D303 (1N60), also a Ge diode, but a special one, is also a suspect. Sub could be AA138.
It states: AM/FM demodulator, 50V, 50mA
So, out of circuit it should measure between +/- 0,3V and 0,6V, with no leakage in opposite direction (to ground). Datasheet can easily be found online.
As for recapping, yes, I think at that age, the receiver could benefit. Just saying, I'm not a guy who recaps in bulk just for the sake of it.
But hey, we'll fix the issues first 🙂
And yes, I too have an old tube book from 1968. Books are nice..
Hugo
It states: AM/FM demodulator, 50V, 50mA
So, out of circuit it should measure between +/- 0,3V and 0,6V, with no leakage in opposite direction (to ground). Datasheet can easily be found online.
As for recapping, yes, I think at that age, the receiver could benefit. Just saying, I'm not a guy who recaps in bulk just for the sake of it.
But hey, we'll fix the issues first 🙂
And yes, I too have an old tube book from 1968. Books are nice..
Hugo
Thanks Hugo,,,
Yes I see that diode,, there are 17 Ge diodes, and 14 Ge transistors... If they are all bad, this will be hopeless!!! I recapped the PS and coupling caps in my Sansui 800 about 10 years ago,,, it still plays well... This one is a year or so older...
Today I think I'll concentrate on the AM meter working... but I dont have a viable plan in mind yet!!
Maybe jump from 3E to the meter? if that works then the only thing left would be the switch contacts or broken wire...
I'm much more comfortable with tubes!!!!!
Yes I see that diode,, there are 17 Ge diodes, and 14 Ge transistors... If they are all bad, this will be hopeless!!! I recapped the PS and coupling caps in my Sansui 800 about 10 years ago,,, it still plays well... This one is a year or so older...
Today I think I'll concentrate on the AM meter working... but I dont have a viable plan in mind yet!!
Maybe jump from 3E to the meter? if that works then the only thing left would be the switch contacts or broken wire...
I'm much more comfortable with tubes!!!!!
No need to panic on Ge's 🙂 The thing works darn well, so with a little more effort you'll fix everything.
I'd first test D303 if I were you.. Unfortunatly, it will be hard to replace it with a tube. 😈
Switching the selector between AM/FM a few time should be enough to 'clean' the contacts at least enough to see some movement in the AM meter, so I don't think this is the cause after all.
I'd first test D303 if I were you.. Unfortunatly, it will be hard to replace it with a tube. 😈
Switching the selector between AM/FM a few time should be enough to 'clean' the contacts at least enough to see some movement in the AM meter, so I don't think this is the cause after all.
I appreciate the humor!!! It really does sound good,,, these little Sui's are amazing,,, full range, very vintage sounding specially with R&R,, blues etc,,, I paid one USD for it!! so a little time and $$ is well worth it,,, It came with new output transistors(2N5038) altho they are a bit overkill... The AUX stage is really good,,, when I sorted that with "on hand" transistors, I was hooked!!!
I did use contact cleaner and exercised the contacts,, many times, they all make/break very quietly,,, I just jumped 3E to the meter, no movement,,, AM must be putting out as it sounds very good, strong, no noise...
I have some little glass diodes similar to D303, if i can find its specs, maybe I can try replacing it...
Out to run some errands,,, I'll get back to it tho!!!
Here's the original pictures and rebuild thread,, on AK, if you are interested,,,
https://audiokarma.org/forums/index.php?threads/sansui-400-receiver.1030326/#post-16458235
Thanks again!
I did use contact cleaner and exercised the contacts,, many times, they all make/break very quietly,,, I just jumped 3E to the meter, no movement,,, AM must be putting out as it sounds very good, strong, no noise...
I have some little glass diodes similar to D303, if i can find its specs, maybe I can try replacing it...
Out to run some errands,,, I'll get back to it tho!!!
Here's the original pictures and rebuild thread,, on AK, if you are interested,,,
https://audiokarma.org/forums/index.php?threads/sansui-400-receiver.1030326/#post-16458235
Thanks again!
I think it's better to just first measure that D303.
Jumpering 3E to the meter will not work. That meter needs C320, R311 and D303 to work with the AM signal.
But since AM works, signal will be present at 3E.
The picture, i cannot see for I need an account over at AK which I'm not planning to make. Too many pictures of beautiful women 🙂
But posting them here would be nice (the amp, not the women, haha).
I'll try to measure,, D303,, just need one pin lifted, correct? I'll see if I can lift it, keep all your GFs!!! I usually delete em after I post pics,,,
This is what's left on the camera,
Pics 003 to 008 are as I found it... others are today... Look at the 536 trans on pic 006 towards top Right of pic,,, the pins corroded off, I soldered them back together to keep signal tracing,,, There were 4 or 5 more of those little black type that crumbled when I put the probe on them,, that's why I replaced them,, You can see how dirty this was when I got it!!!!
This is what's left on the camera,
Pics 003 to 008 are as I found it... others are today... Look at the 536 trans on pic 006 towards top Right of pic,,, the pins corroded off, I soldered them back together to keep signal tracing,,, There were 4 or 5 more of those little black type that crumbled when I put the probe on them,, that's why I replaced them,, You can see how dirty this was when I got it!!!!
Attachments
Last edited:
Nice pics, congrats. I remember the Fisher amps, they were well regarded over here. Nice job on reviving the transistors too.
DMM in diode mode - to chassis and + to cathode. There should be no leak. Or you can measure out of circuit.
While you're at it, also measure R311.
DMM in diode mode - to chassis and + to cathode. There should be no leak. Or you can measure out of circuit.
While you're at it, also measure R311.
Thanks,, these old SS amps are the sound I remember when I was young,, got the Sansui 800 in 1969,,, the Fisher about 8 years ago,,, I built or rebuilt most of the tube amps!!!(avatar 811 SE) I hope this one measures up to its partners!!!
So I can measure D303 in place with Diode test on DMM?? I'll pull a pin of R311
Thanks
So I can measure D303 in place with Diode test on DMM?? I'll pull a pin of R311
Thanks
Sorry to hear that, I hope your meter still works.
From the readings, both components are faulty.
The resistor should read 5600 ohm and the diode didn't measure good either.
So, all in all, not much harm has been done.
A resistor is easy to find but the diode will be a little more difficult, but not impossible.
Note that you can't replace it with just any glass diode, it has to be 1N60 or similar.
I'm sure you'll fix it.
From the readings, both components are faulty.
The resistor should read 5600 ohm and the diode didn't measure good either.
So, all in all, not much harm has been done.
A resistor is easy to find but the diode will be a little more difficult, but not impossible.
Note that you can't replace it with just any glass diode, it has to be 1N60 or similar.
I'm sure you'll fix it.
It was too early this morning. De diode was OK I see from the picture.
Now I wonder if the resistor could be bad, measured out of circuit..
If both are / were good, I have no clue other then the input selector contacts.
That should be easy to measure with an ohm meter:
Now I wonder if the resistor could be bad, measured out of circuit..
If both are / were good, I have no clue other then the input selector contacts.
That should be easy to measure with an ohm meter:
Morning Hugo,,
eyesight is starting to hinder my work!!! I didn't read diode or resistor out of circuit,,, I like to have a part on hand before I mess with an original,,, because this damage can always happen
I was thinking of looking in old SS radios or other gear for a 1N60 diode... easiest way i can think of,,, Resistor should be easier.... meter still works for FM these parts are on teh AM board...
eyesight is starting to hinder my work!!! I didn't read diode or resistor out of circuit,,, I like to have a part on hand before I mess with an original,,, because this damage can always happen
I was thinking of looking in old SS radios or other gear for a 1N60 diode... easiest way i can think of,,, Resistor should be easier.... meter still works for FM these parts are on teh AM board...
I understand and know what you are talking about.
I guess 1N60 is a very common diode used in many vintage radios & receivers.
Take it easy 🙂
So I pondered this dilemma for a while,,, came up with a plan,, and decided to rip apart a trashed 60s Philco AM-FM tube radio I had l here,,, found two diodes,, both 1N60C !! Not sure what the C means,, but they are here, not half way around the world!!! They aren't glass, look like a plastic case, with red lettering... May not be Ge tho... so I'll have to try to find data sheets..
I'm still trying!!!!
I'm still trying!!!!
I found the P and the S version but no C. You could measure them with the diode tester. It's worth a try. What readings do you get from the resistor now?
Also, try to look at the measuring points I provided in post #33. With the input selector on AM you should measure a short.
Also, try to look at the measuring points I provided in post #33. With the input selector on AM you should measure a short.
Pics,, readings,,, I thought they were plastic cases but seem to be some kind of opaque glass or ceramic...
Heres the markings on them,,, I found 1N60C data sheets but they aren't of these,,, the sheets show 3 lead diodes
I will try to take the readings you posted, but need to replace teh diode to complete teh ckt, no??
Thanks.
Heres the markings on them,,, I found 1N60C data sheets but they aren't of these,,, the sheets show 3 lead diodes
I will try to take the readings you posted, but need to replace teh diode to complete teh ckt, no??
Thanks.
