Signal Tracing

[@craxd1]

When I was in technical college, we had an old Eico signal tracer and a Knight signal generator, which my instructor had me use to repair AM/FM cassette car stereo's that were coming out of South Korea back in the seventies (tape eaters). I used to fix those on the bench, after completing my work modules in class, for the other students.

[@RestoreOldRadios]

Very cool and thanks for sharing this. They definitely come in handy at times. Thanks for watching and reaching out. All the best. Don

[@thomasw2509]

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.

[@AndyDaviesByTheSea]

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

[@RestoreOldRadios]

Andy - thank you for watching and reaching out. It’s a lost art and fun to do when the opportunity presents itself. All the best. Don

[@abeleballestri612]

Nice demonstration how a signal tracer is used for looking after distorted output signal. Thanks for the video.

[@RestoreOldRadios]

+abele ballestri You are welcome, glad it helped. Best, Don

[@radioman5615]

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.

[@RestoreOldRadios]

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

[@radioman5615]

The same way I feel I picked up three Bakelite sets this past weekend Maybe I have to do a video I've never done a repair video

[@RestoreOldRadios]

+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

[@radioman5615]

Yes Ill have to do some videos soon getting my newer space set up . This way I can do better videos

[@RestoreOldRadios]

Looking forward to them and hope your new space works well for you. Take care. Don

[@garyhoward3123]

Great video. I was not able to find the part on making the tracer. Would like to make one of those. Thanks.

[@RestoreOldRadios]

I’m not in a position to provide one, but another option is this kit at: bd-electronics.weebly.com/bdst-2.html Best, Don

[@radioman5615]

Thanks will do DonIll try to do a video in the near future

[@skyking1328]

Still using the video in 2021 ! Thanks

[@RestoreOldRadios]

I’m glad it’s helped. Another recent video I published using a signal tracer: Philco PT-25 Transitone - Signal Tracing a Distortion Issue kzbin.info/www/bejne/iXiYXnSerN6gpq8 Best, Don

[@mikaelmcleod4698]

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!!

[@RestoreOldRadios]

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

[@peskycat]

Nice logical approach - thanks, your demonstration was very valuable to me.

[@RestoreOldRadios]

Thank you. A more recent video on the subject if interested: Signal Tracing Demo - Low & High Impedance Test Point Locations kzbin.info/www/bejne/iYGZpn2In9V2sLs All the best. Don

[@friedmule5403]

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?

[@HD7100]

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

[@RestoreOldRadios]

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

[@RestoreOldRadios]

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

[@rodolfogomez382]

Mr. Don thanks for your answer, best regards.

[@RestoreOldRadios]

Thank you and stay well. Best, Don

[@brititalia]

Brought me back to my old days...Great work, a joy to watch (and remember), Oscar.

[@RestoreOldRadios]

+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

[@beckyjohnsondiamond8978]

Does your radio have an patent tag on the back? If so could you add a picture of the patent tag?

[@RestoreOldRadios]

Hey, the radio belonged to my dad and I’m not sure if he still has it or not. I’ll check over the upcoming holiday and reply back. Best, Don

[@SDsailor7]

So when using a signal tracer the component under test has to be on? anyone know? Thank you

[@RestoreOldRadios]

Correct. For safety I use an AC isolation transformer and my most recent signal tracer is battery operated as well. Hope this helps. Best, Don

[@SDsailor7]

@@RestoreOldRadios Thank you for replying back. I do have an isolation transformer with built in variac.It is the Heathkit IP-5220

[@RestoreOldRadios]

Here’s a video I did that you might find helpful: Signal Tracing Demo - Low & High Impedance Test Point Locations kzbin.info/www/bejne/iYGZpn2In9V2sLs

[@earnieb5318]

Nice logical troubleshooting...easy to follow along...TY

[@RestoreOldRadios]

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 kzbin.info/www/bejne/iXiYXnSerN6gpq8 Best, Don

[@kensvintagetoys873]

Is that Radio plugged into the mains, are you working on it live powered up ?

[@RestoreOldRadios]

Hi Ken - yes, it’s powered up through an isolation transformer. Thanks for watching. Best, Don

[@tomstrum6259]

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....

[@RestoreOldRadios]

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

[@armandcorpolongo]

Excellent video and tutorial on signal tracing. Kudos for taking the time to demonstrate how to do it.

[@RestoreOldRadios]

Armand - thank you so much and I'm glad it added value. Best, Don

[@mudspringer]

Still using the video in 2024! Thanks #2 :).

[@RestoreOldRadios]

Thank you and I’m glad it adds value. All the best. Don

[@abeleballestri612]

Thanks for the nice demonstration. I did not quite understood where the loudspeaker of the signal tracer was connected to.? ... thanks.

[@RestoreOldRadios]

+abele ballestri Check out the schematic at: kzbin.info/www/bejne/aZzciXZ5mdmDi7s Let me know if this helps. Best, Don

[@peteleoni9665]

That was just EXCELLENT!@!!@

[@RestoreOldRadios]

Thank you. Best, Don

[@tectalabyss]

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

[@RestoreOldRadios]

+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

[@rodolfogomez382]

Sir this a very old radio I recommend to you a complete restore, probe all tubes and change all the variable resistances.

[@RestoreOldRadios]

👍 I did so after using it as an example for isolating issues. I appreciate you watching and reaching out. Best, Don

[@abeleballestri612]

Good work you have done with very robing in the various point suspect of the schematics of the radi.

[@RestoreOldRadios]

+abele ballestri Thank you, I appreciate you taking time to watch. Best, Don

[@frankgoddard5238]

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

[@RestoreOldRadios]

+frank goddard Hi Frank, try this video link at: kzbin.info/www/bejne/aZzciXZ5mdmDi7s Hope this helps. Please let me know if you have any questions. Best, Don

[@OIE82]

That video is private and not viewable. Do you gave another?

[@madelynmoore8806]

wow, one cap, makes a huge difference. That's impressive.

[@RestoreOldRadios]

It's amazing how one component can affect the operation. Best, Don

[@madelynmoore8806]

:)

[@td7456]

Good stuff Don! Nothing like a leaky coupling cap to mess up the signal chain! Very informative video!

[@RestoreOldRadios]

+Tim Dockery Thanks so much Tim. Those little coupling caps can be problematic for sure. Best, Don

[@worldmusic09]

This was exactly what I needed. Now to find a signal tracer..

[@RestoreOldRadios]

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 kzbin.info/aero/PLjLu4V-71S1KGbxuJbnMPkfXsDjDU0MrX

[@pottypete5593]

Hi Don. Would your signal tracer be ok for solid state HF CB radio. Or would there be an impedance problem? Got a few old 80's radios to learn on.

[@RestoreOldRadios]

The design will work well on solid state or tube… Check out the kits being offered at: bd-electronics.weebly.com/ as well. Best, Don

[@pottypete5593]

@RestoreOldRadios Thank you Don. Much appreciated.

[@RestoreOldRadios]

You’re welcome. I’ve got one of their BDSTs and it works great. Thanks again for watching and reaching out. Best, Don

[@bentrotor4917]

Curious what the voltage was on the plates of the tubes? I need to do some testing using a signal tracer but I have 750 volts on the plate for finals

[@RestoreOldRadios]

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

[@50sTransistorRadios]

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.

[@RestoreOldRadios]

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

[@frankgoddard5238]

Thanks for contact Don. Checked your Tracer Link. Will this probe detect both RF and Audio signals?Thanks. Frank

[@RestoreOldRadios]

+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: kzbin.info/www/bejne/h4bQgXV4o9-eiKc 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

[@chicagomike6666]

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...

[@RestoreOldRadios]

+chicagomike6666 I’m assuming you have a capacitor on the Anode side (between the probe & diode) to block DC? Best, Don

[@kennynvake4hve584]

I have always worried about testing the plate's of tubes..So this will not hurt your signal tracer????

[@RestoreOldRadios]

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

[@Nick215NY]

Why wouldn't you trace backwards from the speaker?

[@RestoreOldRadios]

In most cases I do. It's really a matter of preference. Thank you for watching and reaching out. Best, Don

[@RC-Heli835]

Man I love this stuff! Im building my 1st signal tracer now hoping to fix my Stryker 955!😀

[@RestoreOldRadios]

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 kzbin.info/aero/PLjLu4V-71S1KGbxuJbnMPkfXsDjDU0MrX

[@radioman5615]

this is a very informative wonderful video Thanks .

[@RestoreOldRadios]

Thanks for watching. Best, Don

[@Andrewausfa]

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!

[@RestoreOldRadios]

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

[@theonewease]

Great Channel, Great Videos. Thanks for providing!

[@RestoreOldRadios]

+G Morgan Thank you so much and I appreciate you taking time to watch and again your positive words. Best, Don

[@THOMMGB]

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

[@RestoreOldRadios]

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

[@gwcoty0715]

THOMMGB I

[@scottjohnston804]

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?

[@RestoreOldRadios]

+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

[@XPFTP]

your checking for audio ? but you keep sayin RF ? audio isnt AF ? RF would be input from antenna side ?

[@jp040759]

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.

[@RestoreOldRadios]

+jp040759 It comes in handy at times. Here's a link to an unlisted video that provides a better look at the design. kzbin.info/www/bejne/aZzciXZ5mdmDi7s Hope this helps. Best, Don

[@jp040759]

+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.

[@RestoreOldRadios]

+jp040759 A very creative solution and congrats on your repair. Best, Don

[@donaldm1156]

Do you have your signal tracer schematic somewhere?

[@RestoreOldRadios]

+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 kzbin.info/www/bejne/aZzciXZ5mdmDi7s

[@hamidvahdani8370]

خیلی عالی بود very nic and tankyou

[@RestoreOldRadios]

Thank you for watching. Best, Don

[@annomaus8386]

so you replaced an interstage coupling cap with a dead short? isn't the purpose of that cap to keep DC off the next stage grid?

[@RestoreOldRadios]

+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

[@annomaus8386]

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

[@RestoreOldRadios]

+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

[@annomaus8386]

OK, FB Don es tnx fer reply! I will follow and hope you do more soon. Just getting into tubes as I contemplate a tube linear amp for ham band(s).

[@rciancia]

Excellent overview... thank you !!!!

[@nor4277]

Me I would have recapped it ,check all resisters,all tubes ,then test it .considering how.old those parts are .

[@Radio478]

Great educational video thank you

[@RestoreOldRadios]

Thank you too for watching and reaching out. All the best. Don

[@SoddingaboutSi]

That poor output tube/vale but have been cooking!

[@RestoreOldRadios]

For sure. Best, Don

[@keithjordan7545]

Great video, thanks Don. Good explanation and demonstration. I have the Heathkit signal tracer. I will try it.

[@RestoreOldRadios]

Thank you Keith and hope your future troubleshooting goes well. Best, Don

[@radioman5615]

If this were my day May My Dad Rip. I would do a total recap

[@nor4277]

Your signal.tracer,is very cool ,is there anyone.have a lot for one

[@ajw6715]

Low volume. Why does all you people record such low volume?

[@RestoreOldRadios]

Thanks for your feedback. Best, Don

[@Finom1]

Don, great educational video!!! I am now a new subscriber!

[@RestoreOldRadios]

+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

[@MrUbiquitousTech]

Very helpful, thanks for sharing!

[@RestoreOldRadios]

+ShysterLawyer Glad it helped. Let me know if you have any questions or need anything. Best, Don

[@valakatz3967]

Thank you for the video, this is a very informative. i am going to try my self I have a Conar 230 signal tracer.

[@RestoreOldRadios]

Glad it was helpful! Best, Don

[@the_irishbull4657]

Thanks Don!

[@RestoreOldRadios]

+The IrishBull You are welcome Jerry. Did you get the dim bulb circuit completed? Best, Don

[@garynitkin7373]

BIG help! Thanks!

[@RestoreOldRadios]

Glad it helped Gary. Best, Don

[@kd5ozy]

paper wax caps must go before i ever start

[@RestoreOldRadios]

James, I’m with you. This was for demo only on how a signal tracer could be used to isolate the root cause. Best, Don

[@markjovanelli2607]

gee stop talking so slow mr. Rogers

[@RestoreOldRadios]

Thanks for the feedback Mark. I always increase my playback speed as needed. All the best. Don