Hi, thank you for confirming. So, based on your confirmation, I have put a Dupont cable between pin2 of HI-2 and LO-1 to test it, and the TOS came back to life. Unfortunately, the Diag Cartridge is still not working. I suspect that I have broken some traces while removing the sockets to install the dual tos. I will start the hunt for the problem.
I will keep you posted, if you like.
Thank you for your help
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After 10K
Re: After 10K
Sure! You can't keep your readers in suspence
Re: After 10K
Hi, so I found out that I made a big mess when I removed the TOS sockets, especially on U67.
About the Cartridge not working, I have also found, using the following table, that there was no connection between pin 20 and CPU pin 43.
In the picture with the yellow "Circles" at number 1 you will see the broken trace that goes from pin 2 of U48 to pin 2 of U67 that caused the TOS not to load at startup and the white screen. Next to it, in the same horrible circle, you can also see the broken trace that connects U67 pin 5 to U48 pin 5. U67 pin 5 is common to all 6 pin 5 of the TOS sockets, and it comes from the layer connection point (picture with red circle) that connects all pin 5 to pin 20 of J8 (cartridge connector). So when I removed the socket on U67, if I had used some C4 explosive instead of the desoldering station and the screwdriver (the real culprit), I may have done less damage. ALSO, to desolder the U67 chip after the test, a PHT came out as you can see, and I really need good advice to repair that. I don't even know if I will be able to do that.
I don't understand why it doesn't matter if I use a desoldering station (a cheap one of course) or the iron and a desoldering pen; some joints won't free the pin. Usually happens when the joint is on a large trace, like ground, but the PHT that came out is not the case. Now I don't know what is the best way to fix it.
Table:
J8 pin Signal Goes to
1,2 +5 V CPU pin 14 or 49
38,39,40 GND CPU pin 16 or 53
36 A1 CPU 29
34 A2 CPU 30
32 A3 CPU 31
30 A4 CPU 32
27 A5 CPU 33
25 A6 CPU 34
23 A7 CPU 35
21 A8 CPU 36
24 A9 CPU 37
26 A10 CPU 38
29 A11 CPU 39
28 A12 CPU 40
19 A13 CPU 41
22 A14 CPU 42
20 A15 CPU 43
17 D0 CPU 5
18 D1 CPU 4
15 D2 CPU 3
16 D3 CPU 2
13 D4 CPU 1
14 D5 CPU 64
11 D6 CPU 63
12 D7 CPU 62
9 D8 CPU 61
10 D9 CPU 60
7 D10 CPU 59
8 D11 CPU 58
5 D12 CPU 57
6 D13 CPU 56
3 D14 CPU 55
4 D15 CPU 54
35 /UDS CPU 7
37 /LDS CPU 8
33 /ROM4 GLUE (U45) pin 17
31 /ROM3 GLUE (U45) pin 18
About the Cartridge not working, I have also found, using the following table, that there was no connection between pin 20 and CPU pin 43.
In the picture with the yellow "Circles" at number 1 you will see the broken trace that goes from pin 2 of U48 to pin 2 of U67 that caused the TOS not to load at startup and the white screen. Next to it, in the same horrible circle, you can also see the broken trace that connects U67 pin 5 to U48 pin 5. U67 pin 5 is common to all 6 pin 5 of the TOS sockets, and it comes from the layer connection point (picture with red circle) that connects all pin 5 to pin 20 of J8 (cartridge connector). So when I removed the socket on U67, if I had used some C4 explosive instead of the desoldering station and the screwdriver (the real culprit), I may have done less damage. ALSO, to desolder the U67 chip after the test, a PHT came out as you can see, and I really need good advice to repair that. I don't even know if I will be able to do that.
I don't understand why it doesn't matter if I use a desoldering station (a cheap one of course) or the iron and a desoldering pen; some joints won't free the pin. Usually happens when the joint is on a large trace, like ground, but the PHT that came out is not the case. Now I don't know what is the best way to fix it.
Table:
J8 pin Signal Goes to
1,2 +5 V CPU pin 14 or 49
38,39,40 GND CPU pin 16 or 53
36 A1 CPU 29
34 A2 CPU 30
32 A3 CPU 31
30 A4 CPU 32
27 A5 CPU 33
25 A6 CPU 34
23 A7 CPU 35
21 A8 CPU 36
24 A9 CPU 37
26 A10 CPU 38
29 A11 CPU 39
28 A12 CPU 40
19 A13 CPU 41
22 A14 CPU 42
20 A15 CPU 43
17 D0 CPU 5
18 D1 CPU 4
15 D2 CPU 3
16 D3 CPU 2
13 D4 CPU 1
14 D5 CPU 64
11 D6 CPU 63
12 D7 CPU 62
9 D8 CPU 61
10 D9 CPU 60
7 D10 CPU 59
8 D11 CPU 58
5 D12 CPU 57
6 D13 CPU 56
3 D14 CPU 55
4 D15 CPU 54
35 /UDS CPU 7
37 /LDS CPU 8
33 /ROM4 GLUE (U45) pin 17
31 /ROM3 GLUE (U45) pin 18
- pic1.jpg (271.5 KiB) Viewed 36 times
- pic1-2.jpg (30.9 KiB) Viewed 36 times
- pic2.jpg (247.92 KiB) Viewed 36 times
Re: After 10K
Hi, so this is the end of the story. Using some thin cable, I have connected the broken tracks, creating all the missing links. Covered those ugly fixes with UV resin, and the STF is Alive and kicking.
Thank you for the support.
Thank you for the support.
- tos-bridge.jpg (373.29 KiB) Viewed 6 times
- board1.jpg (371.42 KiB) Viewed 6 times
- TOS-104.jpg (206.71 KiB) Viewed 6 times
- TOS-206.jpg (344.31 KiB) Viewed 6 times
Re: After 10K
Monotamp3 wrote: Wed Oct 14, 2026 9:32 pm Hi, so this is the end of the story. Using some thin cable, I have connected the broken tracks, creating all the missing links. Covered those ugly fixes with UV resin, and the STF is Alive and kicking.
Thank you for the support.
