yamaha m 45 problem

[monsteramp]

hello everyone i wonder if someone on AK can share with me a shematic for a yamaha m 45 thanks for your help

best regards M.

 

[avionic]

What kind of problem are you having with the amp?

 

[monsteramp]

hello avionics

my problem is on the differential amplifier the voltage value of is output is 48 V instead of 0,6 v before the driver stage if you have a advice is welcome tanks for your post
best reagards M.

 

[avionic]

The differentials Q101 & 103 or Q102 & 104 should have 0.0 vdc on the bases & emitters and -58 vdc on the collectors.

 

[Jon_Logan]

+48VDC on the drivers? Are the NPN driver/outputs shorted B-C?? If no and the diffs are trying to DC balance the amp, you might look to the current source for the class A/gain transistor. The current source (typically) is a transistor near the B- rail where it's base is pushed up by a couple of diode drops. The emmiter resistor gets a diode drop across it, establishing a current. If the current source isn't there, you won't have anything to yank down on the collector of the class A transistor. This is general topology and doesn't cover fully complementary circuits or other designs i.e and their use of LED's in place of two/three diodes. You said Yamaha? Check for fuse resistors.

 

[avionic]

Monster
I have a service manual ..But not on pdf..Hardcopy..scanner is a nogo at this time.

 

[monsteramp]

thank you for your posts, after spend a lot of time in mesurments around the amp and unpluged the connector of the driver i find the error was around the first stage or it could be the bias stage control, until now i did this work without schematics cause i dont have, and i dont know how the circuit is made, i hope to fix it when i fund the shematic.
best regards M.

 

[cheltok]

Hi avionics

have you found the yamaha m-45 schematics??
i have some burn parts "fried chicken"
thanks in advance
cheltok

 

[avionic]

Best manuals money can buy.And reasonably priced. About $20 US
mike@vintageaudiomanuals.com

 

[cheltok]

Best manuals money can buy.And reasonably priced. About $20 US
mike@vintageaudiomanuals.com

nothing

i have check a lot of sites in internet... no lucky... ideas??

 

[audiozaz]

I beleive the Yamaha M-40 manual is widely available on the net and, as far as I know, is essentially the same as the M-45 aside for 5W less and not having power meters.

az

 

[cheltok]

I beleive the Yamaha M-40 manual is widely available on the net and, as far as I know, is essentially the same as the M-45 aside for 5W less and not having power meters.

az

Hi

the pcb it s completely different and very bad quality

thanks!!

 

[cheltok]

Monster
I have a service manual ..But not on pdf..Hardcopy..scanner is a nogo at this time.

who said harcopy???