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Problem with my SPX90
Old 9th August 2020
Here for the gear

Originally Posted by Jesse Skeens View Post
What do the rails measure?

+5 reads 5.18

-18 reads -18.80
+18 reads 19.51


+5 reads 5.01

-18 reads -18.68
+18 reads 18.83

Checked +5V @ IC136 (HD74LS266P) = +4.98.
Same at IC153.

Backup battery reads 3.1V

It’s RY102 which is continually/randomly tripping.

Additional note: With CN3 (-18v, +18v, AG, PE, PC, etc) disconnected, but CN4 (+5v) still hooked up, the fault is still present (in that the display still flickers/displays garbage exactly the same), but there’s obviously no relay tripping.

Last edited by urban_paranoia; 9th August 2020 at 01:42 PM.. Reason: Accuracy.
Old 11th August 2020
Voltages are perfect. Now you need to check the ripple. If it's high, you're looking at replacing the inductors. I'd suggest you read the rest of the thread, especially Lee You's posts.
Old 16th August 2020
Gear Maniac

Your problem is not related with the PSU
Old 29th August 2020
Lives for gear
ghostwriter's Avatar
Thanks to anyone who helped answer my questions. I rebuilt the power section and my beloved SPX90 is up and running again.
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