Ok all 5 channels work, but the sub channel has weak audio and measures 27.76 Volts DC on sub out terminals , all fets and drivers check to be ok in circuit
You stated that it has 27v DC and produces audio. Do you have a capacitor in series between the speaker and the amp or did it push the cone fully in/out when you connected the speaker?
When you checked the smaller transistors, did you just check to see if there were any reading 0 ohms?
You may have one leaking. Check them carefully. If one reads lower than you think it should, pull it out of the circuit and re-check it.
You may have one leaking. Check them carefully. If one reads lower than you think it should, pull it out of the circuit and re-check it.
Is the D718 transistor N-channel or P channel? and same question for B688 transistor those are the output mosfets
Neither is N or P-channel. These aren't FETs. The D718 is an NPN. The B688 is a PNP. They are both BJTs (Bipolar Junction Transistors -- or simply bipolar transistors).
both small transistors between output transistors...seem to check good checked several times and saw no leakage
Last edited:
ok , ... im checking one now, checks ok in ohms but what if number slowly increases in diode check?
These are two individual, matched transistors in one case. You test them like regular BJT transistors (I'm assuming that they're not FETs). Look up the datasheet for them. It will tell you what they are and the pin configuration.
I have the service manual for this amp as I have an identical unit sitting here waiting for me to give it CPR.
All of the FETs in the main power supply (bar one) are shorted. My guess is the owner has hooked the DC supply up backwards. There's nothing else I can think of that would cause so many devices to all short at once.
Anyway, if you need any info from the manual, just ask 🙂
All of the FETs in the main power supply (bar one) are shorted. My guess is the owner has hooked the DC supply up backwards. There's nothing else I can think of that would cause so many devices to all short at once.
Anyway, if you need any info from the manual, just ask 🙂
- Status
- Not open for further replies.