How about an “adapter” to play MP3 players through a factory car stereo - over FM? Can you find one? Somebody you know have one stuck in a drawer and forgotten about? I may even still have one lying around from the days of the CD version of the Walkman (and nobody ever heard of blue teeth). Mini-circuits probably has a nice, and cheap, amplifier to give more than a 4 foot range. I wont tell the FCC if you don’t. I was going through junk a few months ago and found a TV modulator, back from the days of Trash80 and Commodore computers.
MP3, blue teeth?? I have nothing like that around!!!! may have a commodore 64 in the attic...
Got my folded dipole antenna half done!!!
Got my folded dipole antenna half done!!!
Hi John,
Sounds good! I want you to succeed here.
Yup, building an antenna is pretty straight forward. Remember when we made stuff like that instead of buying it? I'm glad you found a cable run and ready to go. One less thing to do! Depending on your antenna, you may want to put an amplifier right at the antenna end to boost things.
Hi wg_ski,
I've tried using those early on to avoid buying another (expensive) FM generator. Didn't have any luck with them due to the following:
1. poor quality
2. not on standard often. That rules them out right there.
I ended up buying some more HP RF generators. Then a Panasonic VP-8131A (stereo generator).
Sounds good! I want you to succeed here.
Yup, building an antenna is pretty straight forward. Remember when we made stuff like that instead of buying it? I'm glad you found a cable run and ready to go. One less thing to do! Depending on your antenna, you may want to put an amplifier right at the antenna end to boost things.
Hi wg_ski,
I've tried using those early on to avoid buying another (expensive) FM generator. Didn't have any luck with them due to the following:
1. poor quality
2. not on standard often. That rules them out right there.
I ended up buying some more HP RF generators. Then a Panasonic VP-8131A (stereo generator).
Quick update,,,,
I spent most of the day building and installing the antenna,,, man its hot in that attic!!!! But I get a nice steady strong signal!
Recalibrated the scope and took readings from your list,,,
I have 19kHz at the Collector of TR402
No 38kHz or any scope reading at Base of TR403,,,
FM plays, indicator light stays on briefly... I'm still thinking a bad or leaky lytic on that MPX board isn't helping us...
I spent most of the day building and installing the antenna,,, man its hot in that attic!!!! But I get a nice steady strong signal!
Recalibrated the scope and took readings from your list,,,
I have 19kHz at the Collector of TR402
No 38kHz or any scope reading at Base of TR403,,,
FM plays, indicator light stays on briefly... I'm still thinking a bad or leaky lytic on that MPX board isn't helping us...
Okay John ...
Look at both sides of C409 (coupling capacitor). Also the DC voltages on each side. Also DC voltages on each terminal of TR403 (ignore the schematic, I'm sure that is a typo).
Covering all possibilities, make sure D401 and D402 are good and that the wire to 5A going to the lamp driver PCB is not shorted.
First rule of troubleshooting any problem in any field. Never go in with assumptions. Follow leads only. List facts only, no conclusions and see where that takes you. That means actual measurements and actual observations. I don't care how obvious a conclusion might be - prove it!
I'm glad you now how a strong FM signal to work with! Good job on the antenna.
-Chris
Look at both sides of C409 (coupling capacitor). Also the DC voltages on each side. Also DC voltages on each terminal of TR403 (ignore the schematic, I'm sure that is a typo).
Covering all possibilities, make sure D401 and D402 are good and that the wire to 5A going to the lamp driver PCB is not shorted.
First rule of troubleshooting any problem in any field. Never go in with assumptions. Follow leads only. List facts only, no conclusions and see where that takes you. That means actual measurements and actual observations. I don't care how obvious a conclusion might be - prove it!
I'm glad you now how a strong FM signal to work with! Good job on the antenna.
-Chris
Readings,,, FM playing...
C409,, DCV 19VDC/,4mV
TR403,, B, 20.VDC,,, E, 20.1VDC,,, C, 20.VDC
D401,, 296R/0
D402,, 295R/0
I've been trouble shooting ckts for a long time, just not familiar with these!!! No assumptions, but I usually have an idea of where to start, unlike this uncharted territory!!!!
Thanks for the tests, hope it helps!!!
C409,, DCV 19VDC/,4mV
TR403,, B, 20.VDC,,, E, 20.1VDC,,, C, 20.VDC
D401,, 296R/0
D402,, 295R/0
I've been trouble shooting ckts for a long time, just not familiar with these!!! No assumptions, but I usually have an idea of where to start, unlike this uncharted territory!!!!
Thanks for the tests, hope it helps!!!
Alright, so TR403 might be shorted. If it was off (base-emitter = 0 VDC), which it is, then the collector should be sitting near ground (o VDC) if S1b is in the middle position, 2. I will assume you have it in FM Auto or however they have named it instead of Mono. If it shorted collector - emitter, hopefully the transformer isn't burned open.
If you pull that transistor, the base voltage should drop a fair bit. Check the transistor fo a short emitter - base, then emitter - collector.
There is an awesome transistor tester made by Heathkit. The IT-18, fast and gives you a great idea of how healthy a transistor is. It measures beta and leakage in both modes. You an also determine if a transistor is really heat sensitive, and if it goes open as it warms up. These are so good I have one, and another for a spare. I wore out my original one bought in the 1970's. I have all kinds of transistor testers and curve tracers, this is my go-to. I use a special jig to match transistors (you can't do that with any transistor checker or tester or meter that measures them one by one). Germanium transistors are leaky by nature. If you get one that measures like a silicon transistor, be extremely wary of it.
Now, to measure diodes. Use the diode check feature on your meter. The better ones supply 1 mA and measure the voltage drop across the diode. Germanium will run 2xx mV to 300 mV approx. Silicon >500mV normally and other types measure differently. Resistance measurements of diodes are meaningless because no one else can relate to them.
If you pull that transistor, the base voltage should drop a fair bit. Check the transistor fo a short emitter - base, then emitter - collector.
There is an awesome transistor tester made by Heathkit. The IT-18, fast and gives you a great idea of how healthy a transistor is. It measures beta and leakage in both modes. You an also determine if a transistor is really heat sensitive, and if it goes open as it warms up. These are so good I have one, and another for a spare. I wore out my original one bought in the 1970's. I have all kinds of transistor testers and curve tracers, this is my go-to. I use a special jig to match transistors (you can't do that with any transistor checker or tester or meter that measures them one by one). Germanium transistors are leaky by nature. If you get one that measures like a silicon transistor, be extremely wary of it.
Now, to measure diodes. Use the diode check feature on your meter. The better ones supply 1 mA and measure the voltage drop across the diode. Germanium will run 2xx mV to 300 mV approx. Silicon >500mV normally and other types measure differently. Resistance measurements of diodes are meaningless because no one else can relate to them.
I also took voltage readings of the diodes if that helps... Going to pull TR403 now....
D401 3.8mV/0
D402 3.4mV/0
D401 3.8mV/0
D402 3.4mV/0
Yes FM Auto... TR403 E-B 6.2K, E-C 1.6K
Not sure I'm taking reading as you wanted... Do I need to pull diodes to test them??? Not sure I have been testing properly... I hope R readings are correct for TR403...
Not sure I'm taking reading as you wanted... Do I need to pull diodes to test them??? Not sure I have been testing properly... I hope R readings are correct for TR403...
Hi Chris,,,
Here's TR403 socket readings with transistor out,,, B 19.2,,, E 20.7,,, C .2
Also figured out diode tests with meter, taken in ckt...,,
D401 256,,,, D402 256...
Sorry I misunderstood !!
Here's TR403 socket readings with transistor out,,, B 19.2,,, E 20.7,,, C .2
Also figured out diode tests with meter, taken in ckt...,,
D401 256,,,, D402 256...
Sorry I misunderstood !!
Now the transistor readings make sense. Check that transistor, I think it might be bad.
The diode readings sort of make sense. The junction readings on the transistor, who knows? They do make pocket meters that don't cost much that have diode test functions. Consider getting one. I will say one thing for certain, the more you spend on a name brand meter, the better it will be. Given what you are doing with it, please spend something reasonable, like >$100. I have a test and measurement background and know exactly what you are getting. If you can swing it, get a Fluke or Keysight meter. They are more than well worth it. Advantages:
1. (the biggest!!) They hold their calibration and are normally in tolerance when new. This is not true universally!
2. They are accurate, doesn't matter how many digits, read the specs. May cheap meters have no business displaying 3 1/2 digits. Figure out the error budget to prove it to yourself.
3. AC frequency response is much higher (up to 100 KHz)
I have some old HP 974A meters, and they are still in tolerance (0.05% basic DC accuracy) and they are very old, also a Fluke 85 and 87. Worth more than every penny spent. The new Keysight meters have the same specification, more features but I still count on he old ones. Do not buy a meter on features over reliability and accuracy. What good is an AC rms meter if the high frequency response isn't what it should be? My handhelds are 100 KHz, my bench ones 300 KHz. Many cheap ones that are half decent make it to 400 Hz. What is our common measurement frequency? ! KHz. You don't measure AC mains in dB, you measure audio in dB, so a meter with poor HF response is useless measuring in dB.
Anyway, right at this moment you need a functional diode test. Your friend may have a meter he can lend you.
The diode readings sort of make sense. The junction readings on the transistor, who knows? They do make pocket meters that don't cost much that have diode test functions. Consider getting one. I will say one thing for certain, the more you spend on a name brand meter, the better it will be. Given what you are doing with it, please spend something reasonable, like >$100. I have a test and measurement background and know exactly what you are getting. If you can swing it, get a Fluke or Keysight meter. They are more than well worth it. Advantages:
1. (the biggest!!) They hold their calibration and are normally in tolerance when new. This is not true universally!
2. They are accurate, doesn't matter how many digits, read the specs. May cheap meters have no business displaying 3 1/2 digits. Figure out the error budget to prove it to yourself.
3. AC frequency response is much higher (up to 100 KHz)
I have some old HP 974A meters, and they are still in tolerance (0.05% basic DC accuracy) and they are very old, also a Fluke 85 and 87. Worth more than every penny spent. The new Keysight meters have the same specification, more features but I still count on he old ones. Do not buy a meter on features over reliability and accuracy. What good is an AC rms meter if the high frequency response isn't what it should be? My handhelds are 100 KHz, my bench ones 300 KHz. Many cheap ones that are half decent make it to 400 Hz. What is our common measurement frequency? ! KHz. You don't measure AC mains in dB, you measure audio in dB, so a meter with poor HF response is useless measuring in dB.
Anyway, right at this moment you need a functional diode test. Your friend may have a meter he can lend you.
Thanks for hanging in,,,, I am confused, I thought I the tests I took up til now were accurate, as I was able to find bad diodes and transistors, and replaced them... Can the diode tests you describe be made in ckt? I only ask because the 1N60 diode(s) I replaced in this chassis didn't come out without the leads breaking off,,, actually, most of the small transistors had brittle leads which broke when a test probe touched them,,, and that was the reason I replaced them!
I can ask him if I can borrow a diode meter,, but if they need to be removed to test,, I better have some on hand first!
Here's another diode test I just made with a different handheld meter in ckt....
D401 577mV Ir 10.6uA
D402 582mV Ir 10,6uA
I'll look for a replacement or close sub for TR403,,,
Thanks for all the time you spent helping here,
I can ask him if I can borrow a diode meter,, but if they need to be removed to test,, I better have some on hand first!
Here's another diode test I just made with a different handheld meter in ckt....
D401 577mV Ir 10.6uA
D402 582mV Ir 10,6uA
I'll look for a replacement or close sub for TR403,,,
Thanks for all the time you spent helping here,
Hi John,
No problem. You're learning and making progress.
You can make most diode checks in circuit. With any component to get really accurate results you have to lift all but one lead minimum. Transistors can be checked "diode" in circuit, but that may mislead you some times. Same for resistors and capacitors (no matter what some people say).
D401 and D402 measurements make a lot of sense. Test current is normally 1 mA, this was lower and that can allow circuit effects to play a larger part in the reading. Those are silicon diodes, I expected germanium - but okay.
I use a solder sucker - one of the big ones with recoil. The small ones are useless. The leads should not break off. Also use a soldering station, not an iron (those are damaging and frustrating to use). A station costs no more than $120 Canadian (Solmon), and some Chinese ones are great (KSGER). I use both. The Solomon is a great high power station and is made under several names. Solomon is the actual OEM. I use both of those on the bench, they each have their strong points. Use the largest screwdriver tips, even on surface mount. The need for a small tip is rare.
No problem. You're learning and making progress.
You can make most diode checks in circuit. With any component to get really accurate results you have to lift all but one lead minimum. Transistors can be checked "diode" in circuit, but that may mislead you some times. Same for resistors and capacitors (no matter what some people say).
D401 and D402 measurements make a lot of sense. Test current is normally 1 mA, this was lower and that can allow circuit effects to play a larger part in the reading. Those are silicon diodes, I expected germanium - but okay.
I use a solder sucker - one of the big ones with recoil. The small ones are useless. The leads should not break off. Also use a soldering station, not an iron (those are damaging and frustrating to use). A station costs no more than $120 Canadian (Solmon), and some Chinese ones are great (KSGER). I use both. The Solomon is a great high power station and is made under several names. Solomon is the actual OEM. I use both of those on the bench, they each have their strong points. Use the largest screwdriver tips, even on surface mount. The need for a small tip is rare.
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Good morning Chris,,,
Yep I'm only as good as the info, and if it works, I think I did it right,,,, But the old saying garbage in garbage out is always a factor!!! For instance, D401, 402 are 1N60 diodes, and the parts list says they are Ge diodes,,, your tests seems to state otherwise... So I listen to suggestions, and try them...
Biggest problem I have now is finding a replacement for TR403,,, the last one (TR503) took quite a while to find....
I have a solder sucker with a squeeze ball and found a reasonable way to use it efficiently,,, Remember, this receiver was probably heading for the trash when I got it.... Seems some of the small transistor leads were corroded, and a touch with a probe point just shattered the pins,,, Also one diode had the same problem,,, I guess it was stored in a damp location for a long time, but I got most of that corrected... I can see that high heat and quick in and out with solder is the way to go!!!
Thanks for helping me with this project,,
I'm sure you work with other guys that understand and communicate better than me!!!!!
Now to find a transistor!!!!
Regards, John
Yep I'm only as good as the info, and if it works, I think I did it right,,,, But the old saying garbage in garbage out is always a factor!!! For instance, D401, 402 are 1N60 diodes, and the parts list says they are Ge diodes,,, your tests seems to state otherwise... So I listen to suggestions, and try them...
Biggest problem I have now is finding a replacement for TR403,,, the last one (TR503) took quite a while to find....
I have a solder sucker with a squeeze ball and found a reasonable way to use it efficiently,,, Remember, this receiver was probably heading for the trash when I got it.... Seems some of the small transistor leads were corroded, and a touch with a probe point just shattered the pins,,, Also one diode had the same problem,,, I guess it was stored in a damp location for a long time, but I got most of that corrected... I can see that high heat and quick in and out with solder is the way to go!!!
Thanks for helping me with this project,,
I'm sure you work with other guys that understand and communicate better than me!!!!!
Now to find a transistor!!!!
Regards, John
Hey John,
Well, it isn't about this receiver or the fact it was heading to the trash. Not at all. This is about you learning, having the immense satisfaction of figuring things out and having something to show for it. Yes, it would be a shame to see something repairable hit the garbage, even if you only use it in a work area. If all it takes is effort, then why not? This is a hobby and what we do. It also pays to always do good work - I'm pretty sure you agree.
You do listen and do your best. I'll help all day long for people like you.
You have got to try the large pump model solder sucker with recoil! Toys never allow us to work efficiently, and that takes the fun out of the doing. You should never fight with your tools or equipment. If you are, how the heck can you focus on the task or enjoy what you're doing? You don't have to spend a ton, but do not make life hard on yourself either. These cost about $30 Canadian, the cheap models either don't work well, and they break very quickly. Edsyn (the best) and Jonard seem to be reasonable. OK tools may also be okay. If you buy a cheap one, save the trip and just flush your money down the drain. I use a sucker and solder wick, the wick is for areas you can't get the sucker into, and also to clean things up. It has other uses as well, get the wider sizes.
Okay, the 1N60 is a Ge diode. They can be fragile as it is a point contact, meaning not a junction type. It has a metal contact inside. I don't think your meter is measuring the junction properly - hence my (strong) suggestion you pick up a much better meter.
Used or new, please get a good meter that doesn't lie to you. I am a working technician so what I buy is more expensive as I need the accuracy and reliability. My last two meters I got were Keysight U1273A, and I use a 34465A and 34461A on the bench along with others. I had HP 34401A. These held calibration for over 30 years, most meters aren't in tolerance new out of the box. So if buying used, buy the best. If buying new, but the best quality brand, just not as high in the line. The specs you read on a good one will be worst case what you get. A cheaper brand may not have a hope of achieving he specs they state, and certainly may not be in tolerance even brand new. Then there is a year out and so forth. You cannot assume your meter stays accurate (I'm also a certified calibration tech). So buying cheap is a waste of money, and the cost of calibration would make it the most expensive purchase you ever made in a meter!
That is probably a germanium transistor. Hunt around on Ebay or other places. You really should grab a Heathkit IT-18 if you can. They are not expensive in excellent condition, and they are valuable as heck working on older equipment and especially with Ge parts as you can measure leakage. The scale is in uA, so digital ones only show horrible problems. This older meter is useful beyond what you may think.
-Chris
Well, it isn't about this receiver or the fact it was heading to the trash. Not at all. This is about you learning, having the immense satisfaction of figuring things out and having something to show for it. Yes, it would be a shame to see something repairable hit the garbage, even if you only use it in a work area. If all it takes is effort, then why not? This is a hobby and what we do. It also pays to always do good work - I'm pretty sure you agree.
You do listen and do your best. I'll help all day long for people like you.
You have got to try the large pump model solder sucker with recoil! Toys never allow us to work efficiently, and that takes the fun out of the doing. You should never fight with your tools or equipment. If you are, how the heck can you focus on the task or enjoy what you're doing? You don't have to spend a ton, but do not make life hard on yourself either. These cost about $30 Canadian, the cheap models either don't work well, and they break very quickly. Edsyn (the best) and Jonard seem to be reasonable. OK tools may also be okay. If you buy a cheap one, save the trip and just flush your money down the drain. I use a sucker and solder wick, the wick is for areas you can't get the sucker into, and also to clean things up. It has other uses as well, get the wider sizes.
Okay, the 1N60 is a Ge diode. They can be fragile as it is a point contact, meaning not a junction type. It has a metal contact inside. I don't think your meter is measuring the junction properly - hence my (strong) suggestion you pick up a much better meter.
Used or new, please get a good meter that doesn't lie to you. I am a working technician so what I buy is more expensive as I need the accuracy and reliability. My last two meters I got were Keysight U1273A, and I use a 34465A and 34461A on the bench along with others. I had HP 34401A. These held calibration for over 30 years, most meters aren't in tolerance new out of the box. So if buying used, buy the best. If buying new, but the best quality brand, just not as high in the line. The specs you read on a good one will be worst case what you get. A cheaper brand may not have a hope of achieving he specs they state, and certainly may not be in tolerance even brand new. Then there is a year out and so forth. You cannot assume your meter stays accurate (I'm also a certified calibration tech). So buying cheap is a waste of money, and the cost of calibration would make it the most expensive purchase you ever made in a meter!
That is probably a germanium transistor. Hunt around on Ebay or other places. You really should grab a Heathkit IT-18 if you can. They are not expensive in excellent condition, and they are valuable as heck working on older equipment and especially with Ge parts as you can measure leakage. The scale is in uA, so digital ones only show horrible problems. This older meter is useful beyond what you may think.
-Chris
Hi Chris,,,
I got the receiver for what I thought would be a cheap project,,, and it has been so far... but I didn't know the problem with getting parts for old SS stuff, as tube parts are lying around for next to nothing at hamfests and antique radio shows ,,, neither of which I'm interested in,, but the parts are there and most guys are fun to hang out with... I started this audio hobby less than ten years ago, when I slowed my business down, and wanted to recap the PS in my Sansui 800... And I was gettin too old to get under the cars!!!
Ge transistors were supposed to be very tubey sounding, whatever that means, and I really like my 800... Then I found that Ge transistors were popular for guitar pedals and most new ones are fakes,,, and NOS ones if ya can find them are too leaky to use,,, So they are hard to find and expensive, not anything I'm interested in!!! I got TR503 sub from a hamfest buddy and it worked,,, but I doubt I can go to that well often with the same results, as he gave me 5 or 6 NOS to try, and the rest dont seem to test well, and wont fit this amp anyway...
So before I invest in more meters, I need to secure parts, as I doubt I'll be able to continue much longer in SS work, with my diabetes/eye conditions,,, I do have other meters along with couple of Flukes,,, but they all have issues, so I use the functions that are accurate.. One has an honest résistance range and another measures caps close enough to build tone stacks,,, Voltage and mA are good also,,, But you are saying high frequency meters, and that sounds like the ones my buddy has...
I will keep trying with this Sui, but the next step I see is replacing TR403,,, and there very well could be more!!!!
Thanks for the help'''
I got the receiver for what I thought would be a cheap project,,, and it has been so far... but I didn't know the problem with getting parts for old SS stuff, as tube parts are lying around for next to nothing at hamfests and antique radio shows ,,, neither of which I'm interested in,, but the parts are there and most guys are fun to hang out with... I started this audio hobby less than ten years ago, when I slowed my business down, and wanted to recap the PS in my Sansui 800... And I was gettin too old to get under the cars!!!
Ge transistors were supposed to be very tubey sounding, whatever that means, and I really like my 800... Then I found that Ge transistors were popular for guitar pedals and most new ones are fakes,,, and NOS ones if ya can find them are too leaky to use,,, So they are hard to find and expensive, not anything I'm interested in!!! I got TR503 sub from a hamfest buddy and it worked,,, but I doubt I can go to that well often with the same results, as he gave me 5 or 6 NOS to try, and the rest dont seem to test well, and wont fit this amp anyway...
So before I invest in more meters, I need to secure parts, as I doubt I'll be able to continue much longer in SS work, with my diabetes/eye conditions,,, I do have other meters along with couple of Flukes,,, but they all have issues, so I use the functions that are accurate.. One has an honest résistance range and another measures caps close enough to build tone stacks,,, Voltage and mA are good also,,, But you are saying high frequency meters, and that sounds like the ones my buddy has...
I will keep trying with this Sui, but the next step I see is replacing TR403,,, and there very well could be more!!!!
Thanks for the help'''
"Alright, so TR403 might be shorted. If it was off (base-emitter = 0 VDC), which it is, then the collector should be sitting near ground (o VDC) if S1b is in the middle position, 2. I will assume you have it in FM Auto or however they have named it instead of Mono. If it shorted collector - emitter, hopefully the transformer isn't burned open."
I forgot to ask,, is there a way I can test the Tx in question? Transistors are hard to find for this guy,,, that Tx would be impossible!!!
Thanks,,
John
I forgot to ask,, is there a way I can test the Tx in question? Transistors are hard to find for this guy,,, that Tx would be impossible!!!
Thanks,,
John
Hi John,
I have some Ge transistors, getting then to you will take time.
Measure emitter to collector, should be next to infinite resistance. A low reading means it is likely not well. The IT-18 would tell you for sure. A low emitter or collector base reading is the same. Base - emitter in the reverse direction.
I have some Ge transistors, getting then to you will take time.
Measure emitter to collector, should be next to infinite resistance. A low reading means it is likely not well. The IT-18 would tell you for sure. A low emitter or collector base reading is the same. Base - emitter in the reverse direction.