A Quick Diversion to My Marantz 140 Power Amp

I picked this amp up about 5 or 6 weeks ago at a local Goodwill and was unable to test it. I had plugged it in and nothing lit up, but I could hear the "all clear" relay switch and nothing smoked, so I figured it was worth the risk.

When I got it home, Jeff and I fired it up and it was working rather well. The volume controls were clean and smooth and the output was even and sounded great.

We took it apart and cleaned it inside and out. We pulled the bulbs out of the meters and all 4 of them were blown. This was actually a relief because I was concerned that something else was wrong that they were all out.



I ordered a set of replacements online and we just popped them in and closed it back up!


One of the easier, catch-free jobs we have had in a while.

Finishing up the Wiring and Installing the Switch

So, we are basically finished. We ordered a switch/speed control for a ceiling fan to slow down the motor a bit. It works fairly well and slows it down, but we lose a lot of torque. We can get it to a point where the speed is ok and the torque is ok, but its not quite as slow as we wanted it to be.

Since we do not have many woodworking tools, we ended up drilling out a hole for the switch to be mounted in. It took some time, but with the cover plate on it, it will look fine!



Next week we will just need to button things up and put this project away.

Originally we planned for this to be a bit more involved but it kept getting more and more complex. The motor system really threw us off. Since the motor was too fast and the spindle too short, we spent a lot of time trying to adapt it to work. If we were to do this again, I would say we should spend a lot more time researching the proper motor. We scrapped the vacuum system as well because just the hose portion from VPI was $70+ and since we were compromising here and there anyways, we thought to scrap it.

We have to use a brush to wet the record and to distribute the fluid as is and we would just have to turn the same brush backwards to dry it. Next week we will post some photos of it working.

Setting the Motor and Platter Into Place

After dry fitting it last week, we actually tried to get this thing in straight and at the right height. We basically mounted it with 4 pieces of all-thread with a nut, washer, lock washer and rubber washer on top and bottom of the shelf and the mounting brackets for the motor. We put one set of washers and nuts on both sides so that we could get them nice and tight and to minimize vibration of the motor. With this method we could rise and lower any of the pieces of the all-thread, before tightening everything down to get the spindle as straight as possible.

We have the spindle gear coming up about 1.5" from the table top and it is sitting rather flat.



With the platter on, its starting to look like something useable!



Next, we wanted to fabricate something to add a bit more pressure to the platter. We did a test run with a Discwasher brush and if you hold down on the platter hard enough, you can stop the platter from spinning... but, the spindle will keep moving.

Jeff had picked up an old hockey puck from work and drilled it out to cover the spindle. First, he had to find the center of it by using some old school mathematic procedures!



Go Science!

Then, just drilled out a center hole...



And when added to the spindle, it increases the torque a lot

Getting Everything in place!

We spent some time measuring, sawing and drilling the motor into place. Its a bit crude right now, but we came up with a mounting scheme and will have to get a few more rubber washers and lock nuts, move around a couple of the pieces of all thread, but it looks like the method we have for mounting the motor will work!

We basically have 4 pieces of all thread mounted into the chassis that the motor is screwed to. We then just pulled the all thread through the top of the shelf and isolated it with a rubber washer on both sides and then mounted the other end to the chassis. This allows us to adjust the height of the motor and spindle as well having complete flexibility to make sure it is straight.

It needs work, but is really close!

Parts for final assembly!

Straightening the spindle and a crude assembly

After getting the all thread added to the spindle from the welder we were really concerned about getting it straight. There was a little bit of wobble and when we added the platter, it was all over the place!

Since it was welded, there was not too much we could do but try to flatten it with a vice and hammer. It took us a while, but I do think that we got it pretty straight.





This was our biggest stumbling block and it may be behind us and we may be able to move forward with assembling until into the cabinet. We marked out where it will all fit and have a new list of items to get together for the wiring and mounting etc.

Some Long Awaited Progress

We were able to get to the welder with the correct parts this time! We ended up with the original spindle that was sourced from the broken turntable and a piece of all thread. The hard part with this was getting them to be as centered as they could be.

Being that they are all different diameters, welding them was less than a perfect science. We got one piece at a time on and he tacked them, then we straightened them as much as we could and then secured everything.

It is mostly straight, but we cannot be sure until we get everything in place and spinning!