Hello this is my first post,long time reader and need help. I'm working on a marantz 2226b with a build date of 11-30-1977. I picked this up used and thought I would try to get it working correctly. First the fuse 704 was open and no illumination bulbs worked.replaced fuse with correct one and now all bulbs light up except one,upon closer inspection previous owner replaced the 5 fuse bulbs with regular automotive type ge168 bulbs,and one of the tuning strength bulbs with something wrong. Maybe these bulbs explain a blown fuse 704??? This is not the main concern but I wanted to mention it as you never know when things are related
It powers up and plays but with distortion noticed if you try to turn it up much at all,fm tuner barely works can only tune in to three stations and with a slight hum noticed only on fm mode,I tried to adjust per the manual from hifiengine dc offset on both channels fluctuate around 3.0mv to 7.0mv,,there is no or barely any bias voltage. When trying to adjust power supply and checking on pins j708+ and j715-,,,,I get about 25 volts and it should be 35.0 volts,,moving vr pot to Max only takes it to about 29 volts
Another problem I notice is that r776 is getting very very hot,,Its a big 100 ohm 5 watt ceramic resistor,,I checked the current it was dissapating from stuff I learned here;;voltage on one side 43.64,voltage on other side 8.48volts=35.5 volts difference by 100ohm=12.36watts on a 5watt resistor..please correct me if I did not do that correctly
Also please understand I am not an electronic specialist,,I am a ex Ford dealer tech,I specialize in ford only automatic transmissions,,with a pretty good background in automotive electronics,,I am slowly learning this stuff and I am very interested in learning for my own self,I appreciate any and all help I can get
I did some voltage and resistance checks as follows;;;in circuit
R775 22ohm=good,,checked dc voltage about 43 volts on both sides of resistor
R778 1.5k=good,,34volts one side 25on the other side of resistor
R777 1.5k=good,,34 volts on one side and 43 on the other side
R779 3.87k=good,,,9 volts on one side 24.9 on the other
Checked voltage at diode 748==9volts other side 0 volts dc
Checked q746 b=25.3,c=43.0,e=24.6
Should be b=35.6,c=43,e=35
Checked q747,,,b=10.5,c=25.6,e=9.9
I only new to check these things based on another similar thread where the p/s voltage was too high!!
Please help me out,any and all help appreciated,,sincerely Rob
It powers up and plays but with distortion noticed if you try to turn it up much at all,fm tuner barely works can only tune in to three stations and with a slight hum noticed only on fm mode,I tried to adjust per the manual from hifiengine dc offset on both channels fluctuate around 3.0mv to 7.0mv,,there is no or barely any bias voltage. When trying to adjust power supply and checking on pins j708+ and j715-,,,,I get about 25 volts and it should be 35.0 volts,,moving vr pot to Max only takes it to about 29 volts
Another problem I notice is that r776 is getting very very hot,,Its a big 100 ohm 5 watt ceramic resistor,,I checked the current it was dissapating from stuff I learned here;;voltage on one side 43.64,voltage on other side 8.48volts=35.5 volts difference by 100ohm=12.36watts on a 5watt resistor..please correct me if I did not do that correctly
Also please understand I am not an electronic specialist,,I am a ex Ford dealer tech,I specialize in ford only automatic transmissions,,with a pretty good background in automotive electronics,,I am slowly learning this stuff and I am very interested in learning for my own self,I appreciate any and all help I can get
I did some voltage and resistance checks as follows;;;in circuit
R775 22ohm=good,,checked dc voltage about 43 volts on both sides of resistor
R778 1.5k=good,,34volts one side 25on the other side of resistor
R777 1.5k=good,,34 volts on one side and 43 on the other side
R779 3.87k=good,,,9 volts on one side 24.9 on the other
Checked voltage at diode 748==9volts other side 0 volts dc
Checked q746 b=25.3,c=43.0,e=24.6
Should be b=35.6,c=43,e=35
Checked q747,,,b=10.5,c=25.6,e=9.9
I only new to check these things based on another similar thread where the p/s voltage was too high!!
Please help me out,any and all help appreciated,,sincerely Rob