Tuning increments for Delco Radios
From Lotty (merl@LION.DE)
Here is the description how to modify the Delco-Bose radio
model 16041551 to 0.05 MHz steps on the FM band. This is useful
in countries other than the USA, where radio stations aren't
on odd-tenth megahertz intervals.
- remove the upper cover (3 screws)
- remove the 5 screws holding the first PC board.
- gently lift the PC board.
- locate two diodes (1N4148) between display and
IC labeled "DM 246 DQ 7815D" (28 pin) on the second PC board,
now visible.
- there is spare place for another two diodes.
Add a diode to the location closest to the above IC.
This can be done in two ways:
- Remove the bottom cover and the cassete drive, clean the
soldering pads from solder. Solder in the diode and reinstall
all removed parts.
- Do nothing of point 1), but solder the diode across the
IC mentioned above. Anode to pin 10 and cathode to pin 26.
(This is much easier)
- reinstall PCB and cover.
If you are not familiar with radio electronics and soldering,
ask a friend to do the modification, who is.
Here are the functions the other diodes control:
- Diode 4 installed:
Frequency range on FM is 87.5 - 104.0 Mhz, step 0.05 Mhz, frequency range on
AM is 531 - 1602 Khz, step 9 Khz.
- Diode 3 installed:
Frequency range on FM is 76.0 - 90.0 Mhz, step 0.1 Mhz, frequency range on
AM is 531 - 1602 Khz, step 9 Khz.
Note: D3 and D4 installed does not do anything i.e: radio act as no diode is
installed in D3 and D4
- Diode 2 NOT installed:
No Seek and Scan function on the radio, setting clock is as usual.
- Diode 1 NOT installed:
No clock on display when radio is switched off.
Information about the casette deck:
It is a Blaupunkt Toronto SQR 46.