Solution: Motorola R-2200B low gen. output

[radio_05]

With the help of DJP126, I have solved the fault with My Motorola R-2200B.

My unit had low output in generate mode, over 35dB too low. This fault appears to be common, and may affect the R-2200 through R-2410 models.

In most cases, as mine, the fault comes from the wideband board. The board is easy to service, and can be removed from the bottom of the unit after removing the bottom cover only, removing the board cover, and then removing all board screws with NO DESOLDERING. The SMB connectors on the board use contact pins, only the small phillips screws keep them in place.

First, I troubleshot what appeared to be a defective IC, U202, and replaced with new. It now appears that the low levels measured on the output of U202 may have been due to the vernier setting, which should varied during throubleshooting. I later replaced the failed relay K203 (open coil), Motorola part# 80-80377A59. The part is NLA from Motorola, but I was able to order the OEM part through another supplier. I know the part is a COTO sub-miniature relay, and is likely still being made. Be sure to match the pinout carefully to ensure a proper match. These relays often fail, it would be a good idea to keep some spares of this part even if your unit is working.

[Paul Nelson]

Newark carries the Cato relays, they run about $7.00 and are a drop in replacement. Look for the Cato 2200 series

[Paul Nelson]

Concerning the last post, the company is Coto not Cato and the Newark catalog numbers for the relays are 62K0528 for the 12 volt version and 62K0525 for the 5 volt version.

[radio_05]

I ordered the 62K0525 from Newark earlier, this is Coto # 2204-05-411. The part was physically the needed dimensions. It didn't work, as it didn't have the required 6 pins to match the original PCB layout. It was the right coil, as the original was 5V, 12V wouldn't match. Oddly, the six pins don't show up on the board layout diagram in the service manual, but they are needed. A Coto part number such as 2200-2302 may work better, you would have to compare to the Coto spec sheet.

** It seems many other Coto relays (another part number) are used in the Front Panel Interface Board as well.

[radio_05]

The Motorola part# 80-80377A59 is marked as "Coto 2204-05-420", so many more can be ordered, although the part is NLA from Motorola.