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DOD FX90 rev H schematic?

Started by lars, January 09, 2019, 05:35:47 AM

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lars

I have searched pretty much everywhere, and cannot find any of the revision schematics for the DOD FX90. After the initial version, it went through several significant revisions. The particular version I have is from 1987, revision "H". It is quite a bit different circuit-wise than the schematic everybody (and their grandma) posts as "the FX90 schematic". Mine uses an input buffer and a 1458 op amp, and has no capacitors larger than 10uf. The DC circuit is actually more like the DOD 585, with a jfet-regulated input. It also has a different circuit layout than the pervasive "1985" version. I've seen pictures of the FX90 board I have all over the place; it's very common; so the lack of a correct schematic for it is puzzling.
Does anybody happen to have any of the revision schematics for the FX90? (I'll post a pic of the one I definitely do not need)


lars

A fellow beaner provided the correct schematic; thanks! (it was from a site that doesn't pop up on any search results for the FX90; part of the hidden, useful Internet that's buried under the Google Internet).  And yes, the Rev H is very different than the heavily-regurgitated Rev A schematic.

artstomp

Hi lars...i've got 2 diff vintage DOD90...one is working the other has dry signal but no delay...they have different trannys and capacitors value...i think i might need the schematic...would you mind posting it here or you can send it to my email...vidworks@yahoo.com
Thank you

madbean

Does anyone still have the RevH schem? I have a revF board and I want to compare what the differences are (and also to know if I need to do a full trace on it).

artstomp

Hi Brian..i still have the H schem sent by jMoreno...

madbean

Quote from: artstomp on November 24, 2020, 01:11:03 AM
Hi Brian..i still have the H schem sent by jMoreno...

Thank you!

The FX90 is definitely going to be a thing in the near future here. I bought 3 of them about a decade ago. One for $27! I got all of them out today and realized I never pulled the MN3005 out of two of them. But, after I plugged them in again I realized they actually have something pretty cool going on (despite their barely working condition). So, some new analog delay is on the horizon.

artstomp

Yes!!!.looking forward to madbean's fx90 release!..thnx in advance