Smonson's slow H4 build

[derkom]

Derkom said it just went on a bit wonky https://www.exxosforum.co.uk/forum/viewt ... =40#p29128

Right, to clarify my post, all I had to do to get it to fit was bend the legs on the reset switch metal shield a little bit, not even to the point that any damage was done to the original part. It should straighten out just fine should it ever find itself again on a board with original spacing.

[Smonson]

Yeah, might have to. I just realised that you have NEW switches for sale in your store. That's great, it means I don't have to worry about destroying this one anyway.

By the way, the footprint is perfect, it's just facing the wrong way.

reset-switch.jpg (57.12 KiB) Viewed 4136 times

[exxos]

It is actually out and backwards.. its been fixed on the REV A design.

Don't forget... https://www.exxosforum.co.uk/forum/viewt ... =78&t=2335

[DoG]

I used the reset switch from exxos store with a blue plastic stem. I don't think I had any major problems with it since I can't remember it being that stubborn. The blue stem and the blue pcb is just esthetically pleasing. It seems that I have bent the shield pin a bit outwards on the picture. Could be the angle also.

Blue reset.jpg (38.9 KiB) Viewed 4125 times

[Smonson]

Geez, those 6850s are next to impossible to get out with a manual solder sucker. Dunno if all STs are similar but all the pins on my donor board were folded down pretty much flat before soldering. If I ever manage to get mine out I'll probably have killed them from the heat exposure.

[PaulJ]

Haven't seen that in my donor boards @Smonson , just wave soldered with pins strait. Were they replaced by some repair that went on?

[rubber_jonnie]

Geez, those 6850s are next to impossible to get out with a manual solder sucker. Dunno if all STs are similar but all the pins on my donor board were folded down pretty much flat before soldering. If I ever manage to get mine out I'll probably have killed them from the heat exposure.

@Smonson Not had any donors with bent over pins, but there are couple of pins in the 6850s that I think are ground or power planes and they are really very difficult to desolder. I broke some prior to getting my desolder gun, and it's tricky even with that.

[Smonson]

Hmm, I should have taken a photo of it before I started. Basically the pins were all bent inwards towards the centre. The pins themselves seem to be made from slightly thinner sheet metal than normal, too. I've bent them all up, but the problem with doing that is that it causes them to be slightly S-shaped after being bent twice, and maybe that's part of why they're so hard to get unstuck.

... ground or power planes and they are really very difficult to desolder.

Yes! The air just won't go through the holes - there's no room, or something. It's an airtight seal. And with the holes being through-plated, they're basically soldered on both sides. It's a monster of a task. For some of the packages, such as the CPU (I have a DIP64), they practically fall out of the holes under their own gravity with the slightest effort.

I've bought a couple more 6850s on ebay anyway just on the assumption that this is going to end badly

[rubber_jonnie]

@Smonson I have got some 6850's to recover from a donor, so I will see if I can work out just what is going on, 'cause man those couple of pins are bad!

On the assumption that there is a big copper plane of some sort, and that the board I am pulling from is scrap, I usually turn up the temp to about 400c on my desolder gun, but of course that limits time on target and doesn't always work.

Sometimes I add a big blob of normal solder to to help things liquefy, but those damn 6850s,they just don't want to be set free!!

[PaulJ]

Hmm, I should have taken a photo of it before I started. Basically the pins were all bent inwards towards the centre. The pins themselves seem to be made from slightly thinner sheet metal than normal, too. I've bent them all up, but the problem with doing that is that it causes them to be slightly S-shaped after being bent twice, and maybe that's part of why they're so hard to get unstuck.

... ground or power planes and they are really very difficult to desolder.

Yes! The air just won't go through the holes - there's no room, or something. It's an airtight seal. And with the holes being through-plated, they're basically soldered on both sides. It's a monster of a task. For some of the packages, such as the CPU (I have a DIP64), they practically fall out of the holes under their own gravity with the slightest effort.

I've bought a couple more 6850s on ebay anyway just on the assumption that this is going to end badly

Sometimes using a reclaimed chips can be a pain in the a%% getting all the pins in the holes. I purchased this pin straitner that helps a lot getting all the pins aligned so they cane inserted in a socket.

https://www.jameco.com/shop/ProductDisp ... ctId=99363