Corvette Radios 53~75

DELCO
Factory Certified
Corvette Radio Service
1958 to 1975 models.

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

The only Factory Certified Delco Corvette Radio Service available for the 1958 to 1975 models.

Servicing up to the 1985 pointer models

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


Corvette Radios 1958 to 1967 use a speaker mounted loading coil without 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 shorted.

A large number of aftermarket Corvette speakers have been sold at least back to 1999 and, still to this date 11/6/2014 with a .6 Ohm loading coil on the speaker. This wrong near short impediance will overheat the DS-501 output transistor causing sound to become fuzzy in about 15 minutes destroying it!
When DS-501 cools down it will work properly until it reaches thermal overload and shorts out again. The DS-51 will take less and less time with each thermal cycle to short out and, over time will short out completely. Once the DS-501 has been overheated it Will still go into thermal overload when correct coil load is applied, dumping 12 Volts DC into a new speaker one time and it need replacing! AGAIN! once the DS-501 and related components have been replaced.

Also makes .47 Ohm protection fuse inside corvette radios normally running warm to the touch, get so hot as to blister your hand. Carbinezes insulation on wire from fuse to Emitter of DS-501 turning it from yellow to black.

I never see radios in anything but a cardboard box. But have been told by Corvette Restorers of finding car's wiring harness to radio blistered as well. Pulling excessive current through fuse block, ignition switch all the way back to the battery in a worst case scenario.

Main concern here is the possibility of wiring harness starting an electrical fire. Maybe with the Corvette sitting in some ones garage with a small child sleeping nearby???

If You have replaced Your speaker it is my recommendation that before turning radio on again!!! You unplug the speaker leads from radio, take an ohm meter and measure the impediance on the green and black wires going to speaker IF it is from .6 to 1.4 Ohms it is the wrong value. Correct value is 1.5 Ohms. Any less than 1.2 Ohms and You got real costly problems.

NCRS.org National Corvette Restores Society took my information on this problem and did a half page artical in their DRIVE LINE volume 31 #1 Summer 2004. Recommending You return any Corvette Radio speaker with .6 Ohm loading coil to vendor telling then it is the wrong value.
I add: No matter how long ago the purchase was made! If the coil is .6 Ohms and most especially if listed as .6 Ohms on the coil itself. Return it to the vendor asking for money back on speaker, repair cost of replacing the DS-501 and, IF Your car's wiring harness is damaged for that as well! Selling a speaker such as this is proof positive this vendor knows nothing about Corvette Radios! And, make sure to tell them I Tony Mac Crutchfield said so;}~


Pictured above is a 1966 Factory Corvette speaker frame with Delco's coil. in the foreground is one of the .6 Ohm coils. Many Corvette speakers sold today, correctly wound with 1.5 Ohm coil are still wound on the smaller frame. Though not damaging the output transistor they do not have the same electrical characteristics as the factory heavy mass coil will.

My new modern Day High~Pro Corvette Radios speaker is the best sounding with more SPL than anyone elses offers. Built with a loading coil that is a clone of one Delco used. I order channel case, iron core laminates, magnetic copper wire and, hand wind the coils to Delco's specifications, then assemble them myself, With acoustically transparent Sun shield. 16 awg oxygen free leads back to the radio with correct factory type connectors. Upgrading from factory 22 awg is an amazing improvement with only 3.5 watts of power.

Yes a bit price compared to the average run of the mill speakers sold the Big time .comers selling anything and everything with the name Corvette on it. BUT as we all know You get what You pay for in this world and IF it is of little value to them then it is of little value to You. Ask Your self is it worth wagering saving a few dollars to do the Corvette's Radio against the cost of removing it later. Knowing that many those dash parts are going to be destroyed in doing so?

MY High~Pro speaker added to stock Corvette Radios is a 1000 times better investment that junking up Delco's electronics with tone controls to make up for the inadequate factory Delco Corvette radios speaker response. And not true audiophile want tone control any way with some of the best audiophile preamp ever made having only switching, balance, volume control. All though Delcos Tone Control is listed as the standard today in the Audio Cyclepedia and that is the correct spelling!

With the best ever made professional tone controls having no power to them as they are a cut only control on the frequencies. Because increasing a frequency adds the worst enemy of speakers "DISTORTION" the pros know that IF one want more bass remove some the the treble and turn the volume up.

Do not be fooled by those who do not know and do not know they do not know! Sound Quality! Telling how much better the new DISPOSABLE RADIOS sound.

With FM stations sound quality on all but the best station way down from their peak. Best used for traffic reports today coming no where close to the digital age! With nothing but endless mind dumbing chatter about what on sale at ZoZos! But not to worry BECAUSE:

I can add a line input coming off the back of Delco factory Corvette Radios using professional audio cable the size of a spark plug wire but very flexible with inline professional grade 3.5mm mini headphone type connector not much larger in diameter than the 8mm wire {so no ridiculous box to deal with} for IPhone, Ipod, Ipad, Iwhatever MP3 player, satellite radio or any other digital input for playing into the classic Delco Corvette Radios, then a line out with same wiring with amp turn on wire going into a 12 Volt TUBE pre amp [more TUBE products made today than in the 1950] into a small external true RMS P=EXE/R 200 Watt power amp feed in a High~Pro for the ultimate Corvette radio listening experience Keeping the factory stock Corvette radio. Making for a modern day Corvette Radio truly worthy to be in a Corvette.
Leaves them folks with the fake look alike FAKEDE UP PEAK TO PEAK SALESMANSHIP 22 Watt 4.5 Watt RMS Corvette Radios crying in Your sound waves! Sitting in there own Corvette with their Corvette Radios wide open being drowned out as You leave the parking lot.
And You know i have the ability to do so or Delco GM them self would not have trained and paid a dumb 14 year old kid back in 1967 to service there Corvette Radios $50.00 an hour. Along with my experience in installing and, servicing several of the top name Recording Studios in the World, Including RCA Nashville, SUN, Ardent, WishBone Muscle Shoals AL, Working with live sound crews form the Who, Bobby Whitlock, Molly Hatchett, Tom Jones, Ray Stevens, etc,etc,etc,.




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?



NCRS Member #35748