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 Post subject: Zenith TO 3000-1
PostPosted: Dec Sat 10, 2011 2:26 am 
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Joined: Dec Sat 10, 2011 2:10 am
Posts: 16
Location: Brampton, Ontario, Canada
I was given a Zenith 3000-1 that needed some work. The front cover pins wwere broken, fixed that, dial light didn't work, fixed that and it needed a good cleaning.
I'm a heating technician and have no experience with electronics. I turned the radio on and the only band that works is FM. some static on the SW stations LW and Broadcast are quiet. Does anyone have any suggestions on how to get it working? Is there a "dummies guide" to testing these transistor radios?
Thanks


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Sat 10, 2011 2:49 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 708
Location: Lake County, IL, US
Here's the service info, for a start:
http://www.transoceanic.nostalgiaair.or ... 3000sm.pdf

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Trent Nicol


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Sat 10, 2011 2:57 am 
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Posts: 3993
Location: Sunnyvale CA
tagski wrote:
I was given a Zenith 3000-1 that needed some work. The front cover pins wwere broken, fixed that, dial light didn't work, fixed that and it needed a good cleaning.
I'm a heating technician and have no experience with electronics. I turned the radio on and the only band that works is FM. some static on the SW stations LW and Broadcast are quiet. Does anyone have any suggestions on how to get it working? Is there a "dummies guide" to testing these transistor radios?


I had one like that that I got going just the other day. Fixing these things is just a matter of common sense and a little knowledge of how they work. You are in good shape in that the FM works. I have one where I *never* got the FM to work properly and I am still considering what more I could do. AM is relatively simple by comparison. Your problem is likely to be either a problem with the AM RF section transistors, or problems with the bandswitch.


I have done enough 3000s to have a procedure. Since the FM works, you can eliminate most of the problems right off - the audio stage (all the transistors over on the power jack side of the radio) and the IF transistors are OK. The FM RF section is OK, too, and the audio section. So the remaining issues could be the AM RF section or IF sections. We know the antenna is connected properly for FM and its the same antenna for SW, so that is not it. Since BC and SW both fail, it's probably not just the AM antenna. But check it - it's a 9-pin connector on the upper left as you look in the back of the radio that plugs into a 9-pin socket.

First step is to turn the bandswitch back and forth a bunch of times. That may clean the terminals in it well enough to make it work - check it on all the "am" bands (including SW bands), If you get more-or-less continuous static that changes as you tune the radio, it's probably working to some extent.
Assuming that doesn't work, check that all of the AM RF transistors are actually present - they are the three little silver cans over the tuning cap and coils (upper left as you look at the radio upright from the back. They go into small rectangular black sockets with 4 tiny holes in each. If any of those is missing, it won't work. They can fall out, since they held only by the tension on the pins. If one of them is missing, check around inside for a loose one - frequently they get stuck to the speaker magnet. If any of them is missing, you need a replacement. If its gone, respond back and we can figure out where to get a new one.

Attachment:
royal3000_transistors.jpg
royal3000_transistors.jpg [ 98.9 KiB | Viewed 9477 times ]



If they are all there, make sure the radio is off, then remove them one at a time, and then re-insert them a few times to clean the contacts. If you have contact cleaner (non-lubricant kind) very lightly spray it in the socket. Note that there are 4 pins and they are staggered so you can only insert them one way. Once it's back, try the radio again. This is a very likely cause that has happened to me on at least 4 Royal 1000/3000. After cleaning each of them, if it still doesn't work, you might have a "tin whisker" in the transistor. Remove one of them, and you will see that there are 3 pins in a row, a gap, then a 4th pin. Gently bend the third pin (the one in the middle but adjacent to the gap) over flat against the bottom. Then reinsert it. All this pin normally does is attach the can the transistor is in to ground to act as a shield. If can, however, have a "tin whisker" that shorts out some of the other connections internally. With the pin bent over, reinsert the transistor (with the right orientation) and try again. If it doesn't work, go to the next of the three, then the last, trying it after each step.

Attachment:
royal3000_mixersocket.jpg
royal3000_mixersocket.jpg [ 96 KiB | Viewed 9479 times ]

Attachment:
royal3000_121-351_transpins.jpg
royal3000_121-351_transpins.jpg [ 96.03 KiB | Viewed 9477 times ]


Chances are about 60% that this will make it work on at least some of the AM/SW bands (you'll never know about LW, since unless there happens to be an LW beacon nearby, there's nothing on LW). If not, then it's time to clean the bandswitch and start substituting transistors. The bandswitch requires you to take the chassis out, which is pretty easy but not as easy as checking the transistors.

Try that and see. I will try to get some pictures up later tonight to show what I mean. It's pretty easy to see but not easy to write step-by-step instructions for. Either way, let us know what you do.

Brett

p.s. another thought - while messing with the AM transistors, check that they are in the right slots. Looking at it as in the first picture, the RF transistor should have a part number of 121-349, the oscillator 121-350, and the mixer 121-351. I think you can probably have the oscillator and mixer swapped but it almost certainly won't work with the wrong one in the RF socket.


Last edited by Brett_Buck on Dec Sat 10, 2011 6:12 am, edited 5 times in total.

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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Sat 10, 2011 3:26 am 
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Joined: Sep Fri 04, 2009 7:55 am
Posts: 2184
Location: Mesa, Arizona
What Brett said! :) I'll bet you've either got a dirty band switch or perhaps some of the transistors that are AM-specific were pulled. Sometimes, folks will get one of these sets and "scavenge" parts.

The TOs, unlike many radios, have transistors that simply plug into the chassis, rather than being soldered to other components. So they're easy to get out, and sometimes go missing. Other times, the transistors are just plain bad. Either way, if that's your problem, it's a pretty easy fix.

Beyond cleaning the band switch and checking the transistors as Brett suggested, other repairs on this set can be rather challenging. Hopefully, though, this fixes your problem.

Good luck with your restoration.

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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Sat 10, 2011 4:12 am 
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Joined: Feb Thu 24, 2011 1:29 am
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Location: Dallas, TX - in the city but with bobcats and coyotes
The service info has voltage readings for the seven test points. They are in a row on upper left as viewed from back. This can help if it's not as simple as tin whiskers shorting a transistor to its can.
Measure them and report back if needed.

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In a triode, no one can hear you screen.


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Sat 10, 2011 4:37 am 
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Posts: 3993
Location: Sunnyvale CA
mescalero wrote:
The service info has voltage readings for the seven test points. They are in a row on upper left as viewed from back. This can help if it's not as simple as tin whiskers shorting a transistor to its can.
Measure them and report back if needed.


Here they are
Attachment:
royal3000_testpoints.jpg
royal3000_testpoints.jpg [ 99.63 KiB | Viewed 9477 times ]


Note that the service manual I have has a wrong entry - nothing on the radio is positive relative to ground! This is what it should be:

Attachment:
Picture 11.jpg
Picture 11.jpg [ 48.78 KiB | Viewed 9477 times ]


Brett


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Sat 10, 2011 9:05 pm 
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Location: Dallas, TX - in the city but with bobcats and coyotes
Good point!
BTW: Chassis ground is the reference for measuring those (negative) voltages.

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In a triode, no one can hear you screen.


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Sun 11, 2011 4:44 pm 
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Joined: Jan Sun 06, 2008 3:28 am
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Location: Richmond, VA
Brett, great info and photos. I don't have a problem now, but I'm bookmarking this thread for future reference. Thanks!

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Ed


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Mon 12, 2011 12:21 am 
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Posts: 3993
Location: Sunnyvale CA
Ed Morris wrote:
Brett, great info and photos. I don't have a problem now, but I'm bookmarking this thread for future reference. Thanks!


You're quite welcome. I haven't been posting here for very long but I am astounded at the depth and breadth of knowledge a lot of the posters here have. I am really more of a hi-fi guy than a radio guy. But I have gone through rather a lot of TOs in the last few years and the Royal 1000/3000 in particular, so it was a good target. Plus, they can almost always be made to work to some degree in about 1/2 hour. The original caps seem to be pretty reliable, and they tend to lose capacity rather than leak/short/blow up like a tube radio, so you have a good chance to troubleshoot it without a lot of soldering. I have replaced the electrolytic caps entirely in one of the 1000s (relatively easy) and a 3000 (very difficult without destroying something else) and *couldn't tell spits worth of difference*. Everything else seems to be pretty darn reliable.

I would guess it's 99% either one or more of the transistors, which are trivial to change, or a corroded bandswitch. The other trouble spots are the earphone jack and the damn little power jack on the -1 versions. Once it gets messed up, its very difficult to bend everything back the way it was. Not the problem here, obviously.

I am also a photography guy, and BTW, the best photo gadget for stuff like this is a ringlight. I have this one:

http://www.amazon.com/Macro-Flash-LED-L ... B0031AQ302

but any of them will do the trick (good luck beating $35, though!). The hardest thing about these sorts of photos is setting up the lighting, and the ringlight makes it absurdly simple. I just balanced the radio on the back of the couch, pointed the camera, and hit the button. I need a better program for annotating - this worked but it took a while and the program I used is pretty awkward.

Brett


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Mon 12, 2011 1:19 am 
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Joined: Dec Sat 10, 2011 2:10 am
Posts: 16
Location: Brampton, Ontario, Canada
Ok, I don't know if this already posted or not, but I took the readings at the test point for fm and am bands and they are as follows: FM 1= .08, 2=.87, 3=.87, 4=0, 5=.39, 6=.41, 7=.53
AM 1=.90, 2=0, 3=.63, 4=0, 5=9.36, 6=7.03, 7=6.8
I don't know if these readings are supposed to be exact or if there is a +/- tollerance.
still only getting static except for FM. How do you clean the band switches. Also what are the little brown cylinders with what looks like Allen head screws? I see 10 altogether.
Thanks,
George


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Mon 12, 2011 1:44 am 
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Brett, I like that ring light. I might have to check that out.

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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Mon 12, 2011 1:51 am 
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Posts: 3993
Location: Sunnyvale CA
tagski wrote:
Ok, I don't know if this already posted or not, but I took the readings at the test point for fm and am bands and they are as follows: FM 1= .08, 2=.87, 3=.87, 4=0, 5=.39, 6=.41, 7=.53
AM 1=.90, 2=0, 3=.63, 4=0, 5=9.36, 6=7.03, 7=6.8
I don't know if these readings are supposed to be exact or if there is a +/- tollerance.
still only getting static except for FM. How do you clean the band switches. Also what are the little brown cylinders with what looks like Allen head screws? I see 10 altogether.


Those are coils that resonate for the different frequencies. There are more of them on the front. For now, leave those alone (and be careful around them). They are used to "tweak" the performance (things like make the pointer line up with the actual frequencies).

The voltages are pretty close, assuming your batteries might be a little tired. They're closer than mine, and mine works fine.

Did you try the other suggestions? Cleaning the bandswitch is easy enough but you will need to remove the chassis and have some DeOxit D5 in a spray can to clean it any better than just running it back and forth.

Brett


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Mon 12, 2011 1:55 am 
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George, if you haven't already, you should remove the chassis and then you can check things out. To clean the bandswitches, use a non-lubricating electronic cleaner such as CRC QD Electronic Cleaner available at Auto Zone, and spray the switch contacts and work the switch several times. My experience is that this is not usually as big an issue with ss TO's as it is with tube TO's. Most likely you have a bad cap or transistor. Once you get the chassis out, they aren't that hard to work on, but you need to be careful not to damage the dial drum.

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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Mon 12, 2011 3:30 am 
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Location: Sunnyvale CA
Ed Morris wrote:
George, if you haven't already, you should remove the chassis and then you can check things out. To clean the bandswitches, use a non-lubricating electronic cleaner such as CRC QD Electronic Cleaner available at Auto Zone, and spray the switch contacts and work the switch several times. My experience is that this is not usually as big an issue with ss TO's as it is with tube TO's. Most likely you have a bad cap or transistor. Once you get the chassis out, they aren't that hard to work on, but you need to be careful not to damage the dial drum.



I still think trying the transistors first is a good step, but here's how to remove the chassis. Run the dial pointer all the way over to the left of scale so that the tuning capacitor blades are meshed, less likely to bend them. Take the knobs off the front (just pull off, they will come...). Remove the antenna connections - the black 9-pin plug for AM/LW and the spade lug for the telescoping antenna. There's a clip over near the bandswitch knob, make sure the antenna wires are free of that. Pull the speaker connectors off - just pull straight out. Then remove the 3 screws on the power tap side:

Attachment:
royal3000_chassisscrews1.jpg
royal3000_chassisscrews1.jpg [ 99.62 KiB | Viewed 9375 times ]


Then the bandswitch knob:

Attachment:
royal3000_chassisknob.jpg
royal3000_chassisknob.jpg [ 92.67 KiB | Viewed 9375 times ]


The last screw is over under the knob:

Attachment:
royal3000_chassisscrews2.jpg
royal3000_chassisscrews2.jpg [ 94.35 KiB | Viewed 9375 times ]


I reach in with a nut driver (these are all 1/4") but sometimes I can't fit it and use a flat screwdriver. This particular radio allows the nutdriver to pass easily because it is pretty badly bent from, apparently, being run over with a main battle tank or something similar.

Then lift out the chassis, bandswitch side first. It is a tight fit and you might have to maneuver it around to clear all the screws on the bottom hinge. I grab the bracket that holds the back on. If you feel any tension, check and see what the problem is, probably the antenna wires have caught on something. Once you get the end clear of the sides, pull it out sideways. You need to do it in this order because otherwise it will catch on the shield around the power tap. Then just pull it out.

Attachment:
royal3000_chassisremove.jpg
royal3000_chassisremove.jpg [ 98.03 KiB | Viewed 9375 times ]


This is the general arrangement. The bandswitch is on the left. Be careful to avoid damaging the drum. At this point, the plastic is very brittle and denting it in will probably crack it, and while it's probably possible to make a new one, you don't want to.

Attachment:
royal3000_chassisfront.jpg
royal3000_chassisfront.jpg [ 99.12 KiB | Viewed 9375 times ]


To clean the bandswitch, put the knob back on the shaft. Take the contact cleaner spray with the little red tube, and then squirt each side of the SEVEN, yes, count'em, seven double-sides wafer rotary switches. Squirt it on on side, then rotate the switch back and forth a bunch of times. Then the next side, then rotate, etc, until you get them all. This will make a big mess. Ideally you would like to keep the solution off the coils right below it, but that's pretty tough. As near as I can tell, it has no lasting effect, but will definitely alter the alignment for a few days until it evaporates entirely. Someone in my house has been known to put the radio in a warm oven to dry it out faster but that's really taking a risk of melting something.

Attachment:
royal3000_switchsquirt.jpg
royal3000_switchsquirt.jpg [ 96.46 KiB | Viewed 9375 times ]


These are the contacts you need to clean, close up as I can manage. There are something like 60 of them. It's actually pretty reliable, which is a good thing, since if I had to take one apart I would be tempted to toss it and go get another one on eBay. I took one apart on a tube Transoceanic and got it back together but this one looks a lot worse to me.

Attachment:
royal3000_contacts.jpg
royal3000_contacts.jpg [ 97.9 KiB | Viewed 9375 times ]


While you are at it clean the volume and tone pots, and the dial light and AFC switches:

Attachment:
royal3000_pots.jpg
royal3000_pots.jpg [ 99.41 KiB | Viewed 9375 times ]

Attachment:
royal3000_afc_dial.jpg
royal3000_afc_dial.jpg [ 99.57 KiB | Viewed 9375 times ]


Once you get this far, check back in.

Brett


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Mon 12, 2011 4:02 am 
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Posts: 3993
Location: Sunnyvale CA
Ed Morris wrote:
Brett, I like that ring light. I might have to check that out.


It's pretty useful. You can get ring flashes, and the like, but this one runs on two AA batteries and has a bunch of white ultrabright LEDs. It's very bright, and far beyond the CCD's ability to capture without blowing everything else out. This can give you and idea how bright it is:

Attachment:
led_ringlight.jpg
led_ringlight.jpg [ 94.87 KiB | Viewed 9374 times ]


I know how to set up lighting, but at maybe 5 minutes a shot, it's too much. As long as you aren't trying make a work of art, this takes just about zero thought and generally no important thoughts about shadows. I have in the past written and illustrated many articles and internet posts on various topics of interest (model airplanes, hifi equipment, etc) and the pictures were always a hold up, until I got this little beauty. And $35, hard to go too far wrong.

Brett


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Tue 13, 2011 1:29 am 
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Joined: Dec Sat 10, 2011 2:10 am
Posts: 16
Location: Brampton, Ontario, Canada
hanks again for the info. Before I found this forum, I had already taken the chassis out, just because i like to take things apart. I'll go back and try cleaning all those contacts with the spray. I have to say, the inside of mine looks a lot dirtier than the pictures you posted.
Thanks,
George


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Tue 13, 2011 1:42 am 
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Joined: Aug Wed 24, 2011 4:35 am
Posts: 3993
Location: Sunnyvale CA
tagski wrote:
hanks again for the info. Before I found this forum, I had already taken the chassis out, just because i like to take things apart. I'll go back and try cleaning all those contacts with the spray. I have to say, the inside of mine looks a lot dirtier than the pictures you posted.
Thanks,
George


Go ahead of course, but for goodness sake, do the transistor tests as suggested! This is not the first pass on mine so it's a lot cleaner than it might have been.

The radio in the picture, while previously working, stopped working on AM last night and the issue was bad contact on the AM mixer transistor socket. I squirted a bit of cleaner in there and worked it back and forth, and it sprang back to life.

Brett


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Tue 13, 2011 5:01 am 
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Joined: Feb Thu 24, 2011 1:29 am
Posts: 3149
Location: Dallas, TX - in the city but with bobcats and coyotes
One cool parlor trick to try when evaluating an AM receiver is to use another radio to see if the RF oscillator is oscillating. Tune another (working) radio to a relatively weak station somewhere around 1100 to 1300 KHz or so. Place this radio close to the radio under test and tune the radio under test's tuning dial slowly up and down. When/if the oscillator of the radio under test is oscillating about 455 KHz lower than the working radio's tuned frequency you will hear interference in the working radio's speaker.

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Last edited by mescalero on Dec Tue 13, 2011 3:13 pm, edited 1 time in total.

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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Tue 13, 2011 2:57 pm 
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GREAT posts Brett! Tagski, do the thing with the transistors as suggested. Bend that shield pin out of the way and try it after each one.


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 Post subject: Re: Zenith TO 3000-1
PostPosted: Dec Tue 13, 2011 9:56 pm 
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Location: Brampton, Ontario, Canada
Hey evryone, I tried bending the shield pin on both transistors and still the same, FM works good, all other bands nothing.
George


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