the home of the turntable

My Time with a Garrard Zero 100SB

I have owned the unit since new (circa 1975) but it has not been pressed into service for around 20 years when the teenagers departed the nest.

Now that the MP3 age is with us I thought that it was time to save my favourite records to this portable format, however when presented with the first record it showed it's age and lack of use. So, it was off to the workbench for some serious work.

I hope that the following notes may be of assistance to others who have one of these 100SBs and are faced with one or more of the same problems.

My Zero 100SB

The first issue was that the belt had deteriorated. The belt dimensions are around 0.5mm thick, 4.75 mm wide and should just fit neatly on the 140 diameter drive section under the platter. A replacement belt of similar dimension (except that it was 150mm diameter) was obtained and appears to do the job.

It was now time to turn the unit over and investigate the problems.

As many other posts on the forum state, the main issue with these (and many other) old turntables is that the lubricating grease applied when new turns to an effective glue after years of hibernation. So, the first job was to remove any suspect parts and ensure that they moved freely and subject them to some fresh lubrication.

For sliding pieces I use a light Lithium grease and for pivots etc I use an auto transmission oil. Don't take any short cuts, remove all of the pieces – use a digital camera to record each step as you dismantle, - to use as a reference when refitting them all.

I found that I had three main problem areas – shown in Pic. 2

1. The main cam gear was extremely tight.

2. The levers to the pivot posts at 2 and 3 in the picture were also very tight.

The cam gear was easy to free and to re-oil. While working on this component I ensured that the black plastic lever and the metal trip lever (on the upper side) were also both free to move.

The tight pivots proved more of a problem. They still would not free up after a week of applying penetrating oil so stronger methods were required. I managed to prise both pivot pins out of their respective mountings, and once out I was able to put them in a soft jawed vice and tap them apart with a pin punch. I then used a fine grade emery cloth to polish up the pins and ensured that the levers could turn freely on them.

Pin #2 is mounted in a plastic base and #3 mounts in a metal diecast mount. I was able to carefully refit the two with an application of Loctite to help retain them in position. At the time, I did not pay a great deal of attention to the depth that I was forcing the #3 pin into position – an oversight that came back to haunt me (see later). My main concern was to be reasonably gentle on things and not cause any breakages.

So, it was time to reassemble all of the pieces. It was a reasonably easy job using the pictures that I had taken as a record of where things went. However, I found that I had not taken pictures from enough angles that would have assisted me in later troubleshooting!

During my work, I had detached the panel supporting the L & R audio channel connectors. Thus the panel was free to flop around as I moved the unit during my endeavours to free the above tight pivots.

I had not noticed that several of the fine cartridge shell wires had become detached! So a few hours work was required with reference books and an ohm meter to determine the correct position of the broken wires on the connectors. Then it required a steady hand to resolder them into position. Should this happen to you I have listed the correct positions of these wires below.

Red wire - Right channel signal

Green wire - Right channel earth

White wire - Left channel signal

Blue wire - Left channel earth

Yellow wire - This nominally solders to the metal frame of the socket panel. However, as another post on the forum states it may be removed if it is causing hum in the background.

Pic 3 shows the order of the wires at the cartridge shell connections. Make sure that the sliding surfaces on this and the the Tone arm are electrically clean so that a good contact is made. The electrical signal at this point is very small so any poor contact will have a dramatic reduction in the level of the output audio.

Now, it was time to check out the “overhaul”. With the Auto lever pressed things began to happen – but unfortunately the Arm moved right past the first track and landed somewhere about where a 45 record might start. Dam!. Using the 45 position as a clue I then checked out the operation of the Record size selector and cam but this appeared to be in order. However, I found that what was not in order was the Tone arm when in “Stop” mode, which could not be moved far from the “park” position.

The following pic shows the Record Selector Cam.

The reason that the Tone arm could not move was found to be due to another lever being in the incorrect position (shown in the following pic 5).

In my case, this lever was against the main lever in the picture. Now to find out the reason for the problem. Every time that I moved the mechanism through a complete cycle everything appeared to work OK, levers were in the right place and the Tone arm was free.

However, when I tried to make it work in the Auto mode (with power applied) it failed. To cut a long story short and (hopefully) describe what was going wrong, the following was the problem...

The lever shown in the above picture is “U” shaped around the pivot. That is, the lower (and main part of the lever) has a hole which passes through the pivot, and between that and the upper part that is visible in the pic. is the cam lever that has a boss on it which acts as a spacer so that the depth of the pivot post is fully used. The “U” shaped lever (the brass coloured one) has a small (1 mm?) upward flange on the right hand edge (when looking at the pic) and is not immediately obvious.

However, it's function is to stop the cam lever so that it is in position when the tone arm moves to sense the part of the cam corresponding to the selected record size. This wasn't happening in my case. The reason? When I reinserted the pivot, I had not paid enough attention to making sure that it was inserted to a depth that would not allow any up and down movement of the “U” shaped lever. As there was too much free play, the “U” shaped lever was being pushed down by the cam lever when it approached the small flange and then it moved right past the nominal position so the Cam lever was not being sensed. So, if you have this problem, check out this aspect of the reassembly!

The final small issue that I had was related to the Auto start lever. Intermittently, when I operated the lever, the Turntable would start to turn, then it would shutdown again. The problem here was due to the “trigger” lever (shown in the pic. 5). The spring on the right hand side (with the long arms) needed to be “stretched” apart again to give it some more tension so that the lever flipped over positively to the Play position.

I hope that the above notes will be of some use to a reader in the future who can benefit from my mistakes. However, like myself, we are a dying breed and although there must have been many thousands of these units manufactured, there are probably few taking pride of place in a retro home stereo system. Now that mine is back to it's original condition my problem is a failing personal auditory system that cannot make optimum use of the fine reproduction that the 100SB produces!

posted by allenkeys