Hello guys,
I have a tuner NAD 4220.
It has no reception. When you push the search up or down it runs up or down but does not stop at any channel.
I set it to a known station at 91.00 Mhz with a big outdoor antenna. But nothing.
Absolute quite from the tuner. Even no noise.
I don't know whether it is supposed to noise or that the noise is surpressed.
I don't have a manual nor a service manual. I tried to search the web but was unable to get hold of a service manual.
I'm want to check the voltages and the scope pictures but without any guide lines it is difficult.
Any suggestions where to begin?
I did see some test points.
Marc
I have a tuner NAD 4220.
It has no reception. When you push the search up or down it runs up or down but does not stop at any channel.
I set it to a known station at 91.00 Mhz with a big outdoor antenna. But nothing.
Absolute quite from the tuner. Even no noise.
I don't know whether it is supposed to noise or that the noise is surpressed.
I don't have a manual nor a service manual. I tried to search the web but was unable to get hold of a service manual.
I'm want to check the voltages and the scope pictures but without any guide lines it is difficult.
Any suggestions where to begin?
I did see some test points.
Marc
Hello !
I don't know if it can help you, but these Nad tuners can have problems on their push selectors, prone to bad contacts. Check if there's not a problem on your FM/AM selector (I had this problem on an 4150 and 4155 tuners).
Perhaps this can help you :
- NAD Tuner 4220
Michel
I don't know if it can help you, but these Nad tuners can have problems on their push selectors, prone to bad contacts. Check if there's not a problem on your FM/AM selector (I had this problem on an 4150 and 4155 tuners).
Perhaps this can help you :
- NAD Tuner 4220
Michel
First step is disconnect the "MUTE" function and checking the tuning and operating voltgage at the FM-front-End from Mitsumi.
Check additional the lead between the coax antenna connector at back panel and the FM-front-end.
Service manual you can order from there:
Original Service Manual NAD 4220 Tuner | eBay
Check additional the lead between the coax antenna connector at back panel and the FM-front-end.
Service manual you can order from there:
Original Service Manual NAD 4220 Tuner | eBay
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Thanks for the replies:
I have esthablished that the up and down buttons are working.
I have checked the voltage on the front end.
It's a mitsumi. Found the servicemanual of the 4225 online.
It seems to be pretty close to the 4220 apart from the antenna connection.
The 4220 has only spring clamp terminals
The 4225 has 300 ohm spring clamp and 75 ohm bus connector. This is as far as I can tell the difference.
I have checked the voltage on the front end.
at 108 MHz its 21.150 VDC (supposed to be 20.5±0.5V)
at 87.5 Mhz, its 3.016 VDC (supposed to be 3V±0.5)
SO that does not seems too be to bad.
This was the first step in the service manual.
Then they start testing with a RF generator. That's something I don't have.
Just a frequency generator up to 2Mhz and a scope.
Any suggestions?
Marc
I have esthablished that the up and down buttons are working.
I have checked the voltage on the front end.
It's a mitsumi. Found the servicemanual of the 4225 online.
It seems to be pretty close to the 4220 apart from the antenna connection.
The 4220 has only spring clamp terminals
The 4225 has 300 ohm spring clamp and 75 ohm bus connector. This is as far as I can tell the difference.
I have checked the voltage on the front end.
at 108 MHz its 21.150 VDC (supposed to be 20.5±0.5V)
at 87.5 Mhz, its 3.016 VDC (supposed to be 3V±0.5)
SO that does not seems too be to bad.
This was the first step in the service manual.
Then they start testing with a RF generator. That's something I don't have.
Just a frequency generator up to 2Mhz and a scope.
Any suggestions?
Marc
So I have disable the muting by disabling the signal on Q111.
This prevents Q111 by getting high and thus sound should come (noise at leats)
But it remained silent.....😕
Marc
This prevents Q111 by getting high and thus sound should come (noise at leats)
But it remained silent.....😕
Marc
This is the tuning voltage. What about the operating voltage?
the resolution of the schematic is not sufficient to naming the right devices and measuring points.
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That's what I find bad on the schematics. There is not a single mention of voltage what so ever. NAD can learn something from most japanese manufacturers.😀
So I have no clue what the main voltages should be😕
Only thing I can do is check chip voltage as per specified datasheet and check the voltage on the actual chip itself.
As far as i van tell voltage should be relatively ok since LED is burning like normal and all functions like up / down memory are working.
I can try to enhance the PDF.
Marc
So I have no clue what the main voltages should be😕
Only thing I can do is check chip voltage as per specified datasheet and check the voltage on the actual chip itself.
As far as i van tell voltage should be relatively ok since LED is burning like normal and all functions like up / down memory are working.
I can try to enhance the PDF.
Marc
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As I already mentioned in post #3 I mean the operating voltgage at the FM-front-End from Mitsumi, according the schematic in your post #8 at PIN 5 (so I think) behind the 2,2 uH inductor (naturally between 8 volts and 12 volts).
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