1965 Mustang AM Radio Repair

Overview: After almost 40 years there's a pretty good chance that the original radio in your Mustang doesn't work properly. Bad electrolytic capacitors are the most frequent problem (I'm told over 90% of the time) for these radios. If the radio has extremely low volume, distortion, hum or just makes a put-put noise like a motor boat then the electrolytic capacitors are probably the cause. Basically, if the radio makes any type of sound at all when the switch is turned on, even just the initial chuff noise, then it's a worthwhile candidate for electrolytic capacitor replacement. If the radio makes no sound at all then there's a broken connection somewhere or another electrical component failed.

Electrolytic capacitors contain a wet substance called an electrolyte (hence the name) which can either leak out of the capacitor or dry up. Either way the capacitor doesn't function properly and the problems begin. When the capacitors leak a substance that loosely resembles battery leakage comes out. Those ones obviously need to be replaced. Other times the capacitors will start to bulge but at other times there are no external signs at all that the capacitors have gone bad. Given that, this document will outline the shotgun method for replacing the suspect capacitors. All of them will be replaced regardless if they're still good or not. At this stage of the game any good ones are working on borrowed time anyway. Even if the radio isn't used these capacitors go bad. If you found a NOS radio it would still likely need to have the caps replaced.

It should be noted that this demonstration uses the Motorola variety of the '65 Mustang AM radio. The part number is 5TMZ. The Philco (5TPZ part number) variety of the '65 AM radio is different internally so the procedure is different. The Motorola variety of the '65 Galaxie AM radio is the same internally so this page can be used for that radio also. The radios for other years and are different as well

Also note that there's no need to change the capacitors if the radio is working properly. I've seen 75 year old electrolytic capacitors that still work fine although storage is a big factor. The extreme temperatures encountered by a radio installed in a car dash surely affect the lifespan. Some technicians consider an electrolytic capacitor suspect if it's over five years old.

You may want to consider attempting this project only if you plan on purchasing a working radio. If you damage the radio beyond repair then there's no great loss anyway. All radios will need this done eventually so if you're successful then you're good for many years to come without having to buy another radio. If you buy a currently working radio it may stop working sooner than later with the old caps still in place also.

The radio being worked on is shown above. It's not pretty but it did show sign of life (it went put-put-put and that's it) so it was a candidate for recapping.

Replacement Capacitors Needed: Capacitors store electrical charge. The amount they can store is noted in microfarads which is abbreviated UF on the capacitor. There is also a maximum voltage rating associated with each capacitor. You should try to get as close to the specified values however if they're not available there is quite a bit of leeway for replacements. The microfarad value can be up to 20 percent lower and up to 100 percent greater than the specified value. The voltage rating works a little differently. You should never go lower although higher is OK. Example: if you have to replace a 500 UF capacitor rated at 16 volts then the capacitance can be as low as 400 UF to as high as 1000 UF on the replacement. The voltage rating should never be lower than 16 volts though so 25 would be OK too but not 10. Capacitors can explode if the voltage rating is exceeded. It's somewhat like a firecracker and that can damage the radio internals. Watch the voltage ratings! The electrolytic capacitors used in this radio are as follows:

Quantity	Value (microfarads)	Voltage
2	500	16
1	10	25
1	10	64
1	1.6	25

You probably have to take a trip to an electronics supply store to get these. Radio Shack doesn't carry a large selection of this type of stuff anymore so don't bother going there. Remember that these caps will go bad sitting on the shelf too so try to find a supplier with fresh stock.

Only the bottom cover of the radio needs to removed. Remove the four screws that hold the bottom onto the radio. If you can't get the cover to come off you may have to get it started by prying it with a screwdriver. Don't bother removing the top or the front of the radio.

Step 2 - Remove The Printed Circuit Board Retainer: - Estimated Time 30 Minutes

The back of the printed circuit board needs to be exposed to get the soldering iron in to remove the capacitors. The retainer needs to be removed so the board can be moved to a better position. The areas that need attention are circled in the picture above. Remove the screw on the right side. Note that besides the screw there is solder holding the retainer in place on the left and right sides. Heat the solder with the soldering iron and when it melts use the solder sucker to remove as much as possible. When you remove the soldering iron the solder will quickly harden again. Try rocking the retainer back and forth after the iron is removed to prevent it from bonding back to the radio chassis. After you get the right side done do the same for the left side. You'll have to work at it a bit but it will eventually go. When the left and right sides of the retainer are free move it away from the circuit board. At this point it's easy to remove the circled wire from the printed circuit board to the radio chassis. This wire will limit the amount that the board can be moved so it's better to disconnect it from the board. You could just heat the solder on the printed circuit board and pull the wire out when it melts however if you don't remove the solder with the solder sucker then the hole will tend to get filled with solder which makes things more difficult during reassembly. It's much easier in the long run if you remove the solder now.

The only things left restricting the movement of the circuit board are the three wires shown in the picture above. I took this picture after I removed them but it's clear from the picture what needs to be done. You can also see the retainer moved away from the board near the top of the picture. The printed circuit board can now be pivoted out to gain access to the back side of the board with the solder connections. We're no ready to remove the capacitors!

The capacitors to be removed are outlined and numbered in the picture above. Don't go nuts removing things just yet or you're sure to wind up in hot water. It's best to replace the capacitors one at at time so things don't get mixed up. Also, electrolytic capacitors are polarized so that means they have a positive and negative side. When they're replaced they have to be put back with the positive and negative sides oriented like the old capacitors. The polarity is noted on the side of the capacitor. For the capacitors numbered 1, 2 and 3 above the positive side is the one with circular band. Capacitors 4 and 5 need are a special case that will be discussed later.

Starting with capacitor 1 melt the solder on the rear of the printed circuit board so the leads can be removed. Again, I stress using the solder sucker to remove as much solder as possible so the hole the leads are in don't close. You can pull from one side with needle nose pliers while the solder is a liquid to remove the leads. When the old capacitor has been removed the new cap can be put in. The value for this cap is 10 UF and 25 volts. Make sure the polarity is correct when putting the new one in. When you're sure everything's correct you can solder the new cap to the board. Clip the excess in the leads when the solder hardens. Tip: The printed circuit boards are translucent. If you shine a bright light on it you can see through it. This may be helpful if you're having difficulty determining which solder points correspond to the capacitors.

Repeat the same procedure for the capacitors labeled 2 and 3. Capacitor 2 is 10 UF and 64 volts. Capacitor 3 is 1.6 UF and 25 volts. Remember to note the polarity when you remove the old capacitors and put the new ones in correctly.

Capacitors 4 and 5 are housed together inside the metal can. If you read the side of the can you will see a square and a triangle with the capacitor data next to them. In this case the capacitors are identical. They're both 500 UF and 16 volts. The bottom of the can has legs marked with these symbols so you can tell where to put the new capacitors. Removing the old can is difficult. It's probably the most difficult aspect of the project. There are five or six legs that need to be unsoldered before the old can is removed. The solder sucker is probably necessary here. After removing as much solder as possible I rock the can back and forth while heating each leg. Eventually it will go but you have to take care not to break anything. When the can is removed look underneath and you'll see the square and triangle each next to a leg. The positive side of the new capacitors connect where the marked legs were. The outside of the metal can is the common negative for both of the capacitors so the negative leads get connected to where one of the outermost legs were connected.

The new caps are now in but things have to be put back together before testing can be done. After positioning the printed circuit board back in place solder the three wires back to the cover. Solder the wire removed in step 2 back to the printed circuit board. Put the printed circuit board retainer back in place and tighten the screw. Don't solder the retainer permanently in place yet until the radio is tested.

A 12 volt power source, speaker and antenna is needed for this. If you don't have those then put the bottom back on and try it in the car. You can use a car battery for the power source in a pinch. Jumper cables can be used to make a connection from the radio leads to the battery. The green/black wire gets connected to the positive side. The negative side gets connected to the radio chassis. The mounting bracket stud is a good place for this. The black wires are for the speaker and the blue wire is for the light.

If the radio plays OK (hopefully it will) then solder the printed circuit board retainer back in place. The retainer is a ground point also so it's necessary to do this to ensure a good connection is maintained permanently.

Step 7 - Other Things To Do While The Radio Is Open: - Estimated Time 10 - 45 Minutes