| Posted By
jocktrucker
on 2014-11-13
16:12:46
|  What could be blowing TED Chip
Received a Plus 4. I powered it up and for a brief 10 seconds the start up screen came up,keyboard did not work, then it went to an orange screen.
Switch off and on again black screen. Tested TED in working unit, black screen. Put a tested spare TED into the machine, black screen.
Anyone any answers. Tried a couple of different power supplies, to no avail.
Guessing either CPU or power into the machine might not be at the right voltages?
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Posted By
MIK
on 2014-11-14
02:55:47
 | Re: What could be blowing TED Chip
When the TED dies or is about too go it can take the CPU out with it at the same time, not always but can happen. If you saw random characters on the screen just before the Plus/4 went then that normally means the TED is about to die... If you didn't then chances are it was the CPU.
So you replaced the TED and are still looking at black...
On TED based machines the CPU works like a graphics card and displays what the TED tells it too, however a black screen normally means a dead CPU if you know the TED is ok. As I said, you normally see something on screen when a TED is about to go, but if you have replaced TED with a known working one and are still looking at a black screen it's normally the CPU that has gone.
That last TED you tried hopefully is ok as a fully dead CPU will not harm a TED. I'm sure your PSU's are fine, try a different CPU you know works be it from a C16 or Plus/4 and put that last known working TED back in.
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Posted By
SVS
on 2014-11-14
15:08:20
 | Re: What could be blowing TED Chip
A warning. If you try to insert a surely working chip in the non-working machine, you could obtain to burn the working chip too. In fact a bad circuit or power supplier or other from the bad motherboard can be the cause of the problem.
On the contrary a burnt chip, is fit inside a good motherboard, very rarely can damage it.
Then the correct sequence has to be: try each chip (TED or CPU) if is working inside the good machine, one a time. If you detect that only one is burnt you can inspect the circuit searching a possible cause (brown area, capacitors wrong, or even hot resistance).
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Posted By
jocktrucker
on 2014-11-14
17:32:53
| Re: What could be blowing TED Chip
Thanks guys. I did see a random 'C' character further down the screen. What chip is the CPU, I am familiar with the 64, not as much so the plus 4. I am learning.
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Posted By
JamesC
on 2014-11-14
17:53:44
| Re: What could be blowing TED Chip
CPU is marked 7501 or 8501. They're interchangable, the difference is in the manufacturing process. 
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Posted By
MIK
on 2014-11-15
04:51:47
| Re: What could be blowing TED Chip
Or at a glance looking face down, in a Plus/4 TED is under the metal shield as you know, the CPU is directly parallel to it on the right. If you want to know what all the main chips are, have a look at the hardware section.
As you may of already guessed, the C16 and Plus/4 use the same TED and CPU chips.
Where possible replace the heat paste with fresh on the TED if your putting it in a Plus/4 and intend to use the heat shield they came with, this will extend the life of the TED longer than none at all. Plus/4's run a lot warmer than a C64 or C16, less free space inside a Plus/4 for heat to escape...
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Posted By
Chronos
on 2014-11-15
18:17:56
 | Re: What could be blowing TED Chip
Once my machine produced a "!" on the screen.. it was a faulty ram chip, i've replaced it and everything is fine since.. btw if you or anybody cannibalise a dead machine i'm searching for atleast a working pla chip! i can offer ted or cpu or ram chips...
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