INTL 3:770/1 3:770/3
REPLYADDR fake@ddress.no
REPLYTO 3:770/3.0 UUCP
MSGID:  f9cd03f9
REPLY:  d03b6897
PID: SoupGate-Win32 v1.05
On Fri, 13 May 2022 11:52:25 -0000 (UTC), phigan
 wrote:

>a C64 that powers on with just a
>black screen

The most useful tool for troubleshooting a black screen C64, is the
Dead Test Cartridge. Note that a black screen and a blank screen are
fundamentally different.

Throwing parts at it is a lottery. If you want to continue the
lottery, the RAM chips are a very common fault. The bad news is,
there's eight of them (or two if you have a later revision). Leave the
computer on for a minute or two and check for hot RAM chips. If they
get hot, they are definitely bad, but they can also be bad if they are
not getting hot. The Dead Test can sometimes tell you which specific
RAM chip is bad.

Another common problem is the power switch. It switches both the 5 V
DC and the 9 V AC. If the 5 V DC is not working, you will get a black
screen on the earlier revision (the longboards).

Have you checked voltages? That should come before even the Dead Test.
--
RoRo

--- SoupGate-Win32 v1.05
 * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
SEEN-BY: 1/123 10/0 1 15/0 18/200 90/1 102/401 103/1 705 105/81 106/201
SEEN-BY: 120/340 123/131 129/305 330 331 153/250 757 7715 214/22 218/0
SEEN-BY: 218/1 650 700 840 860 870 880 220/70 221/6 226/17 30 227/114
SEEN-BY: 229/110 111 206 317 400 424 426 428 470 664 700 266/512 267/800
SEEN-BY: 282/1038 301/1 317/3 320/219 322/757 342/200 396/45 460/58
SEEN-BY: 633/280 712/848 770/1 3 100 340 772/210 220 230
PATH: 770/3 1 218/840 700 229/426