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stargazer76 · 06-19-2009, 01:48 PM

The unfortunate thing about these 900's is the use of these dang op-amps! When all is working well, everyone is happy. But when something fails, and it's determined that it's NOT something routine, like tubes, fuses, or maybe a resistor or cap, then you must start considering the possibility of a faulty op-amp. These modern marvels are pretty reliable devices, but when bad can be tough to track down in these amps. The 900-4100 DR has 8 of these buggers, most of which are dual-sided. Channel A using one side and channel B the other through the switching circuit. Input voltage is both +15 and -15vdc supplied from BR1, D3 and D4(zeners). Inputs and outputs are critical to normal operation, and they are very susceptible to static electricity. Not to mention they are troublesome to remove and replace. Take this amp to a Tech who is competent with hybrid and SS amps.

06-19-2009, 01:48 PM	#9 (permalink)
stargazer76 Member Join Date: Mar 2008 Location: Dallas, Texas Posts: 42	Re: Jcm900 problems... Help needed! The unfortunate thing about these 900's is the use of these dang op-amps! When all is working well, everyone is happy. But when something fails, and it's determined that it's NOT something routine, like tubes, fuses, or maybe a resistor or cap, then you must start considering the possibility of a faulty op-amp. These modern marvels are pretty reliable devices, but when bad can be tough to track down in these amps. The 900-4100 DR has 8 of these buggers, most of which are dual-sided. Channel A using one side and channel B the other through the switching circuit. Input voltage is both +15 and -15vdc supplied from BR1, D3 and D4(zeners). Inputs and outputs are critical to normal operation, and they are very susceptible to static electricity. Not to mention they are troublesome to remove and replace. Take this amp to a Tech who is competent with hybrid and SS amps. __________________ JCM 900-4100 JCM 800-2204 1960A/G12T75 1962RI Stratocaster