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AuthorTopic: Recapped, newbie needs second opinion  (Read 894 times)

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Offline looren

Recapped, newbie needs second opinion
« on: January 13, 2021, 02:59:11 PM »
Hi

I've not got any experience soldering through hole components, I thought I'd give it a try and recap my 500+ with a set of high quality caps from ebay.
I'm happy to see that none of the replaced caps had leaked or was even bulging, but as I'm not experienced with soldering on PCB I'd like a second opinion if all checks out or if I need to go back and redo anything before I put the machine back together.

Very much appreciate input on this.

https://imgur.com/a/hOfhDLo
 

Offline Pat the Cat

Re: Recapped, newbie needs second opinion
« Reply #1 on: January 13, 2021, 03:19:19 PM »
Not too shabby. You've got some big blobs that look a bit dry (pic with u34). A bit of solder wick and heat to soak up the excess would help.

I'm guessing you used lead  free solder, which isn't what Commodore used. Makes for ugly joins, although they do work. A little flux can help.

The thing should power up with no capacitors at all, it doesn't look like you damaged anything.

And DO give all the new joins a wipe with isopropyl alchohol, it's not good to leave flux on the board.

Doing that before you solder helps get rid of grease and muck and makes the job tidier.

EDIT: Really, to do a proper job, you have to take the bottom metal shield off and solder on that side. Got a 5mm nut spinner?
« Last Edit: January 13, 2021, 03:28:07 PM by Pat the Cat »
"To recurse is human. To iterate, divine."

A1200, Vanilla, Surf Squirrel, SD Card, KS 3.0/3.z, PCMCIA dev
A500, Vanilla, A570, Rev 5, KS 1.2/1.3 Testbench system
Rasp Pi, UAE4ARM, 3D laser scanner, experimental, hoping for AmigaOS4Arm, based on Watterott Fabscan Pi
 

Offline QuikSanz

Re: Recapped, newbie needs second opinion
« Reply #2 on: January 13, 2021, 03:25:13 PM »
The one on that cap you show does not look solid, may come loose. Remember to touch the solder to the iron firs to get if flowing and be careful. I sewe good one there to so keep practicing, I would do a bit of cleanup there.

Chris
 

Offline looren

Re: Recapped, newbie needs second opinion
« Reply #3 on: January 13, 2021, 03:33:08 PM »
Thanks Pat the Cat, much appreciated !
Does the blobs make any difference for the machine operating in any way, or only for looks you mean? I recon I should have had a pointy tip for my soldering iron, but only have the kind that looks like a flat screw driver unfortunately. I think it would be easier if it was a pointing tip instead.

Correct, I've used lead free solder, its hard to get anything else nowadays it seems, and I have a flux pen which I've used continuously during soldering.

And yes, I've also cleaned up the board afterwards from all the flux with alcohol.

Now, I also had an expansion added to the A500+. Its been so many years, that I cant even remember what exactly it is, but from markings on the board I'm guessing a 1mb expansion? There was also a battery attached to this expansion, which had leaked a bit. I've de-soldered the battery and cleaned it up as much as I could with cue-tip and alcohol. Is it possible to judge from photos if the PCB has been damaged in any way? If not, would it be safe to plug it in and try it? Am I correct to assume, that the expansion board would run fine even without the battery?

https://imgur.com/a/gGCmdNt
 

Offline looren

Re: Recapped, newbie needs second opinion
« Reply #4 on: January 13, 2021, 03:35:18 PM »
Hi Chris,

Okay,
Hm, it gets very messy when there is solder on the big tip I was using. May be it has to do with being lead free?

I've basically put the iron to the hole on the PCB and fed it the solder so it could run through the hole.
 

Offline Pat the Cat

Re: Recapped, newbie needs second opinion
« Reply #5 on: January 13, 2021, 03:38:11 PM »
Thought so. You DEFINITELY want to take the shield off and check the bottom.

Molten solder could have run down and blobbed a short on the underneath.

I'll take a look at that pic and get back to you in a few minutes.
"To recurse is human. To iterate, divine."

A1200, Vanilla, Surf Squirrel, SD Card, KS 3.0/3.z, PCMCIA dev
A500, Vanilla, A570, Rev 5, KS 1.2/1.3 Testbench system
Rasp Pi, UAE4ARM, 3D laser scanner, experimental, hoping for AmigaOS4Arm, based on Watterott Fabscan Pi
 

Offline Pat the Cat

Re: Recapped, newbie needs second opinion
« Reply #6 on: January 13, 2021, 03:45:26 PM »
Memory card looks OK apart from the switch. It probably turns the thing off, it it doesn't work (try later, MUCH later) then a spray of switch cleaner might restore it or it might need replacing.

Check it with a meter but the battery gunk can eat the inside of the switch.

I cant see really bad corrosion on the tracks, looks like the mask kept the gunk at bay long enough for you to take off the battery.

DO NOT APPLY POWER until you have checked over the rear of the board. Lead free solder is muvh higher temperature to melt than lead solder, so you chances for a run down blob are very very high.

They call it "though hole" for a reason. :)
"To recurse is human. To iterate, divine."

A1200, Vanilla, Surf Squirrel, SD Card, KS 3.0/3.z, PCMCIA dev
A500, Vanilla, A570, Rev 5, KS 1.2/1.3 Testbench system
Rasp Pi, UAE4ARM, 3D laser scanner, experimental, hoping for AmigaOS4Arm, based on Watterott Fabscan Pi
 

Offline looren

Re: Recapped, newbie needs second opinion
« Reply #7 on: January 13, 2021, 04:30:53 PM »
Pat the Cat;
I've been very careful for every capacitor I installed, to check the backside of the PCB. Frenetically gone over the PCB both after each capacitor and after all were installed. I'm certain there are no shorts or anything like that. Also, when soldering, I did so with the underside up, so the solder would flow down towards the capacitor. After cutting the legs of each capacitor, I've also re-flowed the solder a bit to not make it bulgy on the bottom of the PCB.

I do have a multimeter here, but I don't have sufficient knowledge how to use it for testing the memory board. Not sure what setting to put it into, or where to measure on the memory board to check if the switch is okay or not.
 

Offline Pat the Cat

Re: Recapped, newbie needs second opinion
« Reply #8 on: January 13, 2021, 04:42:54 PM »
OK, if you're happy there's no bridges, fair enough.

First attempt, you just want to see if the power LED turns on before you turn off quick.

No rising pillars of magic smoke? No fishy smell? Turn it on and leave if until  you get a boot screen.

The reason I wasn't happy with the U34 cap was the big ball of solder looked very dully. Very dry, not properly melted.

Usualy a switch has zero resistance between the middle pin and one of the outer pins, flipping to the other when you flick the switch. Easy enough to check with a multimeter, don't plug it in when you test it that way.

Do plug it in the right way. Upside down it will fry your Amiga.

If you're going to do more of these, do get some real lead solder (look for Pb included), you can find small lengths of it on places like Amazon and Ebay "For DIY use".

All about practice.
"To recurse is human. To iterate, divine."

A1200, Vanilla, Surf Squirrel, SD Card, KS 3.0/3.z, PCMCIA dev
A500, Vanilla, A570, Rev 5, KS 1.2/1.3 Testbench system
Rasp Pi, UAE4ARM, 3D laser scanner, experimental, hoping for AmigaOS4Arm, based on Watterott Fabscan Pi
 

Offline looren

Re: Recapped, newbie needs second opinion
« Reply #9 on: January 13, 2021, 04:54:23 PM »
Okay, I'll do a power check later to see if the LED turns on as they are supposed to.
Unfortunately I can't (or don't want to) check the boot screen right now. Last time I used my Commodore monitor, it was making a quite noisy high pitch sound, which I understand is a sign of it giving up. I read that if it does give up, it can be hard (or practically impossible?) to repair, so I'm currently looking for someone that can perform a repair of my monitor for me. I've emailed a company here in Sweden, hoping the guy running it can help me although have not gotten a reply yet.

I'll tend to the cap you've mentioned and fix the blob of solder.

For checking the pins on the expansion, what should I have the multimeter set to? My knowledge in electronics is very limited as you might understand by now :)

If all checks out, there is no more to repair.
I sent my A1200 for repair like two years ago, and it has been re-capped, but it seems that after I received it, it now has issues. Found a guy with the same problem as me in a thread, and they're discussing memory issues: https://www.radios-tv.co.uk/community/vintage-computers/amiga-a500-graphics-problem/ although I have no idea if this is the case or not but the graphical issues seem to be the same in games. Everything seems to work just fine, besides having these strange corrupted graphics. Due to the monitor issues, I basically just packed away the 1200 again. Figured it wasn't worth it if I risked killing my monitor.
 

Offline looren

Re: Recapped, newbie needs second opinion
« Reply #10 on: January 13, 2021, 05:32:58 PM »
Powered the A500+ without monitor, green LED lights up and it makes lovely floppy sounds :)
Tried booting from a floppy and it seems to load. Feels promising :)
 

Offline Pat the Cat

Re: Recapped, newbie needs second opinion
« Reply #11 on: January 13, 2021, 07:14:43 PM »

For checking the pins on the expansion, what should I have the multimeter set to? My knowledge in electronics is very limited as you might understand by now :)

Ohms, resistance. If a switch is working, there should be 0 ohms (or very close to zero). If a switch is open, it shows as one (blikning, very high resistance).

Powered the A500+ without monitor, green LED lights up and it makes lovely floppy sounds :)
Tried booting from a floppy and it seems to load. Feels promising :)

Good. The monitor sounds very ill.
"To recurse is human. To iterate, divine."

A1200, Vanilla, Surf Squirrel, SD Card, KS 3.0/3.z, PCMCIA dev
A500, Vanilla, A570, Rev 5, KS 1.2/1.3 Testbench system
Rasp Pi, UAE4ARM, 3D laser scanner, experimental, hoping for AmigaOS4Arm, based on Watterott Fabscan Pi