User avatar
grshaw

Posted Sun Jan 05, 2020 11:50 am

Spent today removing all the components that I needed from the A500 motherboard. For the chips, that meant removing them from the sockets. For the Connectors and VIDIOT , that meant desoldering them. The chips all came out pretty easily, with the exception of Agnus. Man that was a pain! I think that the PLCC extractor that I was using was cheap crap. Instead of gripping the chip when you squeeze, it would just slip off and scratch the top of the package. I finally gave up on the PLCC extractor and used a tiny screwdriver. I put this in the the same hole and levered up one side, then the other, bit by bit. I wish I had done this from the start and avoided those scratches on the top of Agnus. You live and learn I guess.

For the desoldering work, I had my desoldering station and my soldering iron both set up to the maximum temperature of 480 C. Normally it would be foolhardy to use such a high temperature. However, in this case, I am not trying to preserve the A500 motherboard. The hot temperature made it easier to get the connectors and the VIDIOT out without damaging them.

Here is the result of my days work. :D
IMG_0234.jpg
Poor Agnus. I promise to treat you better in the future. :D

User avatar
nadoom

Posted Sun Jan 05, 2020 1:04 pm

grshaw wrote:
Sun Jan 05, 2020 11:50 am
Spent today removing all the components that I needed from the A500 motherboard. For the chips, that meant removing them from the sockets. For the Connectors and VIDIOT , that meant desoldering them. The chips all came out pretty easily, with the exception of Agnus. Man that was a pain! I think that the PLCC extractor that I was using was cheap crap.

Poor Agnus. I promise to treat you better in the future. :D
I think I had the same crap tool u had.. I have scratch also.. what's the actual best method for removing them? They are in so tight.

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intric8
Seattle, WA, USA
Website

Posted Sun Jan 05, 2020 1:52 pm

grshaw:
I think that the PLCC extractor that I was using was cheap crap. Instead of gripping the chip when you squeeze, it would just slip off and scratch the top of the package. I finally gave up on the PLCC extractor and used a tiny screwdriver.
I've had this same experience before. Add insult to injury, that Agnus socket can be very prone to cracking, too.

At the sea-ccc club member Christian uses a simple extractor where, instead of pulling (and typically scratching the top) he squeezes both arms very firmly and, eventually, the chip just pops out. I've never been able to do it myself, but seeing him do it is a thing of beauty. I actually bought a really expensive PLCC remover and he wouldn't even touch it.

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obitus1990
New Orleans, LA, USA

Posted Sun Jan 05, 2020 5:40 pm

You're using the PLCC extractor incorrectly. I use a cheap one, and, once you learn how to do it, it will work flawlessly. Once you get the legs engaged into the slots in the socket, you push down towards the board so that the black plastic frame makes good solid contact with the socket, and while maintaining this downward pressure, you then begin gently squeezing the black plastic frame together at the part where it bends. It is, for me, a two hand operation. The chip will then pop out almost effortlessly. The key is keeping the black frame in contact with the socket and letting the instrument do the work for you. Whatever you do, don't rock it side to side.

One more thing... if you're taking the chips out of one board to donate to another, the AGNUS socket has two holes on the underside of the PCB, which you will see once you take off the bottom RF shield. All you need to do then is take two pencils (not sharpened) or other type of pushing instrument, insert them both into the holes (with the motherboard inverted and flat against your work surface) and push both towards the Agnus simultaneously. Out it will come, no extractor needed, and no chance of scratching the IC or, worse yet, breaking off pins.

User avatar
grshaw

Posted Mon Jan 06, 2020 1:36 am

intric8:
I've had this same experience before. Add insult to injury, that Agnus socket can be very prone to cracking, too.
In fact I did crack the socket too. However, it's not a problem because I wasn't planning to re-use it in any case.

intric8:
At the sea-ccc club member Christian uses a simple extractor where, instead of pulling (and typically scratching the top) he squeezes both arms very firmly and, eventually, the chip just pops out. I've never been able to do it myself, but seeing him do it is a thing of beauty. I actually bought a really expensive PLCC remover and he wouldn't even touch it.
obitus1990:
You're using the PLCC extractor incorrectly. I use a cheap one, and, once you learn how to do it, it will work flawlessly. Once you get the legs engaged into the slots in the socket, you push down towards the board so that the black plastic frame makes good solid contact with the socket, and while maintaining this downward pressure, you then begin gently squeezing the black plastic frame together at the part where it bends. It is, for me, a two hand operation. The chip will then pop out almost effortlessly. The key is keeping the black frame in contact with the socket and letting the instrument do the work for you. Whatever you do, don't rock it side to side.
Sounds like there is a knack to it, which I don't currently have. Also, counter-intuitively, sounds like a cheaper PLCC extractor may be better in this case. I will bear this advice in mind next time I need to extract a PLCC chip. Hopefully, that won't be any time soon. :D

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BloodyCactus
Lexington VA
Website

Posted Thu Jan 09, 2020 10:48 am

I would get new colour coded audio connectors and composite out, cheap and easy to get, those look old and nasty.
new red/white/yellow look nicer than 3 old beat up reds!

User avatar
grshaw

Posted Fri Jan 10, 2020 6:31 am

Yeah - they do look a bit old and worn don't they.

User avatar
grshaw

Posted Sun Jan 19, 2020 11:33 am

Still waiting for three components before final assembly and ( hopefully no ) smoke test. :D

A couple of bits for the real time clock. Specifically a trimmer capacitor and the clock itself ( OKI MSM6242 ). Additionally, I need an EMI filter for the position EMI200. Strangely, the instructions https://dev.sigpipe.me/dashie/A2000 I have been following don't have this position anywhere. What's more, the BOM I got from Acill doesn't have a component for this either. However, I think it is required, so I had to order just that one specifically.

Yesterday, I fitted the RCA Plugs. It turns out that the Amiga 500 RCA plugs didn't actually fit in the holes, so I had to follow BloodyCactus' advice and buy some new ones. I got them from AmigaKit.
IMG_0238.jpg
The RCA plugs sure look new and shiny. They kind of make the rest of the back panel look old and worn. Also - I don't think they are really a great fit. It took a lot of "persuading" with some pliers to fit them into the holes.

Spent much of the afternoon cleaning off solder flux from the bottom of the board. Wish I had just done it whilst I was going along really. Real pain of a job. I was using IPA and cotton buds. I wonder if anyone knows of any easier technique?

User avatar
grshaw

Posted Sun Jan 26, 2020 5:04 am

Well. Bad news I'm afraid guys. Did the smoke test today. No Smoke at least. It's booting up to a Red screen which then quickly goes black. The helpful guide pinned to the top of the hardware forum tells me that this is a bad ROM checksum. I will try swapping the Diagrom out for 2.0.4. Also - I will try checking the solder around the ROM socket...

User avatar
Olem
Norway

Posted Sun Jan 26, 2020 8:57 am

Too bad! But if you get one of the color codes, you're quite close to getting it to work. Reflow the solder joints around the ROM and try with another chip, that sounds like a good start. Have you tried reading the serial output from the diagrom? I have never tried myself, but you can get some info from that, if you have cable and adapters to connect it to USB.
The 500++ is nearly done BTW, just waiting for some jumper caps for the df select, of all things. Will post some images when I get the last few bits, in a week or two!





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