1934 AW 15 Electrical Restoration, Questions Please - EH Scott Radio Enthusiasts2024-03-28T22:10:37Zhttps://ehscott.ning.com/forum/topics/1934-aw-15-electrical-restoration-questions-please?xg_source=activity&feed=yes&xn_auth=noI want to thank all members w…tag:ehscott.ning.com,2017-07-17:3925821:Comment:600742017-07-17T22:23:00.592ZJon Ketronhttps://ehscott.ning.com/profile/JonKetron
<p>I want to thank all members who were able to help with this restoration. This AW-15 has been delivered back to the customer. He is very thrilled to have the unit playing again.</p>
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<p>I hope to have another E.H. Scott surface soon! </p>
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<p>Thanks,</p>
<p>Jon</p>
<p>I want to thank all members who were able to help with this restoration. This AW-15 has been delivered back to the customer. He is very thrilled to have the unit playing again.</p>
<p></p>
<p>I hope to have another E.H. Scott surface soon! </p>
<p></p>
<p>Thanks,</p>
<p>Jon</p> Thank you Mike for the inform…tag:ehscott.ning.com,2017-07-11:3925821:Comment:600682017-07-11T00:41:30.308ZJon Ketronhttps://ehscott.ning.com/profile/JonKetron
<p>Thank you Mike for the information and schematic.</p>
<p></p>
<p>Jon</p>
<p>Thank you Mike for the information and schematic.</p>
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<p>Jon</p> Joe;
I forgot to include a sc…tag:ehscott.ning.com,2017-07-10:3925821:Comment:600632017-07-10T16:52:18.146Zmike hadleyhttps://ehscott.ning.com/profile/mikehadley
<p>Joe;</p>
<p>I forgot to include a scope across the cap under test to measure ripple,</p>
<p>half wave rectification is used as it gives far more ripple current than full wave,</p>
<p>this gives a better idea of the internal condition of the cap</p>
<p>Mike</p>
<p>Joe;</p>
<p>I forgot to include a scope across the cap under test to measure ripple,</p>
<p>half wave rectification is used as it gives far more ripple current than full wave,</p>
<p>this gives a better idea of the internal condition of the cap</p>
<p>Mike</p> Mike;
Thanks for that informa…tag:ehscott.ning.com,2017-07-10:3925821:Comment:599672017-07-10T16:34:40.824ZJoseph W Stricklandhttps://ehscott.ning.com/profile/JosephWStrickland
<p>Mike;</p>
<p>Thanks for that information. It would be nice to combine that with one of the older capacitor testers made in the days of vacuum tubes, such as the ones by Eico and Heathkit with an eye-tube and variable control to measure the capacitance of the electrolytic under test. Some of those also had test ranges for film type coupling and bypass capacitors too.</p>
<p>Joe</p>
<p>Mike;</p>
<p>Thanks for that information. It would be nice to combine that with one of the older capacitor testers made in the days of vacuum tubes, such as the ones by Eico and Heathkit with an eye-tube and variable control to measure the capacitance of the electrolytic under test. Some of those also had test ranges for film type coupling and bypass capacitors too.</p>
<p>Joe</p> Jon;
I have attached the meth…tag:ehscott.ning.com,2017-07-10:3925821:Comment:597632017-07-10T14:59:05.956Zmike hadleyhttps://ehscott.ning.com/profile/mikehadley
<p>Jon;</p>
<p>I have attached the method we use for cap testing, it allows for the slow application of dc and the whole thing is current limited by the lamps, there is also the facility to over volt the cap, this is a particular nasty thing to do to the cap but does provide the ultimate test if you like, do not exceed more than 10% higher than the working voltage when doing this otherwise the cap will act like a giant zener and may not recover.</p>
<p>the setup also allows for reforming if you…</p>
<p>Jon;</p>
<p>I have attached the method we use for cap testing, it allows for the slow application of dc and the whole thing is current limited by the lamps, there is also the facility to over volt the cap, this is a particular nasty thing to do to the cap but does provide the ultimate test if you like, do not exceed more than 10% higher than the working voltage when doing this otherwise the cap will act like a giant zener and may not recover.</p>
<p>the setup also allows for reforming if you wish to do that sort of thing, but I have never had much luck doing this.</p>
<p>all of the values are guestimated for uk mains, you will have to adjust values for your supply,</p>
<p>mind the fingers and have fun.</p>
<p>Mike<a href="http://storage.ning.com/topology/rest/1.0/file/get/2771123592?profile=original" target="_self"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2771123592?profile=RESIZE_1024x1024" class="align-full" width="721"/></a></p> Joe,
Thank you for the comme…tag:ehscott.ning.com,2017-07-10:3925821:Comment:595782017-07-10T00:41:55.123ZJon Ketronhttps://ehscott.ning.com/profile/JonKetron
<p>Joe,</p>
<p></p>
<p>Thank you for the comments. All tuner chassis dog bone resistor's are Scott originals testing between 10%-20% tolerance. The only resistors changed were all located within the power supply. My plan was to originally "re-stuff" and replicate everything. It was decided early on to drop this idea. Mike's chassis contains reproduction dog bones, they are done very well. Thank you for the comment on the neat work.</p>
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<p>Jon</p>
<p>Joe,</p>
<p></p>
<p>Thank you for the comments. All tuner chassis dog bone resistor's are Scott originals testing between 10%-20% tolerance. The only resistors changed were all located within the power supply. My plan was to originally "re-stuff" and replicate everything. It was decided early on to drop this idea. Mike's chassis contains reproduction dog bones, they are done very well. Thank you for the comment on the neat work.</p>
<p></p>
<p>Jon</p> Jon;
Glad you managed to get…tag:ehscott.ning.com,2017-07-09:3925821:Comment:595772017-07-09T23:59:46.151ZJoseph W Stricklandhttps://ehscott.ning.com/profile/JosephWStrickland
<p>Jon;</p>
<p>Glad you managed to get the unit operational again. You do very neat work. The underside of the chassis looks very nice and neat. Like Mike, I approve of your original appearing resistors. It looks like a well preserved original, except for the few orange drop capacitors. Even the orange drop capacitors have been around since the 1950s.</p>
<p>Congratulations on a job well done!</p>
<p>Joe</p>
<p>Jon;</p>
<p>Glad you managed to get the unit operational again. You do very neat work. The underside of the chassis looks very nice and neat. Like Mike, I approve of your original appearing resistors. It looks like a well preserved original, except for the few orange drop capacitors. Even the orange drop capacitors have been around since the 1950s.</p>
<p>Congratulations on a job well done!</p>
<p>Joe</p> Mike,
I am interested in a d…tag:ehscott.ning.com,2017-07-09:3925821:Comment:596752017-07-09T23:30:02.940ZJon Ketronhttps://ehscott.ning.com/profile/JonKetron
<p>Mike,</p>
<p></p>
<p>I am interested in a diagram of the circuit if you get a chance. Speaking of reception, this entire week between 9AM and 10AM I have been able to pull in Radio China on the customers AW-15. My location is Lexington Kentucky here in the United States. I don't know Radio China's exact broadcasting location. Many religious stations on the local broadcast band and U.S. shortwave these days. Much of AM in the United States has been taken over by religious stations. I…</p>
<p>Mike,</p>
<p></p>
<p>I am interested in a diagram of the circuit if you get a chance. Speaking of reception, this entire week between 9AM and 10AM I have been able to pull in Radio China on the customers AW-15. My location is Lexington Kentucky here in the United States. I don't know Radio China's exact broadcasting location. Many religious stations on the local broadcast band and U.S. shortwave these days. Much of AM in the United States has been taken over by religious stations. I utilize my SSTRAN AMT3000 low power AM transmitter most of the time as a result unless DX'ing. I listen to local news and evening talk shows on occasion. As an amateur radio operator I have been working to set up a 136 ft. dipole antenna facing North/South. I eventually plan on using this antenna for my 350/450 Watt AM tube transmitter once restored. When not utilizing my amateur equipment, I plan on using this antenna for my standard consumer receivers. I look forward to test the results after restoration on a Scott as I have an AW-23 and early AW-15 heading my way this week. I may not be quoting exact text next, I have read within E.H. Scott literature that anything more than an 80ft antenna will produce unsatisfactory results. Anyone here on the forum ever experiment with antenna's regarding Scott receivers? What about results with various antenna lengths?</p>
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<p>Jon</p> Jon,
I only performed the tes…tag:ehscott.ning.com,2017-07-09:3925821:Comment:595762017-07-09T22:57:42.932Zmike hadleyhttps://ehscott.ning.com/profile/mikehadley
<p>Jon,</p>
<p>I only performed the test because the caps could be removed from the chassis and I has access to the test equipment, otherwise I would have restuffed.</p>
<p>I'm still thinking about replacing the caps as I can easily find some cans to fit and maybe going up a size or two on the value,</p>
<p>set was on today china network really strong, but there does seem to be a lot of religious stations in the usa, maybe because it was sunday afternoon here and am in the us,</p>
<p>if I get a…</p>
<p>Jon,</p>
<p>I only performed the test because the caps could be removed from the chassis and I has access to the test equipment, otherwise I would have restuffed.</p>
<p>I'm still thinking about replacing the caps as I can easily find some cans to fit and maybe going up a size or two on the value,</p>
<p>set was on today china network really strong, but there does seem to be a lot of religious stations in the usa, maybe because it was sunday afternoon here and am in the us,</p>
<p>if I get a chance I will sketch the circuit for the cap tester, scan it and send it over.</p>
<p>Mike</p> Mike,
I see your reasoning a…tag:ehscott.ning.com,2017-07-09:3925821:Comment:596742017-07-09T22:18:41.934ZJon Ketronhttps://ehscott.ning.com/profile/JonKetron
<p>Mike,</p>
<p></p>
<p>I see your reasoning and fully agree. I didn't realize you performed extensive leakage testing on the tuner electrolytic's. That is great they still measure good after all these years. I see why you are still utilizing them. I swapped out my original's for 10 MFD to add a bit more filtering. I must admit I did not perform extensive testing or calculation as to whether or not this value of electrolytic would strain the rectifier during warm up. I typically never…</p>
<p>Mike,</p>
<p></p>
<p>I see your reasoning and fully agree. I didn't realize you performed extensive leakage testing on the tuner electrolytic's. That is great they still measure good after all these years. I see why you are still utilizing them. I swapped out my original's for 10 MFD to add a bit more filtering. I must admit I did not perform extensive testing or calculation as to whether or not this value of electrolytic would strain the rectifier during warm up. I typically never deviate from the value's shown on the schematic when performing all electrical restorations. If I do deviate as in this instance, I only increase MFD value by a small margin. It would be wise to measure strain on the rectifier if I ever decide to increase value on future restorations. Thank you for the advice regarding this suggestion.</p>
<p></p>
<p>Jon</p>