I own (2) PA-250 FOSGATE branded amps, one with the original box/wires and 2 knob pre amp box. I also own one that came with a PR 2100pre amp only. I also own a PR-2100 Type II EQ box. The EQ boxes all appear to operate fine. One PA-250 WORKS but only on ONE channel sadly. I notice the IC chip FE133, upon operation ONE of them gets HOT, the other no real heat. Other than that I cannot find any other noticeable defects. MY OTHER PA-250 Has an EXPLODED.... 68k 16v, "TICK".... I think thats a Capacitor. Sorry I am Extremely Dangerous, I know that little. Regardless, I have these and hope to one day see them operate once again in 2022. It pleases me that I see Perry Babin here in this thread as I have intentions of purchasing that amplifier course. Glad to see these amps might have some HOPE. Be in touch, BDBD//2022
Hi, one more thing, I would like to use these EQ boxes on OTHER THAN Fosgate amps. FOSGATE Amps I remember from the past as being a bit of a crap shoot but the EQ sections appear rock solid and sound very nice even today. I notice a 18 volt voltage supply to them from the AMP... 18 volts?.... I wonder if these would operate on 14.3 volts. Also where to start... How to power these up somehow. Once I figure out how to power em up I gonna do the DIN CABLE thing..... Have not soldered any DIN CABLES since the late 80's It seems.... hmmmmmm. BDBD/2022
These processors require a bipolar voltage from the amp's power supply via the DIN. It's actually +18V on one leg and -18V on the other. Fosgate, PPI, Orion all used the format back in the old days, though the other two brands used +/-15V.
Regular +14V and ground won't work.
Regular +14V and ground won't work.
Correct. I used to do a couple things to make these amps reliable. One, drop the 18 V rails to 15 volts. Replace the exploded tantalum with the highest rated voltage tantalum capacitor you can. Drill and tap the mounting holes in the heat sinks to 4-40 screws. You may have to replace the power transistors as the case flexes a lot and the leads break. Changing to a 4-40 screw makes the case solid.
I can't tell you how many I rebuilt back in those days. I learned early that the flimsy cases were a basic reliability issue, that tantalum another. Other enhancements were changing the op amp to something good, and using a resistor to provide bias for the bias network instead of drawing it from the op amp. These designs were designed to be cheap, you an really improve them by putting just a little work in. Remember, they saved every component they could, and every manufacturing step. Other amplifiers of that era used either 4-40 screws or M3 screws (about the same).
I can't tell you how many I rebuilt back in those days. I learned early that the flimsy cases were a basic reliability issue, that tantalum another. Other enhancements were changing the op amp to something good, and using a resistor to provide bias for the bias network instead of drawing it from the op amp. These designs were designed to be cheap, you an really improve them by putting just a little work in. Remember, they saved every component they could, and every manufacturing step. Other amplifiers of that era used either 4-40 screws or M3 screws (about the same).
Hi JTFX,
I can't remember all the model numbers that Fosgate used. I worked on so many they could surface just about anywhere! Fosgate very probably changed to 4-40 screws as the ones they used were useless in keeping the case from flexing. They were self-tap and maybe #2 screws. I saw them stripped and loose / missing often enough.
I removed and cleaned the heat sinks, drilled and tapped plus deburred. So one I did would look neat and factory I guess. The tantalum in the supply would have been an Electrolytic, or a much higher voltage Tantalum. They would literally split and burn leaning soot on the PCB and adjacent components. I also moved the driving tap on the diodes in the output section to the mid-point and add a resistor to the other rail. The op amp then drove a balanced load. I can't remember which op amps I was using, probably a J-Fet input as they were faster and less noisy. I always cleaned the flux off as well.
I can't remember all the model numbers that Fosgate used. I worked on so many they could surface just about anywhere! Fosgate very probably changed to 4-40 screws as the ones they used were useless in keeping the case from flexing. They were self-tap and maybe #2 screws. I saw them stripped and loose / missing often enough.
I removed and cleaned the heat sinks, drilled and tapped plus deburred. So one I did would look neat and factory I guess. The tantalum in the supply would have been an Electrolytic, or a much higher voltage Tantalum. They would literally split and burn leaning soot on the PCB and adjacent components. I also moved the driving tap on the diodes in the output section to the mid-point and add a resistor to the other rail. The op amp then drove a balanced load. I can't remember which op amps I was using, probably a J-Fet input as they were faster and less noisy. I always cleaned the flux off as well.