Help with Technics SU-Z45!

[P3ta]

Hello I am asking for help because an amplifier resistance is broken, and I can not see how many ohms is because it is burned and black, the specific resistance is the R151





Greetings and thanks.

[stratus46]

Originally Posted by P3ta

Hello I am asking for help because an amplifier resistance is broken, and I can not see how many ohms is because it is burned and black, the specific resistance is the R151

Greetings and thanks.

Not once have I seen a burned resistor completely disappear. Where is the rest of it? You really need to get the service manual to find out what (if anything) should be there. If there really _should_ be something there, why did it completely fall out? I suspect R151 is a 'no install' part. It's not unusual to find parts lists with 'no install' parts.

G²

[Ian Finch]

Well, I see signs of solder in those holes, Combine that with the scorch marks and the fact that P3ta is looking for a replacement part because there is likely not much of R151 left to look at. I tend to pull parts that are burned - they're not much use in the circuit anyway!

Perhaps you could look about and see if this part is for the amplifiers and there may then be a duplicate resistor in the other channel which can be identified. It might then be even an obvious number like R251. If it is in a control circuit or power supply, not so lucky - you need the schematic and/or parts list as you will not find too many who are familiar with the model and have the details to hand.

[riotpack]

It does look like solder in those holes, though sometimes unfilled holes get solder treatment when going through a wave solder machine. Perhaps look under the board and see what components that resistor connects to? Also what are the connections for in the background of the picture? RCA inputs with a ground on the right? My instincts would go with stratus46's post, unless it has been around 10kV distribution lines, it maybe a manufacturing flaw and not related (the burn marks), what is the actual fault ?

[P3ta]

Hello I have the resistance outside of the plate, is burned in half and broken in two parts, then I will upload the image

[Ian Finch]

Not a bad reason to remove it, P3ta. Have you done a search here and a Google search for the brand /model yet? You may have help with a schematic there sooner than guesses what the resistor does without specific clues.
Can you identify where in the circuitry this part fits?
As I read it, there are at least 4 threads here already - good place to look for clues on where info. might be

[P3ta]

Hello I have looked everywhere online but I have not found the pattern, I found the Z55 model but not the same.

I teach you what is left of the resistance:

[Ian Finch]

Mmm..roast resistor. Well, it begins with 4.., and is 1 or 2 % tolerance - not much help there, I'm afraid. Have you checked for a similar located part in the other channel, perhaps?

Now, you may have wondered, just like us, what is the reason this resistor burned? Even if you do replace it, it will likely just burn again because this is not the fault, for sure. It burned because something in series - perhaps a shorted part or circuit - overloaded it.

0o you know what happened to cause this? Can you trace circuits well enough to find what it does or connects to?
Read this short thread, it may give you the reason you have a problem and the solution could be a drastic one.
Old Technics Amp SU-Z45

[unclejed613]

it could be the resistor part of a zobel network, and as such might be 4,7 ohms, i would look for a shorted cap in series with it.

[jaycee]

From the look of it it is near the signal level inputs - the board looks similar to a SU-Z55 i gutted for parts. It is possibly 4.7 ohms as a ground loop breaker. See if one end of it is connected to signal ground