Sunday, September 3, 2023

Technics Cassette Deck RS-BX828 Maintenance and Mod

The RS-BX828 cassette deck from Technics is a high-end model released in the early 90's. It features 3 Heads, Direct Drive mechanism and 3 DC motors being 1 quartz direct-drive motor for the reel, one for the capstan and one motor for opening and closing the cassette compartment.

Such robust motor construction allows for a very small wow and flutter of just 0.03%. 

The Technics RS-BX828


As this unit is now over 30 years old, some basic maintenance is required to keep it running from several more years.

Mainly, the existing 2 rubber belts (one for the cassette door and one for the capstan) needs replacement and the famous plastic gear (Technics Part Number RDG0034) tends to crack overtime. The unit I own has a very low mileage and the gear is still in good shape. Unlike another DD Cassette Deck from Technics (RS-B555) that I own, where the gear has cracked. To fix the gear issue you would either need to source another modern gear replacement, keeping in mind that NOS (New Old Stock) are likely brittle as well. Some folks have been 3D printing such gears with resin 3D Printers, capable of making parts that are very accurate and have the strength required for its torque-transfer duty.

Another alternative to such gear replacement, is to to "reinforce" that gear hub (where the hairline crack tends to start). I learned about this technique from a few posts on, in particular this one:

I added a tight washers to both my deck RDG0034 gears I got from Aliexpress some time ago, the washers were similar to this one.  

Firstly, before opening the deck make sure to download and follow the official Service Manual that can be found at the HiFiEngine website.

RS-BX828 with the lid removed

Be careful when removing these cables as some connectors need to pushed to release while others, need to be pulled to unlock the wires

The first pick on the white gear on the right

The first belt that could benefit from a replacement (mine was still working but noticeable softer than it should)

Disassembly of the cassette unit

Cassette unit disassembled (be careful not to damage the fragile electromagnet copper coils)

I pulled the the gear off the shaft and inserted the washer (first, I slightly open with a plier to cover more of the gear surface) on the gear and re-inserted the gear on the shaft (it was noticeably tighter which was a good sign!)

The final result with the washer in place embracing the gear

Another angle showing the washer in place

With the gear taken care of, it was time to replace the capstan belt which was very lose

Those multi-size rubber belts package from Aliexpress come in handy

Now to mod part of it...

I always like those cassette decks that had a light to show the (fascinating experience) of a cassette tape turning/spinning. 

I had a few white LEDs already prepared for 12VDC supply, so I soldered the LED to the motor power supply

I used a piece of natural color PLA to help refract the LED light on top of the cassette deck unit

I glue to piece on top of the lid

The white LED glowing on the top of the cassette deck

There you go! The effect I was looking for!

I noticed some bad contact when connecting the power cable, so I re-solder the power connector which had a hairline crack on the original solder joints

The power connector

The main board on its whole glory

I inspected and re-soldered a few joints that didn't look very good

I hope you enjoy the post and that it helps others preserve such fantastic decks running.

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