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  #1  
Old 03-23-2017, 04:08 AM
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Jeffhs Jeffhs is offline
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Zenith Transoceanic 3000-1 realignment

Please do not think I am trying to be difficult, and please do not get upset with me because I am starting another thread (the last one I started here, in which I expressed a desire to go to the ETF convention in Columbus, Ohio, has been blocked from receiving further responses because someone thought it had "run its course").

I am truly up the creek with this radio, and would like to get it working again, at least on AM. I had an offer (on ARF) to realign the set from a Zenith radio collector near Canton, Ohio, but I'd like to find someone a lot closer (in the Lake County, Ohio area if at all possible), since I don't drive.

While trying to correct the tracking on the FM band, I messed up the alignment of my Zenith TO 3000 so badly it no longer works on AM or SW. FM works well. I was wondering how much work it would be to realign this set so it works on AM and shortwave again; if this is not possible or would be too difficult (as I think it would be, considering I have no test equipment here), I will leave it as is, since it works exceedingly well and sounds wonderful on FM. I'm tired of seeing this set sitting in my bedroom unused, and with most of the bands dead silent. The TO3000 was a great radio in its day, and I'd like to see mine working again every bit as well as it probably did when it was new, without changing capacitors or doing anything inside the chassis. I am in no position to do any kind of repair work anymore since I moved to an apartment and gave up my workshop, against my will at the time (long story and OT), seventeen years ago.

Also, if it is possible, how would I rewire the AC adaptor socket to use a standard Zenith wall wart? The radio has been modified by its former owner to use a rechargeable battery pack, but I have a Zenith TO 1000/3000 wall wart that I'd like to use. I cannot find the wall wart that would recharge the battery, and even if I could find it, I don't want to risk damaging the radio by incorrectly wiring the plug (the original wall wart is missing the plug that would normally be at the end of the output cable; the transformer is in a box somewhere around here, but I'm darned if I know where, and I don't want to go looking for it).

Thank you.
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  #2  
Old 03-23-2017, 11:22 AM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by Jeffhs View Post
Please do not think I am trying to be difficult, and please do not get upset with me because I am starting another thread (the last one I started here, in which I expressed a desire to go to the ETF convention in Columbus, Ohio, has been blocked from receiving further responses because someone thought it had "run its course").

I am truly up the creek with this radio, and would like to get it working again, at least on AM. I had an offer (on ARF) to realign the set from a Zenith radio collector near Canton, Ohio, but I'd like to find someone a lot closer (in the Lake County, Ohio area if at all possible), since I don't drive.

While trying to correct the tracking on the FM band, I messed up the alignment of my Zenith TO 3000 so badly it no longer works on AM or SW. FM works well. I was wondering how much work it would be to realign this set so it works on AM and shortwave again; if this is not possible or would be too difficult (as I think it would be, considering I have no test equipment here), I will leave it as is, since it works exceedingly well and sounds wonderful on FM. I'm tired of seeing this set sitting in my bedroom unused, and with most of the bands dead silent. The TO3000 was a great radio in its day, and I'd like to see mine working again every bit as well as it probably did when it was new, without changing capacitors or doing anything inside the chassis. I am in no position to do any kind of repair work anymore since I moved to an apartment and gave up my workshop, against my will at the time (long story and OT), seventeen years ago.

Also, if it is possible, how would I rewire the AC adaptor socket to use a standard Zenith wall wart? The radio has been modified by its former owner to use a rechargeable battery pack, but I have a Zenith TO 1000/3000 wall wart that I'd like to use. I cannot find the wall wart that would recharge the battery, and even if I could find it, I don't want to risk damaging the radio by incorrectly wiring the plug (the original wall wart is missing the plug that would normally be at the end of the output cable; the transformer is in a box somewhere around here, but I'm darned if I know where, and I don't want to go looking for it).

Thank you.
Before touching any alignment points, you should have some kind of service information, so you know what coils pertain to what circuit. Either a Sams or an original Zenith manual. I learned that, way too many years ago.
A lot of my friends and I started working in the hobby by working on the kitchen or dinette table, with minimal tools and equipment, the first being an inexpensive soldering iron and a multimeter.
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  #3  
Old 03-23-2017, 11:54 AM
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Electronic M Electronic M is offline
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Quote:
Originally Posted by dieseljeep View Post
Before touching any alignment points, you should have some kind of service information, so you know what coils pertain to what circuit. Either a Sams or an original Zenith manual. I learned that, way too many years ago.
A lot of my friends and I started working in the hobby by working on the kitchen or dinette table, with minimal tools and equipment, the first being an inexpensive soldering iron and a multimeter.
+1

If you can get the alignment info for the TO you can do it yourself. First do as Dave says and familiarize yourself with all the different adjustments, and make note of which bands the service info indicates that they affect (so you can avoid touching the FM adjustments).
The next step depends on how you want to go: cheap, or precise.

If you want to go precise you should look for an alignment generator with AM modulation (hopefully with a ~400Hz internal audio osc. for modulation) and a frequency range from 100kHz/Kc-~10MHz/Mc. Tube ones that need a recap can be had for ~$10-20 at swap meets and better ones can be had for more. Most are about the size of an AA5 table radio or smaller so shipping/storage should be manageable. Once you have a working generator go through the AM alignment procedure on the schematic.

If you want to go cheap, find another set (needs to be analog tuned) with the same frequency of IF, tap into that set's IF and feed it into the TO's 1st IF input. Make sure to power one set with batteries or use a .1uF 600V cap in series with the IF patch over or use an isolation transformer to power one set. Tune the good set for a station, turn it's volume down, and then adjust the TO's IF for max volume. Once the TO's IF is peaked, you can then use the second set as an RF generator to tune the RF stage and osc. of the TO....There are a few ways to do this part. First off no connection between sets is needed, but the two sets should be close to each other. Both sets radiate and should be able to pick up each other's local osc. If the two loc. osc's are on the same freq they will 'beat' against each other and create a squeal in one or both set's speakers. You can use that to determine what freq the local osc in the TO is tuned to you can then walk the tuning dial of the TO towards the correct setting for that freq while adjusting the TO's osc trimmer/coil to keep the two beating against each other. If the good reference set was tuned to a station there you can turn it off and try adjusting the RF trimmers/coils for max volume. An alternate method is to use the reference set to "make" a station....When the osc and incoming carrier mix they produce a sum frequency and difference (IF) frequency. The local osc is always lower than the tuned station carrier by the IF freq (usually 455KHz in AM/SW) so based on the station your tuned to you can do the math on the sum and difference signals made. These tips should allow you to at least get the AM band back if you are patient and logical about it...You may also be able to get the lower SW back, but you may need a second working SW set to get the upper SW bands back...If you are too broke for a signal generator. It has been a good 10 years since I last tried this method (then I got a good generator and never looked back) so I may be off a tad on the details...You can/may want to try verifying things on two working sets with the same IF freq if something is off.
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Last edited by Electronic M; 03-23-2017 at 12:58 PM.
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  #4  
Old 03-23-2017, 04:25 PM
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jr_tech jr_tech is offline
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Lots of good info, and a link to the service manual (post#7) in this old thread:

http://www.videokarma.org/showthread.php?t=264494

jr
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