Corvette Radios 53~75

DELCO
Corvette Radio Service
Factory Certified
1958 to 1975 models.

Crockett Sound Laboratory
704 Hwy 54 South
Alamo, TN. 38001
EMAIL
(731) 696-4163

Lots more radio info on my main web www.WonderBarMan.com page so make sure to check it out!




9/15/2014:
Have a customer wanting great sounds out of his mid-year Corvette with Air Condition. Adding Line Output to the 986281 Deco Radio to drive a 200 Watt mono amp, with High~Pro speaker

Spent several hours searching for a high quality new replacement speaker for the 6X9X1.75 Special for 1958 to 1967 Air Condition Corvettes
Finding only replacement offered was a baffle board to fit in the 6X9 opening with two 3.25 speakers. Which at best would be no better sounding than a pair of HEADPHONES crammed up under the dash. With no Sun Shield or necessary 1.5 Ohm Corvette Loading Coil, or Corvette wiring pigtale.
Along with a Retro Sound 6X9 that seemed promising with a 1.77 depth quoted that turns out to be 2.33 when mounted from the bottom.
Also found old tired worn out speaker cores offered as usable for $200.00 that would actually need a $250.00 recone to be RELIABLE enough for me to give my 5 Year Warranty on his project and the with same Delco sound and quality. And not expecting a very long life for the voice coil with 200 Watts energizing it.

So after sleeping on it i came up with the idea of using a baffle board BUT mounting the best modern day High~Pro speaker i could find {that would fit in the limited space under dash because of the aid duct} add on my custom hand would Delco Corvette Speaker Loading Coil clones, Sun shield, 16 awg oxygen free speaker wire with correct connector for a drop in installation to replace the Delco Slim / Shallow Mount 6x9 used in the 58 to 75 Corvette Air Condition Cars. PRICE $250.00



For Years i have offered a High~Pro drop in replacement for the normal depth 3 inch non AC 58 to 75 Corvettes. BUT only with my full restoration jobs.
Using the very best for the money new 6X9 speakers offered. Adding a Sun shield, Corvette Loading Coil, 16 awg. oxygen free cable, correct connector. for $200.00.
Since it is GAMBLING just to replace the speaker! Because a radio with a shorted output transistor will take out the voice coil with 12 Volts DC in NANOSECONDS.

However IF You are a Gambling Man i will build one for You. With a limited warranty.
Keeping in mind i have to order needed parts then assembly speakers. So it can be 2 to 4 weeks before i can ship out a speaker.



Corvette Radios 1961 to 1967 use a speaker mounted loading coil with out this coil bias on speaker goes from the normal 1.5 Volts D.C. to 12 Volts D.C. burning out the voice coil in the speaker and, shorting out the DS-501 Output Transistor. 12 Volts on the speaker leads tells You Your radio needs the coil or the DS-501 is shored.

See NCRS DRIVE LINE VOLUME 31 #1 Summer 2004


Factory 6X9 Delco Corvette speaker with loading coil have an impedance of 1.5 Ohms!
Several radios come in with a replacement speaker with an impedance of .5 Ohms. This overheats outputs transistor in about 15 minutes witch then shorts and sounds becomes FUZZY! Once the temperature drops it will work fine until it gets hot again! After several heat cycles the output transistor will then over heat and, short out even with a correct value coil.

You can test the speaker loading coil in two ways.
Measure the DC Resistance across the speakers leads. IF it is less than 1.5 Ohms it will not work on the Corvette radios!
To test a speaker connected to a radio measure the DC Volts. Radio on volume all the way down DC Voltage will be 1.5 Volts on a correct value coil and 1.1 is the max on one with the .5 Ohm coil.

The only way I know of getting a clone of the coils Delco used is to order case, iron core lamanits, hand wind the coils, then assemble them myself.

1963 to 1967 Vett Coupes are the best sound chambers on the road! An ipod, MP3 player or 10 disk CD playing into the Delco then an Alesis nano verb feeding the power amps, Set the rear up with: one 15" bass speaker 600 watts, two 10" 300 watts per channel, two 6X9" 150 watts per, two mids and twetters up front 150 watts per channel 1 Then You have a system worthy to be in a CORVETTE! WARNING!: a system like this will make YOUR CORVETTE the center of attention where ever You go! and You will need a second battery in the rear to pull the load! Not to mention straps to keep from BLOWN the rear glass out!

1965, 1966, 1967 Corvette Radio Removal:
WARNING!: REMOVE BATTERY GROUND CABLE BEFORE ATTEMPTING RADIO REMOVAL!

A. Remove both side trim {the cover that Your knees would hit} from center dash console (one Phillips screw at top of each side).

B. Remove black plastic heat distributor duct two 5/16" screws. {under dash between gauges, radio, speaker}

C. Remove radio support screw (7/16" lower right hand side of radio).

D. Remove glove box. Disconnect speaker, antenna and power connections.

E. Remove knobs and hex nuts. {knobs may have a set screw that uses a allen wrench or flat blade screwdriver}

F. Carefully tilt radio top back. It may now be removed by carefully manipulating through the side.

To re install radio, reverse above procedure. Important: Be sure to peak antenna trimmer for AM after re installing. Radio performance may suffer if this is not done. {small flat blade that can be seen through a hole in dash with knobs off}

SPEAKER REMOVAL: Accessible after glove box removal. {Best to send in with unit i get nasty calls after radio is returned go through a two week battle to get folks to check speaker and then all the paper is gone?}


Now as to the 986281 1965, 1966, 1967 Delco Corvette Radio I have done at least 5K in my life time first one was in 1966 at the age of 13, two years before i got Certified by Delco. MOST of them did not work right from the factory suffering form poor assembly. I think this was the first radio some of these folks ever built they sho did not know how to solder! I get $300.00 to do other AM/FM MONO units that are clean cores BUT these units have tuning board problems that require me to completely disassemble radio and rebuild that board as well and since these are the only ones i have to do that to, i charge another $100.00 for that service, only takes a day IF i am lucky. For a TOTAL OF $400.00 + return shipping/handling/insurance.
69 Corvette Radio Removal:
WARNING!: REMOVE BATTERY GROUND CABLE BEFORE ATTEMPTING RADIO REMOVAL!

A. Remove right instrument panel pad. [5 Phillips screws]

B. Disconnect speaker connectors. NOTE: on some vehicles it may be necessary to remove the kick pads to access speaker connectors. [To remove door sil plate remove two 5/16 hex head screws and four Phillips screws.]

C. Remove tree wiper switch trim plate screws and tip plate for access to switch connector. Remove switch connector and trim plate from cluster assembly.

D. Unclip and remove right and left console forward trim pads. Remove forward most Phillips screw on right and left side of console.

E. Inserting a flexible drive socket between the console and metal horseshoe brace, remove the nuts from the two studs on the lower edge of the console cluster.

F. Remove remaining four Philips screws retaining cluster assembly to instrument panel.

G. From rear of console, disconnect radio electric connector, brace and antenna lead-in.

H. Remove radio knobs and bezel retaining nuts.

I. Pull top of console forward [toward ear of car.] Separate radio from console and remove it from the right side opening. CAUTION: The center instrument cluster trim plate is designed to collapse under impact. Consequently, do not try to deflect the cluster plate forward to gain more access to remove the radio. Also use care so as not to damage the plastic oil pressure line when pulling console forward.

SPEAKER REMOVAL:

G. Remove kick pads by removing three Phillips screws.

Remove two 3/8" screws and remove speaker.


1975 Corvette Radio Removal
WARNING:
REMOVE BATTERY GROUND CABLE BEFORE ATTEMPTING RADIO REMOVAL.

RADIO REMOVAL

A. Remove right instrument panel pad. [5 Phillips screws]
B. Disconnect speaker connectors.
C. Remove three wiper switch trim plate screws and tip plate for access to switch connector. Remove switch connector and trim plate from cluster assembly.
D. Remove forward most Phillips screw on right and left side of console. Unclip and remove right and left console forward trim pads.
E. Inserting a flexible drive socket between the console and the metal horseshoe brace, loosen the nuts on the two studs on the lower edge of the console cluster. [Do not remove nuts]
F. Remove remaining four Phillips screws retaining cluster assembly to instrument panel.
G. From rear of console, disconnect radio electric connector, brace and antenna lead-in.
H. Remove radio knobs and bezel retaining nuts.
I. Pull top of console forward [toward rear of car]. Separate radio from console and remove it from the right side opening. CAUTION: The center instrument cluster trim plate is designed to collapse under impact. Consequently, do not try to deflect the cluster plate forward to gain more access to remove the radio. Also use care so as not to damage the plastic oil pressure line when pulling console forward.

SPEAKER REMOVAL

I. Remove instrument panel cover by removing 6 Phillips screws along forward edge.
K. Remove 2 Phillips screws from window post pads and remove pads.
L. Pull instrument panel cover towards rear of car and remove.
M. Remove screws securing speakers and remove.



1953 to 1957 WonderBar Tuning take from the 57 Chevrolet Radio Service manual 3725156. [Are my comments.] These instructions are the same for all 53 to 57 Delco ''Wonder Bar'' radios found in all GM models.

AUTOMATIC TUNING:

The Corvette radio includes the "Wonder Bar" electronic tuner witch is operated electrically by depressing the "Wonder Bar" momentarily.
The tuner will electrically and automatically tune in the next station on the dial.
The sensitivity control can be set so the tuner will stop at all stations as just the high powered stations.
The radio can also be tuned manually by the manual tuning knob.
The tuner also includes five push buttons witch can be preset to automatically select five favorite local stations.

PROCEDURE FOR SETTING PUSH BUTTONS:

Turn on the receiver and allow for warm up. [Let radio play for about 15 minutes]
1. Open the hinged door below the dial exposing the five red selector tabs.
2. Tune in the desired station nearest the left end of the dial. [Push the "Wonder Bar" to tune in stations]
3. Move the first red selector tab (one farthest left) until it lines up with the pointer tip.
4. Repeat set up steps 2 and 3 for all red tabs and, push buttons. [First tab works only with first push button, second tab only with second push button, etc.]
5. Check the setting of each red selector tab by depressing the corresponding push button. IF the correct station is not tuned in, readjust the red selector tab; either slightly to the right of the dial pointer or slightly to the left of the dial pointer until the desired station is obtained by the push button.
[IF a working station is not found where You have red tab set for push button the pointer will not stop. Once a push button is seated push another push button or ''Wonder Bar'' to release it.]
[Push buttons are electrical switches and only require enough force to push them in to the click position. To much force breaks the mechanical stops and, ''JAMS'' stopping all the pushbuttons as well as the "Wonder Bar" function from working!]

TURNING ON COLD TUBES CAN BREAK THEM! IF it is below 40 degrees F. warm the inside of the car for about 15 minutes after heater starts to work to bring glass tubes up a safe temperature.



1956 & 57 Corvette radios are the only model to use a DC to AC inverter, instead of the traditional B+ power supply.

Of the 30 or so of these units i have serviced only one has B+ problems. In dealing with it i found that NO replacement transformer is made. Leaving a parts donor unit the only option.

Transformer is very small .5" bobbin with over a 1000 turns of 40awg wire [about the size of a human hair] making it very difficult to rewind and very time consuming, very costly.

On that same unit i also had problems with the audio output transformer going up in smoke after playing for several days. Failure was caused by the bad B+ power supply. Output transformer was not that difficult to rewind BUT when it smoked it took out the 2 audio output transistors AND, the 2 power supply transistors!





FACTORY CERTIFIED
1958 to 1975
DELCO CAR RADIO SERVICE

Crockett Sound Laboratory
Tony Mac Crutchfield
704 Hwy 54 South
Alamo TN 38001 USA

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The ONLY! Delco Certified Radio Service Shop for
Vintage Delco Classic Car Radios

Including the signal seeking Wonder Bar. 1958 to 1975 Buick, Cadillac, Corvette, Chevrolet, GMC, Oldsmobile, Pontiac, Jaguar, Lincoln, Chrysler, Imperial, Avanti, Studebaker, Packard, Willys, Opel, &, John Deere units.

Servicing all analog "POINTER" unis from 1958 to 198?






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