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DBX 900 Mods

This 900a Series is in to get TRS jacks in to replace the terminal connectors. I made a Custom PCB to replace the board mount terminal connector and reuse the original metal work with a 3D printed mounting plate.


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Profile picture for user Link555
Member for
14 years 2 months

Link555 Mon, 05/04/2020 - 21:00

Circuit boards came today... a couple stand offs and 3D printed insert and this will work!



Profile picture for user Link555
Member for
14 years 2 months

Link555 Sun, 05/10/2020 - 21:15

Desoldering was a lot of work.....but it's finally done..

Profile picture for user Link555
Member for
14 years 2 months

Link555 Thu, 05/14/2020 - 06:42

Now onto the Power supply. Just doing some recapping. Interesting design the Power transistors are connector mounted...

Profile picture for user Boswell
Member for
15 years 2 months

Boswell Thu, 05/14/2020 - 08:00

Ah-ha, the old TO-127 package! It looks like the middle 4 Darlington transistors are in this package mating with the 0.156" connectors. The outer two regulators are conventional TO-220, going directly into 0.1" sockets.

Easy to take apart, but it's a very unreliable way of connecting to power device leads. Any increase in contact resistance through ageing can quickly build into a run-away failure.

Profile picture for user Link555
Member for
14 years 2 months

Link555 Thu, 05/14/2020 - 10:17

Exactly what I was thinking, I might be taking that connector off and soldering straight to the pcb

Profile picture for user Link555
Member for
14 years 2 months

Link555 Sun, 05/17/2020 - 22:57

Well the plate is done.... 38 holes and two squares later... not bad for a sparky..





Profile picture for user Boswell
Member for
15 years 2 months

Boswell Mon, 05/18/2020 - 00:28

Pretty impressive! Is the rear panel in the same position as it was originally, or did you have to move it back a bit to cater for the length of the TRS sockets?

Profile picture for user Link555
Member for
14 years 2 months

Link555 Mon, 05/18/2020 - 01:08

Actually I brought the back out further, the racks has wings the project backwards ...so it works

Profile picture for user Link555
Member for
14 years 2 months

Link555 Tue, 05/19/2020 - 12:36

Power Supply Recapped and Transistors and IC soldered directly to the PCB. I removed the connector to hopefully increase the future reliability...

Profile picture for user Link555
Member for
14 years 2 months

Link555 Thu, 05/21/2020 - 07:07

With a little fiddling I got the DBX 900 chassis back together and working.... Now onto the card repairs...



Profile picture for user Link555
Member for
14 years 2 months

Link555 Sun, 05/24/2020 - 07:11

And now repairing 8 dbx 900 series cards... 6 904 noise gates and 2 903 compressors.



One compressor was the worst off three funky opamps and one internally disconnected 20k threshold pot.

Profile picture for user Link555
Member for
14 years 2 months

Link555 Mon, 05/25/2020 - 20:30

Repairs done cards inserted and blank off panel made...tested and ready for pick up...

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