Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
At least for now, I am going to
only scan and post schematics & parts lists like this one featuring the RCA
Victor Portable Table Electrola Model R-95 radio in graphical format, rather than
run OCR on them to separate the textual content. There are still many people who
restore and service these vintage radios, and often it can be difficult or impossible
to find schematics and/or tuning information. I will keep a running list of all
data sheets to facilitate a search.
RCA Victor Portable Table Electrola Model R-95
(Synchronous motor; takes records up to
12 ins.; pickup and tone arm in 1 unit; 8 in. dynamic speaker.)
The voltages on the illustration at the left are measured from the tube socket
terminal to the negative side of the electrolytic condensers. Voltages should be
within ± 2.0%, as measured on a 1,000 ohm-per-volt meter. Values over 50 V. should
be read On the 250 V. scale, while those under are taken from the 50 V. scale. Since
a voltage-doubling circuit is employed in this instrument, it cannot be used on
D.C. The power consumption is 75 W. total and the power output is 2. W. Turntable
speed is standard 78 r.p.m. The motor is started by giving it a clockwise spin with
the hand. Difficult starting may be cured in many cases by applying a small amount
of oil to the bearing surfaces of the motor. A small amount of hum when the motor
is starting, decreasing to a negligible amount when running is entirely normal.
If there is excessive vibration either when starting or running, the motor supports
should be examined and the position of the leather washer on the center bearing
should be checked. It should be under the steel washer. After a long period of operation,
the spacer cushions of the pickup may become hard and should be replaced. The viscoloid
block which is attached to the front end of the armature shank serves as a mechanical
filter to eliminate undesirable resonance and to cause a uniform frequency response.
If the block is replaced it will be necessary to heat the shaft slightly to hold
it firmly to the viscoloid block.
Posted August 27, 2015
Radio Service Data Sheets
These schematics, tuning instructions, and other data are reproduced from my
collection of vintage radio and electronics magazines. As back in the era, similar
schematic and service info was available for purchase from sources such as
SAMS Photofacts, but these printings
were a no-cost bonus for readers. There are 227 Radio Service Data Sheets as of
December 28, 2020.
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
