klem kedidelhopper wrote:
On Mar 12, 11:59 am, klem

(...)

Well I couldn't resist, so to take this a bit further I checked the
power supply supplied with the radio. It is rated at 9.00V .200A. The
no load voltage is 9.50V. With it connected to the radio and with the
radio playing softly its output drops to 9.25V. In looking at the
schematic again and rereading the statement a few more times I now do
believe that in spite of the ambiguity, the original intention was to
supply 7.50 V to the battery terminals, however reference all
adjustments and voltages to the positive side of C59, (system ground).
So I did that and set the bias on FM to -1.18V. (AF126 I E) I then
recorded the following voltages:

Here, I added a Vnom column.

Voltage readings
Test point Radio working: Nominal V
------------------- ---------- -----------

E. AF178 -1.15V -0.85
B. AF178 -1.48V -1.15
E. AF124 -1.14V -0.94
B. AF124 -1.37V -1.12
E. AF121 -0.90V -0.85 (MW) -0.60 (FM)
B. AF121 -1.24V -1.05 (MW) -0.95 (FM)
E. AF126 (1) -1.18V -1.18 (MW) -1.15 (FM)
B. AF126 (1) -1.47V -1.45 (MW) -1.4 (FM)
E. AF126 (II) -1.14V -1.05 (MW) -1.0 (FM)
B. AF126 (II) -1.34V -1.33 (MW) -1.0 (FM)

The voltage across C59 is 6.65V

You are testing at Vrail = 6.65 V?

Grundig says "don't bother warming up the VTVM unless
Vrail ==7.5 V" ( I heard them. Really I did.

So now although the radio has been working fine on both AM and FM, I
notice that the first two stages are reading a bit high. I wonder if I
may have another leaky cap. I was looking at possibly C12, C19 and
C32.

The little 'K' symbol next to these three apparently
denotes a ceramic cap. These 500 V units could become
extremely leaky at 2 V I suppose.

I wouldn't bet that way, however.


There are lots more things that need your attention more
than your beloved radio. Personally, I think that at this
rate, in another 30 days, you will become borderline
obsessive.

My advice: Button it up and listen to it while doing one or mo

Clean or replace the sacrificial anode in your water heater

Do an oil change on your car

Flush and fill your car radiator

Rotate your tires

Replace the transmission fluid in your car
(Clean your funnel and flush with clean ATF first!)

Grab a basket and fill it with stuff from the back seat
and trunk. Neatly put away, toss or donate the contents
of the basket.

Shampoo car carpets

Diagnose that rattle in your clothes dryer

Vacuum out your dryer exhaust vent

Clean your gutters

Replace clogged rafter end vents with new ones

Replace the nasty 'wiring' job in the garage with
real Romex or conduit as code permits.

Install a chimney - mount 'Over The Air' antenna and cancel
your cable TV subscription

Scavenge stuff out of one room or garage that you
honestly will never need and give it to your local
Freecycler

Buy a little microcontroller board and teach yourself
assembly language. Make a robot.

etc. etc.


--Winston