On Sat, 4 Feb 2006 09:14:07 -0700, (Ken G.) wrote:

Model 2400 low flat receiver . It powers on like its supposed to but has
no sound . The volume lights work properly . Other problem is it wont
turn off when i touch the off button , it has to be unplugged .

So far i have taken off all the covers and replaced any burned out bulbs
I have restored 5 of these with no trouble but cant figure out this
one

Several common things with these.

1. The small bridge rectifier for the low voltage (+15?) has one diode
o/c, and/or the filter cap has lost capacitance.

2. The lamps you changed must be 30-40mA, if more you can have trouble
turning the unit off.

3. Check the center voltage of the outputs, just take the emitters of
the four large transistors, must be close to 0V. If not, change caps
and all semi in the affected output.Also check the solderings of the
output transistors.

4. The red "ROE" capacitors has always been a problem, after 30 years
you can expect at least half of them to e defective. I will sugegst to
change them all. Standard values, you shold be able to get them all
for a couple of dollars.

5. Check the bulb in the volume controller. If the bulb is o/c you
will get no sound. It is a small square aluminiumbox with four LDRs
and a bulb in the middle. You can check the bulb with an ohmmeter from
the bottom, do not disassemble if not necessary!

6. One of the on/off switches (TR9) was often seen to be leaky. Change
if strange on/off behaviour.

7. The Balance pot often goes o/c - can be bypassed by 4x10K resistor,
or repaired mechanically, it is not so hard, but takes some creativity
and patiience.

The above list should 90% + get your unit up running again.