Memorex CP8 TURBO UNIVERSAL REMOTE CONTROL Instrukcja Użytkownika Pobierz pdf (Strona 81)

100

seven -tube circuit includes a 6A8 os-

cillator- mixer, a 6K7

IF amplifier, a

6H6

diode

detector, a 6F5 first audio

amplifier, and a 6F6 audio output.

The

rectifier tube is a 5Y4,

and a 6T5 is used

as a "magic

-eye" tuning indicator.

I'd

estimate that its date of

manufacture is

about 1938.

The radio

includes three bands:

broadcast, shortwave,

and police. Since

the shutters are stuck right

now, I can't

give

you

the frequency

ranges covered

the

shortwave and police bands.

But

I'll report

that

in a future column.

At first glance, it looks as

if the cab-

inet

contains a

lot of

wasted space

perhaps the set

was made unnecessarily

large

look extra -imposing.

And

while there's no doubt

that Zenith

was

going

for an imposing

look when they

designed the

75232,

there

is actually

very

little extra

vertical

space in the

radio. First of all, the set's chassis

unusually deep to accommodate

large, below

-deck, tuning flywheel.

Stack

the large tuning -dial assembly

top of that, cap the

whole works with an

eight

-inch dynamic

speaker,

and

you've used up most of two

feet.

Zenith obviously

intended

for the

dial assembly to be

the focal point of the

radio,

sparing

no pains to make it beau-

tiful, smooth -operating,

and conve-

nient to use. I've already told you

how

the

shutters work. The dial -drive

mech-

anism itself is also

worthy

of mention.

It contains a

vernier -drive setup that

resembles a

clock mechanism.

Turning

the tuning

knob moves a long pointer,

somewhat like a sweep

second hand,

around the outer -or

vernier -scale of

the dial.

Continuing

the clock

analogy, the

scale

is divided into 60

second -like in-

tervals. As the

long pointer sweeps

around that scale, a

shorter, inner point-

er moves, somewhat

like a minute

hand, at a much -slower

rate. That

"hand" points to the actual

frequency-

view

of the chassis

looking towards

the rear of the dial assembly.

The

horizontal cylindrical unit at the top

the

magic

-eye

tuning indicator.

calibration

marks on the

shutters. A

heavy

flywheel mounted

on the tuning

shaft makes

operation of

the tuning

knob

unusually

smooth

and positive.

The settings

of the set's three

other

controls (volume,

tone, and

band -

switch)

are

displayed around

the periph-

ery of the tuning

dial. Each

has a

numbered or lettered circular

scale that

turns as the control

is rotated. And

each

scale

is arranged

so that a

segment of it

visible through a crescent -shaped

window. All the

lettering is beautifully

done in

white on a jet -black

back-

ground, and the total effect

very im-

pressive

indeed.

Taking Stock

If you

look at the photo of

the set in

its cabinet,

you'll notice that the grille

cloth directly

in front of the speaker

charred and torn.

That

was

caused

the furnace explosion,

which shot

through

the cabinet at that point,

rip-

ping the speaker cone

right out. I'll

need to

locate

appropriate replace-

ment cloth,

but the speaker problem

was

solved

some

years

ago: I had it

reconed by an expert

not long after I

bought the set.

Knobs are going to be a problem.

The large main- tuning knob

was

still

the set, as

was

one of the

three smaller

control knobs (although

the latter has a

broken

flange). The other two

control

knobs are missing. Those are

ornate

wood

knobs bearing the

Zenith logo,

and

will

be difficult to replace.

The dial

glass is also

missing -possibly a

victim

of the explosion.

Maybe a clock parts

supplier will have one that

fits.

Instead

of using easy -to- replace dial

cord, the

set requires a special

drive

belt. The

original is brittle and broken,

but could

be used as a model

for some

type of expedient

replacement.

The

set's

original

owner presented me

with

replacement that

he fabricated

from

nylon -monofilament

fishing line. He

assured

me that it

would fit perfectly

because he had

made several just like

for

similar models.

We'll see!

All tubes

in the set tested

good,

which

is certainly

a plus. However,

few of the original

"G"

-style

(tall

glass)

tubes

have been

replaced

with

their "GT" (short- glass)

or metal

equivalents. In one case,

the top

cylindrical tube

shield had to

pinched -in to give

the grid lead enough

clearance to extend

down to the

much

shorter replacement

tube.

another

case,

where no tube

shield was used,

There are lots of

wide

-open spaces

under the chassis. Note the

tuning fly-

wheel (lower center) and the

long, light -

colored

resistor (to left of center)

with

some of

its

paint

burned off. The

burned condition

may indicate a short.

the grid

lead looks

absurdly

long on the

shorter replacement. If I can find them,

I'd like

reinstall "G" types fora more

authentic look.

Thus far, the only test I've made on

the

electronics of the

set

is my standard

pre- start-up procedure.

With the rec-

tifier tube removed, I plugged in the set

and turned it

on. That allowed

check

the on -off switch and power

transformer without

applying

volt-

age to the radio. The switch functioned

normally,

the tubes and pilots lit up, and

an AC

voltmeter

across the trans-

former's high -voltage

secondary indi-

cated a normal reading. So far, so good.

I did note, though,

that the paint on

one of the set's carbon resistors

was

partially burned off and

that

there

seemed

to be a deposit of soot on the

chassis surface

directly above the re-

sistor.

That evidence of overheating

will

not

be ignored, because it could be

symptomatic of a short- circuit

con

dition that will have

to be corrected

before power is

applied to the radio.

To complete our overview of the

ra-

dio's more obvious problems, let's talk

about

the cabinet. The cabinet itself is

very

sound, but the finish is

almost

completely

gone;

it's down to the bare

wood

in most areas. That may be due to

the explosion and/or storage conditions

over the years.

What

concerns me is the complete

lack of grain in the exposed

wood.

suggests that the cabinet originally

had

grain that

was

created using

pho-

tographic

procedures (very common in

sets of this era),

which

disappeared

along

with the finish. That can't be re-

stored, of course, and

I'll have to con-

tent myself

with

a careful

stripping,

staining, and

refinishing of the

wood

surface as it now exists.

When

we meet, we'll probe

more deeply into the

7S232.

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