Marantz 2440 help!

[jFF_Bulbo]

Hello! I recently got a 2440 unit, nice shape, horrible sound!!, it has a pair of 2CS1445 transistors on output stage and a pair of NTE175 in the same stage, so, i think it has been repaired/modified befor.
The thing really worries me is the unit doesn´t have the "dimension" potentiometer. I have a 4230 unit to spare parts, i see 4230 unit also has the "dimencion" pot, so i need your help to kown if both "dimension" pots are compatibles. Aind, if one of you could helpme with a photo of the cable arrengement in the dimension pot it could be great for me!! the cables were cutted and i don´t know which should i connect in each potentiometer pin!!

 

[Dingman]

I have a stock 2440, but it's kinda buried.
If no one comes up with a pic, I can maybe help.

I can't comment on the comparison of pots, you'll want to compare the specs in both manuals.

EDIT: I just looked, I would have sworn there was a 2440 service manual in the database, but there isn't. Sorry.

 

[jFF_Bulbo]

I have a stock 2440, but it's kinda buried.
If no one comes up with a pic, I can maybe help.

I can't comment on the comparison of pots, you'll want to compare the specs in both manuals.

EDIT: I just looked, I would have sworn there was a 2440 service manual in the database, but there isn't. Sorry.

HELLO!! THANK YOU. I have both manuals, (and many other manuals) and the pot specs not mentioned. If you can give me photo of the "dimesion" pot and how is it connected, 50% of my problems will be solved. Regards.

 

[Dingman]

Does this help? It's from item#253991535309 on epray

 

[jFF_Bulbo]

Does this help? It's from item#253991535309 on epray
View attachment 1346571

Hello!!! Thanks you!!! Looks like the info i need!! Just need the Specs of the dual pot to check the compatibility with 4230 dimension pot!!!

Again , thanks you so much!!!

 

[Dingman]

Heh, one step at a time.

It's a dual Dual 50K ohm, I got that much.

 

[jFF_Bulbo]

Thanks you !!!!

Heh, one step at a time.

It's a dual Dual 50K ohm, I got that much.

 

[jFF_Bulbo]

Heh, one step at a time.

It's a dual Dual 50K ohm, I got that much.

Hello! well. the pot is installed and now, the unit has left front channel not working.

Unit has installed 2 - 2sc1445 and 2- nte 175 transistor. So. where coud i start?

So, i have to say H802 transistor (2sd315) run hot when unit is tured on. No sound on front left channel.

2240_1

• jFF_Bulbo
• Dec 19, 2018

2240_2

• jFF_Bulbo
• Dec 19, 2018

I couldn´t adjujs bias to 20mV in the channel what is affected by R730... resistors r729 works fine for its channel, adjusted to 22mV, but R730 dont tuns more than 1/4 spin.

I recapped the power supply, and test it offers 35V......

 

[bktheking]

2sd315 will run hot, is it on a heat sink?

 

[jFF_Bulbo]

2sd315 will run hot, is it on a heat sink?

tHIS IN THE P800 board before recap.
I didn´t check temperature od H802 (2sd315) with old caps.

2240_3

• jFF_Bulbo
• Dec 19, 2018

 

[Dingman]

It sounds like that trimpot might be bad - and a person has to be careful with those old pots - they can goto short when failing.

Some people replace all those 40 year old pots as a matter of course.

If you really get into a bind, I have a working 2440 here that we'll use for reference. But it's in a new wood cabinet that I'm trying to not muck up.

 

[jFF_Bulbo]

It sounds like that trimpot might be bad - and a person has to be careful with those old pots - they can goto short when failing.

Some people replace all those 40 year old pots as a matter of course.

If you really get into a bind, I have a working 2440 here that we'll use for reference. But it's in a new wood cabinet that I'm trying to not muck up.

Will be appropiate to change them with the trimpot shown on photo above?

Trimpot

• jFF_Bulbo
• Dec 19, 2018

 

[jFF_Bulbo]

It sounds like that trimpot might be bad - and a person has to be careful with those old pots - they can goto short when failing.

Some people replace all those 40 year old pots as a matter of course.

If you really get into a bind, I have a working 2440 here that we'll use for reference. But it's in a new wood cabinet that I'm trying to not muck up.

yes. i´d like to repair it. I am searching 4 nte 175 transistors.

 

[bktheking]

Newark has 170+ in stock.

 

[jFF_Bulbo]

Newark has 170+ in stock.

Hello!!!
i have worked on the amplifier board, i changed: H001-H004, they was 2SC1445, i installed NTE175 (4, news).
I´ve changed H711, it was 2sc606, i installed 2n5416 (both, news)
i´ve changed H709, it was 2sa959, i installed 2n3440 (both, news)
I´ve replaced R739 and R730 (470 omhs variable resistor) with 1k trimpots
changed c703 and c704
manual says adjust r729 and r730 to 20mv in j713-j717 for one channel and j714-j718 for the other, i couldn´t set it that value, it varies even until 32mv...

... and the problem persist. left rear chanel is dead. I also recaped the power suply board. Power suply have the 35V tested.

Analizing schematics, i started following R601 wich adjust the vumeter of the left rear chanel, i supose is a problem in the preamplifier, so, i think it could be the H401 (2sc1327), h601 (2sc945), H501(2sc1327)...
Any suggestion where could i search?