Marantz 1250 Recap/Restore

[CohibaJoe]

hi everyone,

I've acquired a Model 1250 very recently. It's in pretty good shape.

I've an issue which is really bugging me with this amp is an almost dead right channel.
There's hardly any sound output from right channel for almost 30 mins every time when I switch it ON. Afterwards it slowly comes alive. This issue is there on every inputs except phono1. (Ph1/Ph2/Tuner/Aux) While playing via phono1 its fine.

Later on, I've found that when I press Tone defeat button on the face plate the right channel suddenly comes alive and it can sing as long as the Tone is defeated. Pressing again on Tone Defeat (activate tone) the right channel goes dead.
I've also observed a popping sound from the right channel every time when I switch off the power button on the amp (even though the volume is at min).

Hope someone here can help me understand the problem?

I've already posted this query earlier in a different thread in AK.....but once I've found this thread and read through it, finds more appropriate to post here.

You should start your own thread on this but in the meantime clean/Deox all your switches and controls as that is most likely your main problem.:yes:

Bob

Agree....Start your own thread Please.....

 

[skillace]

Ok, I'm gonna get dirty then.....most probably will get to the work bench by next week and will open a new thread to update the progress.

 

[skillace]

CohibaJoe, your posts about the restoration was much inspiring for me and will be a great help too.
Probably, it will be guideline for my job.

 

[CohibaJoe]

CohibaJoe, your posts about the restoration was much inspiring for me and will be a great help too.
Probably, it will be guideline for my job.

Will be good to see another Thread on 1250 restore...

Very easy to do....The Dual Main Caps are no longer sold...And I checked.

Sounds WonderFull after the Recap.

 

[skillace]

Congratulation Joe, fantastic job.
Hope you're enjoying it.

I've started a new thread for my 1250 project.
http://www.audiokarma.org/forums/showthread.php?t=656393

But I'm stuck while going through the parts list and now in doubt what caps to choose exactly because here everyone has different approach on choosing components and this is my first recap project.
What was your approach on the choice of caps for this 1250 project?
What I've noticed is that instead of going for Audio grade silmic iis or FGs, most of the caps you've chosen were Nichicon KLs and PWs!
Please shed some light....maybe there are things that I still don't know.
Thanks

 

[CohibaJoe]

Congratulation Joe, fantastic job.
Hope you're enjoying it.

I've started a new thread for my 1250 project.
http://www.audiokarma.org/forums/showthread.php?t=656393

But I'm stuck while going through the parts list and now in doubt what caps to choose exactly because here everyone has different approach on choosing components and this is my first recap project.
What was your approach on the choice of caps for this 1250 project?
What I've noticed is that instead of going for Audio grade silmic iis or FGs, most of the caps you've chosen were Nichicon KLs and PWs!
Please shed some light....maybe there are things that I still don't know.
Thanks

As Pat said....Nichicon PW and KL are what MTF would use. For P400 Phone/Mic Amp I upgraded this board.

High Temp 105Deg and Low Leakage Caps I was looking for.

I look forward on your choice of Caps and how it sounds.

 

[skillace]

Oh! that makes sense and sounds logical too.
So will it be actually a trade off between supreme sound quality & long reliability or what?

Joe, I've also noticed a generous use of tantalum caps in original 1250, (stated as electrolytic caps in the service manual) especially in the Mic/phono & pre/tone boards. Why do you think of replacing them with electrolytics....were they already drifted & went out of spec?

Please don't think that I'm questioning your methods or something....just curious to know your approach and can take an informed decision.
One more thing, I didn't get what you mean by MTF....
Thanks

 

[hirscwi]

Tantalums are in fact a type of electrolytic capacitor. They are excellent capacitors when they work but they tend to fail with age. So most people replace them in vintage euipiment to avoid ancillary damage upon failure. New, low ESR aluminum cpas work just fine.

 

[skillace]

Tantalums are in fact a type of electrolytic capacitor. They are excellent capacitors when they work but they tend to fail with age. So most people replace them in vintage euipiment to avoid ancillary damage upon failure. New, low ESR aluminum cpas work just fine.

So if they are excellent ones, why do most people replace them with aluminum electrolytics instead of a new tantalum.
Are new electrolytics better in any other means...
But why the manufacturer had chosen tantalums over aluminum electrolytics in those places....is cost/size one of the factors?

Joe, please put up a parts list of your upgraded Phono/mic amp board?
Looks very interesting with WIMA MKS film caps!
I've already sent you a PM.

 

[Fhamre]

I know this is an old post but I thought I would quickly share a couple of points I learned after just finishing a 1250 restore. First off the relay in my unit was not an LY2 it was a MY2-02 48VDC, http://ca.mouser.com/ProductDetail/Omron/MY2-02-DC48/?
qs=%2fha2pyFaduj2wOw5oH5%252bdUXw7m6hCr7D%2fGzZfqUWxM5JKtLxVcK%2fsQ%3d%3d
Also I was successful in stuffing the original can to preserve the look. Although it sits higher and just fits with the case on. I am happy with the result.
Actually quite enjoyed working on this piece and I note it nearly hits 160 watts into 8 ohms before clipping.

 

[bluebirdsss]

I have a 1250, which is a Japanese model (100volt unit). Thought I would recap the power supply board, on removing I noticed that C801 and C802 were 680uf 80v capacitors, not 1000uf 70v as stated in the service manual. would it be OK to place 1000uf 100v units in their place?