I really miss my BGW 750 C-B and my 110 real work horses and very clean. My only repair in 25 years was the replacement of the triac in my 750 B and I never had a problem with my fans or transistors in all that time ....Just amazing amps especially in bridge mode....I tri amped my system and used JBL drivers 2225H lows E110 mids and 2405 bullet tweeters
Nice job fixing this one! Indeed a very silent fan! and because of the lower voltage the life duration of the fan wil be much better as wel! I wish you lived closer, would have love to bring in my Philips 686 Stereo Receiver to get it serviced by you! :-)
Nice job! I thought the fan should blow outward, so that it drew in fresh air from the top of the case over the heatsinks and exit out the back of the unit. Great idea to drum up some low voltage DC
Ooow and i thought you were going to put a capacitor in series with the original fan, but that new fan seems very quiet and works loverly :-D. I have loads of those flyback supplys, came with routers/modems and tv boxes :-).
For those who want an alternative solution, 2 of the thermal switches on the output transistors are for fan speed control. On the 2 units on worked on one of those switches was shorted. There is a resistor in series with the AC fan and the switch would short the resistor to run the fan at high speed. It is still noisy at low speed though so I replaced the fan with a quiet Papst I had around. Those Papst are expensive though and 12voltvids solution is cheaper and effective. Another thing I have seen is people assuming ball bearing fans are quieter, bushing fans are quieter.
Neat mod. For longevity purposes, I would of re-cap'd that adapter with a good Japanese 105C cap, cuz we know how crappy the caps in those adapters are and fail after a few years. Also for fan choice I'd went with a Noctua. But maybe I like to overkill :)
If somebody runs that kind of power in their rec room, they won't hear any fan... they'll become deaf! What kind of speaker systems do they hook up to it? Altec Lansing Voice of the Theatre? That'll rattle the neighbor's windows... a few blocks away, aye! Don
The owner is the same guy that owns the rotel cd changer, Haffler amps, and my old denon cd player. That's how I met him, and now I have become his guy to look after his cool toys. I'm sure if he let this thing and his 2 Haffler amps loose you would hear it in the next town. But seriously he doesn't crank them. He has all that power for "overhead" So when using these devices in a home theatre set up he doesn't want to hear fans running during quiet scenes.
I have a BGW 750E. It's toroidal tx is not ok at the primary winding. I need to replace it bt i don't understand it's specifications. Please advice on which tx to replace with. In Kenya we use 220-240vac.
Not sure if I would had upgraded components and started changing design characteristics at the same time. This is more a of a mod than a better parts swap. I wouldn't turn my fan around on my car radiator to force air through ,not even taking into consideration that this would compound the uninefficiency by using the added heat from the engine compartment. Also running that fan with a lower than recommend voltage should be done through a resistance controller. Then you can set the rpms at optimal levels without unnecessary drag on the motor. I would do a temperature assessment of components in operation. Those t-stat controls fail regularly but they were efficient in that run temperature was kept in a safely predetermined level.
Hello, I have two BGW 750c which I would like to bridge. Unfortunately, I can not find anything about it. Can you please tell me how I can bridge the power amp? Greetings and thank you, Thilo
The proper way to solve this noise problem would have been to install a lower wattage/lower CFM fan. They are available in all wattage levels and CFM's. That would have been a direct swapout without any added power problems.
The client asked for a "computer" fan. Yes I know you can get AC fans in different CFM, but they all make more noise than this one. It really wasn't a big deal. There was plenty of space to tuck the adapter down between the power transformer and the filter capacitors. They both move air, and a small DC fan is about 1/3 the cost of an AC fan. Remember this original setup used a modulated speed. So there are temperature sensors designed to run the fan at full speed if the unit gets too hot, and then turn it down to a slower speed, or off completely if it is cool. There was also a circuit that monitored the output level. When a high power demand came, the fan would ramp up full, and then drop. This was the annoying part of this design. Used in a home theatre, a loud sound effect would put the fan in full cool mode, or course after the effect has gone the fan is still running, and then slows down, and goes off. This modulating fan is very annoying. The solution, a constant quiet fan.
Didn't they use these kind of amps in theaters during the earthquake movie and massive Cerwin Vega folded horn subwoofers. Maybe someone out there knows.
Wouldn't a fan create electromagnetic noise inside the amplifier which would cause output noise? I recently bought a Cerwin Vega amp that cost me around 920 Canadian dollars with the current exchange rate. When powered on, I can hear a buzzing sound coming out of the speakers when sitting in my couch that is around 10 feet away. Sent it back for repair on warranty, but it still makes the same noise when I got it back a month later. I were told it is because of the fans and there is nothing to do about it. The fans themselves doesn't make noise, what does bother me is the speaker output noise. Hooking my scope up to the output I could see a signal that is around 100 Hz (probably rectified 50 Hz AC) and another signal that is about 15 times higher.
When I hooked this unit up off camera for test I didn't hear any noise. This is a small DC fan that isn't going to generate as much magnetic Flux as the original.
That's a very nice mod sir (sorry I don't know your name). Would you think the small adaptor would introduce any noise on the amplifier outputs? Or would it be negligible to none at best? Enjoy all your videos!
Shouldn't be any. It is a switcher supply. They run up around 70khz. Not tied to any amplifier circuits. Just the ac side. I buried the adapter along side the power transformer away from any audio circuits on the opposite side to the audio inputs.
Ah no problems. Thanks for the clarification. A cool idea indeed running a small switch mode supply in there. I personally wouldn't have thought to do that!
I think you went the easy way out of this fan :D - there is no thermostat or thermistor to control the rotation of the fan ? as they say, what a complicated life (say that stopgap endure the longest) I do not know how well I translated but in a good sense
I did what was asked by the client. He isn't an idiot an has done research. He brought it in and asked for a new improve quiet fan. This is what all the shops are doing. Back when this thing was made the only reliable fans were ac induction motors. BSL DC motors were not around. All DC motors of the day were brush type motors and they induce a lot of impulse noise. Now we have nice quiet DC BSL motors. You should think before you open your mouth and put your foot in it. I'm not the first one in this unit. The triac has been bypass before I saw it. That would have been done so the fan ran at full speed all the time as this came out of a night club. That would ha been because the temp sensor failed before that and the amp overheated and shut down. The temp detection on these units wasn't the best to begin with. That is why people put in a constant running quiet fan. Now the unit has good cooling all the time.
I do not call anyone an idiot, and my opinion you do not have to agree. - I am saying what I have observed and do not know it personally Well apparently not allowed to tell you anything (rough as you say so) " You should think before you open your mouth and put your foot in it. I'm not the first one in this unit." sorry but something I do not understand What are you up to target? if I said something to make fun of you? I do not think so and if I point to this passage! I suggested that a good solution would be to reduce noise of motor rotation the controller based on the thermistor (measuring system) with increasing temperature radiators increase in turnover of fan and that's it while the temperature is normal rotations are within 20% and already you can decide if you want to set up to 80% that was my message and you jumped that criticizes your work strange?... Always I see your content because they are interesting
When I see something like "you went the easy way out" that strikes me as a comment that I do not know what I am doing.Others already suggested the resistor, or changing to a lower CFM fan, the reason this was done is because the person paying me to do the mod specifically asked for a low voltage computer fan. Is it better than the original design? Not necessarily, as when the original fan is cranked up to full power it will move more air over the outputs for sure, but the problem with these units was all it takes is a small loud sound, such as a gunshot in an action movie, and the cooling system ramps up to full power for several seconds. That sound is unacceptable in a living room environment, so the previous owner disconnected the fan entirely. That is also unacceptable, as now the unit will over heat. What many do is disconnect the fan and run the unit with the top cover off, and transistors exposed. This is also unacceptable as there is 130V DC potential difference between the PNP and NPN transistor cases, and with the size of capacitors in this unit, there is enough current available to be fatal of someone contacted both power rails. So this mod is a solution that keeps the unit cool, it is still moving a good amount of air over the unit, and you can barely hear it in operation.
I really miss my BGW 750 C-B and my 110 real work horses and very clean. My only repair in 25 years was the replacement of the triac in my 750 B and I never had a problem with my fans or transistors in all that time ....Just amazing amps especially in bridge mode....I tri amped my system and used JBL drivers 2225H lows E110 mids and 2405 bullet tweeters
Nice job fixing this one! Indeed a very silent fan! and because of the lower voltage the life duration of the fan wil be much better as wel! I wish you lived closer, would have love to bring in my Philips 686 Stereo Receiver to get it serviced by you! :-)
The old fan was from the 80's, that little DC fan won't be around in 35 years.
Nice job! I thought the fan should blow outward, so that it drew in fresh air from the top of the case over the heatsinks and exit out the back of the unit. Great idea to drum up some low voltage DC
Nope that was the original design.
Ooow and i thought you were going to put a capacitor in series with the original fan, but that new fan seems very quiet and works loverly :-D.
I have loads of those flyback supplys, came with routers/modems and tv boxes :-).
For those who want an alternative solution, 2 of the thermal switches on the output transistors are for fan speed control. On the 2 units on worked on one of those switches was shorted. There is a resistor in series with the AC fan and the switch would short the resistor to run the fan at high speed. It is still noisy at low speed though so I replaced the fan with a quiet Papst I had around. Those Papst are expensive though and 12voltvids solution is cheaper and effective. Another thing I have seen is people assuming ball bearing fans are quieter, bushing fans are quieter.
Neat mod. For longevity purposes, I would of re-cap'd that adapter with a good Japanese 105C cap, cuz we know how crappy the caps in those adapters are and fail after a few years. Also for fan choice I'd went with a Noctua. But maybe I like to overkill :)
Great job. I like the mod. Good approach.
I've done that a few times with them small wall plugin power supplies too. Good idea I think.
Yes the reason for the separate power supply was to prevent any induced noise into the low voltage supply for the preamp.
If somebody runs that kind of power in their rec room, they won't hear any fan... they'll become deaf! What kind of speaker systems do they hook up to it? Altec Lansing Voice of the Theatre? That'll rattle the neighbor's windows... a few blocks away, aye! Don
The owner is the same guy that owns the rotel cd changer, Haffler amps, and my old denon cd player. That's how I met him, and now I have become his guy to look after his cool toys. I'm sure if he let this thing and his 2 Haffler amps loose you would hear it in the next town.
But seriously he doesn't crank them. He has all that power for "overhead"
So when using these devices in a home theatre set up he doesn't want to hear fans running during quiet scenes.
I have a BGW 750E. It's toroidal tx is not ok at the primary winding. I need to replace it bt i don't understand it's specifications. Please advice on which tx to replace with. In Kenya we use 220-240vac.
Not sure if I would had upgraded components and started changing design characteristics at the same time. This is more a of a mod than a better parts swap. I wouldn't turn my fan around on my car radiator to force air through ,not even taking into consideration that this would compound the uninefficiency by using the added heat from the engine compartment. Also running that fan with a lower than recommend voltage should be done through a resistance controller. Then you can set the rpms at optimal levels without unnecessary drag on the motor. I would do a temperature assessment of components in operation. Those t-stat controls fail regularly but they were efficient in that run temperature was kept in a safely predetermined level.
Not turned around. Still pressurising the cabinet but much quieter than original jet engine. Original fan far too noisy.
Why not just add resistance in line to reduce the voltage going to the fan?
Nice Mod.....Cheers!
Hello, I have two BGW 750c which I would like to bridge. Unfortunately, I can not find anything about it. Can you please tell me how I can bridge the power amp? Greetings and thank you, Thilo
That is what the "stereo-mono" switch is for. Put it in mono and hook your speakers to the 2 red binding posts.
Hot snot!! Ha ha ha! I never heard that before!
I have a BGW 750a that has a broken part that I cannot identify.... but you might be able to! could I send you a pic?
The proper way to solve this noise problem would have been to install a lower wattage/lower CFM fan. They are available in all wattage levels and CFM's. That would have been a direct swapout without any added power problems.
The client asked for a "computer" fan. Yes I know you can get AC fans in different CFM, but they all make more noise than this one. It really wasn't a big deal. There was plenty of space to tuck the adapter down between the power transformer and the filter capacitors. They both move air, and a small DC fan is about 1/3 the cost of an AC fan. Remember this original setup used a modulated speed. So there are temperature sensors designed to run the fan at full speed if the unit gets too hot, and then turn it down to a slower speed, or off completely if it is cool. There was also a circuit that monitored the output level. When a high power demand came, the fan would ramp up full, and then drop. This was the annoying part of this design. Used in a home theatre, a loud sound effect would put the fan in full cool mode, or course after the effect has gone the fan is still running, and then slows down, and goes off. This modulating fan is very annoying. The solution, a constant quiet fan.
Didn't they use these kind of amps in theaters during the earthquake movie and massive Cerwin Vega folded horn subwoofers. Maybe someone out there knows.
Yes this is the amp used.
Wouldn't a fan create electromagnetic noise inside the amplifier which would cause output noise? I recently bought a Cerwin Vega amp that cost me around 920 Canadian dollars with the current exchange rate. When powered on, I can hear a buzzing sound coming out of the speakers when sitting in my couch that is around 10 feet away. Sent it back for repair on warranty, but it still makes the same noise when I got it back a month later. I were told it is because of the fans and there is nothing to do about it. The fans themselves doesn't make noise, what does bother me is the speaker output noise. Hooking my scope up to the output I could see a signal that is around 100 Hz (probably rectified 50 Hz AC) and another signal that is about 15 times higher.
When I hooked this unit up off camera for test I didn't hear any noise. This is a small DC fan that isn't going to generate as much magnetic Flux as the original.
That's a very nice mod sir (sorry I don't know your name). Would you think the small adaptor would introduce any noise on the amplifier outputs? Or would it be negligible to none at best? Enjoy all your videos!
Shouldn't be any. It is a switcher supply. They run up around 70khz. Not tied to any amplifier circuits. Just the ac side. I buried the adapter along side the power transformer away from any audio circuits on the opposite side to the audio inputs.
Ah no problems. Thanks for the clarification. A cool idea indeed running a small switch mode supply in there. I personally wouldn't have thought to do that!
Can i change my amplifier fan wich has led?
Might have been easier to use those fat screws for mounting pc fans into cases. Either way good video..
I would have to spend more time looking for screws than sticking down the original clips.
I think you went the easy way out of this fan :D
- there is no thermostat or thermistor to control the rotation of the fan ?
as they say, what a complicated life
(say that stopgap endure the longest) I do not know how well I translated but in a good sense
I did what was asked by the client. He isn't an idiot an has done research. He brought it in and asked for a new improve quiet fan. This is what all the shops are doing. Back when this thing was made the only reliable fans were ac induction motors. BSL DC motors were not around. All DC motors of the day were brush type motors and they induce a lot of impulse noise. Now we have nice quiet DC BSL motors. You should think before you open your mouth and put your foot in it. I'm not the first one in this unit. The triac has been bypass before I saw it. That would have been done so the fan ran at full speed all the time as this came out of a night club. That would ha been because the temp sensor failed before that and the amp overheated and shut down. The temp detection on these units wasn't the best to begin with. That is why people put in a constant running quiet fan. Now the unit has good cooling all the time.
I do not call anyone an idiot, and my opinion you do not have to agree.
- I am saying what I have observed and do not know it personally
Well apparently not allowed to tell you anything (rough as you say so)
" You should think before you open your mouth and put your foot in it. I'm not the first one in this unit."
sorry but something I do not understand What are you up to target?
if I said something to make fun of you?
I do not think so and if I point to this passage!
I suggested that a good solution would be to reduce noise of motor rotation the controller based on the thermistor (measuring system) with increasing temperature radiators increase in turnover of fan and that's it while the temperature is normal rotations are within 20% and already you can decide if you want to set up to 80%
that was my message and you jumped that criticizes your work strange?...
Always I see your content because they are interesting
When I see something like "you went the easy way out" that strikes me as a comment that I do not know what I am doing.Others already suggested the resistor, or changing to a lower CFM fan, the reason this was done is because the person paying me to do the mod specifically asked for a low voltage computer fan. Is it better than the original design? Not necessarily, as when the original fan is cranked up to full power it will move more air over the outputs for sure, but the problem with these units was all it takes is a small loud sound, such as a gunshot in an action movie, and the cooling system ramps up to full power for several seconds. That sound is unacceptable in a living room environment, so the previous owner disconnected the fan entirely. That is also unacceptable, as now the unit will over heat. What many do is disconnect the fan and run the unit with the top cover off, and transistors exposed. This is also unacceptable as there is 130V DC potential difference between the PNP and NPN transistor cases, and with the size of capacitors in this unit, there is enough current available to be fatal of someone contacted both power rails. So this mod is a solution that keeps the unit cool, it is still moving a good amount of air over the unit, and you can barely hear it in operation.
What mm size is the new fan?
Same size as original 4"
please talk about bgws subwoofers M2200 speakers ? thanks
I got swr 400 working pro amp with loud fan does anyone know what quiet fan I can replace it with? Thank you!!!!
First