Flaxmill19
Active Member
Marantz 140 Stereo Power Amp – Restoration Work – Part 1
Hi All,
I have just completed a substantial refurbishment of my 140 power amp. Most of the changes and components used were gained from research off AK, so I though I should share my experience and hopefully help someone like my self in the restoration of these beautiful audio amplifiers.
I have previously replaced the VU meter fuse lamps with LED’s and replaced all the Elec. Capacitors with Elna RFS Silmic II series and one Panasonic FC capacitor on the Relay CB. This excluded the 13000 x 2 µf main power filter capacitor.
I have always been frustrated with the speaker connections on these amps and also replaced these.
So the scope of work was to replace:
> The single dual filter capacitor
> Replace the speaker binding posts with banana type posts
> Test and replace transistors on the right channel amp board, refer http://www.audiokarma.org/forums/showthread.php?t=545939
> Replace wiring between the new capacitor and the power & amp boards.
> Replace the wiring plugs on the power and amp boards
I started by trolling through the AK site and searching and reading as much information on the 140 as I could, I finally chose the two Mundorf – MLGO63 – 63V - 15000 µF filter capacitors, supplied by Parts Connexion. These were mounted via a 35mm capacitor clamp bolted to 2.4mm thick G11 insulation board, this is essentially a fibreglass board with exceptional strength and insulation properties. All the screws holding the board, capacitor clamps are M3 stainless steel caps screws, flat and spring washers. Under the ground wire terminals I have fitted M3 external toothed shakeproof washer A2 Stainless Steel (DIN 6798) these will hopefully gain the best connection to ground possible.
The new speaker binding posts took a lot of research to find and to be honest I am not totally happy with these posts, but they appear to work OK. My aim was to mount the four new binding posts in the same space that the original connections were in, there was no way that I was going to cut the rear panel. This meant I had to find the smallest diameter binding posts I could, the posts I finally chose were from Digi-Key, part 7006K-ND that had a base outside diameter of 8mm and an overall diameter of 11.7mm, that provided a gap of 2.7mm between the posts, just enough!. Even with these to gain the maximum spacing you have to fit one of the binding post once the mounting board (2.4mm thick G11) is fitted to the back cover. I would have liked to fit a higher quality post, but I could not find ones with a small enough diameter, if any AK’ers know of something suitable, please let me know. I replaced the cabling from the post to the PN00 Relay Board with 22 awg, LEGENBURG rectangular hook-up wire and Utilux M3.5, 0.5-1.5mm² lugs soldered and heat shrink applied to the connection.
Stay tuned for Part 2.
Tony
Hi All,
I have just completed a substantial refurbishment of my 140 power amp. Most of the changes and components used were gained from research off AK, so I though I should share my experience and hopefully help someone like my self in the restoration of these beautiful audio amplifiers.
I have previously replaced the VU meter fuse lamps with LED’s and replaced all the Elec. Capacitors with Elna RFS Silmic II series and one Panasonic FC capacitor on the Relay CB. This excluded the 13000 x 2 µf main power filter capacitor.
I have always been frustrated with the speaker connections on these amps and also replaced these.
So the scope of work was to replace:
> The single dual filter capacitor
> Replace the speaker binding posts with banana type posts
> Test and replace transistors on the right channel amp board, refer http://www.audiokarma.org/forums/showthread.php?t=545939
> Replace wiring between the new capacitor and the power & amp boards.
> Replace the wiring plugs on the power and amp boards
I started by trolling through the AK site and searching and reading as much information on the 140 as I could, I finally chose the two Mundorf – MLGO63 – 63V - 15000 µF filter capacitors, supplied by Parts Connexion. These were mounted via a 35mm capacitor clamp bolted to 2.4mm thick G11 insulation board, this is essentially a fibreglass board with exceptional strength and insulation properties. All the screws holding the board, capacitor clamps are M3 stainless steel caps screws, flat and spring washers. Under the ground wire terminals I have fitted M3 external toothed shakeproof washer A2 Stainless Steel (DIN 6798) these will hopefully gain the best connection to ground possible.
The new speaker binding posts took a lot of research to find and to be honest I am not totally happy with these posts, but they appear to work OK. My aim was to mount the four new binding posts in the same space that the original connections were in, there was no way that I was going to cut the rear panel. This meant I had to find the smallest diameter binding posts I could, the posts I finally chose were from Digi-Key, part 7006K-ND that had a base outside diameter of 8mm and an overall diameter of 11.7mm, that provided a gap of 2.7mm between the posts, just enough!. Even with these to gain the maximum spacing you have to fit one of the binding post once the mounting board (2.4mm thick G11) is fitted to the back cover. I would have liked to fit a higher quality post, but I could not find ones with a small enough diameter, if any AK’ers know of something suitable, please let me know. I replaced the cabling from the post to the PN00 Relay Board with 22 awg, LEGENBURG rectangular hook-up wire and Utilux M3.5, 0.5-1.5mm² lugs soldered and heat shrink applied to the connection.
Stay tuned for Part 2.
Tony
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