Marantz Model 2325 - Getting the Treatment

[jbeckva]

Hey gang,

Got a 2325 in the other week. Said had some sort of buzz, issue etc on the left channel, where so far hasn't been replicated. Also wants a FM alignment.

Put her up for a check and listen first. Oh man.. where's the heart? Really tinny and weak in bass and punch. The filter caps tested like a wet noodle, with barely a peep for a spark when running a current limited charge and discharge check.

Then the low voltage power supply needs a real good going over. It has some issues.

Now when I look at that underside shot where the relay looks like it's been "borg'd" to the last parts of traces left.. and also look at the top end.. I have to ask - If it checks out electrically and operationally with some test coil voltage, should I still say replacing is worth the risk when removing the old one? I have wick...

 

[Bob Boyer]

Hey gang,

Got a 2325 in the other week. Said had some sort of buzz, issue etc on the left channel, where so far hasn't been replicated. Also wants a FM alignment.

Put her up for a check and listen first. Oh man.. where's the heart? Really tinny and weak in bass and punch. The filter caps tested like a wet noodle, with barely a peep for a spark when running a current limited charge and discharge check.

Then the low voltage power supply needs a real good going over. It has some issues.

Now when I look at that underside shot where the relay looks like it's been "borg'd" to the last parts of traces left.. and also look at the top end.. I have to ask - If it checks out electrically and operationally with some test coil voltage, should I still say replacing is worth the risk when removing the old one? I have wick...

View attachment 85814 View attachment 85815 View attachment 85817 View attachment 85818

Ooof... even for those early solid state receivers, that doesn't sound good. I've yet to meet an original of any manufacturer from that era that didn't sound wooly to my ears, but weak bass was never an issue. However, I don't get out much anymore.

 

[jbeckva]

Ooof... even for those early solid state receivers, that doesn't sound good. I've yet to meet an original of any manufacturer from that era that didn't sound wooly to my ears, but weak bass was never an issue. However, I don't get out much anymore.

Progress is well, it's in progress. The LV board has been recapped with those Kemet 16K's getting ready to go back in with it. I figure take care of the obvious first. From there hit the tone and buffer amps while checking on the amp modules. Went with one of those BA 312 replacements for the buffer, after seeing some really good reviews on it.

 

[jbeckva]

Well, relay's fine. Good solid click and no resistance.

 

[62vauxhall]

I had a look inside the 23** (something, something) that a friend bought just after he got it around 2010. 130-ish watts per channel. There was only a single large cap inside that one but it had two layers. Despite that, not of a very impressive size.

Oh man.. where's the heart? Really tinny and weak in bass and punch.

That pretty much summed up my impression as well. He had Wharfedale E90's for speakers so lots of screech but two 10" in a ported box so there should have been some thump. But bass was, as you described, weak.

 

[jbeckva]

I had a look inside the 23** (something, something) that a friend bought just after he got it around 2010. 130-ish watts per channel. There was only a single large cap inside that one but it had two layers. Despite that, not of a very impressive size.



That pretty much summed up my impression as well. He had Wharfedale E90's for speakers so lots of screech but two 10" in a ported box so there should have been some thump. But bass was, as you described, weak.

Pretty sure that between the weak filter caps and what was found on the LV supply that it'll improve after all is back together. I'm figuring it's also best to wait for the BA312-M modules. The plan is to pull the preamp board cleaning the pots in the process. I should probably do that today to also inspect it for other weak components.

And in true Phoenix fashion, a "B.A.B.B." is coming in along with the new Kemets. I chose those with the screw terminals over the solder lugs, with that in mind.

Ugh.. noted on the LV board this morning.. Looks like the glue did a real number on a few resistor leads, and a few transistor leads to boot. Time for stocking up on a few 1/2 watts.

 

[wattsabundant]

Did this thing take on water? Otherwise, it's not common to see rust on transformers. The Luxman I'm working in has the same glue/resin all over the place. I don't think it's glue because the same gunk is under 1/4 watt resistors. There is none under the electrolytic cap, just around the edge. Look at transistor H805 in the lower left corner of the photo. It's got the gunk around it. I wonder if it's the chemical make up of the board along with heat. I understand Sansui has the same issue. It is corrosive and attacks tin plated leads.

I wouldn't hesitate to change the relay. Install a socket for it.

 

[jbeckva]

Did this thing take on water? Otherwise, it's not common to see rust on transformers. The Luxman I'm working in has the same glue/resin all over the place. I don't think it's glue because the same gunk is under 1/4 watt resistors. There is none under the electrolytic cap, just around the edge. Look at transistor H805 in the lower left corner of the photo. It's got the gunk around it. I wonder if it's the chemical make up of the board along with heat. I understand Sansui has the same issue. It is corrosive and attacks tin plated leads.

I wouldn't hesitate to change the relay. Install a socket for it.

Hi Don, been a bit!

I'm thinking same thing now as I'm inspecting for the resistors. All 3 in that line of transistors seem to be pretty suspect under a mag glass. There's another cluster towards the heat sink on the left to consider too.

Overall on the rust. I am unsure of it's history. I figure all will eventually be torn down to bare chassis. Taking it slow and methodical in the meantime. I want this Marantz as good as it can get, when it's ready to go back to it's owner. I had a 2385 in a few months back. It was anti-climatic tho since it was just a loose molex feeding the main signals into the preamp. It did sound pretty good tho!

 

[WOPL Sniffer]

Hey gang,

Got a 2325 in the other week. Said had some sort of buzz, issue etc on the left channel, where so far hasn't been replicated. Also wants a FM alignment.

Put her up for a check and listen first. Oh man.. where's the heart? Really tinny and weak in bass and punch. The filter caps tested like a wet noodle, with barely a peep for a spark when running a current limited charge and discharge check.

Then the low voltage power supply needs a real good going over. It has some issues.

Now when I look at that underside shot where the relay looks like it's been "borg'd" to the last parts of traces left.. and also look at the top end.. I have to ask - If it checks out electrically and operationally with some test coil voltage, should I still say replacing is worth the risk when removing the old one? I have wick...

View attachment 85814 View attachment 85815 View attachment 85817 View attachment 85818

Damn Jer, yer right, the back side of those boards are f-ed.............. I got a Sansewer AU-999 on the bench right now and it isn't quite as bad but almost. I used some left-over WOPL back plane solder cups (as Vias to hold down the pads) and repaired what I could. Friggin single sided boards, all we got between us and chaos is a bit of adhesive.

 

[J!m]

[QUOTE="WOPL Sniffer] all we got between us and chaos is a bit of adhesive.[/QUOTE]

Similar with most passenger jets.

 

[jbeckva]

Got some work now as well on the amp modules. One 0 ohm fuse resistor for sure, a tantalum close to it as well. Pulled them this evening..

Yeah I hear ya Perry on the PCB's.. No place nowadays to find one of those 69B repair kits with the punch and traces, anymore? I have been searching around for them.. no luck so far.

 

[wattsabundant]

Unlike electrolytic caps, which becomes open as the electrolyte dries out, the failure mode of tantalum is a short. The attached document discusses tantalums on page 5.

 

[jbeckva]

Well aware of tantalums, Don. We had em all over the place causing hate and discontent

Found a lot of them on the amp boards.. oh vey.

 

[jbeckva]

Now I'm a bit on the fence here about the tantalums. I took a look at what can be used instead, but the ESR is pretty high compared to the originals I think? The only rating I could find was around 150 ohms @ 120hz. The tants I viewed were a lot LOT lower than that...

Where I see the main issue could be the 1 uF ones being used there to couple between the buffer IC and the preamp's final output pair. reduced gain being the only drawback, or could it be more of a problem than that?