Posted By
Majikeyric
on 2016-02-04
09:32:23
 |  C16 64K Upgrade (failure?!!)
Hi,
I want to upgrade my C16 to 64K,
I have cleanly removed the 2 memory chips U5 and U6, soldered sockets and put in 2xTMS4464-10NL chips.
When I test to see if there is still 16K displayed at start screen, I have a blank screen and no power on ?!!
I searched for shorts but found nothing... What can be wrong ?
Thanks for your help.
|
|
Posted By
siz
on 2016-02-04
09:40:54
| Re: C16 64K Upgrade (failure?!!)
As far as I remember you should cut two traces and add 2 new ones for the address bus upper 2 bits. But that should not be a problem to prevent startup. Try to put the original RAMs (16k) into the sockets to check if they work.
|
|
Posted By
Majikeyric
on 2016-02-04
11:11:03
| Re: C16 64K Upgrade (failure?!!)
I have "destroyed" the original RAMs in order to remove them :/
But I have tested with 2 different couples of 64k chips.
Did I damage another component ???
I have another C16, I can swap socketed chips to check....
|
|
Posted By
crock
on 2016-02-04
11:38:39
 | Re: C16 64K Upgrade (failure?!!)
It's also worth checking your solder joints. Did you check if you'd pulled out via's when you removed the old chips? The picture of the back side of the board is a bit fuzzy, but some of the solder joints don't look like they have flowed very well.
edit: when you say "no power on" you mean the light does not come on? As well as checking for shorts, check for continuity between the chip sockets.
|
|
Posted By
Chicken
on 2016-02-04
11:47:48
 | Re: C16 64K Upgrade (failure?!!)
Even with the sockets and new RAMs (before cutting and adding the traces that siz mentioned) it should power up normally (just still displaying "12277 bytes" as you expected).
What do you mean by "blank screen"? Is it white with the standard purple border and you just don't get the "Commodore …" stuff? Or is it just black?
|
|
Posted By
icbrkr
on 2016-02-07
15:54:20
| Re: C16 64K Upgrade (failure?!!)
The pictures are too poor for me to see what's going on here.
Here's an album of me doing the same upgrade that worked the first time:
https://www.facebook.com/icbrkr/media_set?set=a.10205255128955696.1073741862.1170907465&type=3
And here's an album of me doing the same upgrade wrong  :
https://www.facebook.com/icbrkr/media_set?set=a.10201770461441186.1073741849.1170907465&type=3
What probably ended up happening, is like what I did when I did it wrong - when you pulled out the old chips, you either ripped a trace on the bottom of the board, or between U5 and U6. One of those is the latches to the kernal and will fail miserably if it's missing.
|
|
Posted By
Majikeyric
on 2016-02-10
07:44:47
| Re: C16 64K Upgrade (failure?!!)
I found some time to investigate a bit more according to your comments.
I checked the solder joints, the continuity, the continuity between chips.
I have even swapped all socketed chips with a working C16, to see if I had damaged one of those.
@crock : I don't understand "via" in your sentence : "Did you check if you'd pulled out via's when you removed the old chips?"
The screen remains blank : black, no light like if the C16 was not powered. :-/ Arf.....
|
|
Posted By
gerliczer
on 2016-02-10
09:39:38
| Re: C16 64K Upgrade (failure?!!)
Via is the thin layer of metal residing on the wall of holes passing through the PCB. It is used to lead the signals between the two (or more) layers of PCBs. Destroying it (pulling out - e.g. with a de-soldered component) can be the same as cutting a trace on a PCB layer.
|
|
Posted By
MMS
on 2016-02-10
16:17:05
 | Re: C16 64K Upgrade (failure?!!)
yep, the via damage is one of the most annoying and hard to repair ones. 4 or 6 layer boards:
it need a magician.
But as far as I know, the C16 used only two layers, so it is more or less easy to repair, only make sure that soldering completely filling the hole at both sides, right?
|
|
Posted By
crock
on 2016-02-10
17:23:57
| Re: C16 64K Upgrade (failure?!!)
If there's no light, that should be pretty simple. First check the fuse, if that's blown you've probably shorted +5V to ground somewhere. If it's not, either your PSU has died or the regulator has failed - there's not much else that would cause the light not to be on.
|
|
Posted By
icbrkr
on 2016-02-10
19:24:50
| Re: C16 64K Upgrade (failure?!!)
Nothing there should have killed your power LED. You may have it plugged into the board wrong, or right, the fuse or regulator is broken. You sure you plugged the right power supply back to the 16?
|
|
Posted By
Blake 7
on 2016-02-10
22:49:25
| Re: C16 64K Upgrade (failure?!!)
If the PSU is believed to be still working...
Maybe a wire has come lose inside the round jack plug that goes directly into the C16. Or a wire has broken inside the lead close to the jack plug, (all too often people would pull the wire to remove the PSU).
Try holding the power cable up or down close to where it plugs into the C16, if the light flickers or stays on you know what to do.
Fingers crossed you get it sorted any way.
|
|
Posted By
Majikeyric
on 2016-02-12
04:52:59
| Re: C16 64K Upgrade (failure?!!)
Via seems ok, the PSU and fuse are ok too.
Which component is the regulator and how to check it ?
|
|
|
|
Posted By
Chicken
on 2016-02-12
15:42:37
| Re: C16 64K Upgrade (failure?!!)
Majikeyric: In your sentence "The screen remains blank : black, no light like if the C16 was not powered. :-/ Arf....." does "light" refer to the red power LED? Or do you mean there's nothing on the screen/display? Re-reading this, I wasn't sure what you meant.
Screen is black and the power LED is off or on?
Are the RAM chips tested?
|
|
Posted By
Majikeyric
on 2016-02-13
03:30:47
| Re: C16 64K Upgrade (failure?!!)
Thanks gerliczer ! I gonna give it a try.
The screen is black and the power led is off.
The RAM chips are not tested but I tried with 4 different.
|
|
