Preamp with weak output. Somewhat less body and punch. Anyone willing to fix it for pay? I am in Socal. Doesn't need to be speedy.
Let me know. I would even do the work, once you have troubleshat it. 😕
Let me know. I would even do the work, once you have troubleshat it. 😕
This is quite an old preamp I think, perhaps you could tell us a bit more about the fault.
1/ Is the fault on one or both channels ?
2/ Describe the fault... is it just low volume or is the tonal balance affected (such as poor bass) ?
3/ Is the fault apparent when using any input.
4/ Is the fault still present for all settings of the tone controls and switches ?
1/ Is the fault on one or both channels ?
2/ Describe the fault... is it just low volume or is the tonal balance affected (such as poor bass) ?
3/ Is the fault apparent when using any input.
4/ Is the fault still present for all settings of the tone controls and switches ?
Yes early 80's vintage, some of the last real Luxman units.
I have had two of those in the last years, and one was still in very good shape, but the other one had been slow cooked from sitting right on top of the matching power amp M-02. Luxman stupidly didn't make the preamp case deep enough for the power amp to stand on top, so most put the pre right on top of the power.. And the M-02 gets pretty hot when working hard!
Anyways, I found many of the capacitors way out of spec, and a few completely dead, and the phono stage looked pretty roasted. My point is that if your C-02 has been sitting on top of the M-02 for 33 years, it will likely need a lot of work. But if not, it could just be some minor thing.
Have you found the schematics online? If not I can post them here if needed..
Edit: A weak channel on old amp is often just due to a worn out volume pot with poor channel balance, and bad connection. So I would check that to start with.
I have had two of those in the last years, and one was still in very good shape, but the other one had been slow cooked from sitting right on top of the matching power amp M-02. Luxman stupidly didn't make the preamp case deep enough for the power amp to stand on top, so most put the pre right on top of the power.. And the M-02 gets pretty hot when working hard!
Anyways, I found many of the capacitors way out of spec, and a few completely dead, and the phono stage looked pretty roasted. My point is that if your C-02 has been sitting on top of the M-02 for 33 years, it will likely need a lot of work. But if not, it could just be some minor thing.
Have you found the schematics online? If not I can post them here if needed..
Edit: A weak channel on old amp is often just due to a worn out volume pot with poor channel balance, and bad connection. So I would check that to start with.
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It was on top of AB amp as far as I know. I don't care about phono. I don't even care about balance. If that helps. I don't care about using the SAME components. I just want it to output equal.
So if this happens on line level inputs (not phono) then I would look at C206 in the appropriate channel as a first step. Its a bipolar electrolytic however if you can measure and confirm that there is no DC voltage across the cap then you may as test short it out. It appears to be the only electrolytic in the signal path as far as I can see.
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Hi Highfido,
Sounds like a coupling capacitor, but the whole thing should be looked at. That is a very nice unit. One set of preamp and power amp I've always really liked a lot.
So, where are you so someone close can maybe give you a hand with that? It's good enough equipment that it should be treated well. Not to mention how pretty the set is ...
Consider having the power amplifier gone over before something fails. They are pretty old now, but fixed up they should last years and years.
-Chris.
Sounds like a coupling capacitor, but the whole thing should be looked at. That is a very nice unit. One set of preamp and power amp I've always really liked a lot.
So, where are you so someone close can maybe give you a hand with that? It's good enough equipment that it should be treated well. Not to mention how pretty the set is ...
Consider having the power amplifier gone over before something fails. They are pretty old now, but fixed up they should last years and years.
-Chris.
First clean:
- Input selector
- Tape Monitor
- Mono/Stereo switch
- Subsonic switch
- Tone switch
- Bass bust switch
- All pots: Volume. Balance, Bass, Treble.
But be careful what you use for cleaner and don't use too much!!
I still recommend that a good technician does this. It would be a shame to lose a nice component like that.
-Chris
Tried cleaning the switches with Caig. Not good at getting it in.
I didn't test phono lately.
One thing, I added point to point wiring, to add separate RCAs. One track lifted. It was a ground, and so I attached it to the ground next to it on another RCA. They were ganged on others. Are ALL the grounds supposed to be separate?
I am in Garden Grove, calif, in orange county. I WAS using it with a Jeff Rowland Model 5. Now, a Talk Electronics boutique UK thingie.
I was thinking about a passive. But, my Wiring will be 10 feet. Unless I add DAC with enough gain. Is this reasonable? Then use RCA spdif.
I didn't test phono lately.
One thing, I added point to point wiring, to add separate RCAs. One track lifted. It was a ground, and so I attached it to the ground next to it on another RCA. They were ganged on others. Are ALL the grounds supposed to be separate?
I am in Garden Grove, calif, in orange county. I WAS using it with a Jeff Rowland Model 5. Now, a Talk Electronics boutique UK thingie.
I was thinking about a passive. But, my Wiring will be 10 feet. Unless I add DAC with enough gain. Is this reasonable? Then use RCA spdif.
Is this the one with PCBs mounted upside down ? Repaired a few of those many years ago but later on had to tell owners that they were unrepairable in an economical sense. AFAIK this occurred mostly when they were used with the M02 as heat was transferred. All electrolytic caps have to be replaced and many transistors also were off from heat. PCB tracks also lifted as the boards had been too hot. Then most of them ended up in the landfill, nowadays they are sold on Ebay.
Of all the gear I repaired I recall this one as a tough one as everything was off because of heat. Same with Marantz SC-80 and for instance Proton 1100 which are also nearly unrepairable devices.
Of all the gear I repaired I recall this one as a tough one as everything was off because of heat. Same with Marantz SC-80 and for instance Proton 1100 which are also nearly unrepairable devices.
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So there is the possibility the fault is 'man made'. Grounds are supposed to go where the designer intended because even though they may appear to be the same point, they are routed and connected to avoid ground loops... although none of that would cause your problem... as long as you were routing to 'ground'.
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Luxman C-02 Manual - Duo-Beta Circuit/S Separate Pre-Amplifier - HiFi Engine
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