Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, is the message "...PS PRT 135:H..." immediately displayed on plugging back in ? ...or after attempting to power on? ....or only after running Self-Diagnostic Function?
I understand; PS PRT = power supply protection; a power supply issue likely on the 5V line.
H = logic / voltage is high.
Possibly a 5V regulator that has failed.
Sorry, but which power supply board was checked please?
I understand and this would be the standby power supply circuit.
Please note that this 5.5V is present even if the Yamaha is just plugged (but not turned on) hence the standby +5V.
Since the suspect +5V line is detected when running the diagnostics (not just plugged in), then it would be any of the other +5V supply fed from the main transformer.
Do you have access to the schematics?
Please see p. 142 grid L7 IC334, a +5V regulator.
A potential suspect.
Since would be checking, it would be to your advantage to likewise check for the presence & consistency of its mate, the -5V.
...and another +5 after IC333.
As well as resistor R330.
Technically correct; a case of the chicken and the egg.
A moment please, composing a workaround.
Sorry, that should be R3304.
A workaround / bench test would need a small 1Ampere 6-0-6 transformer to feed AC-5/E/AC-5 pins of the connector. This is to simulate the supply from the main transformer.
Unfortunately, no other easy bench test method except to use a substitute transformer.
Incidentally, there is another +5V after IC457 on p. 136 and some other +5Vs
6-0-6; i.e. 6VAC center tap
It would also help to get some alligator clips with wires similar to the products shown HERE.
Please consider HERE also from Jaycar but higher current 1Ampere not just 150mA.
Yes should work though the voltage may dip a bit.
IC457 would need a 12V supply. Aside from the above transformer, an 1N4001 diode would also be needed. Use the 6-6 of the transformer to get 12V + the diode and the result would be 12VDC fed to the IN and COM of IC457.
Agree but since we're just after the output voltage, should do the job for test purposes.
There are other voltages derived from these +5V (such as the 3.3, 1.8, 1.3) but for the moment, checking these 5V would do.
Of course, please note that a short at the output of a regulator would also cause the 5V to go down or the output to short to the input.
The regulator as its name/description implies would always be the same +5V output irregardless of the input voltage (as long as more than 5V) and/or the current drawn from it.
Simply, it should output 5V always (or thereabouts); no minimum/no maximum.
I have to add that it would be to your advantage likewise to re-do the solder in case of a cold solder on the pins of the regulator as well as the other components around it.
Yes; ...R3304 of course can be checked with just the Ω function of the multi-meter.
This is tricky; measure 12V supply between pin 1 and 3. Measure the output between pins 2 & 3. Expected is +5V but only if pin 4 is triggered with a separate +5V.
Yes; a + or a - sign before the voltage value would denote that it is a DC voltage.
Ideally, an external +5V source but if IC333 checks good first, its +5T output would also serve the purpose of triggering pin 4 of IC334.
To be expected or nearly so; it is 0.22Ω
No; it's good.
It would really depend on the sensitivity of the meter; but 0.22Ω is nearly a short.
Incidentally, resistance values are preferably measured out-of-circuit.
What is the input AC Voltage of the bridge diode D3304 please? ...and what is its output DC Voltage?
Please see p.145 grid I8 VIDEO (1) board.
Yes please; connect the transformer. The 6-0-6 transformer would power IC333 and IC334 through bridge diode D3304. 6-0-6 to be connected to AC-5/E/AC-5 pins.
What is the ACV from first yellow wire to the white wire? ...second yellow wire to the white wire? ...first yellow wire to the the second yellow wire?
A bit low but should still work. Then the inputs of IC333 and IC334 should both be this 9.23V DC.
Witn an input of 9.23V DC, the output of both ICs should be 5VDC subject to the description above.
What are the readings please?
What is the DC Voltage across C3309 ? ...how about across C3310?
Yes, J4142 and J4141 links the + of bridge diode D3304 to the + of capacitor C3309 and eventually to IN pin of CIC333.
Voltage is low (or missing) on PS1. See p.61
The same way the +5 were checked but this time, test for -5 and the other voltages as listed right of PS1. See p. 139
Is everything connected / assembled back?
As posted above, for starters see p. 139 grid location G8, regulators IC101 and IC102.
Hi again and appreciate your kind understanding; mobile with sluggish Internet.
Use the above proposed alligator clips with wires to connect D1041 to the main transformer.
Appreciate the background information on the previous work done.
Still, what is more significant is the error code pinpointed that it is a power supply issue.
Interestingly, that the power supply circuit has initially a fault of PS PRT 135:H and then changed to PS PRT 61:L makes me suspect more of a loose wiring/connector or even a cold solder and no real component has failed.
As posted above; "...Voltage is low (or missing) on PS1...." -> ACBL, AC12, AC5, ±7, +3.3, -5VA.
Re-check connections to the board from the transformer and the solder points of the MAIN board p. 139 and VIDEO board p.142
Consider a careful bench test for the different voltages cautiously using the alligator clips with wires to connect the main transformer to all the connectors of the MAIN and VIDEO boards.
A friendly reminder: voltage measurements by its very nature requires that the main transformer is powered up and therefore the circuit is LIVE! Please exercise due care and caution.
These -12V and +12V are also produced by IC102 and IC101 (p.139). Measure the voltages at the output pins of these regulator. If the same then, there would be no issue.
On the other hand, if the voltage at the output pins of these regulators are different than "...-11.07V and +12.89V...", then there is an issue along the wires/connections from these 2 regulator to the Operation (2) board.
Sorry, which "...power up this board..."; Operations (2) or Main (1)?
I understand and as posted before; "...Use the above proposed alligator clips with wires to connect D1041 to the main transformer..."
Yes; I was under the impression that the boards were disconnected.
Oh....cautiously jumper the switching contacts of relay RY371 (p.143 / grid C7) . Doing so would force the main transformer to turn on hence all the secondary of the main transformer would have power including "...D104...through CB102..."
Not necessarily fully turn on; BUT, there would be power to those connected thus "... test IC101 N IC102..." can be performed.
Please ensure no loose wire or any that may cause a short.
The resistor would expectedly burn as it is unable to carry the onrush of current drawn by the transaformer.
Jumper with short lengths of electrical wire and a 2.0 A fuse
The pinout of IC101 is different with IC102. Please click HERE and HERE.
It is surprising that the regulator outputs +12.03V but CB456 reads +12.89. The voltage would have to come from somewhere
there is a ground issue between the boards.
It is expected that voltage can go down from -11.95V to -11.84V but not -11.07V . It is either the regulator is not performing well
there is a load/part attached to the - supply line that is drawing too high a current thus forcing the voltage to dip.
Does the IC102 heats up faster/hotter than IC101?
Based on "...has initially a fault of PS PRT 135:H and then changed to PS PRT 61:L..." and then "...PS PRT 135H is still present..." back to "...PS2 PRT : 66L...", then yes; something is wrong and as posted before, it would appear likely to be a connection, wiring or even a solder issue but definitely intermittent.
Bear with me as the only approach would be to review the wiring, connections and solder points particular of the power parts; i.e. those that carry the power/voltages (not the signal parts).
Let's look at the HDMI board.
Please see p. 91. These are the different regulators that would warrant checks.
Likewise of interest then would be the capacitors coupled to their outputs.
All since all have their inputs from the same source.
IC65, IC6, RP130Q501D, R1172H501D, IC945, IC946, IC26 and IC930
Yes, the +5.5V input would be the same to all others.
And likewise yes on the +3.3 expected output.
The +4.52 is an over-voltage hence would cause fault in the circuit that it feeds.
Strongly consider a replacement.
And further bear with me as I would be mobile again shortly; 500+KM trip.
Yes on RP130Q501D and R1172H501D as the Part Numbers on some of the regulators. There are others such as IC65 / NJM2888 for +5HT1
Please review pp. 127-134 of the Service Manual for the actual Part Numbers of the other regulators.
+5A is produced by IC457. Please see p. 138 grid J5
-VP is produced by Q4085. See p.137 grid G6
The input of IC457 should be +12V and is fed from from the output of IC101 through resistor R4293.
No, the input of IC930 is a different +5V source. If present, then its output should be +3.3V
If "... IC101...+12.03V...", then "...input V to IC457..." should be +12.03V also.
If not and as measured 3.34V, then a connection issue or resistor R4293 as posted above may have failed or went high value.
I understand;...then likely a connection issue.
What is the voltage before and after the resistor please?
The easiest would be to measure the voltages at the 2 ends of the resistor itself.
Sorry but no; that was done already "...voltage across that resistor is 3.34V...".
Black probe to common ground, red prove to 1 end of the resistor __V?
Black probe still to common ground, red prove to the other end of the resistor __V?
Is the resistor hot?
I would beg to differ based on "... R4293 and it was 21.5 ohms..."
I am more inclined to suspect IC457 (most likely) and/or +12A is loading the resistor/+12V line (least likely) or C4288 (just a possibility).
Disconnect jumper J4186 or de-solder / remove IC457. Then re-test the voltages of the resistor. If the 3.34V shoots up to 12, then IC457 is faulty.
Likely yes as 61L is indicative of a low or missing +5V
I was under the impression that the voltage measurements done on IC457 and resistor R4293 were without the HDMI board installed/connected.
Is this not so?
Repeat please. The same as how it was done now; with everything connected except the regulator or jumper.
...and would look forward to an update when able.
With the unit unplugged, test the resistance to ground of J4178 (p. 96 grid G4)
voltage across the resistor Is almost 0, with ic457 removed - is to be expected hence good.
J4178's resistance to common ground please?
Agree a short at he load hence the input voltage is brought down;....should not be.
Please repeat/confirm resistance with jumper J4173.
"...the resistance is 2.8 ohms..." which please J4173?
Surprising that C4278 is shorted. Was this resistance check done with C4278 out-of-circuit / de-soldered ?
Doubtful then; still, please consider repeating the test on C4278 out-of-circuit.
Test / follow J4178, J4176, J4173 then to where CB460 is connected to...
...and it will lead us back to CB944 where you found out first the missing +5A. This test point if checked with resistance would most likely show very very low Ω.
Then locate and carefully de-solder / remove L9401. Test again for short where the +5A was originally found low/missing. Then test resistance of pin 11 of IC941.
Yes please; always with respect to the common ground.
The fault is too low resistance or even a short of the +5A to ground and we have to find out which component causes this low Ω reading.
It is rightful to suspect the capacitors as well but must be tested always out of circuit.
Personally, I use tweezers when handling SMDs.
Please see p. 92 grid B3
Tested on CB460?
De-solder / remove all the jumpers; J4178, J4176, J4173 and test resistance to ground of all the now empty solder holes.
Can you also please re-check the empty solder points of the removed IC457.
Might as well check D4203.
Appreciate the image.
With J4176 & J4178 removed, then please check or even temporarily remove (also) C4252 and then J4177. After each removal, determine if the "...points...have a low resistance (short)..." would still persist.