Yamaha A-1000 Repair and Info Thread

I did on the D164, but I already have it pulled "halfway out, so I have to get to the green side of the power board to put it back..any tips?

How'd you pull it out without desoldering from the green side?
You might be able to get to some of the board with the iron if you take the side bar off the amp (have to hold the transformer / be careful once that brace is removed since it provides most of the structural support) but at least in my experience I had to remove the 4 caps to be able to solder on that board properly.

I'd also diode test D167 both ways in-circuit (easy) just because I've seen that guy failed in similar amps before. Probably not the issue but worth checking.
 
The good side left the right side is what blew up. The transistors are not soldered on, the "test" resistors are on base and emitter instead:
LP+ 33.5
LP- 33.5
RP+ 49.2 <---- I know enough to know that this ain't right, but as to why, I know not..
RP- 33.5
If the circuit diagram is correct and (RP+) equals (HB+), D164 must be OPEN circuit (AIR) and some transistors in the TR136 - TR156 ballpark must be SHORT circuit (WIRE): i.e. Something is no longer a semiconductor. :yikes:

Yamaha_A-1000_TurboProcess.jpg

What voltages do you measure in the coloured (I hope you're NOT colour-blind) boxes?
Use 0V (GREEN) as the reference point.
Check for AC (as well as DC) on the DC voltage points. :blah:
Please post the results.

Yamaha_A-1000_PSU.jpg

AC voltages are boxed-out in GREY.
DC voltages are boxed-out in VIOLET.

Good Luck!

EDIT: Don't forget (as I did...) to measure the plus & minus 22V rails ('x' marks the spot).

Yamaha_A-1000_22V.jpg
 
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How'd you pull it out without desoldering from the green side?

I heated the "bar" of solder that is on the tan side, thinking (why I don't know) that the diodes were perhaps secured that way. Using my hemostats I got on leg partially lifted when I realized that said leg was way to long to be simply attached via the "solder bar". So I stopped, turned the unit over, and saw that it was through hole mounted. I wasn't thinking very well that day; I had to put my dog down the week prior, along with some other personal disasters, and really had no business messing with it. I see that if I undo the big caps that I will be able to pull the board. If I have to do that, I might as well check all the components on it out of circuit, and rework the solder on that board while I'm at it.

Which leaves me asking a question: How do you test the bridge rectifier? I assume using the diode test function on the multimeter, but it has four legs, so I am a little unsure on that. The diode I "partially" pulled was measuring the same voltage both ways, but I don't know if that is because of the circuit or because of the diode.
 
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If the circuit diagram is correct and (RP+) equals (HB+), D164 must be OPEN circuit (AIR) and some transistors in the TR136 - TR156 ballpark must be SHORT circuit (WIRE): i.e. Something is no longer a semiconductor. :yikes:

View attachment 1002328

I will have to look at my notes Hamish, I think I tested those but I am not certain. The rest of your post I will come back to after I have finished working on the power board and have time to look over your post it greater detail. I thank you for input and suggestions.
 
How do you test the bridge rectifier? I assume using the diode test function on the multimeter, but it has four legs
4 pins = 4 diodes
bridge-rectifier-shunt-before.png
 
Well, after a month long hiatus I am finally able to start, slowly working on this project again. After a delay from my solder sucker bulb's nozzle slitting in half I finally got the power filter caps de-soldered.
The wire was corroded somehow at the turns around the posts of the caps, and so this happened:

IMG_20171015_034627975.jpg

I also managed to burn about 4-5 wires' insulation, so that will be fun heat-shrinking. a hot air gun is on the way.

it's what I get for stopping and getting rusty with my dexterity :bigok:
 
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I get rusty with the iron so quickly and it always irritates me the first few times.

Good luck with the renewed rebuild!
I am in the middle of my own A-1000 I bought from eBay with a nuked left channel.
 
Well, I got my burned wire mess cleaned up:

IMG_20171021_031037153.jpg

I also resoldered the power board since the solder joints are just as lovely here as they were everywhere else:

IMG_20171021_031011592.jpg

I went ahead and pulled the four diodes and the two bridge rectifiers and tested them: they all measure as normal out of circuit. They all measured uniformly in circuit as well. I'm going to go ahead and put the caps back and the all the aforementioned back in.

I'm kinda at a loss at this point.
 
With no further input, I am going to go back up the thread and review Hamish's posts. To recap (no pun intended), I checked D168,D162,D163,D164,D165,and D166, out of circuit, as in, unsoldered and on the bench, both with my multimieter's diode function and with my little chinese component tester. They all came back normal.
 
If the circuit diagram is correct and (RP+) equals (HB+), D164 must be OPEN circuit (AIR) and some transistors in the TR136 - TR156 ballpark must be SHORT circuit (WIRE): i.e. Something is no longer a semiconductor. :yikes:

View attachment 1002328

As far as what is inside the triangle you marked up on the schematic, the only components I have tested there was TR136 and TR156, with R256 and R260 which tie to aforementioned TR156. Not tested anything else. Will do once I get everything re-attached to the main filter capacitors.
 
What voltages do you measure in the coloured (I hope you're NOT colour-blind) boxes?
Use 0V (GREEN) as the reference point.
Check for AC (as well as DC) on the DC voltage points. :blah:
Please post the results.

View attachment 1002331

AC voltages are boxed-out in GREY.
DC voltages are boxed-out in VIOLET.

Good Luck!

EDIT: Don't forget (as I did...) to measure the plus & minus 22V rails ('x' marks the spot).

View attachment 1002346

OK, When I do these measurements, just so I am clear, I connect my negative of my muiltmeter to the chassis, correct? I apologize, but I have forgotten some of what I have learned, Life has kinda gone sideways one me recently and I am short on time, as my Dad is about to have 3 major surgeries and once that starts up I may never get back to this for a long, long time. I need my tunes! :bowdown:
 
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OK, When I do these measurements, just so I am clear, I connect my negative of my muiltmeter to the chassis, correct?
That's incorrect! Never use the chassis as a reference - it may be at a different potential (potential difference) to the 0V ref.
Always use the designated ZERO VOLT REFERENCE point (or the common 0V between the reservoir/smoothing capacitors in this amplifier). It avoids misleading/erroneous measurements.

Yamaha_A-1000_0V.jpg

Good Luck!
 
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That's incorrect! Never use the chassis as a reference - it may be at a different potential (potential difference) to the 0V ref.
Always use the designated ZERO VOLT REFERENCE point or the common 0V between the reservoir/smoothing capacitors. It avoids misleading/erroneous measurements.

View attachment 1032069

Good Luck!
OK, Sorry Hamish. That makes sense now. As I mentioned, I am having a mental block right now, but I am also in a bit of a slow, yet ever present, rush to get this repaired, due to some life changes that are about to happen to me.
Thank you for the clarification - makes me less nervous. This unit was purchased to be a fill in substitute while I refurbished my main/only system. That was a mistake on my part, from the very beginning.

Question, how do you measure the reference voltage to see if it is at zero?
 
Question, how do you measure the reference voltage to see if it is at zero?
Assuming that no wires have been cut/disconnected and with the power off/removed, measure the resistance (use the lowest resistance setting on your multi-meter) between 0V on the transformer secondary and the designated ZERO VOLT REFERENCE point. It should measure 0R (ZERO Ohms).
If it measures zero Ohms, power on and measure the AC & DC voltages between both points. Again, you're looking for a ZERO - 0V (ZERO Volts).
Anything other than ZERO (allowing for meter inaccuracies) indicates an unknown fault.

View attachment 1002331

View attachment 1032069

Good Luck!
 
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Assuming that no wires have been cut/disconnected and with the power off/removed, measure the resistance (use the lowest resistance setting on your multi-meter) between 0V on the transformer secondary and the designated ZERO VOLT REFERENCE point. It should measure 0R (ZERO Ohms).
If it measures zero Ohms, power on and measure the AC & DC voltages between both points. Again, you're looking for a ZERO - 0V (ZERO Volts).
Anything other than ZERO (allowing for meter inaccuracies) indicates an unknown fault.

Good Luck!

I got zero on the meter after accounting for inaccuracy, and the reference is zero, So I will move forward to the next step. I plan on keeping my DBT connected throughout all of this unless there is reason I shouldn't.

EDIT: I powered the unit up in a DBT with a 100watt bulb and 0v on both AC and DC on the reference.
 
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If the circuit diagram is correct and (RP+) equals (HB+), D164 must be OPEN circuit (AIR) and some transistors in the TR136 - TR156 ballpark must be SHORT circuit (WIRE): i.e. Something is no longer a semiconductor. :yikes:

View attachment 1002328

I tested all of the components inside of the triangle, and they all read identical to the corresponding components on the opposite (working) channel. This was done with the power disconnected.

I am now moving on to the voltages. It may take me a bit to do, but when I finish i will post the results.
 
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