Hey all! Been awhile since I've made a restoration thread as I have been busy. This is my first time making a thread on a Marantz restoration, and I am goin all out with the 2500. I bought this on that "auction site" as is, in hopes that it was'nt going to be too bad of a restoration. Well I was wrong. Boy was I wrong. This thing was all jacked up. It had been stored for forever and all banged up. Even dropped a couple times! Back panel was caved in on the bottom left corner and RCA jacks were destroyed along with the ground screw. The power cord had been yanked and frayed. The metal cab looked like someone took a hammer to it and the fly-screen was all tore up. Bottom feet were sheered off and the faceplate was banged up on the edges. This was not because of poor packing. It was packed well! Seller mis-represented it totally and I bought into it. These are just the cosmetic issues! The gutts are another story......It looked to me as if someone had tore it apart and figured out they were in over their head and put the cover back on. Ya! Left everything un-plugged and all the boards were laying loose inside the unit! I was sick when I opened it up. I just stared at it for 30 mins. and did'nt say a word. My only thought was "Is everything still there?" I did'nt get alot of before pics as I just tore into it frustratedly and did'nt know at that point if I was even going to fix it. The one thing, and I mean "ONE" thing it had going for it was the faceplate was perfect aside from the bashes on the edges and a couple of the corners. This is what pushed me to restore it and am now glad I did. I called on the help of my father for the cosmetics on this one as he just has a way of making candy out of $#IT. I will start with the pics of the bondo work and new screening on the cab. He pounded it out and smoothed it up with Bondo, then he put new fly screen in it. Amazing is all I can say. Take a look!

Next is the faceplate. Sorry as I don't have any before pics but I got an after pic to check out. Pops took it to the floor-standing belt sander and grinded all the bashes out of it superbly! May be a little smaller than most of the 2500 faceplates out there, but to look at it you would'nt be able to tell. He said "It's like a big heat sink" as he was burning his hands while sanding. That was kinda funny I thought.

Here's some pics of the back panel and again, I have no before pics but the corner where the phono inputs and the ground screw were destroyed! The panel was sprung as well and had to be completely removed and beat straight. We got the replacement RCA jacks off a Pioneer sx-1010 parts unit I had laying around that matched the stock 2500 ones perfectly. We got the ground screw, again matching the stock one perfectly off another marantz parts unit. It was tricky getting it all in but not too bad. Looks good!

On to the electronics, here are some pics of it gutted. This is the only way to make this thing easy to work on. GUTT IT! and this was no novice task.

On a good note, so I thought, all the original outputs and driver transistors were good! I found a leaky diode and a resistor out of range on one driver card. I also discovered after looking at the wiring diagram that two of the disc thermostats that are supposed to be NO (normally open) were shorted closed. Digikey has them and they call them thermal regulators. I had to make an educated guess on what switching temp to buy as the manual does'nt say and the original part number no longer exists, and chose 120 degrees F. They bolted right in! These are what turn the fan on high after it getts too hot. Here are some re-cap pics just short of the oddball values I had to order. I replaced every single capacitor in this thing. The pre-amp was very difficult to re-cap and some of it just don't come apart. I had to sneak the new caps in there and had to have an extra hand from pops to hold the flashlight.

I put it all back together and powered it up slow. The soft start would'nt engage untill I thumped the relay and then the speaker relay engaged and the fan was working on low speed! Well that's a good thing! I then powered it down and tackled the soft start problem. I quickly discovered after looking at the schematic, that someone put a 160 ohm 25watt resistor in series with the AC line. The schem calls for a 10 ohm 15 watt! What were they thinking! I replaced it with a 10 ohm 25 watt that fit the original bracket perfectly and the soft start issue was solved. Worked like a charm with the right dam part in there! Offset adjusted perfectly and when I went to check the bias, I had none. No biggy I thought, just turned down. Well needless to say, that was not the issue. No bias both channels. Dammitt! Pulled the amp out and found the shorted bias transistors. Both channels had the same problem. Replaced with a good sub and put it all back together. Fired it up and on the right channel adjusted bias to 25mv no problem! On to the left channel, started turning up the bias and got it up to 21mv then all of a sudden the meter pegged and the main fuse blew instantly! I was very pissed. Took it all apart again and found two outputs, both driver transistors, and the bias transistor were all shorted and one other output was open. The driver card however, was un-scathed. I contacted the infamous Echowars to see if he had the original output devices, and he told me to put the On-semi devices, MJ21195 and MJ21196 with matching drivers in there and live happily ever after as the original outputs in the 2500's are too weak to begin with. Ordered the parts and stuck them in. Check it out! Not bad work for an Oklahoma boy!

Put it all together again and powered it up slow. Relays clicked and I proceeded to adjust the bias. Got a rock steady 25mv on both channels! Victory is finally mine! Determined that one or more of the outputs were weak and showed it's ugly face upon adjusting the bias. That's the $#its man! I then hoped that the pre-amp was functioning and aside from one of the push switches that did'nt clean up with the first round of deoxit, it did! Scope also works! Here are some jamming out pics!

Here it is going back together. Replaced the lamps and repaired the lamp housing, neatened up the wiring mess, and done some detailin. Looks pretty darn good!

Here are some power check pics on the bench and this thing is a power house! Hooked up the 4 ohm dummies and cranked it. Got it hot enough to turn the fan on high! It flat goes into turbo mode! turned it down and 2 minutes later went back to low speed. 120 degree thermal regulators are perfect! All systems go!

Lastly, the listening room for final evaluation. Awesome! I almost cried when I seen it all together and working. Glad I decided to go ahead with the restoration. It's a big ol beast! Realy like this receiver and the scope is about the coolest thing ever. Never get anything like that on the new crap they are sellin these days. This is why I do what I do to these ol units. I'd like to get my hands on the guy that sold me this thing, but then again, It went to the right place. Hope you like the thread and special thanks to my pops and Mr. Echowars for the advice on the outputs.

i thought my 2235B had lots of insides....:yes: that's some nice work. hope that toroidal power supply doesn't blow up on you. it's always nice to see another marantz saved, especially when it's a 2500. :thmbsp: oh yeah, sweet avatar, Neil Peart rules.

Wow! That Looks GREAT!

That 2500 is a beauty of a receiver. I used to have two of them and now I think I should have kept one.

Great restoration :banana::banana:, great thread :banana::banana:

Beautiful in every way. Great job. Those things are audio sex sitting on an equipment stand. I miss my 2600 (the bigger brother,) but I'm having more fun playing "musical seperates" and swapping out all kinds of obscure components.

http://members.aol.com/gto69ra4/audio/mvid1.wmv
http://members.aol.com/gto69ra4/audio/mvid2.wmv

Damn fine work! :tresbon:

Awesome workmanship by you and your Pops, Paul!:banana:
You really made a silk purse out of that one. What part #'s did you use for the on semi drivers?

Tom

Awesome workmanship by you and your Pops, Paul!:banana:
You really made a silk purse out of that one. What part #'s did you use for the on semi drivers?

Tom

MG15032 and MG15033

God Speed John Glen.... It always looks easier on the internet.

Nice yob man....

jk

Thanks to all. That scope is one heck of a cool thing. No two songs are the same on the scope. Very cool!

fantastic! :thmbsp:

Enjoyed the hell out of your restoration story. A classic saved and sounding good for a long time - couldn't ask for a better ending. It's good that you picked that one up, I'm certain. Congrats!

impressive work, impressive post

I wish you had gotten some more before pics... I'm sure many of us would be gasping for air in shock. Still, a beautiful restoration. Very ambitious. I don't think even I would attempt such a tough job. But, beautiful! :music: Enjoy! :music:

Wow, that is some amazing work... I can't even imagine... here I am still trying to fix the 120V power supply on an oscope after like 4 months... I would've cried faced with that much to figure out... :D

Now that was one serious restoration. Great job!

Absolutely stunning! Nobody would ever imagine that was a parts unit. :no:

Very Very nice, Paul:) Now she's MINE MINE MINE!!!! heheheheh!
Check out my SX 1980 and me with my silly grin:yes:

http://www.audiokarma.org/gallery/showphoto.php?photo=5043&size=big&cat=

Charlie:nutz:

Thanks again to all. Glad to share the experience as it was an interesting one.

Fantastic!!!!! :thmbsp::thmbsp::thmbsp:

Outstanding work. congrats. After all that work, it's probably the only reliable 2500 in existence. :) Nicely done.

Beautiful work and very nice that you saved your 2500 from an uncertain future.

I have two 2500's and a 2600 and they will always have a place in my collection. What machines they are!:banana: