Hello everyone, the other day I had gotten a Zenith Royal 2000-1 AM/FM Radio from 1961 (according to some dates stamped in the radio) that still had its original manual with it yet.
When I got it home and went to try it out, I turned it on and I wasn't getting anything out of the unit (no static, or anything) and so I went to check the battery compartment to see if there were any batteries in it or not, and there were some batteries in it that were fairly new looking and they weren't leaky or anything, and the battery compartment was pretty clean (very minimal corrosion), but the 12V Wall Wort power supply plug on the side of the radio was badly corroded, and so was the headphone jack.
My question is, what would cause this radio to not power up?
It does have socketed Germanium Transistors of which they all are original to the set, and unfortunately my transistor checker died on me otherwise I would be checking the transistors.
Any help with this would be appreciated.
I did download the Sam's for this radio so I can follow along with what you guys are talking about when you are telling me what to check.
If the AC adapter socket is corroded, that may be the problem. They typically have switching contacts which disconnect the internal batteries when the adapter plug is inserted. Trace the wires from the battery terminals and see where they connect and compare to the schematic.
OK, thanks, I have completely disassembled the radio, and I took a look at all of the electronic components and it has all mylar and film capacitors in there and electrolytics that are more modern looking (the iei branded caps), and the resistors are the more modern style Allen-Bradley Resistors, and its really clean inside overall except the power adaptor plug-in on the side of the radio and the headphone jack.
So how do I test if the AC Adaptor plug-in on the side of the radio is what's causing the radio not to work on batteries? Is there a way to remove that AC Adaptor Plug-in from the circuit (or manually override it) so that i can confirm if it is indeed the AC Adaptor Plug-in that's causing the issue? I know I've seen Shango do something like that on an old Zenith Royal 850 AM/FM Radio that had a similar issue where the power adaptor plug-in was corroded to the point that it was causing the radio to no longer function on batteries, so he "by-passed" the AC Adaptor plug-in and got it to work on batteries.
Can you post the schematic or provide a link so we can see how the power jack and batteries are wired? It should be simple to bypass the jack so the batteries are directly connected.
Have the same radio picked up several years ago. The battery holder needed lots of cleaning and so did the on/off and volume control. Cleaned using WD-40 had to remove all the transistors and carefully clean plus the sockets with the same WD-40 the caps and resistors all checked good. Please be careful when cleaning the transistors one at a time. David
Ok here's the schematic, but to be honest when I looked over the schematic, I couldn't find where the AC Adaptor and Battery clip wired into the overall circuit design...
there was 3 wires attached to the AC Adaptor plug-in on the radio, Gray, Black and Brown, the Black wire went to the (+) terminal on the battery clip, the gray wire went to the power switch, and the brown wire went to chassis ground if that helps any.
(This post was last modified: 03-22-2022, 07:27 PM by captainclock1988.)
The battery holder holds 8 1.5V batteries, and provides 12 volts total, as does the AC adapter. The positive goes to ground and the negative goes to one side of the power switch. See the diagram at the very lower right of the schematic. You will need a very low noise power supply putting out 12 volts DC and 45 ma MINIMUM. On the auction site I see a suitable power supply for less then $10, 12 V DC at 1.5 A. You may have to adapt its connector, and add a large filter condenser to the output, say 1000 mfd, 25 V, but it should work OK.Be sure, when you make the power adapter, that the positive goes to ground and the negative goes to one side of the switch. If there is currently an input jack for this, check how it is polarized.
Never used a power adapter only the 8 D cells. Just to be safe I remove the batteries out of the radio when in storage the D cell will last a long time guess 200+ hours.
Hi Cap'n Clock, 3 good divide and conquer points, break out your DVM.
1. Verify the output of the power supply, both at its output plug and when plugged into the radio. Should be 12V or more. If the power drops to Zero when plugged into the radio and the radio powered on, then C7, C8 or others may be shorted. Remember, this is a Positive Ground Radio.
2. Find C7 and C8, and measure across them individually. C7 should be 12V if on batteries, may be higher if on wall wart power supply. If 0V, then check connections, power switch, etc. Also check for shorts. The voltage across C8 should be at least 1.4V lower than across C7. If the same as C7, check for opens, particularly around the Audio Output Stage.
3. Attempt to inject an audio signal from a cell phone, computer, CD Palyer, etc into the Amp at the middle terminal (wiper) of the volume control. If no joy, troubleshoot the Audio Amp until resolved. If Sound is good, check all before it.
Good Luck,
John, MrFixr55.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
The power adaptor socket on the side of the radio I had to disconnect it from the radio because it was so badly corroded, it was basically an 1/8" headphone jack style socket.
I do have many old 12v wall worts that I picked up from a box of wall worts and power supplies from Goodwill that I might be able to rig up to this radio if I can find the right type of socket for the side of the radio which was threaded and held into place with a washer and nut.
OK, well I had removed the AC Adaptor socket from the radio/circuit because the socket was so badly corroded, which was basically just an 1/8" headphone jack style socket that was threaded on the end and was held to the cabinet with a washer and a nut.
I do have several 12v AC Adaptors that I picked up once in a box of old AC adaptors and power supplies and other related electronic stuff from Goodwill once, but I would have to find a proper socket to fit those adaptors to install in the radio.
The corrosion oddly enough isn't battery acid corrosion it seems to be moisture related corrosion because the corrosion is only on the AC Adaptor socket and the headphone jack the inside of the battery compartment including the terminals are spotless.
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