06-08-2020, 09:52 AM
(This post was last modified: 06-08-2020, 09:55 AM by Mike Watterson.)
I replaced the o/p capacitor 640 uF C23 as its leakage is high. Only 6.5V rated and was getting over a minute of 8V to 9V at power on every time.
I readjusted RV3, quiescent current, to 3.5mA. It's very sensitive. The RV2 needed a larger adjustment with replacing TR3, AC128. It's not so sensitive due to R14 in series. Replacing the lockfit TR2 BC148 with the BC547 didn't require any change as the Vbe and hFE was virtually identical.
I've no idea which version of IF module is fitted as only the Roberts label warning not to service it is on it.
Is the R600 really later than the R700?
Anyway it's working well. I think it's the same model as the last radio my Grandfather had and he had it till the 1990s when he died. My mum threw it out.
I readjusted RV3, quiescent current, to 3.5mA. It's very sensitive. The RV2 needed a larger adjustment with replacing TR3, AC128. It's not so sensitive due to R14 in series. Replacing the lockfit TR2 BC148 with the BC547 didn't require any change as the Vbe and hFE was virtually identical.
I've no idea which version of IF module is fitted as only the Roberts label warning not to service it is on it.
Is the R600 really later than the R700?
Anyway it's working well. I think it's the same model as the last radio my Grandfather had and he had it till the 1990s when he died. My mum threw it out.
