The FX90 always used an analog MN3005 BBD chip, the same chip used in the first version of the Boss DM-2 Delay. We have found that the FX90 can be easily coaxed into self-oscillation, if the Mix and Repeat knobs are turned up high enough, without having to tweak any of its three internal trim pots. DOD produced the FX90 into the 1990s, well after their DFX9 Digital Delay was introduced, but it was discontinued by early 1993.The DOD FX90 is closer in design to the first version of the Boss DM-2

Technical info:

Specifications (from the manual): Input impedance = 500 k Ohms; Output impedance = 4.7 k Ohms; Gain = 0 dB; Band Width = 30 Hz to 25 kHz (dry), 30 Hz to 1.3 kHz (delay)

Notable IC chips: one MN3005 4096-stage BBD chip driven by a MN3101 clock generator/driver CMOS chip; one NE570N compander; and one misc op amp tied into the Mix control (early models always used a TL022CP, while later models used a LM1458N, a TL022CP, or a TL062CP)

Internal trim pots: three; however, we do not recommend messing with trim pots

Check out my other listings for more cool vintage, boutique, DOD, Delay, and other guitar pedals! Any other pictures needed or questions please ask!

I'm trying to avoid from instituting a no refund policy on vintage gear, so other than guaranteeing that it will not be DOA, ANY return on vintage gear is an automatic 15% restock fee. Any questions, please ask.