First off , thanks for your Positive response, I feel a bit more reassured that it can be brought back to life.The L and R channel amp boards are the same. The L amp is rotated half a turn so that the adjustment pots are to the bottom side whereas they are on top side for the R channel. The service manual call them the P750 board.
Did the Tech say what is wrong with the L channel board? If the board is not damage, repairing it would be the way to go. The output transistors are mounted on the heat sinks. You can buy replacements for those. The transistors, capacitors and resistors on the board are replaceable. Did he check the output transistors?
The early 2270 use the same design running at 47 vdc vs. 37 vdc for the 2245. Some of the components are different values like resistors. I think you need to stay with a 2245 board if you buy a used board. Others may know for sure about alternates.
Perhaps the mica insulator is what he was talking about, keep in mind I don't know what I'm talking about. As for tech's in town here not knowing where to find 40 yr old replacement parts I would imagine they may or may not have the connections like you guys here on this Great Forum.Not sure what he's talking about if it's actually the outputs he is discussing. They are mounted on the heat sinks with mica insulators under them the same way pretty much all audio output transistors are mounted. And replacements for the outputs are readily available, and I would think any qualified tech would know that.
On a 2245, the output transistors plug in. Remove two screws on each one and it will slide out to be tested and/or replaced. It's best to test transistors out of circuit. Here is a thread by the esteemed Echowars that is a tutorial on transistor testing.Perhaps the mica insulator is what he was talking about, keep in mind I don't know what I'm talking about. As for tech's in town here not knowing where to find 40 yr old replacement parts I would imagine they may or may not have the connections like you guys here on this Great Forum.
I've been researching on this site and its amazing what I'm finding/learning.
Was wondering though how do you test transistors when they are soldered into a board if there connected into a circuit board? This is really getting exciting.
Yes , there is no click but even with more volume did not give sound.You originally said there was no relay click, right? This does not sound like an issue with the relay its self.
The only issue that is common with a relay is dirty contacts. It clicks in but cuts out or takes some volume before the sound cuts in.
Not sure why they would suspect the relay then. The only reason the relay its self would be responsible for it not clicking would be physical damage. Not likely if no one messed with between it working and not working. And easy to rule out by putting an ohm meter across the coil. Likely reasons for no relay click are a bad power supply voltage, issue with power amp, or issue with protection circuit.Yes , there is no click but even with more volume did not give sound.
I agree that Relay is probably good. I'm hoping with the Marantz service and parts manual pdf's I emailed them they can narrow down the issue. If the left side output amp is warm and right side output amp is cold while powered up ( as the tech said ) would that indicate anything definative?Not sure why they would suspect the relay then. The only reason the relay its self would be responsible for it not clicking would be physical damage. Not likely if no one messed with between it working and not working. And easy to rule out by putting an ohm meter across the coil. Likely reasons for no relay click are a bad power supply voltage, issue with power amp, or issue with protection circuit.
Depends how hot. Sounds like the bias is off. Have they checked that? If it is very high that could indicate an issue. If just a little bit high it could just need adjustment. Also would check DC offset coming at the output pin on the amp boards.I agree that Relay is probably good. I'm hoping with the Marantz service and parts manual pdf's I emailed them they can narrow down the issue. If the left side output amp is warm and right side output amp is cold while powered up ( as the tech said ) would that indicate anything definative?