TAPE PATH KIT IS BACK!

[Doc B.]

We've been getting a steady stream of inquiries about the tape path kits since we retired them a year ago. So we have decided to open an order window for a limited run of both Technics and Otari kits. That window will open Monday, April 1st and close on tax day, April 15th. If you have been wanting this kit now is your chance. If you know of a friend who wants one please tell them. We'll order up the parts on the 16th and hopefully begin shipping a week or two after that. There are no runs after this one planned for now.

https://bottlehead.com/?product=technics-rs150015201700-tape-path-modification-kit/

[cbaudio]

I have serviced a few of the Technics 1500 series tape machines over the years (currently own a 1520) and, for as good as they are, I’ve always had a complaint about the stationary guides at the very beginning and end of the tape path. The folks at Bottlehead seem to have addressed this and some other weaknesses of the machine so, I opted in. The kit is aimed at those that have no tools, supplies or apparently any knowledge of the situation. The documentation is very well done, easy to follow, and contains some excellent advice.
For  $225.00 you get about $60.00 worth of parts and a link to download a pdf of the instructions. The first thing that I noticed is that none of the supplied bearings have any numbers or identifying marks of any kind. I thought that all bearings had a numbering system. For example, the Technics 1500 series use NSK 6052 bearings for the incoming and outgoing idlers. Could the “No Name” bearings supplied in the kit possibly be better than the NSK 6052’s which are listed as precision bearings?  Obviously, I feel somewhat cheated and am still kicking myself for not doing the research. That said, I’m going to press on and install the kit. Since I have the tools, test equipment, and expertise, I will be making both before and after electrical and mechanical measurements.  I will be happy to post the results if anyone is interested. 

[Doc B.]

The bearings we sent with your order are rated ABEC-5 the same as the bearings we have used in the kits previously. The previous bearings were 440C Martensitic stainless steel. Though corrosion resistance is good 440C bearings will tend to be slightly noisy. For this reason we are using bearings made of 52100 chrome steel. The uniform fine grain material structure makes the bearing very quiet, and one complaint we had with past kits with the SS bearings was a slight whirring noise when in fast wind or rewind.

[cbaudio]

I finally got a round-tuit.
I did not install the brake pads because the brakes work fine (If it works, don't fix it). The tape counter belt needs to be replaced (have one) so, when I dig into that, maybe I'll install the cork pads. Meanwhile, I upgraded the guides using the kit:

TECHNICS RS1520 UPDATES

08/18/19, Pre-installation:
Attached the provided sandpaper to a ceramic tile using removable double stick tape. Also attached a similar size of 1000 grit wet-or-dry sandpaper to the same tile.
Sanded both sides of all 3 washers per the instructions and then wet sanded each on the 1000 grit sandpaper.
Applied a small drop of Lubit-8®, to each of the supplied bearings and allowed them to sit overnight, covered, on a pad of Texwipe®. The next day, I insured that the outside of the bearings were oil-free before installation.

MEASUREMENTS

Wow & Flutter measurements were taken with a (Calibrated) Leader LFM36A Wow & Flutter meter.
A 3kHz tone was recorded at 2Tr, 15IPS, played back and measured.
The results were divided by 2. The final results are as follows.

STOCK:

W&F Weighted; 0.02

UNWEIGHTED: Wow; 0.01                          Flutter; 0.02                                                             


MODIFIED GUIDEPOSTS

With stock Tension Arm bearings:

W&F Weighted; 0.02

UNWEIGHTED: Wow; 0.005                         Flutter;  0.02                                                                       


With ABECK 5 Tension Arm bearings (Provided):

W&F Weighted;  0.0225  (Meter deflection was between 0.04 and 0.05)

UNWEIGHTED: Wow;  0.015                         Flutter;  0.02                                           

Notice that the Wow measurement was cut in half after installing the kit. Although the measurements came out basically the same, the overall meter deflection was about half as much which, is something that is left up to interpretation.

Since the measurements were slightly better with the stock Tension Arm bearings, they were reinstalled.

In conclusion, IMHO, the modified guides are a success.
The instructions did not delineate between the “.020 metal bearing shim” and the “.020 metal washer.” They all looked the same so, I measured them and, they are all the same. According to my measurements, not only did they all measure the same but were, in fact, .0185 thick.
A heads up when modifying the guides: Cover the slots for the Tension Arms (wide masking tape works well) so that any of the small parts don’t fall inside the deck. Heaven won’t help you if they do. If you are at all fumbly, cover everything!
~CB