DEAD Robyn SB 520D

Any idea how many attempts have been made to fix it since it first broke down? A radio that still won't work after somebody has "worked on" it tends to have added faults in it besides whatever it was that failed to begin with. I would guess that the average is about 1.5 new faults for every failed attempt at repair.

The built-in power supply may be the whole problem. What's inside is a 12-Volt (13.8 Volt) DC mobile radio. There is a DC power jack on the rear. Do you have a power cord that will fit and a 3-Amp or larger DC power supply to try it that way? Just make sure there is a 3-Amp fuse in line with the DC cord before you key the mike. This model has a failure-prone capacitor that can pop the fuse, or damage the relay inside the radio when you key the mike. That relay is no longer made and finding one is neither easy nor cheap.

This is a 1977 or 1978 radio, so who knows what has been done to it over the last 40 years?

The mike socket is NOT wired like all the other modern-day radios with this socket. Pins 1 and 2 are the reverse of a "normal" Cobra/Galaxy mike. Pin 3 is the same, and pin 4 is not used.

Any of those that get serviced here will also get the mike socket changed to match the Cobra/Galaxy pin arrangement that has become more or less universal over the last 30-plus years. This is just easier than having to have a separate "Robyn-only" mike for the radio.

It's not just the years, it's the miles. If it has a lot of wear and tear that could make the cost of "restoring" the radio out of reason. After 40 years the line between "repair" and "restore" can get mighty thin.

73

You can still get the relay for this radio, as it is available on Ebay:

https://www.ebay.com/itm/TEN-10-OMR...219909?hash=item33da9f86c5:g:TcgAAOSwNSxVD3mp

There is a wealth of info on this radio if you are planning on restoring it from unit_399 (forum member):

http://unit399.wixsite.com/858ssb

Just finished restoring a Realistic TRC-458 which uses a very similar chassis. But as Nomad said, be prepared to roll up your sleeves and do some work to it to get there. You are just scratching the surface getting it working again.

In addition, there is an Ebay seller that sells a high quality electrolytic capacitor kit for that radio; since the radio is ~40 years old and they will need to be changed out:

https://www.ebay.com/itm/Electrolyt...543714?hash=item21106dac22:g:ZUAAAOSwJMhXEEPa

Does anyone have a Service Manual for the Robyn 520D?

All I have is similar radios schematics etc. But not one specific for this radio.

Attached is the most close I've found. The 18ch version called Ferris 5500

cobra service info: cobra 139 xlr has the same pcb as your radio the pc176ab...(?)

Cobra 139XLR (cbtricks.com)

Realistic TRC449 (21-1562) (cbtricks.com)

Might help(?) good luck!

Sams CB-170. May be available on eBay. Or you can order it direct from Sam's publishing if you want to spend that much.

Robb said:

... In addition, there is an Ebay seller that sells a high quality electrolytic capacitor kit for that radio; since the radio is ~40 years old and they will need to be changed out:

Click to expand...

A more current link to a kit below;
https://klondikemikescapkits.com/pr...-138-139xlr-electrolytic-capacitor-kit-deluxe