Sir Diamond _ingot . . . . .
As the " Optician " sez, DON'T find fault with that current inrush / " shock absorber " 1 ohm resistor UNLESS
it has gone open circuit !
If its too hot, you have an over current consuming fault being associated with the circuitry, on down past my RED
UNITIZED SCHEMATIC MARKUP . . . . .
( Direct Hot Link . . .as long a its kept hosted )
INITIAL EVALUATION . . . .
Now, with your photo, that looks like "wire wound-ish" construction.
Now I 'm Showing the FULL power supply and its BIG power hog users in the unit . . . . the AUDIO POWER OUTPUT TRANSISTORS . . . Herein I am .signifying them as RED
mark ups, of their cases..
The short RED
arrowheads are locations of one . . .1 ohm . . . . resistor being associated with each transistor
Initially refer to bottom left corner for the unit power supply and its use of two diodes in a full wave rectifier circuit , to alternatively catch phase of the AC line output at the secondary of the power transformer.
The configuration that they are using here is what I call an upside down and backward hook up.
Your problematic resistor is being the ORANGE
Two voltage readings are being given on that SAME line, the disparity is due to the X701 transostor being series inserted in the other bottom supply line. That accounts for the voltage differences referenced.
A touch upon that circuitry design . . . . . . . with its use of a gyrator or " capacitance multiplier" circuit.
Positive power supply voltage from the center tap of the transformer is fed to the C702 main E-filter . . . C702 which charges up.
Additionally + voltage is routed to C702 minor filter and with use of a supply resistor of adequately supplying enough base drive, that X701 will solidly conduct C to E , on a bit above the most current ever expected to be needed.
If the power pull should be enough that the SMOOTH DC level drops enough such that there is a starting of ripple presence, the transistor conducts to make up and get smooth DC again.
The end effect is that minor 200 ufd times the beta / gain of the transistor , ends up with the filtering effectivity of MUCH MORE
C704 sits down there end for HF filtering and any proclivity for the circuit to transition into a power ultrasonic oscillator after time induced development of ESR within C703.
TROUBLESHOOTING . . . . .
Have your . . . a good . . .R702 in circuit, power up just long enough to be able to take a DC voltage measurement across R702.
Since it is being a 1 ohm unit, you automatically have yourself a current measurement shunt there . . .ergo . . . . the DC voltage reading across that resistor is also your current in milliamperes that is now passing thru it. Now if its in EXCESS of 2 volts you are abusing it. What is it ?
Next procedure is to move to the schematic and you will find 4 RED marked up 1 ohm resistors associated with your audio power transistors circuitry.
Do the same procedure in reading the DC voltage across each of them, on time being just enough to get a DC meter reading..
Ideal situation, would be like readings from all 4.
Expecting you to not find that .
After analyzing your readings , we can then see if we have bad or leaky power transistors or quirky diodes or leaky E-caps or mis biasing of the output transistors.
Back referencing to the power supply section again . . .CURRENT PULL . . . . .
referencing suggest the unit pulling 220 ma at no volume or going upwards to 680 ma, at full volume.
Now GODOITTOIT and do tell us your findings . . .therewith..
73's de Edd
In deeeeeeeeeep thought . . . . . . . If I melted dry ice, could I swim in it and not get wet?