This amp showed up on my stoop with the right channel being dead.
Got another project nearing completion. I tore open the Crown Macro Reference amp open to diagnose the right channel "In Protection" Issue. It had 3 original issue output transistor decided to say screw it and fail with a BE short. The same channel had been "Worked On" before and failed again so I looked a little deeper and found the -15 regulator getting hot which was caused by the 2 resistors in that circuit which are 200 ohm 1/2 watt resistors changing values over the years. One was 90 ohms and the other was 140 ohms. I replaced the resistors with 2 new ones, installed a new 7915CT regulator IC, and doubled up the heat sink along with the fresh thermal compound which had dried up and flaked off. I ordered new outputs and they are out for delivery along with the pre-driver IC's. I'm not one to just find the bad culprits o it is getting 12 new MJ21196G's and 12 new MJ21195G's. I pulled all the heatsinks and put new whale spooge on them, along with the dual Power Supply regulators. All the old stuff has dried out and losing it's mojo. It took me hours to get all the goo out of the holes for the outputs in the heatsinks on both channels. On the control board I cleaned up all the old flux after the resistor and +- 15 volt regs, rework. This amp is a lot easier to work on than the Krell amp being the Crown has an AWESOME Owners/Service Manual. I used MJ21195/96 which have a lower current gain (hfe) but has a higher working voltage. The originals are MJ15003/4 which has a higher current gain but a lower SOA. The originals have a 140 volt rail swing whereas the 95/96's are good for a 250V swing. I'll have to look at the topology of the amp which has a High Side Low Side output transistors so only half of the 12pnp/12npn outputs are working at low listening levels. Maybe one of you experts can chime in as to what you think about the MJ15003/4 and MJ21195/6 swap. I guess I need to look at the plus and minus rails of the power supply to see if it was a good move. The output transistors get soldered in so it's easier to make the decision now. JOE!!!!!!!
I don't know if any of you know anything about these Crown Macro Reference amps but they have a P.I.P. (Programmable Input Programmer) module which plugs into the back of the amp and gives you the ability to tailor the amp to your own preferences. This one has the newest module in it which is a FPX model and that gives you many switchable options to be able to use XLR Balanced Input, RCA input (Quasi Balanced or Single Ended switchable) and the ground lift in case the 3 prong power cord is giving ground loop hum. I guess that helps when you have a preamp with a 2 prong power cord. Most of these amps had 1/4" Jacks on the back for input like some PL 700's, so with this PIP, you no can do 1/4" jacks, XLR Balanced OR RCA inputs. Pretty versatile. I'm anxious to hear it to compare to my WOPL's. It's a pretty rare amp and maybe I'll keep it and pare down to 2 WOPLS. This amp would be handy if it sounds good because I can power 2 sets of speakers down to 2 ohms and the amp will take pretty much what you throw at it. It has the Mono switch on it too but it is nearly impossible to find another one of these to get crazy. This amp, in this configuration, was $4000 with this version of PIP. Its not a real "Looker" but that helped the bean counters keep the price down. It's rated to 760 WPC into 8 ohms, 1160 at 4 ohms, and 1500 into 2 ohms. Switch to mono in either bridged or parallel and that ups the ante to stupid levels. It had VERY good reviews and was seen to be quiet and powerful. This model came with 2 filters on the front and a temp activated fan which is reported to be pretty quiet so you'll hear nothing until the heat builds up, the fan kicks in, and it'll be so fuckin loud you won't hear the fan anyway. The front panel has a switch which controls the backlighting of the "Crown" logo (On or off) and it has GREEN BACKLIGHT!!! My fav.
Pictures to follow shortly.
Let me know what you think about the Output Trans choice.
Got another project nearing completion. I tore open the Crown Macro Reference amp open to diagnose the right channel "In Protection" Issue. It had 3 original issue output transistor decided to say screw it and fail with a BE short. The same channel had been "Worked On" before and failed again so I looked a little deeper and found the -15 regulator getting hot which was caused by the 2 resistors in that circuit which are 200 ohm 1/2 watt resistors changing values over the years. One was 90 ohms and the other was 140 ohms. I replaced the resistors with 2 new ones, installed a new 7915CT regulator IC, and doubled up the heat sink along with the fresh thermal compound which had dried up and flaked off. I ordered new outputs and they are out for delivery along with the pre-driver IC's. I'm not one to just find the bad culprits o it is getting 12 new MJ21196G's and 12 new MJ21195G's. I pulled all the heatsinks and put new whale spooge on them, along with the dual Power Supply regulators. All the old stuff has dried out and losing it's mojo. It took me hours to get all the goo out of the holes for the outputs in the heatsinks on both channels. On the control board I cleaned up all the old flux after the resistor and +- 15 volt regs, rework. This amp is a lot easier to work on than the Krell amp being the Crown has an AWESOME Owners/Service Manual. I used MJ21195/96 which have a lower current gain (hfe) but has a higher working voltage. The originals are MJ15003/4 which has a higher current gain but a lower SOA. The originals have a 140 volt rail swing whereas the 95/96's are good for a 250V swing. I'll have to look at the topology of the amp which has a High Side Low Side output transistors so only half of the 12pnp/12npn outputs are working at low listening levels. Maybe one of you experts can chime in as to what you think about the MJ15003/4 and MJ21195/6 swap. I guess I need to look at the plus and minus rails of the power supply to see if it was a good move. The output transistors get soldered in so it's easier to make the decision now. JOE!!!!!!!
I don't know if any of you know anything about these Crown Macro Reference amps but they have a P.I.P. (Programmable Input Programmer) module which plugs into the back of the amp and gives you the ability to tailor the amp to your own preferences. This one has the newest module in it which is a FPX model and that gives you many switchable options to be able to use XLR Balanced Input, RCA input (Quasi Balanced or Single Ended switchable) and the ground lift in case the 3 prong power cord is giving ground loop hum. I guess that helps when you have a preamp with a 2 prong power cord. Most of these amps had 1/4" Jacks on the back for input like some PL 700's, so with this PIP, you no can do 1/4" jacks, XLR Balanced OR RCA inputs. Pretty versatile. I'm anxious to hear it to compare to my WOPL's. It's a pretty rare amp and maybe I'll keep it and pare down to 2 WOPLS. This amp would be handy if it sounds good because I can power 2 sets of speakers down to 2 ohms and the amp will take pretty much what you throw at it. It has the Mono switch on it too but it is nearly impossible to find another one of these to get crazy. This amp, in this configuration, was $4000 with this version of PIP. Its not a real "Looker" but that helped the bean counters keep the price down. It's rated to 760 WPC into 8 ohms, 1160 at 4 ohms, and 1500 into 2 ohms. Switch to mono in either bridged or parallel and that ups the ante to stupid levels. It had VERY good reviews and was seen to be quiet and powerful. This model came with 2 filters on the front and a temp activated fan which is reported to be pretty quiet so you'll hear nothing until the heat builds up, the fan kicks in, and it'll be so fuckin loud you won't hear the fan anyway. The front panel has a switch which controls the backlighting of the "Crown" logo (On or off) and it has GREEN BACKLIGHT!!! My fav.
Pictures to follow shortly.
Let me know what you think about the Output Trans choice.
