Looks great!
A piece of rag soaked in deoxit and stuffed in the end of a 9mm socket takes a lot of the drudgery out of it.
Cheers,
James
Yamaha newbie A-700 resto thread
- Thread starter analogwisdom
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- a-700 recap repair restoration
Looks great!
A piece of rag soaked in deoxit and stuffed in the end of a 9mm socket takes a lot of the drudgery out of it.
Cheers,
James
analogwisdom
When in doubt, stuff in a WIMA
Fired up great off of the DBT and idle current dialed in nicely. I accidentally destroyed the mica pad last week when I took everything off so I used some thermal pads I have from PC building to mount to the heatsinks instead. The smaller devices got a shot of Artic Silver thermal paste. Everything is cool to the touch.
I'm going to bed, will report back tomorrow after everything is fully reassembled and booked up to speakers
I became a member here for little tid bit time saver tips like that...will add that to my notebook of esoteric redneckisms. Good stuff. Thanks Bratwurst.
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Recommend soldering the fuses to their clamps for less noise in Class A mode. I've noticed a difference when doing that.
Check your DC offset before putting the cover back on. Aka DC voltage at the speaker out terminals in a quiescent state to make sure everythings right & tight.
Check your DC offset before putting the cover back on. Aka DC voltage at the speaker out terminals in a quiescent state to make sure everythings right & tight.
Fired up great off of the DBT and idle current dialed in nicely. I accidentally destroyed the mica pad last week when I took everything off so I used some thermal pads I have from PC building to mount to the heatsinks instead. The smaller devices got a shot of Artic Silver thermal paste. Everything is cool to the touch.
I'm going to bed, will report back tomorrow after everything is fully reassembled and booked up to speakers
Those isolators you used look pretty thick, Id go with original micas to make sure the heat sink gets the heat transfer so the outputs don't fry .
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Nashou
OK, this has nothing directly to do with your thread analogwisdom but it might be useful to you and Soundscape in a general way, for me too I hope.
I was doing some browsing just now searching for info to better understand transistor specs and stumpled across a treasure trove of old pdf docs from Tektronix. Specially nice for me is the one describing testing with a curve tracer because I am completely new to that.
http://w140.com/tekwiki/images/a/a0/062-1009-00.pdf
http://w140.com/tekwiki/wiki/Concepts_Series
Cheers,
James
analogwisdom
When in doubt, stuff in a WIMA
Well, we have a problem. Sound is only coming out of both speakers with the mono switch pressed. Here's everything I've tested.
- Same behavior on both speaker terminals
- Tape out works fine (so no problem at the inputs or with the tape selector switch)
- Same behavior with Class A, same behavior with Direct
- Sounds great with mono turned on, all tone controls work as expected.
- Muting switch works as expected.
- Speaker on/off button works as expected.
I think that mono mode sums the channels? Since both speakers output sound in mono mode, that means the problem isn't in the power amp section, or my new speaker terminals, correct?
the cherry on top of this all is that the desoldering gun part of my desoldering station literally melted this morning (not sure what happened, I think there was a temperature regulation failure. The heating element got so hot it melted the gun.) so I have to wait for the warranty replacement to come before I can fix anything, once I find the problem. I must have wired something incorrectly.
I wish I had an oscilloscope to trace the signal, guess this is a sign to buy one.
- Same behavior on both speaker terminals
- Tape out works fine (so no problem at the inputs or with the tape selector switch)
- Same behavior with Class A, same behavior with Direct
- Sounds great with mono turned on, all tone controls work as expected.
- Muting switch works as expected.
- Speaker on/off button works as expected.
I think that mono mode sums the channels? Since both speakers output sound in mono mode, that means the problem isn't in the power amp section, or my new speaker terminals, correct?
the cherry on top of this all is that the desoldering gun part of my desoldering station literally melted this morning (not sure what happened, I think there was a temperature regulation failure. The heating element got so hot it melted the gun.) so I have to wait for the warranty replacement to come before I can fix anything, once I find the problem. I must have wired something incorrectly.
I wish I had an oscilloscope to trace the signal, guess this is a sign to buy one.
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Avionic will probably step in shortly and zero in on the correct answer like a laser, but a cursory look at the schematic shows that the muting section is between the inputs and the stereo/mono switch.
Cheers,
James
Cheers,
James
analogwisdom
When in doubt, stuff in a WIMA
Thanks for replying. I added that the muting switch works as normal too, I forgot to mention that.
analogwisdom
When in doubt, stuff in a WIMA
Okay, I really looked over the schematic. Notes to self to check:
- ML/E/MR connector (Power Source 2 -> Power Source 4)
- MOL/E/MOR connector (Power Source 4 -> Main2 2/2)
- ML/E/MR connector (Power Source 2 -> Power Source 4)
- MOL/E/MOR connector (Power Source 4 -> Main2 2/2)
Since both channels work in Mono, I'd clean the stereo/Mono switch real good and the Main/Direct. That usually means removing it and disassembly , clean the contacts and reassemble .
and if you mess it up there are modern replacements, I bet its a DPDT switch
I usually replace them. Sometimes if they are in a chassis switch carrier they won't fit right and a little cutting of the switch housing is needed.
Athanasios
and if you mess it up there are modern replacements, I bet its a DPDT switch
I usually replace them. Sometimes if they are in a chassis switch carrier they won't fit right and a little cutting of the switch housing is needed.
Athanasios
analogwisdom
When in doubt, stuff in a WIMA
Am I correct in my assessment that the problem is likely at the stereo/mono switch or before, since everything else works correctly in mono mode?
It maybe, I over looked the mute switch, that also should be cleaned well.
try cycling those switches many many times , like 50-100 . It may clean up some corrosion .
I am guessing that you hooked your input device to each input jack to test?
James
James
analogwisdom
When in doubt, stuff in a WIMA
Yep, same story on every input, even Phono. I also reflowed the joints on the switches, no dice. I have to wait until the desoldering gun gets here before I can take any parts out, unfortunately.
It would have to be before the input side of the direct switch at a minimum if the channel is out regardless of it's position.
Since the mono switch delivers signal to both channels of the direct switch in mono mode then I would think that you are correct.
Well, that gives you time to visually inspect the wiring.
At one time I tried to buy a desoldering gun but Haco are not available here and I didn't like the looks of the Chinese copy stuff so I just go old school and use a soldering station and solder wick. I do not like to use hand held spring loaded solder suckers at all. Any movement of the tube while it is working and they spray little solder balls all over the place.
analogwisdom
When in doubt, stuff in a WIMA
Yeah, this one I have is the a model from Yihua, a Chinese brand. Apparently there was a recall I didn't know about for the desoldering gun, so it's getting replaced for free. It worked great until it didn't, that's kinda the story for Chineseium products, huh? I'm saving up for the nice Hakko one.
The downside of solder wick is that I am dependent on buying a constant supply of it. I have tried a number of different brands but the only one that I really like is Chemtronics and I can't find that here, so with every Mouser order I buy a few rolls.