sae-7125
Super Member
dusting off the amp and achieving a stable pulse under controlled conditions. why did they decide an oddball fuse size (physical) was a good idea (agx-8).
found a schematic and basic info on a few sites including ak but still hunting for a service manual that isnt behind a paywall (sites selling documents) or another forums registration barrier.
dc bias was mentioned to be around 325mv measured across a 10r resistor amongst the moderate mess soldered to the output devices. on the small board mounted to the heat sink rear of the chassis i am noticing 3k 3w power resistors instead of 3k 5w as stated on the schematic. this amp has a serial number a couple numbers below 1600, wonder if there were a few versions/revs of this model.
so the journey begins with fuse shopping and some cleaning while determining possible design quirks to update. other sources have indicated unbundling the wire harness due to noise bleed of parallel conductors and converting the system to a star ground wiring scheme. also some talk about adjusting a resistor value from 680r to 860r or 1k in regards to bias circuit.
the class-b design is nice due to its natural high efficiency but crossover distortion at low volume levels is common. bumped into the "pink floyd way" of cooling the amp by packing the heat sink with dry ice, i have no idea how accurate that description might be. other than the commonly held title of "flames linear" and a few other metaphorical variances this brand of pre carver corp amplifiers has a pyrolytic history with consumers.
i am using a normal length 7a fuse as a temporary fast blow alternative to evaluate slow power up activity of the amp (variac plus dim bulb). so far things seem functional with mains dialed up to 110v. currently have bias at minimum to reduce initial load factor on the power supply even though this is class-b. display board needs some updates since the dancing red dots are a little bit cross-eyed/stuck with or without signal applied. 8r test speakers used with the high-z mode, looks like lower dc bus voltage if using low-z after reading up about the two different dc bus modes (125 vs 80).
the heavy monster amp, back when an all metal chassis was the norm.
rats nest plus umbilical of noise potential.
rear pcb, at least its easy to service.
reminds me of last years sae amp.
found a schematic and basic info on a few sites including ak but still hunting for a service manual that isnt behind a paywall (sites selling documents) or another forums registration barrier.
dc bias was mentioned to be around 325mv measured across a 10r resistor amongst the moderate mess soldered to the output devices. on the small board mounted to the heat sink rear of the chassis i am noticing 3k 3w power resistors instead of 3k 5w as stated on the schematic. this amp has a serial number a couple numbers below 1600, wonder if there were a few versions/revs of this model.
so the journey begins with fuse shopping and some cleaning while determining possible design quirks to update. other sources have indicated unbundling the wire harness due to noise bleed of parallel conductors and converting the system to a star ground wiring scheme. also some talk about adjusting a resistor value from 680r to 860r or 1k in regards to bias circuit.
the class-b design is nice due to its natural high efficiency but crossover distortion at low volume levels is common. bumped into the "pink floyd way" of cooling the amp by packing the heat sink with dry ice, i have no idea how accurate that description might be. other than the commonly held title of "flames linear" and a few other metaphorical variances this brand of pre carver corp amplifiers has a pyrolytic history with consumers.
i am using a normal length 7a fuse as a temporary fast blow alternative to evaluate slow power up activity of the amp (variac plus dim bulb). so far things seem functional with mains dialed up to 110v. currently have bias at minimum to reduce initial load factor on the power supply even though this is class-b. display board needs some updates since the dancing red dots are a little bit cross-eyed/stuck with or without signal applied. 8r test speakers used with the high-z mode, looks like lower dc bus voltage if using low-z after reading up about the two different dc bus modes (125 vs 80).
the heavy monster amp, back when an all metal chassis was the norm.
rats nest plus umbilical of noise potential.
rear pcb, at least its easy to service.
reminds me of last years sae amp.
