Need help with resistors (jumpers?).

[Ricky Spanish]

Long story short. Received my 1200XL OS Rev11 ROMS , got the cart before the horse and removed the resistors (jumpers?) @  W6, then removed W7, W8, W9 & placed them @ W11, W12, W13. I then realized my rev10 are 24pin, whereas the rev11 are 28 pin. Yes, I'm a dummy. Anyways, go figure, lost the w6 jumper. No idea where to find replacements. 

 

PS I'd do the socket replacement, but I don't have the proper equipment.

 

Thanks.

[+mytek]

28 minutes ago, Ricky Spanish said:

PS I'd do the socket replacement, but I don't have the proper equipment.

On one of my 1200XLs I didn't feel like removing the 24 pin socket to replace it with a 28 pin, so instead I just cut the end off of another 24 pin socket and soldered that into the extra 4 holes to make the 24 into a 28. It worked very well, and all I needed to do was clear the solder out of the 4 holes using a straw to blow the solder out after heating up the pads with a soldering iron. Only special tools required besides the soldering iron which I assume you have, is something to cut the end off the spare socket with (small coping or hack saw), and a straw from MCDonalds.

 

P.S. Remember to blow through the straw, because sucking could be a health hazard

[Ricky Spanish]

1 hour ago, mytek said:

P.S. Remember to blow through the straw, because sucking could be a health hazard

Thanks. I'll keep that in mind. Any idea on where to get those resistors/jumpers ? Otherwise kinda dead in the water here. 

[+mytek]

28 minutes ago, Ricky Spanish said:

Any idea on where to get those resistors/jumpers ?

Digi-Key Part Number:  13-ZOR-25-T-52-0RCT-ND

[BillC]

2 hours ago, Ricky Spanish said:

Thanks. I'll keep that in mind. Any idea on where to get those resistors/jumpers ? Otherwise kinda dead in the water here. 

These jumpers are 0 ohm resistors and can be replaced with a short length of wire.

[Ricky Spanish]

15 hours ago, BillC said:

These jumpers are 0 ohm resistors and can be replaced with a short length of wire.

Ya I metered them @ 0ohm but wasn't sure for some reason. thanks for confirming. 

[ACML]

17 hours ago, mytek said:

Digi-Key Part Number:  13-ZOR-25-T-52-0RCT-ND

While you're ordering the 0 ohm jumpers, add this to your list.  These Single Inline Package (SIP) are exactly what you need.

https://www.digikey.com/en/products/detail/harwin-inc/D01-9973242/3727905

 

I just cut off section of two leads and stick them in the missing pins to make the 24 pin to 28 pin.  Very easy, done it at least a dozen times on 1200XL for this very same purpose. 

 

[_The Doctor__]

the picture is showing shouldered through hole pins, is that correct?

[ACML]

1 hour ago, _The Doctor__ said:

the picture is showing shouldered through hole pins, is that correct?

Yes.  You are just adding the two missing legs to each end so there are 2x14 (28) instead of 2x12 (24).  Works great.  You don't need to touch the existing 24 pin socket, you're just appending the last two missing legs.  I've never understood why so many would desolder the existing socket and risk PCB damage when this is so much easier and safer.

Just need to ensure they are inline so the EPROM goes in easily.

 

[Ricky Spanish]

K so did everything according to instructions and no joy. See anything obvious here ?

[ACML]

32 minutes ago, Ricky Spanish said:

K so did everything according to instructions and no joy. See anything obvious here ?

 

Three observations:

1)  The 2 pin extensions do not appear to be lined up with the existing 24 pin socket (they look bowed out).  Looks like you had to bow out the legs 1,2 and 27,28.  Maybe the photo, but pin 28 on U12 looks damaged from being bowed out.

2)  Check your solder work on jumper locations W9-13 (especially the cartridge side).  Make sure no solder is inadvertently shorting a neighboring pad  (like W9/13, W8/12, W7/11).  Accidently shorting to neighboring pads will cause a blank screen.

3)  You have a loose 0 ohm jumper laying on the board between W9 and L2.

 

Remove EPROM first: You can use a small pair of needle nose pliers to bend 2 pin socket back inline with the 24 pin socket so legs 1,2 and 27,28 aren't bowed out causing stress.

 

Look over pin 28 on U12, is it damaged?

 

Now that I look at it again, did pin 28 on U12 actual go into the hole?  it might have bend the pin under the socket and didn't go in the hole.

 

 

 

Edited May 6, 2023 by ACML

[Ricky Spanish]

Everything looks good to me used a multimeter to confirm.

Checked, rechecked, & checked again all of it.

w9 to w13 have a factory bridge.

w8 to w12 have a factory bridge.

w7 to w11 have a factory bridge.

Edited May 6, 2023 by Ricky Spanish
added info

[ACML]

Look at this pin on the EPROM.  Is it in the hole?

Looks like it bent under the chip and didn't go into the hole.

Edited May 6, 2023 by ACML

[ACML]

1 hour ago, Ricky Spanish said:

Everything looks good to me used a multimeter to confirm.

Checked, rechecked, & checked again all of it.

w9 to w13 have a factory bridge.

w8 to w12 have a factory bridge.

w7 to w11 have a factory bridge.

I meant the other side of the jumpers (i.e. cartridge side).  Check the other side of the jumpers W9/13, W8/12 and W7/11 for a short between pads. 

[Ricky Spanish]

1 hour ago, ACML said:

I meant the other side of the jumpers (i.e. cartridge side).

All good .

[TZJB]

12 hours ago, ACML said:

Look at this pin on the EPROM.  Is it in the hole?

Looks like it bent under the chip and didn't go into the hole.

 

I agree, U13 Pin 28 looks bad. Please send a close-up picture. I like your labels @Ricky Spanish, Brother machine?

Edited May 6, 2023 by TZJB

[ACML]

1 hour ago, TZJB said:

 

I agree, U13 Pin 28 looks bad. Please send a close-up picture. I like your labels @Ricky Spanish, Brother machine?

It's actually U12, but yeah, pin 28 doesn't look like it's in the hole.

 

Edited May 6, 2023 by ACML

[BillC]

What upgrade instructions did you follow? Some convert the 1200XL to use a single 16kB OS chip instead of the original dual 8kB.

I followed Bob1200XLs instructions, using Rev.3 OS(16kB EPROM)/internal Rev.C BASIC(8kB EPROM)/CO61618 MMU, it essentially became an 800XL without the PBI.

[_The Doctor__]

45 minutes ago, BillC said:

What upgrade instructions did you follow? Some convert the 1200XL to use a single 16kB OS chip instead of the original dual 8kB.

I followed Bob1200XLs instructions, using Rev.3 OS(16kB EPROM)/internal Rev.C BASIC(8kB EPROM)/CO61618 MMU, it essentially became an 800XL without the PBI.

and you can add the PBI in to the 1200XL or 800 if you like

[Ricky Spanish]

1 hour ago, ACML said:

pin 28 doesn't look like it's in the hole.

Well visually it is, and using the multimeter (one lead under the board, the other on the chips tang) also agrees.

[Ricky Spanish]

1 hour ago, BillC said:

What upgrade instructions did you follow?

Removing w6, and moving w9 to w13, w8 to w12, & w7 to w11. then extend the 24 pin socket to 28 pin x 2.

[BillC]

46 minutes ago, _The Doctor__ said:

and you can add the PBI in to the 1200XL or 800 if you like

I already have one of the @MEtalGuy66 1200XL cartridge port to PBI adapters, just need to connect the extra PBI signal ribbon cable.

 

 

[ACML]

Any chance the stickers got inadvertently on the wrong chips (i.e. swapped by accident)?  If you have a way to read the EPROM, verify that the checksum matches.

 

[+mytek]

12 minutes ago, ACML said:

Any chance the stickers got inadvertently on the wrong chips (i.e. swapped by accident)?  If you have a way to read the EPROM, verify that the checksum matches.

Or just swap them, since nothing bad will happen

[Ricky Spanish]

8 minutes ago, mytek said:

Or just swap them, since nothing bad will happen

Did that. Whole lot of notta.