Marantz 2385 Receiver Repair And Restoration

This Marantz 2385 needs some repairs along with restoration both cosmetically and electrically. Lot's of different issues made this unit a challenge.

This Marantz 2385 solid state receiver is pretty dirty inside. I'll get some of the dust out before I start troubleshooting. 

I have removed the faceplate for cleaning. I used warm water and dish soap followed by mother's aluminum polish.  

 Any repair or restoration involves changing the old lamps With the faceplate of the Marantz 2385 removed the fuse lamps can easily be replaced.

Don't forget to clean up the decades of dirt and dust that collects everywhere. No better time as everything is already apart.

This Marantz 2385 solid state receiver is looking better after some dish soap and water.

I use a small clip on LED light to help see in the dark areas like when I am cleaning the push button switches.

Do your Marantz meters glow green instead of the original blue? It's because your original white vellum paper has turned yellow.

There is adhesive holding the meter. Use the point of an x-acto and slowly work the point between the meter and the case to loosen. 

You will need to unsolder two wires from each meter to remove them from the Marantz 2385 receiver.

The image below shows the old vellum paper that was removed during this Marantz 2385 restoration and the new vellum paper.

Changing this paper is worth the effort. The new vellum paper has brought back that Marantz blue glow.

The audio muting board and soft start board had all electrolytic capacitors replaced. The soft start relay was cleaned and reinstalled.   

A part of any vintage stereo restoration should be replacing the electrolytic capacitors in the power supply as shown below.

The transistors that have been under heat stress for more then 40 years will also be replaced during this Marantz 2385 repair and restoration.

The old thermal compound was cleaned up from the heatsinks and new applied along with the new transistors.

The power amp section had an issue and had to be removed. Also a good idea to label the connectors for easy reassembly. 

With the power amp assembly removed from this Marantz 2385 receiver it will be much easier to troubleshoot any issues.

This Marantz 2385 had it's share of issues including two open resistors on the power amp assembly.

I also replaced the 40 year old electrolytic capacitors on the power amp assembly. Any restoration includes replacing the old electrolytic capacitors.

New transistors will replace the one's that have a history of failing in Marantz 2385 receivers. New thermal paste and insulators will also be installed.

The power amp assembly is back in the Marantz 2385 and now we have sound. Idle current and DC offset looks good.

Be careful and take no chances when taking measurements. Shorting leads together in this part of the Marantz 2385 is not a good idea.

The FM section was broke also. Replacing a bad transistor got the FM working somewhat. 

I found that I had intermittent distortion in the left channel during FM radio operation. This was caused by the FM buffer assembly.

I replaced the defective transistor and at the same time I replaced all of the small signal transistors along with the electrolytic capacitors.

I also replaced the transistors and the one electrolytic capacitor on the FM noise amp.

The power switch needed to be replaced during this Marantz 2385 repair and restoration.

When turning on the power of this Marantz 2385 receiver the panel lights would flicker as well as hearing a sizzling sound.

The original Marantz power switch is no longer available but modern equivalents are.

The pre & tone amp, phono amp, filter amp, tape copy, tape monitor boards will be all have the 40 year old electrolytic capacitors replaced.

There are many different cables to remove so they should be marked in some fashion so that everything can be reassembled correctly.

The push button switches should be cleaned. Dirty switches are the cause of many intermittent noise and distortion issues,

With the assemblies removed from the chassis component removal and replacement is made much easier.

Once again you should have a plan to get keep track of the removed cables. It will save you time or possible damage later.

I now have the phono amp and selector board removed from this Marantz 2385 solid state receiver for capacitor and transistor replacement.

Don't forget to clean the cable connector pins. Any vintage audio repair or restoration involves plenty of cleaning.

Liquid deoxit along with Q-tips works well for cleaning individual pins.

With the selector assembly removed during this Marantz 2385 repair and restoration the selector switch is much easier to clean correctly.

Many of the low level transistors were replaced during this Marantz 2385 repair and restoration.

Nichicon PW series electrolytic capacitors were used. These are high temperature and long hour rated capacitors.

Some of the electrolytic capacitors in this Marantz 2385 receiver have audio rated specifications

Nichicon KT series audio capacitors were used where audio rated capacitors were required.

I have replaced the capacitors and transistors in the phono amp and selector board. It's ready to be reinstalled.

I have replaced capacitors in the pre and tome amp board. This Marantz repair and restoration is getting closer to completion.

Hopefully this Marantz 2385 will now be able to operate reliably for another 40 years

This Marantz 2385 powered up fine after getting everything back together. I'll do a check of the controls before moving on.

This Marantz 2385 is a little beat up, a little crusty but ready to be bench tested.

Nice blue glow and ready for some music. This Marantz 2385 solid state receiver repair and restoration is complete.