STANDARD C520 C528 Repairing setting of TX-audio and 1750-tone Replacement

Cover the plastic-front against scratches and daamages.

Loose the screws on the back and on the bottom

Remove the screws, marked red. Locate the old capacitors, marked yellow. And locate the old battery, marked green.

Replace the old caps. At best exchange to tantalium. The three caps on the left uper side and the above the CPU must be replaced against 220µF 6V. Replace the battery It is a wired CR2016.

Next lets have a look on the RF-unit. Loose the screws and desolder the antenna connector. Unmount the board. Then locate and replace the caps.

Remember to replace the cap bottom left as well. The marked trimmer is for freqeuncy-alignment

When you have problems setting deviation of audio and tone, then desolder the trimmer R392, R395 and R397. Clean up the board in this area and reinstall the trimmer. Pleace test them and replace the trimmer agains new ones if values do not fit.