 death chord

Chipquick?


Daily Drivers: 27" iMac 2.8 GHz Quad-Core i7 (Late 2009), 21.5" iMac 2.7GHz Quad-Core i5 (Late 2013), 11" Macbook Air 1.6 GHz i5 (Mid-2011)
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#7 2016-04-05 00:51:43

Dnal
Member
Registered: 2015-01-03
Posts: 58

Re: Q605 death chord

Wow.  Just watched a YouTube on Chipquik.  Just wow.  Might go that way just cause it is cool.

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#8 2016-04-05 04:45:44

MacOS Plus
Member
Registered: 2015-12-09
Posts: 107

Re: Q605 death chord

Ya, Chipquik, I was going to mention that.  I've swapped out a number of 160-pin PQFP ICs before using it.  Still a bit tricky at that level of complexity, but proven doable.   Getting a quality digitally-controlled Weller soldering iron was also a very worthwhile investment.  Get yourself some good-quality braided solder wick for clearing away all the low-temp alloy and any other remnant solder before re-installing components.  Be sure to purchase the Chipquik flux along with the Chipquik solder.  They sell starter sets of the materials.

I should also mention that I use Chipquik to assist with removing components that are tied into ground or power planes in the PCBs, particularly large electrolytic capacitors.  This helps quite a bit to melt these joints.  The power planes act like a huge heatsink - The lower you can get the melting point, the less likely you are to damage the tracings and pads at these heavy points.  The residual heat from the iron also keeps the joint liquified for a bit longer after you remove the iron from contact.

One other tip - I clear most through-holes of residual solder using a micro drill-bit in a hand-held pin vice.  The solder is soft enough that the bit just goes through that and doesn't damage the hole itself.  This is far better than applying yet more heat for more time to the board while trying to extract all the solder.

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#9 2016-04-05 14:17:45

bigmessowires
Member
Registered: 2014-05-15
Posts: 183

Re: Q605 death chord

I've only ever tried Chipquik once, and while it worked, it didn't go particularly well. Maybe I just need more practice with it, but the stuff stayed molten for so long, it was really hard to work with and made a mess. I normally use hot air for desoldering, with a rework tool similar to this one from Sparkfun: https://www.sparkfun.com/products/10706 But I agree that hot air can be tricky if there are other nearby components you don't want to desolder.

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#10 2016-04-05 18:57:09

mcdermd
Member
From: Corvallis, OR
Registered: 2014-05-12
Posts: 970
Website

Re: Q605 death chord

Yeah, I was trying to think what to use if I didn't have my hot air station, Hakko 808 and nice Weller station. Tools make a HUGE difference.


Daily Drivers: 27" iMac 2.8 GHz Quad-Core i7 (Late 2009), 21.5" iMac 2.7GHz Quad-Core i5 (Late 2013), 11" Macbook Air 1.6 GHz i5 (Mid-2011)
See the restored heroes here.

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#11 2016-04-05 23:40:46

Dnal
Member
Registered: 2015-01-03
Posts: 58

Re: Q605 death chord

I ordered some CQ, will let you know how it goes in a few days.

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#12 2016-05-17 01:59:36

uniserver
Member
From: Sf, Mi
Registered: 2014-05-15
Posts: 956
Website

Re: Q605 death chord

I use hot air… the nice thing about the LC475/ Q605 ram is you can remove it all (onboard 4mb) and then just run the thing from a 72 pin simm.
I found in some benchmarks that it performs between 5-10 % faster as well.


#I Re-Cap √Mac √NeTX √Amiga Boards - A/B - PSU# (MacCaps.com)  Modern SCSI HD's - For Old Macs - Pre Cfg'd - 10k RPM! 73gb!! $50 + free shipping  -- Mac 128K Re-Ram kits (16 Chips) $35 + shipping, Floppy Issues?-> Bourns Filter Solution 128k - SE/30, $16 + shipping

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