Marantz 510m & 3800 Preamp

[jefferylhenr]

As fate would have it I came across an estate liquidation and ended up with 3 - 510m’s, 1 - 250m and 2 - 3800’s in virtually museum condition. Clean and not a mark on them.

They had minimal issues besides a couple rattling fans. So the power up and go through began. Adjusting bias, DC offsets, fan replacements and the testing and checkouts.

Who ever thinks this gear is middle of the road is lacking in faculties. They sounded absolutely fantastic in original form. However, given the age and random parts testing, I have mostly recapped and restored the lot while addressing service bulletins. I have the IC upgrade parts for the 3800’s but haven’t gotten to that yet.

With proper speakers and source materiel, I am still beyond amazed by the sound..

So why all the naysayers?

 

[jefferylhenr]

The challenges of the beautiful multiple layered blue boards

 

[jefferylhenr]

Built like tanks and not easy to work on.

 

[TomInKY]

I have the same setup along with the 125 tuner. I'm trying to figure out how to remove the 4 knobs off the front panel of the 510M amp. I thought it would simply take an allen wrench, but having no luck at all finding anything that works. Anyone willing to give a guy some help? Thanks in advance. Tom

 

[jefferylhenr]

I have the same setup along with the 125 tuner. I'm trying to figure out how to remove the 4 knobs off the front panel of the 510M amp. I thought it would simply take an allen wrench, but having no luck at all finding anything that works. Anyone willing to give a guy some help? Thanks in advance. Tom

Turn it upside down and take a look. Get some lube into the threads. Use a mag glass if needed. I will take a look at mine. Why do you want to take them off? I rebuilt my entire unit including bulbs an don’t remember taking the front panel off.

 

[TomInKY]

Well, haven't had it long. It sounds great. But, I noticed I had to turn the right gain knob up a bit to make it equal to the left per the meter. As I look at the knobs now, they are both in the exact same position in either the on or off positions. So, apparently the knobs are in the proper place and it's something else. Thanks for the reply. Any suggestions?

 

[TomInKY]

Turn it upside down and take a look. Get some lube into the threads. Use a mag glass if needed. I will take a look at mine. Why do you want to take them off? I rebuilt my entire unit including bulbs an don’t remember taking the front panel off.

I found another older thread here on AK, but the posts died-out and I don't know if the same issue got resolved. I have a right channel that is lower output than the left. I first thought maybe the knobs were not on right, but they are. However, it looks like they may have to come off anyway for a fix. I'd still like to know how they come off, even if I take this unit to my tech.

 

[jefferylhenr]

I found another older thread here on AK, but the posts died-out and I don't know if the same issue got resolved. I have a right channel that is lower output than the left. I first thought maybe the knobs were not on right, but they are. However, it looks like they may have to come off anyway for a fix. I'd still like to know how they come off, even if I take this unit to my tech.

I will take a look

 

[damacman]

(3) 510s? OMG man.

Personally, I've never heard a bad word on any of these units, tuners included.

 

[TomInKY]

Ok, to those I pestered trying to figure out how to get the 4 front knobs off the 510M, I apologize. Went to the Depot and upgraded my allen key collection. Turns out the knobs on the 510M require a 5/64" SAE hex key. The problem I have with my "trio" of separates, being the 510M amp + 3800 preamp + 125 tuner is the right channel is weaker, according to the right channel meter. I have to turn the right gain knob up about 1/4" or so to balance out the sound and meters. I wanted to check the knobs to make sure they were on right. Guess I'll leave it to my tech, beyond my abilities, but I am curious as to cause.

With separates that each have a way to adjust the volume, should the preamp & tuner be set to max and then use amp for main volume control? Is there a proper/safe way to do it, just as there is in which order you turn each separate on and off?

Thanks.

 

[Coolhandjjl]

Ok, to those I pestered trying to figure out how to get the 4 front knobs off the 510M, I apologize. Went to the Depot and upgraded my allen key collection. Turns out the knobs on the 510M require a 5/64" SAE hex key. The problem I have with my "trio" of separates, being the 510M amp + 3800 preamp + 125 tuner is the right channel is weaker, according to the right channel meter. I have to turn the right gain knob up about 1/4" or so to balance out the sound and meters. I wanted to check the knobs to make sure they were on right. Guess I'll leave it to my tech, beyond my abilities, but I am curious as to cause.

With separates that each have a way to adjust the volume, should the preamp & tuner be set to max and then use amp for main volume control? Is there a proper/safe way to do it, just as there is in which order you turn each separate on and off?

Thanks.

I always thought proper gain staging was to have the power amp wide open. I have a 250M, 3600, and 125 tuner. My tuner is just under 1/2 way up.

 

[TomInKY]

I always thought proper gain staging was to have the power amp wide open. I have a 250M, 3600, and 125 tuner. My tuner is just under 1/2 way up.

Cool - I can't seem to find anything posted anywhere about the correct sequence. I'd be afraid to leave the amp gain turned all the way up, in case one might forget how far up the tuner or preamp knobs were turned last time used. I guess it could go either way. Thanks for your input, sir.

 

[Coolhandjjl]

Consider that many power amps have no controls. They are wide open like my 250M. All the gain dials are are attenuators anyway.

My shutdown procedure is alway to turn the preamp volume down first. Then the first device to get turned off is the power amp.