Scott Philharmonic--started restoration--need some help - EH Scott Radio Enthusiasts2024-03-28T21:09:12Zhttps://ehscott.ning.com/forum/topics/scott-philharmonic-started-restoration-need-some-help?feed=yes&xn_auth=noProgress Report: I'm starti…tag:ehscott.ning.com,2015-05-20:3925821:Comment:485722015-05-20T18:09:11.328ZMark Kaplanhttps://ehscott.ning.com/profile/MarkKaplan
<p>Progress Report: I'm starting to work on the top of the chassis. I've removed the coil and tuning cap covers. I see some original and some replacement caps. I plan to replace all of the paper caps and check the resistors. One cap , in particular, on the rearmost IF coil (IF #1?) seems to have the wax melted out of the bottom of the paper cap. I hope that didn't do any damage. I've attached a couple of photos. Still, progress is being made!</p>
<p>Progress Report: I'm starting to work on the top of the chassis. I've removed the coil and tuning cap covers. I see some original and some replacement caps. I plan to replace all of the paper caps and check the resistors. One cap , in particular, on the rearmost IF coil (IF #1?) seems to have the wax melted out of the bottom of the paper cap. I hope that didn't do any damage. I've attached a couple of photos. Still, progress is being made!</p> Dave:
For capacitance I use a…tag:ehscott.ning.com,2015-05-19:3925821:Comment:487762015-05-19T01:00:47.733ZNorman S Braithwaitehttps://ehscott.ning.com/profile/NormanSBraithwaite
<p>Dave:</p>
<p>For capacitance I use a late model digital capacitance meter that I inherited. I believe it is an early Tenma digital instrument. Generally I am not a fan of digital instruments but based on use I have developed great confidence in this instrument. Before inheriting the digital capacitance meter I relied on a General Radio 1650A bridge for accurate capacitance measurement. For leakage and for reforming electrolytic capacitors I use a Sprague Teleohmike…</p>
<p>Dave:</p>
<p>For capacitance I use a late model digital capacitance meter that I inherited. I believe it is an early Tenma digital instrument. Generally I am not a fan of digital instruments but based on use I have developed great confidence in this instrument. Before inheriting the digital capacitance meter I relied on a General Radio 1650A bridge for accurate capacitance measurement. For leakage and for reforming electrolytic capacitors I use a Sprague Teleohmike TO-6A.</p>
<p>Regarding Sprague "Black Beauty" capacitors, it is my understanding that only the black cased capacitors with red printing were called Black Beauty capacitors by Sprague. These are Mylar and paper "Difilm" capacitors and are very reliable. The Mylar layer is responsible for very low leakage and high reliability. The black cased Sprague capacitors with yellow printing are wax-paper and with silver printing are paper in oil. Both of these types are very leaky and unreliable today, the paper in oil capacitors due to cracking and evaporation of the oil. The black cased Sprague capacitors with colored stripes (AKA "bumble bee") are OEM parts almost all of which are wax-paper but some of which are difilm and paper in oil. They must be tested individually. The only place I have found difilm "bumble bee" capacitors are in the high voltage circuits of a late McIntosh MC-275.</p>
<p>Norman</p> Norm - what instrument do you…tag:ehscott.ning.com,2015-05-18:3925821:Comment:487742015-05-18T23:39:41.995ZDavid C. Polandhttps://ehscott.ning.com/profile/DavidCPoland
<p>Norm - what instrument do you use to measure the cap values?</p>
<p></p>
<p>I have a choice of an EICO 950-B I recapped ... and the big Hickok 209 A. For capacitance, neither is real accurate, so when I care, I compare to new stock. The big revelation was using the EICO 950-B to check for leakage under real voltage instead of just using my VTVM. The old Sprague black beauties seem to be particularly bad now.</p>
<p>Norm - what instrument do you use to measure the cap values?</p>
<p></p>
<p>I have a choice of an EICO 950-B I recapped ... and the big Hickok 209 A. For capacitance, neither is real accurate, so when I care, I compare to new stock. The big revelation was using the EICO 950-B to check for leakage under real voltage instead of just using my VTVM. The old Sprague black beauties seem to be particularly bad now.</p> These values are available fr…tag:ehscott.ning.com,2015-05-18:3925821:Comment:486672015-05-18T16:03:37.693ZNorman S Braithwaitehttps://ehscott.ning.com/profile/NormanSBraithwaite
<p>These values are available from <a href="http://www.justradios.com" target="_blank">www.justradios.com</a>. However, I used 0.022-mfd capacitors that measured 0.021 and 0.027-mfd capacitors that measured 0.026.</p>
<p>Norman</p>
<p>These values are available from <a href="http://www.justradios.com" target="_blank">www.justradios.com</a>. However, I used 0.022-mfd capacitors that measured 0.021 and 0.027-mfd capacitors that measured 0.026.</p>
<p>Norman</p> Without digging thru the arch…tag:ehscott.ning.com,2015-05-18:3925821:Comment:486662015-05-18T14:03:43.753ZScott Seickelhttps://ehscott.ning.com/profile/ScottSeickel
Without digging thru the archives, I believe the solution was to measure thru a bunch of caps and find a pair that measured high, and a pair that measured low. It may be possible to find NOS film caps that are a better fit value wise. I don't think you can get new stock in these values, but I have not looked.
Without digging thru the archives, I believe the solution was to measure thru a bunch of caps and find a pair that measured high, and a pair that measured low. It may be possible to find NOS film caps that are a better fit value wise. I don't think you can get new stock in these values, but I have not looked. Scott Seickel said:
Plan ca…tag:ehscott.ning.com,2015-05-18:3925821:Comment:486652015-05-18T13:46:33.352ZNorman S Braithwaitehttps://ehscott.ning.com/profile/NormanSBraithwaite
<p><br></br> <cite>Scott Seickel said:</cite></p>
<p></p>
<p>Plan calls for a pair of .02 and a pair of .025 caps. I think most have replaced all with .022 and all worked fine.</p>
<p></p>
<p></p>
<p>No, replacing all four capacitors with 0.022 will not work. The trap will not be tuned to the remnant hum from the power supply and will allow hum through the very sensitive expander circuits. The radio will work but with some hum. This subject has been discussed on this forum recently.…<br></br></p>
<p><br/> <cite>Scott Seickel said:</cite></p>
<p></p>
<p>Plan calls for a pair of .02 and a pair of .025 caps. I think most have replaced all with .022 and all worked fine.</p>
<p></p>
<p></p>
<p>No, replacing all four capacitors with 0.022 will not work. The trap will not be tuned to the remnant hum from the power supply and will allow hum through the very sensitive expander circuits. The radio will work but with some hum. This subject has been discussed on this forum recently.<br/> <br/></p>
<p>Norman</p>
<blockquote cite="http://ehscott.ning.com/forum/topics/scott-philharmonic-started-restoration-need-some-help?commentId=3925821%3AComment%3A48476&xg_source=activity#3925821Comment48475"><div><p></p>
<p></p>
</div>
</blockquote> Thanks Scott, that's very cle…tag:ehscott.ning.com,2015-05-18:3925821:Comment:484762015-05-18T13:25:43.488ZMark Kaplanhttps://ehscott.ning.com/profile/MarkKaplan
<p>Thanks Scott, that's very clear. Appreciate the photo. Right now I've got the chassis upside down on my bench on a big sheet of styrofoam. Slowly replacing the capacitors underneath the chassis. Once I get that done I'll flip the chassis and start removing the cans on the top.</p>
<p>Thanks Scott, that's very clear. Appreciate the photo. Right now I've got the chassis upside down on my bench on a big sheet of styrofoam. Slowly replacing the capacitors underneath the chassis. Once I get that done I'll flip the chassis and start removing the cans on the top.</p> No, it is not potted Mark. I…tag:ehscott.ning.com,2015-05-18:3925821:Comment:484752015-05-18T10:21:10.332ZScott Seickelhttps://ehscott.ning.com/profile/ScottSeickel
<p>No, it is not potted Mark. It looks like this:</p>
<p></p>
<p>Label the wires before you pull them out. </p>
<p></p>
<p>Plan calls for a pair of .02 and a pair of .025 caps. I think most have replaced all with .022 and all worked fine.</p>
<p>Someday when I have a chance I would like to run a SPICE LT simulation to see how big of a difference there may or may not be in the response. …</p>
<p></p>
<p>No, it is not potted Mark. It looks like this:</p>
<p></p>
<p>Label the wires before you pull them out. </p>
<p></p>
<p>Plan calls for a pair of .02 and a pair of .025 caps. I think most have replaced all with .022 and all worked fine.</p>
<p>Someday when I have a chance I would like to run a SPICE LT simulation to see how big of a difference there may or may not be in the response. </p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2771122927?profile=original"><img width="721" class="align-left" src="http://storage.ning.com/topology/rest/1.0/file/get/2771122927?profile=RESIZE_1024x1024" height="888" width="430"/></a></p> David,
Thanks for your sugges…tag:ehscott.ning.com,2015-05-18:3925821:Comment:484742015-05-18T03:22:22.771ZMark Kaplanhttps://ehscott.ning.com/profile/MarkKaplan
<p>David,</p>
<p>Thanks for your suggestions. I've found the soldered metal box with the 7 caps inside (my schematic shows them as 0.5MFD, 200V 400V) but I didn't know about the tone reactor case. I will look for it. This set , is absolutely loaded with paper caps and many of them were replaced at some point and with different values than shown on the schematic. It almost looks like the repairman? used whatever he had available that was somewhat close; like using 0.03UF instead of 0.01UF. …</p>
<p>David,</p>
<p>Thanks for your suggestions. I've found the soldered metal box with the 7 caps inside (my schematic shows them as 0.5MFD, 200V 400V) but I didn't know about the tone reactor case. I will look for it. This set , is absolutely loaded with paper caps and many of them were replaced at some point and with different values than shown on the schematic. It almost looks like the repairman? used whatever he had available that was somewhat close; like using 0.03UF instead of 0.01UF. Many of the replacements are old black beauty caps and I'm finding that some I've removed are still OK as far as leakage goes but others are very leaky....</p>
<p>OK, I found the chrome case and I see four wires coming out into the bottom of the chassis. I think I found it on the circuit diagram; four 0.02UF caps with two associated coils and wires going to the bass control? Do you recall if those caps are potted in tar or can I get to them by removing the chrome case cover on the top of the chassis? That would certainly make life easier...Thanks, Mark</p> Think of the XXX a Roman Nume…tag:ehscott.ning.com,2015-05-18:3925821:Comment:484712015-05-18T03:15:34.362ZDavid C. Polandhttps://ehscott.ning.com/profile/DavidCPoland
<p>Think of the XXX a Roman Numeral for 30 for the 30 tube AM Philharmonic. Same for the 12 tube Super XII, fifteen tube Alwave Fifteen XV, etc.</p>
<p></p>
<p>Agree, cut off the grid wires and thread new wire when reinstalling the coil covers and tuning cap cover.</p>
<p></p>
<p>In recapping, the top left rear rectangular chrome tone reactor case (between the 3 audio 6J5's and the pair of 6L7 expander tubes) - inside are 4 caps to replace, and failure to do so could lead to damaged bass…</p>
<p>Think of the XXX a Roman Numeral for 30 for the 30 tube AM Philharmonic. Same for the 12 tube Super XII, fifteen tube Alwave Fifteen XV, etc.</p>
<p></p>
<p>Agree, cut off the grid wires and thread new wire when reinstalling the coil covers and tuning cap cover.</p>
<p></p>
<p>In recapping, the top left rear rectangular chrome tone reactor case (between the 3 audio 6J5's and the pair of 6L7 expander tubes) - inside are 4 caps to replace, and failure to do so could lead to damaged bass control.</p>
<p></p>
<p>Below that reactor riveted to the side of the chassis - a soldered medal box- has 7 caps inside, all .05 MFD as I recall.</p>