Hi raveenvijendren,
If you turn the unit over onto it's back, you can undo all the large screws. The unit will then slide out the front. Watch you don't damage the from of the wood sleeve as it comes out.
When checking the fuses, if there is a little "puff" of black or silver on the glass it may be okay to replace the fuse. If the glass is blackened or silvered to a large extent, do not replace the fuse! The unit will need service. You will only extend the amount of damage if you try to turn it on again.
Nice unit, really worth fixing.
-Chris
If you turn the unit over onto it's back, you can undo all the large screws. The unit will then slide out the front. Watch you don't damage the from of the wood sleeve as it comes out.
When checking the fuses, if there is a little "puff" of black or silver on the glass it may be okay to replace the fuse. If the glass is blackened or silvered to a large extent, do not replace the fuse! The unit will need service. You will only extend the amount of damage if you try to turn it on again.
Nice unit, really worth fixing.
-Chris
Thank you Mr. Chris,
The fuse has been blackened to an extent that the fuse wire is not visible. This is the fuse on the primary section of the power transformer that has blown. Other fuses on the power amplifier and tuner section are fine. If this is the case, what sort of trouble am I looking at? A shorted transformer? Shorted filter capacitors?
Thank you very much.
The fuse has been blackened to an extent that the fuse wire is not visible. This is the fuse on the primary section of the power transformer that has blown. Other fuses on the power amplifier and tuner section are fine. If this is the case, what sort of trouble am I looking at? A shorted transformer? Shorted filter capacitors?
Thank you very much.
Hi raveenvijendren,
With any luck, a shorted rectifier or filter cap. Shorted outputs could do this also.
Since the fuse has blown in a high energy fault (blackened or silivered), do not try another fuse. You will eventually damage the power transformer doing this.
How ever you get it repaired, this amp is worth the attention of a proffesional. That means a known good technician. Not someone who is cheap and fast.
I just got in a Marantz 240 power amp that a bad technician worked on. The wrong parts were <poorly> installed. Now the owner has to pay for the work all over again - and there are some parts missing too.
So it does not pay to have a TV tech or friend work on good gear.
-Chris
With any luck, a shorted rectifier or filter cap. Shorted outputs could do this also.
Since the fuse has blown in a high energy fault (blackened or silivered), do not try another fuse. You will eventually damage the power transformer doing this.
How ever you get it repaired, this amp is worth the attention of a proffesional. That means a known good technician. Not someone who is cheap and fast.
I just got in a Marantz 240 power amp that a bad technician worked on. The wrong parts were <poorly> installed. Now the owner has to pay for the work all over again - and there are some parts missing too.
So it does not pay to have a TV tech or friend work on good gear.
-Chris
Thank you Mr. Chris,
The problem turned out to be a shorted rectifier diode. The amplifier section of the receiver works fine. Surprisingly, the potentiometers on this unit work flawlessly, no cracks or pops... although it's thirty years old.
They sure don't make stuff like this anymore.
However, there seems to be some problem with the tuner section. It does not receive stations clearly in both AM and FM, and when switched to stereo mode, the signal to noise ration degrades terribly. What sort of problem am I looking at? RF amplifier troubles, alignment?? Any help would be greatly appreciated. Thank you.
The problem turned out to be a shorted rectifier diode. The amplifier section of the receiver works fine. Surprisingly, the potentiometers on this unit work flawlessly, no cracks or pops... although it's thirty years old.
They sure don't make stuff like this anymore.
However, there seems to be some problem with the tuner section. It does not receive stations clearly in both AM and FM, and when switched to stereo mode, the signal to noise ration degrades terribly. What sort of problem am I looking at? RF amplifier troubles, alignment?? Any help would be greatly appreciated. Thank you.
Hi raveenvijendren,
Cool
I love a simple problem!
I would check the low voltage power supply for one. Reception depends greatly on where you are and the antenna used. Most units I see could use an alignment (all brands).
The higher noise in stereo is understandable and normal under low signal conditions.
-Chris
Cool
I love a simple problem! I would check the low voltage power supply for one. Reception depends greatly on where you are and the antenna used. Most units I see could use an alignment (all brands).
The higher noise in stereo is understandable and normal under low signal conditions.
-Chris
This is a kit of am/fm receiver... here you can see how to align
a classic superheterodyne circuit.
http://www.elenco.ws/manuals/amfm-108k.pdf
In this case the schematics would be necessary...
also an oscilloscope and a RF generator.
http://www.antiqueradios.org/gazette/align.htm
bye
a classic superheterodyne circuit.
http://www.elenco.ws/manuals/amfm-108k.pdf
In this case the schematics would be necessary...
also an oscilloscope and a RF generator.
http://www.antiqueradios.org/gazette/align.htm
bye
Alignment in few word...
- tuner bandpass : align for center the antenna signal
- local frequency oscillator : align for generate the middle frequency
(455KHz for AM 10.7MHz for FM but it can change from model to model . )
- middle frequency transformer : align for max output.
Alignment of "classic" FM detector is more difficulty.
http://www.dephison.com/luxman/r1050/R-1050.pdf
- tuner bandpass : align for center the antenna signal
- local frequency oscillator : align for generate the middle frequency
(455KHz for AM 10.7MHz for FM but it can change from model to model . )
- middle frequency transformer : align for max output.
Alignment of "classic" FM detector is more difficulty.
http://www.dephison.com/luxman/r1050/R-1050.pdf
Thank you Mr. Gold_xyz,
The information you provided was very helpful. I do have access to an oscilloscope and an RF sweep generator. However, my oscilloscope only has a bandwidth of 20MHz. Is this sufficient to undertake the alignment procedure for the FM stages? (alignment of the AM stages is not very important for me as there are no AM broadcasts anymore in Malaysia). Thank you.
The information you provided was very helpful. I do have access to an oscilloscope and an RF sweep generator. However, my oscilloscope only has a bandwidth of 20MHz. Is this sufficient to undertake the alignment procedure for the FM stages? (alignment of the AM stages is not very important for me as there are no AM broadcasts anymore in Malaysia). Thank you.
Hi raveenvijendren,
Sorry for the late reply. I have not been around much.
If you use an RF detector probe you may be able to use your scope. If you work in the IF section (I have not read the linked material), you can use your 20 MHz 'scope just fine. The frond end work is done last, and after you have the detector (discriminator) set up. You tune for "maximum smoke", or peaking the signal strength meter. You do need a distortion analyzer and a modulated FM generator. A frequency counter may be required also.
-Chris
Sorry for the late reply. I have not been around much.
If you use an RF detector probe you may be able to use your scope. If you work in the IF section (I have not read the linked material), you can use your 20 MHz 'scope just fine. The frond end work is done last, and after you have the detector (discriminator) set up. You tune for "maximum smoke", or peaking the signal strength meter. You do need a distortion analyzer and a modulated FM generator. A frequency counter may be required also.
-Chris
With a 20MHz scope it can see the Intermediate Frequency
but not the local oscillator that work from 98 to 118 MHz
Luxman have a multi stage front-end, really excellent but more
difficult to align.
The Intermediate Frequency don't need any alignment because
the filters are ceramics.
Also check the trimmer on IC LA1230 LA3350
This tuner needs to Align for centering the frequency.
bye
but not the local oscillator that work from 98 to 118 MHz
Luxman have a multi stage front-end, really excellent but more
difficult to align.
The Intermediate Frequency don't need any alignment because
the filters are ceramics.
Also check the trimmer on IC LA1230 LA3350
This tuner needs to Align for centering the frequency.
bye
Attachments
Hi Gold,
The front end is the easy part. Getting the discriminator and distortion adjustments right are key. Do those first, then you go after pointer registration and tracking, IF and then finally touch up the sensitivity.
The front end is the easy part unless you mess with the LO. It's rarely out by much, if at all.
-Chris
The front end is the easy part. Getting the discriminator and distortion adjustments right are key. Do those first, then you go after pointer registration and tracking, IF and then finally touch up the sensitivity.
The front end is the easy part unless you mess with the LO. It's rarely out by much, if at all.
-Chris
Good Day,
Thank you Mr. Chris and Mr. Gold_xyz. Sorry for the insanely slow progress of repairing this receiver, as I am busy with my college studies. I just got hold of the original Luxman R-1050 service manual. According to the manual, I need an FM sweep generator and FM signal generator (which I have), to perform a correct FM mono alignment of the receiver . I would like to know what an FM sweep generator is. I always thought that FM sweep generator is another name for a standard FM signal generator. Please correct me if i am wrong. Thank you.
Thank you Mr. Chris and Mr. Gold_xyz. Sorry for the insanely slow progress of repairing this receiver, as I am busy with my college studies. I just got hold of the original Luxman R-1050 service manual. According to the manual, I need an FM sweep generator and FM signal generator (which I have), to perform a correct FM mono alignment of the receiver . I would like to know what an FM sweep generator is. I always thought that FM sweep generator is another name for a standard FM signal generator. Please correct me if i am wrong. Thank you.
Hi raveenvijendren,
-Chris
It is a generator that will sweep it's output frequency across a band. You input the start and stop frequencies and the sweep speed (or duration). For example, you could start at 10.2 MHz and end at 11.2 MHz at a rate of 0.5s per sweep, multiple sweeps (not just one). You could then use a 'scope to see what the IF bandpass looks like.
-Chris
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