Using a Signal Tracer to isolate an audio distortion issue on a Gilfillan 731T-C from 1937. I will publish a second video that covers the Signal Tracer design, etc. RestoreOldRadios
There's a real joy in in tracing a signal and breathing life back into an old radio. I'll never forget the first time that I did it, gave me a real kick. Mind you I've also had a few real high voltage DC kicks from the HT rails along the way. Thanks for sharing, play safely guys. Kind Regards . . . Andy
Nice helpful troubleshooting video ! .....That's a really nice radio brand I'm not familiar with....Really impressed with the relatively Large & spread out, uncrowded chassis wiring & Durable large hiqh Quality componets appearance....Never seen that brand before but it looks unusually special & high quality....
Thank you for watching and reaching out. This radio belonged to my Dad and as you noted, the chassis was not filled up with caps, etc. like many for that period of time. I don’t think it was a high dollar radio (west coast) if I recall correctly. I appreciate you watching and for reaching out. All the best. Don
The method You were using scares me. When I worked on tube electronics starting 45 years ago, this was the first rule to save my live: Never ever touch the thing with both hands., always put one hand in my pocket. Second. When searching for the source of failure I would rathe pull tubes and start with putting back (known working good) & injecting a test signal. Starting at the end of the amplifier chain, instead of walking the whole path starting at the input stages. Just my two cents, experience collectect in 10 years of working with old tube based electronics.
I’m glad it’s helped. Another recent video I published using a signal tracer: Philco PT-25 Transitone - Signal Tracing a Distortion Issue ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-SG5-AhwympM.html Best, Don
The best troubleshooting video I have seen to date, In most cases the technician would just replace the caps and magic occurs. Thanks for a really great video!!
Mikael, thank you. I replace all caps too, but it’s fun to step back and troubleshoot an issue to understand the root cause. Thanks again for watching and your kind words. Best, Don
Thanks Don I been a radio collector for about 15 years now and restoring them is awesome. I am slowly learning to use test equipment. I use to and still do a total recap.
Like you, I love bringing these old sets back to life. It's so rewarding not only from the historical value, but it really helps keep my mind sharp and allows me to relief some stress from my real job. I usually do total recaps too, but this radio provided a unique opportunity to use my probe to isolate the trouble. Thanks again for following along and I hope your future projects are rewarding. Best, Don
+Radioman56 Three bakelites, that's a great find. It sounds like a video is in your future. Hope to see one soon and good luck on the repairs. BTW - what did you score? Best, Don
Thank you. A more recent video on the subject if interested: Signal Tracing Demo - Low & High Impedance Test Point Locations ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-SP6uJRjpCzY.html All the best. Don
Earnie - thank you. I just finished up on a Philco PT-25 and used one of my Signal Tracers and O-scope to isolate an issue. The video if interested: Philco PT-25 Transitone - Signal Tracing a Distortion Issue ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-SG5-AhwympM.html Best, Don
+brititalia Thank you Oscar. Anymore, I find myself replacing all caps and out of tolerance resistors, but there's someone special and therapeutic about this technique. Thank you for watching and sharing yours thoughts. Best, Don
Thanks for a great demonstration of signal tracing. It's one thing to just go ahead and replace all the caps right away but another point to show what can happen when those caps are very aged and have gone bad. Gary
Thanks Gary. I usually shotgun the cap replacements too, but it does prove how beneficial signal tracing can be when warranted. Thanks again for watching and again your kind words. Best, Don
Thanks Gary. I usually shotgun the cap replacements too, but it does prove how beneficial signal tracing can be when warranted. Thanks again for watching and again your kind words. Best, Don
Michael - they are easy to build. Check my videos below on the subject. My latest design ( publish) is my best performer overall. Thanks for watching. Best, Don How To Build A Signal Tracer ru-vid.com/group/PLjLu4V-71S1KGbxuJbnMPkfXsDjDU0MrX
Hello Don.Thank you for a well made and explained how to video. Signal tracers are very useful indeed, My little Heath kit has made a huge difference in finding the trouble,in my radios. I am looking forward to your next video showing your home built tracer. Till next time,all my best. Bobby
+Bobby Tectalabyss They definitely come in handy. I just published the video on the simplistic RF/Audio probe. Bobby, thanks again for following my channel. Best, Don
Blade - hope it helps. The playlist below for all videos I’ve published to date regarding signal tracers. All the best. Don How To Build A Signal Tracer ru-vid.com/group/PLjLu4V-71S1KGbxuJbnMPkfXsDjDU0MrX
Wow. I like that troubleshooting technique. I will have to build a signal tracer for myself.. That seems to make things much easier and quicker to evaluate circuit flow.
+jp040759 It comes in handy at times. Here's a link to an unlisted video that provides a better look at the design. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-3kyXCCdtPUY.html Hope this helps. Best, Don
+RestoreOldRadios I just used this technique yesterday. I used a poor (lazy) mans version. I used a high impedance crystal earphone for crystal radio use. I used it in series with a .001uf capacitor to block DC. I was able to find a bad transistor without the aid of a schematic of the amplifier. Thanx for the inspiration. I will definitely be making an amplified signal tracer soon. Great vids. Keep up the great work. Thanx for the video link also.
Really great video, thanks for sharing! :-) I hope that you please will answer a noob question. Am I right in thinking that you are going from input to output and then listen to the sound from the probe and when you get to the place where the sound gets bad, it's the spot where something is wrong?
Good stuff Don. I have two valve/tube signal tracers (rare-ish things over here) so I must get one fired up and actually use it! I did make a home brew one with a probe in a marker pen case and that went into an LM386 amp. It was a bit rubbish though!
Thank you Andrew. These little signal tracers come in handy for sure. I'm considering building another one myself. I like the idea of an integrated amplifier as you mentioned with a speaker. Thanks again for checking this out. Best, Don
Thanks for the informative video, it seems like your homemade probe has fairly high gain and low noise. All of the ones I have tried so far pick up too much stray interference to be useful for troubleshooting problems with RF circuitry.
Matt - it's been some time since I used it before producing this video, but it is actually on par with my Heathkit. I should note, my Heathkit has not been restored, so it's not a fair comparison. However, it does illustrates how low cost test equipment can be used to isolate troubles in a set. Thanks for checking this video out. Best, Don
I admire your patience in tracing that through. In order to save repair time and aggravation, isn't it sort of customary in troubleshooting older electronics, now, to automatically replace the old paper and wax capacitors with updated robust caps, then trace out any remaining problems?
Kennynva If the signal tracer has a blocking capacitor with a higher voltage than the plate voltages the circuit would be protected. My signal tracer design uses a 630V, but this could be increased to 2K if required. Best, Don
I don’t recall exactly, but just north of 150VDC. Your capacitor at the front end of your signal tracer would need to exceed the 750VDC, so a capacitor rated at 1000V to block the DC would be required. Best, Don
This is an excellent tutorial on how to use a signal generator. I'm still learning and am wondering, could the bad capacitor that you removed somehow ruined the 6F5 tube? Thanks, Tom
Thank you Tom. It may have taken the tube out as the capacitor was shorted best I recall. I appreciate your kind words and taking time to view the video. Best, Don
Great Video Don and now I have another little project to keep me busy this winter. I have been admiring your bench and especially the green mat. Can I ask where you got it?
+Scott Johnston Thank you Scott. I'm considering building another one for myself. The green mat is a "Alvin Professional Cutting Mats Green/Black Size - 36L x 24W inches". Do a search on Amazon for it. I think it was ~$30. Thanks again for checking out my channel. Best, Don
Here’s a video I did that you might find helpful: Signal Tracing Demo - Low & High Impedance Test Point Locations ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-SP6uJRjpCzY.html
Hello DonDid you ever make the 'how to make a signal tracer video? Thank you for your postings. They are a great help to a novice such as myself. Frank
+frank goddard Hi Frank, try this video link at: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-3kyXCCdtPUY.html Hope this helps. Please let me know if you have any questions. Best, Don
+frank goddard Frank, I've used it for both with no RF/Audio switch with good results. I built this many years ago and the schematic source is a mystery to me. I would check out +AllAmericanFiveRadio video at: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-QUmPBBnzkRE.html Rick, who I admire and respect just built and tested one that performs like an original from the period. I would like to build his circuit and compare the results of both probes to understand the differences in performance when time permits. Hope this helps and thank you again for following my channel, it's appreciated. Best, Don
great video--I built a tracer extremely similar to yours--even same speakers....lol but my diode keeps blowing constantly--using a 1n34a....any suggestions, tips etc...? guessing I'm doing something wrong...
+Chuck Yahrling Hi Chuck - to be certain I answer your question correctly, are you referencing the jumper across the coupling capacitor C17 at 16:21 into the video? Best, Don
yes. perhaps I misunderstood what you did or the connection to the next stage. just wanted to clarify for my own edification, as I would not whave expected this to work at all. tnx fer reply
+Chuck Yahrling Hi Chuck - to your point the coupling capacitor C17 blocks DC to the next stage. In this case, the old one was leaky and thus created the distorted audio. I know the video at 16:11 was not very clear, but I cut one lead of the existing C17 capacitor to remove it from the circuit and used two jumper wires with a new capacitor of the correct value and inserted it across the circuit, which normalized the operation of the radio outside of the AC hum created by the aging electrolytic caps. To your point, if I had jumped across the two points without a capacitor, the radio would have been inoperable. Hope this helps and it provides clarity. I appreciate your question and for watching this video. Please let me know if you have any additional questions. Best, Don
+Finom1 Thank you for subscribing and I'm glad the video added value. Please let me know if you have any questions or comments. Thanks again. Best, Don
+Donald M Hi Donald - here's a link to an unlisted video that shows a close up of the schematic. Hope this helps. Thanks for watching. Best, Don ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-3kyXCCdtPUY.html
