Marantz 2230 diodes 1N60 GE

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CJ

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was wondering if we could swap out these 0.3 FWD 1N60 GE diodes for 0.6 FEW 1N4148 SI diodes without a meltdown, thanks!

 

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No big deal in replacing H758 and H759 Ge diodes for Si ones, since they are part of the short circuit protection ,and currently everybody uses Si diodes there, think 1N4148 .
Even 1N4002 would do.

Let me think a little about H757 .... it is not directly the bias setting diode (H005, a dual diode , 99.9% certain it´s Si, and which must be glued or clamped to heat sink) BUT bias current passes through it , I bet it works like bias "fine tuning" because it has trimmer R765 in parallel with it.

If/when your amp is alive, measure voltage drop across R774 and R775, you should measure some 15 to 30 mV  across each one.

If at least one of 3 Ge diodes is alive, use it on the H757 position; if none and you can´t get a Ge one, I bet a small Schottky diode will do there.
One with a "1N60 sized" casing, not a large "TO220"  sized one.

Current there is nil, a couple mA.

Post results.
 
it is working great with the 1N4148's!

the other diode is a varistor which was modded by marantz with a 100 ohm resistor across it.

this whole board was blown out so we replaced with modern parts as Hitachi/Toshiba stuff is hard to get,

here are the new parts that work, also, we adjusted the pot for  5 mv across the .22 resistors as per the service manual,

clipping pot adjust does not seem to do much on either channel, supposed to adjust for symetrical clipping, but it clips pretty even regardless of 100k pot setting, thanks John!

 

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there are a ton of people selling them on evilbay,

i think this guy is the cheapest>

https://vintagehifiaudio.com/product-category/parts-kits/marantz/

it is a piece of cake to install as long as you do not have a model with a melted bezel from the old lamps getting it too hot,

plenty of youtube instructionals also.

we have done the 2215, 2230, 2245, 2270, model 20, and a few more and they look fabulous, with no heat and longer life.

you can also buy black face plates for the Euro look, but they are about 100 US.
 

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I love the weighted flywheel tuning dial on those recievers ,
I did have ,or do have a beast of a Marantz model 1250 somewhere, one of the big 125 rms per channell with the big shiny alloy console controls on the front ,that beast actually caused a small hifi speaker to catch fire once  ,and kept on working .
It looks like a kilowatt transformer in there at least . As far as I remember I could never source the proper output transistors so only one channel worked .might dig it out someday .
 
I had to put new power transistors in my 2238. Still have problems with one channel though. Have a 2215 I need to mess with too. Great recievers. Boy does that schematic look familiar haha.
 
Tubetec said:
I love the weighted flywheel tuning dial on those recievers ,
They did have a nice feel, but sometimes they had just too much mass.

I guess they had to find a use for all those surplus 8-track player giant capstan flywheels.

Gene
 
and we get to relearn the lost art of dial cord stringing,

early models had a hand painted dial, i guess that saves doing a full IF alignment,
 

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I've brought this up before somewhere.....but my neighbor's kid found a Sansui 8080 on the side of the road along with an old Akai tape deck and neither were working.....Deoxit brought the 8080 right back to life... Lucky kid....

I don't know what's up with the tuners in these things but man it was like magic..... thing sounded so sweet.....

 

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yeah something about those Japanese transistors,

here is the lamp kit for a 2245,  dial lights and function lights and a tuner pointer LED also,

the lamps fit into fuse holder like devices,
 

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CJ said:
was wondering if we could swap out these 0.3 FWD 1N60 GE diodes for 0.6 FEW 1N4148 SI diodes without a meltdown, thanks!
I can't read the numbers well but some of those diodes look like they are in the bias string so the forward voltage is important.

I wouldn't, but YMMV.

JR
 
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