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Author Topic: HRO-50 Band Selector shaft o-ring  (Read 2118 times)
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K4RT
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« on: February 09, 2023, 09:03:06 PM »

The rubber o-ring on the shaft of the band selector in my set (black ring in photo) slips when I turn the control and so doesn't grab the wheel on the shaft of the band drum. Tiny drop of super glue? New ring? Other? I tried heat from a hair dryer. I didn't find anything about this searching old threads here.

Brad


* FDB8C48A-2C65-4F8F-B1A6-56837B71F132.jpeg (1664.35 KB, 4032x3024 - viewed 190 times.)
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W3SLK
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« Reply #1 on: February 10, 2023, 09:58:55 AM »

When I was at Wyle Labs a lifetime ago, I would do maintenance on the computer and batch printers at NASA LRC. Many times on different printers the friction of the platen was critical to maintaining the paper in the correct position. We used a solvent called Fedron to rejuvenate the rubber on the platens and tape drives. Shy of replacing that O-ring, (which doesn't look to difficult), I would make an attempt with some Fedron.

Edit: I just did a search and here it is on Amazon: https://www.amazon.com/Fedron-Rejuvenator-Duplicating-Processing-Accessories/product-reviews/B00PKNQ2BS
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Mike(y)/W3SLK
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Jim, W5JO
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« Reply #2 on: February 10, 2023, 12:14:59 PM »

Glycerin will also rejuvenate rubber.  Put it on with a Qtip and let it absorb into the O ring or take the shaft out and take it to an auto parts store to get a new one.
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W1DAN
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« Reply #3 on: February 10, 2023, 09:04:52 PM »

Replace the rubber O-ring.

Dan
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WB4AM
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« Reply #4 on: February 12, 2023, 01:23:30 PM »

Not sure, but looking behind the wheel that is being turned, the axle of the wheel has signs of something dragging against it.   Perhaps the plate above?   Any chance of to much drag wearing out the Oring?

Am I looking at it correctly?

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K4RT
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« Reply #5 on: February 12, 2023, 02:13:10 PM »

Thank you for your suggestions.

Looks like Fedron is no longer available but thanks for the link.

The o-ring is loose but I hadn't noticed something might be dragging against the wheel axle. I will check that out.

73,
Brad
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WB4AM
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« Reply #6 on: February 12, 2023, 06:15:23 PM »

Also for the time being, if you want to place a Band Aid on the fix until you find the appropriate Oring, maybe slide the Oring off to one direction and then tape the metal rim where the Oring would go with medical tape or a type of tape that has a rough feel to it.  Then slide the Oring back on.  I am thinking the tape would cause the Oring to expand making the Oring tighter against the other moving part and the rough tape may help the Oring from slipping.

Again, just a Band Aid suggestion until the appropriate Oring is found! 




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WA2IXP
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« Reply #7 on: February 14, 2023, 09:39:12 PM »

change the o-ring
                           jay
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K4RT
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« Reply #8 on: February 16, 2023, 09:58:13 PM »

Thanks for the suggestions for a fix. There's no appreciable drag on the axle. On closer inspection, the ring is broken where it is flattened, probably from being parked during non-use. I've got a replacement ring now.

Brad


* 1B623C2A-74EB-470C-A460-ADF89F29E10D.jpeg (373.7 KB, 1732x1523 - viewed 133 times.)
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K4RT
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« Reply #9 on: February 20, 2023, 11:27:09 PM »

I have installed the replacement o-ring and the dial scale drum is working perfectly.

A few additional notes. For my set, a rubber o-ring 3/16 inch inside diameter (ID), 5/16 inch outside diameter (OD) appears to be an exact replacement and fit on the BAND knob shaft. Take care removing the tiny snap ring and washer from the end of that shaft when replacing the o-ring. If you decide to remove the dial scale drum, first look at how the drum axle fits into the slotted flanges that support it. In my set, the notches in the axle do not rest in the flange slots and the "knob" at the far end of the axle rests against the spring-tensioned wheel on the OSC knob shaft. This may be standard based on HRO-50 photos I found on the web.

Thanks for your replies.

Brad K4RT
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