Transcript Tube Radio Restoration

Tube Radio Restoration
Paul from Penn Hills
KB3LZP
Oct 23, 2007
KB3LZP
Introduction.
This lecture is to cover the basic techniques of
Tube Radio chassis electronics restoration.
Cabinet is not covered.
Resources
No knowledge of electronics is required but it does
help a lot.
A properly restored tube radio can give many
year of service, pleasure and a sense of
accomplishment.
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What is covered.
1. What level of technology are we dealing
2.
3.
4.
5.
6.
7.
with.
Identify your tube radio candidate.
To plug it in or not.
Safety.
Steps to restoration.
Parts identification.
Why replace good looking parts.
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What is covered Cont’d.
8. Tubes go bad often, NOT.
9. Replacing Capacitors
10. Replacing Resistors
11. Power Cords and polarized cords.
12. Cleaning, Dial cords, Miscellaneous.
13. Power up.
14. Initial tests and checks
15. Alignment equipment
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What is covered Cont’d.
15. Alignment
16. Burn-in
1940 Motorola
Catlin
17. Alignment again.
US $2,550.00
Sep-05-07
22:39:25 PDT (6 days 1 hour)
18. Enjoy
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1. Level of technology
Pre war 1930’s up through 1960s
Hollow state.
AM
Old FM 42 - 49 megahertz pre-war band
– The Zenith Bakelite set pictured had the old 45MHz FM band.
Domestic or European
These restoration techniques apply to any vintage
technology, Hollow or solid state.
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Radio Tubes
http://en.wikipedia.org/wiki/All_American_Five
80
12SA7
http://en.wikipedia.org/wiki/Vacuum_tube
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12SQ7
Tube Data
Beam Power Pentode
High Voltages
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2. Identify your tube radio candidate.
Is it a family radio of sentimental value?
Do you like the way it looks?
Will you like tube sound.
Do you just like it?
Is the price right?
– $101 and 25hrs left
– 150154946655
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•Black Dial
•Tube Count
•Popularity
•Exposure
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•Wires
•Alignment
•Availability
•Cost
•Sockets
37-611
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•Hallicrafters. HAM GEAR
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Sonorette France
Saba 310w 1930
Volksempfänger (Germany)
•Like Brands
•Cost, availability,
•Personal choice
•Restorable
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Grundig
•Cost High End
•Chassis
•Case/cabinet
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Zenith Stratosphere console radio 16-A-63
eBay item
320150565279
Oct 23, 2007
Closed at: US $21,000.00
Estimate: US $12,000.00 - US $15,000.00
History: 23 bids
Auction Date:Sep-15-07 07:00:00 PDT
High Bid: Internet Bidder
Item location:
Nashville,
KB3LZP Tennessee USA
3. To plug it in or not.
Do not plug in your newly acquired
UNRESTORED radio.
Parts can be made of “Unobtainium”.
Shorted rectifier tubes can let the magic
smoke out of the power transformer.
Varriac Dim Bulb tester
Emerson Catlin
$610 4days left.
Hairline crack.
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1929 Radiola 60 after power up
The Unobtainium leaked out.
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4. Safety
Power Cord
AA5’s are Transformer less
Isolation Transformers
– Store bought
– Home made
– VA verses Watts
Transformer internal shorts use a meter.
– Dim bulb
Work Surface, Shoes, humidity.
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Isolation Transformer
Key Features:
Primary 115VAC, 50/60 Hz., Secondary
115VAC
Provides circuit isolation.
Electrostatic shield between primary &
secondary.
Hi-pot tested to 2 KV RMS.
Circuit breaker in primary.
Standard 3-wire, grounded plug &
receptacle.
Input (primary) connected to 5 foot long cord
& standard North American plug (NEMA 515P).
Output (secondary) connected to 1 foot long
3-wire, standard North American grounded
receptacle (NEMA 5-15R).
North American Mark of Safety - C UL & UL
listed (File #E211544)
Remember - These units do NOT convert
line frequency
http://www.hammondmfg.com/171.htm
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5. Steps
Documentation
Pull Schematic and Alignment procedure
www.nostalgiaair.org/Resources/
www.radiomuseum.org
BAMA
http://bama.edebris.com/manuals/
http://tdsl.duncanamps.com/
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More Resources
http://www.ppinyot.com/ Click on “Links”
http://antiqueradios.com
http://www.radiomuseum.org
PHILCO REPAIR
BENCH •
USENET GROUP -
http://www.philcorepairbench.com/
News:rec.antique.radio+phono
alt.binaries.pictures.radio
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5. Steps to restoration - Gear
ISOLATION TRANSFORMER
100w gun, Flux, Solder, sponge
Solder sucker
Pliers, screw drivers, sockets
VOM DVM impedance
Alignment tools
RF Oscillator with modulation tone
Freq meter or Digital SW receiver.
Screw drivers, nut drivers etc.
Work surfaces
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5. Steps to restoration – Chassis prep
Separate chassis and cabinet
Protect dial glass!
Cover speaker
Close tuning gang
Blow off dust outside.
Clean chassis
Fabricate chassis stand.
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5. Steps to restoration cont’.
Initial checks
Check for bad parts made of Unobtainium
Varmints
Band switch!
Power transformer (Pwr Xfmr)
Audio Output transformer (OPT)
IF transformers
Oscillator coils
Pots.
Bias resistors CANDOHMs
Variable air cap
Antenna coils
Low volts Power Transformer check
Full voltage no Pwr Xfmr load check.
Tube Testing
Use the Red and Green pencil on the schematic.
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Nice Radio?
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Mr. Jingles slept here
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5. Steps to restoration cont’
Selecting and acquiring parts
Capacitors
– Electrolytic
– Silver Mica
– Poly……
Resistors
– Inductive resistors
– Power
Tubes,
– Test with Emissions or mutual conductance tester.
– See http://www.tpub.com:80/content/neets/14178/index.htm
for some tube theory.
– Metal Tubes Pin 1. Tube base size in Philco shields.
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Using GT tubes as substitutes
for non-GT tubes
From "Radio News"
Warrn J. Dougherty11/44
Warren J. Dougherty, a serviceman of Kinkaid,
Kansas, has called to our attention one of the factors most overlooked when
replacing G-type tubes with the more newly-designed GT tubes.
Invariably these GT tubes, with metal base, have their No. 1 pin grounded.
Inasmuch as many manufacturers use all available socket pins for common
tie-points, considerable damage may be caused when grounding the No. 1
pin.
A particular case is the RCA Model BT-42 which was originally equipped
with G-type tubes. When changing to GT tubes with metal base, the
condenser, C16, 400-µfd. condenser and 1-megohm resister, R7, in the
plate circuit of the 1H5 should be disconnected from the No. 1 pin of the
1N5 tube socket, as in this particular case, it was used as a common
terminal connector. The metal base occasionally will short out the plate
voltage from the 1H5 tube, resulting in a nonoperating receiver.
© 1996-2004, Nostalgia Air
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Gas
Bad Tube
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5. Steps to restoration cont’
Wire, hookup, power cord.
Dial glass/plastic, Dial scales.
Hardware
Cabinet parts for another day.
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Tubular Axial Capacitors
Orange Dips
Metalized Polypropylene Film
Good replacement for Wax/paper caps.
Metalized Polyester Film
Self-healing property
Metal-Foil Polypropylene Film
500 Volt Dipped Silver Mica Capacitors
•Orange epoxy coated for superior
heat, solvent and moisture resistance.
•Excellent stability for High Current /
High Frequency / Temp.
Compensation Applications.
Metalized Polyester Film
•Highly reliable with "self-healing"
performance
1 pF to 5000 pF,
Electrolytic Capacitors
Y2 Safety and
Interference Suppression
Capacitors
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Max capacitor voltage
Replacing Wet Electrolytics and High Surge Dry Eelectrolytics
From "radio service dealer"
Solar Capacitor Sales Corp.9/44
Properly installed miniature size capacitors can
replace wet and high surge voltage dry electrolytics in practically all receivers. To
insure satisfactory operation, the circuit surge voltage must not exceed the surge
peak voltage of the replacement capacitor (525 volts for 450 volts working). In many
cases this means series connection of replacement capacitors.
To determine the circuit surge voltage, temporarily replace the faulty unit by a 1 or
2 mfd., 600 or 1000-volt paper capacitor. Then connect a 1000 ohms/volt or higher
reistance voltmenter across the capacitor. Watch the meter pointer as you snap the
set switch. The surge voltage is the voltage at which the pointer hesitates after its first
swing before begining a relatively slow decrease to operating voltage as the set
warms up. This test should be made with the highest line voltage which may occur in
the location where the set will be used.
If the surge voltage is too high for a single miniature unit, connect units of the
proper capacitance and voltage rating in series to serve as the replacement.
Dry electrolytics with a capacitance as low as two-thirds of the original
capacitance will usually be found satisfactory when replacing wet electrolytics.
© 1996-2004, Nostalgia Air
Oct 23, 2007
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Carbon Film 1/2 w 5% about $0.07
Carbon composition ½ w about $0.20
•Use above 18 MHz
•5 % tolerance
•Low inductance
•Low capacitance
•Watch for inductance.
•High quality performance at
economical prices
•1/2 & 1 Watt
•General shotgun replacement.
Metal Oxide 1 and 2 watt 12/17 cents
• 5 % tolerance
•Power Supply section.
•Cathode Bypass
•Candohm replacements
Metal Film ½ w about 11 cents
POWER Resistors Wire Wound very inductive.
1 % tolerance
•Epoxy coated precision resistors
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5 watt $0.37
Power Supplies
Candohm replacements
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10 watt $0.50
AKA Sand, cement,
Ceramic, wire wounds
Hardware
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Dial Scales and Covers
www.Radiodaze.com
eBay My World: jmpalm 190
(
)
Ben Dijkman & Co
[email protected]
http://www.oldradioparts.net/dials_intro.html
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Decals
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6. Parts Identification
Waxed paper capacitors
Electrolytic
Mica capacitor
Ceramic Caps
Polystyrene capacitors
MicaMold capacitor
Carbon Comp resistors, American, European
Power Resistors
Candohm
Selenium Diode
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7. Why Replace good looking parts
Capacitors
Resistors
Pilot lamps
Wire
Line Cord
Fuse
Dial String
Known problem parts (i.e. Philco 370pf, 6X5
rectifier tube shorts)
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Candohm
Grounded tab
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8. Tubes go bad often, NOT.
Tubes last a long time unless abused
Test all tubes - Does it work in the radio?
Mutual Conductance
Emissions
Eye Tubes
EM34, 6E5, 6E5C, 1629
Sources of tubes, NOS or Used
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http://www.akh.se/tubes/eyes.htm
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Filament voltage booster
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Add a B+ switch to extend tube life
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9. Replacing Capacitors
Test all new caps
Leave tubes in sockets!
Waxed paper caps clip and solder
Electrolytic
Restuff
Add a terminal strip
Solder onto convenient points
RF Bypass/UL rated safety caps.
Transoceanic comments
Silver Mica Disease
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Transoceanic B600
C46
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~90v
C40
C45
Silver Mica Disease
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~90v
C2
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10. Resistors
Test all new resistors
Clip and solder
Combinations parallel and series.
Add a terminal strip.
Heat dissipation power resistors
Inductance above 18MHZ
Pilot lamps on a rectifier tube filament.
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Volume Controls
High Resistance
Tapped
Switched
Cleaning/replacement.
Linear, logarithmic, audio
taper.
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11. Power Cord
Replace it with Zip Cord and a new plug.
AA5 Hot chassis
Audio Output tube is to be near neutral
potential.
HUM
Ref. Radiotron Designer's Handbook,
Fourth Edition, P. Langford Smith, 1952?
– http://geek.scorpiorising.ca/RDH4.html
GFI on an AA5
Adding a fuse.
Power Transformer chassis leakage.
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12. Cleaning, Dial cords,
Miscellaneous.
CRC Contact Cleaner
Chassis cleaning (Tape tube sockets)
Replace Dial cord.
Grommets for tuning cap and line cord
Dial scale replacement.
Speaker cone repairs
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13. Power up
Clean the bench first.
Look at each tube pin, terminal lug and trace
parts for cold solder joints.
Use an Isolation Transformer even on
transformered units!
Use a Variac with
– volt
– amp meters
Amp Clamp Multiplier trick
Dim Bulb Tester.
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Inrush Current limiters
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Initial tests and checks
Tube filament glow
Snapping sound
Magic smoke.
Static
– Thunder Storm static crashing silenced with volume
control.
Hum
– Tuned to a station swap plug.
– No station
– Not affected by volume control.
Check transformer phasing for minimal leakage.
Check all B+ and bias voltages.
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Alignment - Gear RF Generator
Isolation Transformer time!
Coverage of radios capabilities
– 400khz to 20 MHz
– Harmonics
– 110 MHZ for FM radios
IF frequency
– 450-470 khz
– 225 khz autos
– 12.7 mhz FM radios
AF modulated tone
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Alignment - Gear
VTVM or High Impedance DVM
– B+, Line voltage, AGC and Audio Output
Frequency Counter
Digital SW receiver
Alignment tools
– IF core
When to use - Wood, plastic, fiberglass, metal, Allen wrench.
– Trimmer caps
Seal from slipping.
– Birthday candle
– Fingernail Polish
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Alignment - Procedure
Burn in 30 minutes
No fast moving breezes
Follow Instructions
–
–
–
–
IF affects dial linearity
Clean and bake band switch
Denatured Alcohol
Bake oscillator and IF coil(s)
Don’t forget to Align dial indicator
Use generator lead draped over chassis, loop or
internal antenna
Watch max output on HP-606 signal generator.
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AA5
Hot Chassis AC-DC Radio.
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http://www.nostalgiaair.org/Resources/811/M0014811.htm
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Grundig 88U 3 tube 5 sections
Transformered AC radio
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Parts Sources
www.dialcover.com
tubesandmore
.com
"King Of Controls!"
Rubber, knobs, buttons
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Mark Oppat's
For more vendors see: www.ppinyot.com and follow the “Links” button
Resources
USENET Newsgroup
rec.antiques.
radio+phono
www.radiomuseum.org
Parallel Resistor
calculator
philcorepairbench.com
Converting to a
6E5C Octal
tube
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www.hippy.freeserve.
co.uk/e12calc.htm
www.
Tuberadio.it
DjVu Solo 3.1
Use for BAMA files.
Philco 38-9
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Thank You
You can find this presentation on:
www.ppinyot.com
Links Page.
Oct 23, 2007
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