I have an Yamaha RX-V357 that suddenly stopped working , no protection mode , no display , no diag mode - only power relay toggle (clicking on and off).
I've already disconnected power stage voltages in order to avoid any output / speaker DC protection and also power relay is by-passed in order to have all voltages ready-to-be-checked from power transformer.
Almost all voltages seem to be correct, except 5MS that missing. If 5MS externally provided no more relay clicking but still no display.
Any help ?
I've already disconnected power stage voltages in order to avoid any output / speaker DC protection and also power relay is by-passed in order to have all voltages ready-to-be-checked from power transformer.
Almost all voltages seem to be correct, except 5MS that missing. If 5MS externally provided no more relay clicking but still no display.
Any help ?
Attachments
in any case, if you dont have it, here is a link for you,
YAMAHA AV-RECEIVER-RX-V357-HTR-5830 Service Manual download, schematics, eeprom, repair info for electronics experts
YAMAHA AV-RECEIVER-RX-V357-HTR-5830 Service Manual download, schematics, eeprom, repair info for electronics experts
Yes, I have it and studied it ... The picture attached above is extracted from page 58...
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you mention you have made alterations to the amp, ie "disconnected power stage voltages" and "power relay is by-passed", in my opinion none of this should be done, if anything is in jeopardy of blowing, chances are they have been stressed enough by the fault to render them "weak" and will need to be replaced anyway, that is if you want an original spec amp ofcourse.
All cautions have been taken already ... A. Power stage voltages have been disconnected in order to avoid any protection / DC - due to unknown state of 3 STK integrated circuits ... Is some kind of temporary "passivisation" of power stage ... B. I had to by-pass the power relay in order to check the rest of DC voltages / currents associated to main transformer due a lot of them seems to be in use by protections ...
I can not figure how std-by transformer only supply the mCOM voltage , mCOM should power on the unit (via power relay) but same time all protections (on mCOM) use secondary voltages that presume main tranformer also to be on (via power on relay) ...
i also downloaded the schematic, to be honest im running thru it now, assuming i understand your problem correctly, i would start at the power transformer.
most important, high voltage so all precautions needs to be adhered to!
check the rails first, the transformer, the good ones atleast, should have the wire colours and what voltages they provide, check this with DMM set to AC voltage directly as they come out from the transformer. if the wires and voltages arent labeled on the transformer, check the SM for labels. last resort, with AC power completely disconnected, check each of the transformer wires in an effort to locate each end of "winds". home audio rarely has a center tap so, outputs should come in pairs.
if that all checks out, those voltages will need to be rectified before they can work. check the rectifiers/diodes. i also saw some "Power Detector /Reset" function as well so be mindfull of that.
injecting voltage is tricky, and important. firstly your "grounds" need to be aligned. this requires a ton of explaining so i leave you to google this.
once your grounds are aligned, make sure you inject you voltage as far back in the circuit as you safely can. inject too far forward MAY not disable "voltage detection" protection circuits.
most important, high voltage so all precautions needs to be adhered to!
check the rails first, the transformer, the good ones atleast, should have the wire colours and what voltages they provide, check this with DMM set to AC voltage directly as they come out from the transformer. if the wires and voltages arent labeled on the transformer, check the SM for labels. last resort, with AC power completely disconnected, check each of the transformer wires in an effort to locate each end of "winds". home audio rarely has a center tap so, outputs should come in pairs.
if that all checks out, those voltages will need to be rectified before they can work. check the rectifiers/diodes. i also saw some "Power Detector /Reset" function as well so be mindfull of that.
injecting voltage is tricky, and important. firstly your "grounds" need to be aligned. this requires a ton of explaining so i leave you to google this.
once your grounds are aligned, make sure you inject you voltage as far back in the circuit as you safely can. inject too far forward MAY not disable "voltage detection" protection circuits.
i trust that you know what you are doing but just a word of caution, protections are there so as to prevent catastrophic failure, if you have disabled a "protect function", and perhaps supply power to a shorted STK IC, make sure you have a fire extinguisher close buy! best case scenario you'll see blue sparks.
_check the rails first, the transformer - both tranformers are ok, AC voltages are ok
_all rectifiers are ok, main DC voltages are ok
_"Power Detector /Reset" ... it's a long story here due microcomputer toggles the power relay ... not easy to check any other state ... click on , click off , click on , click off ...
_this was the reason I've by-passed power relay , somehow to have secondary voltages available - these voltages are used by multiple protections
Meanwhile, I think the solution (anihilate the toggling) shoud be found using only std-by transformer , main transformer shouldn't be part of all this protections ... The reason is simple... Main transformer is powered by power relay and power relay is powered via std-by transformer (by microcomputer) , therefore POWER ON / START / OPERATE solution seems to be only between std-by transformer & mCOM & power relay ...
_all rectifiers are ok, main DC voltages are ok
_"Power Detector /Reset" ... it's a long story here due microcomputer toggles the power relay ... not easy to check any other state ... click on , click off , click on , click off ...
_this was the reason I've by-passed power relay , somehow to have secondary voltages available - these voltages are used by multiple protections
Meanwhile, I think the solution (anihilate the toggling) shoud be found using only std-by transformer , main transformer shouldn't be part of all this protections ... The reason is simple... Main transformer is powered by power relay and power relay is powered via std-by transformer (by microcomputer) , therefore POWER ON / START / OPERATE solution seems to be only between std-by transformer & mCOM & power relay ...
ok great stuff, next i would check that the rails arent shorted to ground.
if the relay is clicking on-off-on-off, i would assume the std-by transformer/circuit is working as desired, but there is a short across the main transformer rails that's tripping over current and causing disengagement of the relay.
if the relay is clicking on-off-on-off, i would assume the std-by transformer/circuit is working as desired, but there is a short across the main transformer rails that's tripping over current and causing disengagement of the relay.
_std-by transformer/circuit is working as desired - I agree with you
_the relay is clicking on-off-on-off no matter main transformer is connected or not !!!
_all DC voltages after rectifiers are ok (both transformers) , as per diagram , no overload , ± 52V on power rail also ok, STK are TOTALLY disconnected by jumper 108, jumper 113 , r143, r133, r144 - therefore nothing pass to STK and for the moment I'm not concerned if STK are in good order or not , I am focused to find what protection toggle the mCOM ...
_the relay is clicking on-off-on-off no matter main transformer is connected or not !!!
_all DC voltages after rectifiers are ok (both transformers) , as per diagram , no overload , ± 52V on power rail also ok, STK are TOTALLY disconnected by jumper 108, jumper 113 , r143, r133, r144 - therefore nothing pass to STK and for the moment I'm not concerned if STK are in good order or not , I am focused to find what protection toggle the mCOM ...
Normally , if only STK fault , should be displayed "PROTECT" etc .... Therefore I'm not focused on STK ... As I said , no display , no DIAG mode , only toggling with or without main transformer ....
Apologies sir, i don't understand "mCOM"
However, the trigger for the main transformer relay is in the std-by section. i would start looking at the base of Q371.
assuming R371/2/3, Q371 and RY371 is fine, you have to find out whats troubling IC242.
this is a PIC, and understanding its outputs is heavily dependent on having the firmware. replacement is near impossible from my en-devours, and when possible it tends to be cost destructive!
you could monitor the "I" input "protection XX detect" pins of IC242 and figure out which circuit is tripping the protection circuit. but there's not much else that could trip protection other than a bad STK.
if I where you, i would simply remove the STK's and im willing to bet it will power up.
i do have another suggestion, but thats for another time.
the PIC could be toast, BUT my moneys still on a shorted STK.
remember, i faulty STK doesn't need power to send out a fault signal. if "protection detect" has internal pull up, and signal is active low, the STK simply needs to be shorted to ground!
However, the trigger for the main transformer relay is in the std-by section. i would start looking at the base of Q371.
assuming R371/2/3, Q371 and RY371 is fine, you have to find out whats troubling IC242.
this is a PIC, and understanding its outputs is heavily dependent on having the firmware. replacement is near impossible from my en-devours, and when possible it tends to be cost destructive!
you could monitor the "I" input "protection XX detect" pins of IC242 and figure out which circuit is tripping the protection circuit. but there's not much else that could trip protection other than a bad STK.
if I where you, i would simply remove the STK's and im willing to bet it will power up.
i do have another suggestion, but thats for another time.
the PIC could be toast, BUT my moneys still on a shorted STK.
remember, i faulty STK doesn't need power to send out a fault signal. if "protection detect" has internal pull up, and signal is active low, the STK simply needs to be shorted to ground!
mCOM = micro Computer IC242
at the base of Q371 is pin 82 P06 PRY O Power Relay Output of IC 242 where we have rectangular signal of clicking on and off by 1 sec all the time. Note: during std-by there is no click-on-click of, only if tried to powered on the unit, so first instance of PRY of IC 242 is quiet. If std-by / on button is pressed , in all circumstances , with or without main transformer connected (main voltages or secondary voltages) , with or without STK connected or not on power rails, we'll get the click-on-click of.
I'll try to check each STK , one by one , separated , powered at minimal voltage (± 10V a/p datasheet) and I'll came back to you
If any STK shorted, I will remove it and test the unit again
Regarding protections, I've found: 82 P06 PRY O Power Relay Output std-by mode protection ?
86 P02 PRI I Protection Excess Current Detect non-std-by protection
90 AN6 PRD AD Protection DC Detect non-std-by protection
91 AN5 PREMT AD Power Limiter Detect non-std-by protection
92 AN4 THM AD Temperature Detect -> power limit non-std-by protection
97 AN0 PRV AD Protection Power Supply Voltage Detect non-std-by protection
Question: 1. do you find some other ? Is missing something - see point 3 below ...
2. how is that mostly of these protections used main transformer voltages (not std-by transfomer) to be operable ? Protections are dependable of main transformer , IC 242 itself is powered by main transformer voltages !!!
3. Analise this , pls , and help me to figure out which protection is activated in std-by mode and which one by main transformer (non-std-by protection)...
Meanwhile i will check the STK but my heart is in doubt... If only STK fault why no "protection" mode , no display etc ...
at the base of Q371 is pin 82 P06 PRY O Power Relay Output of IC 242 where we have rectangular signal of clicking on and off by 1 sec all the time. Note: during std-by there is no click-on-click of, only if tried to powered on the unit, so first instance of PRY of IC 242 is quiet. If std-by / on button is pressed , in all circumstances , with or without main transformer connected (main voltages or secondary voltages) , with or without STK connected or not on power rails, we'll get the click-on-click of.
I'll try to check each STK , one by one , separated , powered at minimal voltage (± 10V a/p datasheet) and I'll came back to you
If any STK shorted, I will remove it and test the unit again
Regarding protections, I've found: 82 P06 PRY O Power Relay Output std-by mode protection ?
86 P02 PRI I Protection Excess Current Detect non-std-by protection
90 AN6 PRD AD Protection DC Detect non-std-by protection
91 AN5 PREMT AD Power Limiter Detect non-std-by protection
92 AN4 THM AD Temperature Detect -> power limit non-std-by protection
97 AN0 PRV AD Protection Power Supply Voltage Detect non-std-by protection
Question: 1. do you find some other ? Is missing something - see point 3 below ...
2. how is that mostly of these protections used main transformer voltages (not std-by transfomer) to be operable ? Protections are dependable of main transformer , IC 242 itself is powered by main transformer voltages !!!
3. Analise this , pls , and help me to figure out which protection is activated in std-by mode and which one by main transformer (non-std-by protection)...
Meanwhile i will check the STK but my heart is in doubt... If only STK fault why no "protection" mode , no display etc ...
st-by pin of STK 403-130Y is pin no.8 or pin no. 7 ? And amplifier is "on" (operating mode) by + or grounded that pin ?... I only have japanese datasheet and it seems to be like pin 8 with + for "on" and ground / NC for "off" - std-by ... for STK STK 404-130Y is clear, std-by is pin no.13 Voltage at pin 13: 5V, Current limiting resistance R1: 13kΩ
ok from this angle we are quite far down the rabbit hole. further than this is going to increase complexity drastically.
attacking it from another angle, "I" would "clone the "ON" signal and inject it into Q371 base.
bare in mind, you need to have major circuits isolated because this is a danger zone.
highly unlikely but still probable, is a protection circuit fault. if this is the case, them voltage injection will be a half meassure to achieve opperation.
next and more likely, once the "on" signal is cloned and injected, whatever is causing a problem, should become more pronounced, some sort of heat/smoking possibly.
but like a said, precautions precautions precautions!!! if its a major current drawing line, without isolation, could be a hazard.
but i would definately align grounds and inject an "ON" signal next.
the correct thing to do next is map all these pins:
82 P06 PRY O Power Relay Output std-by mode protection ?
86 P02 PRI I Protection Excess Current Detect non-std-by protection
90 AN6 PRD AD Protection DC Detect non-std-by protection
91 AN5 PREMT AD Power Limiter Detect non-std-by protection
92 AN4 THM AD Temperature Detect -> power limit non-std-by protection
97 AN0 PRV AD Protection Power Supply Voltage Detect non-std-by protection
on paper and record all there voltages in "ON" and "OFF" states, and a pattern should emerge. but then again that is quite complicated
attacking it from another angle, "I" would "clone the "ON" signal and inject it into Q371 base.
bare in mind, you need to have major circuits isolated because this is a danger zone.
highly unlikely but still probable, is a protection circuit fault. if this is the case, them voltage injection will be a half meassure to achieve opperation.
next and more likely, once the "on" signal is cloned and injected, whatever is causing a problem, should become more pronounced, some sort of heat/smoking possibly.
but like a said, precautions precautions precautions!!! if its a major current drawing line, without isolation, could be a hazard.
but i would definately align grounds and inject an "ON" signal next.
the correct thing to do next is map all these pins:
82 P06 PRY O Power Relay Output std-by mode protection ?
86 P02 PRI I Protection Excess Current Detect non-std-by protection
90 AN6 PRD AD Protection DC Detect non-std-by protection
91 AN5 PREMT AD Power Limiter Detect non-std-by protection
92 AN4 THM AD Temperature Detect -> power limit non-std-by protection
97 AN0 PRV AD Protection Power Supply Voltage Detect non-std-by protection
on paper and record all there voltages in "ON" and "OFF" states, and a pattern should emerge. but then again that is quite complicated
Check the film capacitors, I had a Yamaha that was completely dead. It turned out to be a simple open film capacitor in the start-up circuit. All these repairs are simple in the end, so check all the components for faulty resistors, capacitors, transistors, etc...
# Dear Azeem, below it is what I found before reading your post:
Next step done, checked all STK , found the small one STK 404 shorted, pulled out. The 2 big STK403 checked powered externally ±10V and are operational, no overload , no idle current , no DC on output coil, test speaker on output coil : good sound (curios thing due I expect to found them in std-by mode but doesn't matter at this point) . So, all yesterday alterations undone (except power relay by-passing), j108, j113,R143, R133, R144 back on position in order to check 2 big STK403 at ± 52V. Checked and seems ok, again, like before on ±10V , checked now on ± 52V : no overload , no idle current , no DC on output coil, test speaker on each output coil : good sound. Mainboard it's back on it's position (the only way to connect all plugs is to have it back on initial position), no more STK 404 on board (I'll buy it only if IC 242 & comp. is not dead) , but click-on-click-off again, no display.
a. I think missing STK 404 will trigger no protection
b. still have the question why no error display ?
I'm not shure what to start with now, mCOM testing or DSP (display circuit / board) ?
Case 1 : If some fault on DSP board, mCOM coud be functionally and expects some keyboard inputs but due no display, no human keyboard inputs.Case 1 seem improbable due eternally click-on-click-off of IC 242 but, also, something is also wrong on DSP due no display.
Case 2 : mCOM IC 242 ... difficult to test due is opposite side but I will manage somehow to test ... it easy to test on std-by power, difficult to test with all main transformer voltages on ... anyway, for IC242 main tranformer does not exist due myself I by-passed power relay ...
For case 2: what to start with ? how to check the state of this mCOM with no display? all protections are triggered by main transformer voltages but IC242 is click-on-click-off no matter main transfomer connected or not.
I mean, IC 242 to be tested with or without main tranformer voltages ?....
Also, based on my experience, rarely to have 2 distinctive problems on same unit same time but here we are, STK 404 found shorted and still remain at least 1 problem ...
# Dear Azeem, below it is what I wrote after reading your last post:
Agree with you, should be a "protection situation" on IC 242.
1."clone the "ON" signal and inject it into Q371 base - already done safely by-passing power on relay. By this method Q371 and IC 242 not "touched" by injection.
2. some sort of heat/smoking possibly - not the case, no overheated semiconductors or resistors etc
3. "align grounds" , shortly , what does it means ? I'm not a native english speaker but maybe I've already done it but in other words ...
4. so , your opinion is to try checking protections directly with all voltages on board. I hoped to work with main transformer disconnected but maybe will be not enough information for IC 242 to have a complete picture...
Next step done, checked all STK , found the small one STK 404 shorted, pulled out. The 2 big STK403 checked powered externally ±10V and are operational, no overload , no idle current , no DC on output coil, test speaker on output coil : good sound (curios thing due I expect to found them in std-by mode but doesn't matter at this point) . So, all yesterday alterations undone (except power relay by-passing), j108, j113,R143, R133, R144 back on position in order to check 2 big STK403 at ± 52V. Checked and seems ok, again, like before on ±10V , checked now on ± 52V : no overload , no idle current , no DC on output coil, test speaker on each output coil : good sound. Mainboard it's back on it's position (the only way to connect all plugs is to have it back on initial position), no more STK 404 on board (I'll buy it only if IC 242 & comp. is not dead) , but click-on-click-off again, no display.
a. I think missing STK 404 will trigger no protection
b. still have the question why no error display ?
I'm not shure what to start with now, mCOM testing or DSP (display circuit / board) ?
Case 1 : If some fault on DSP board, mCOM coud be functionally and expects some keyboard inputs but due no display, no human keyboard inputs.Case 1 seem improbable due eternally click-on-click-off of IC 242 but, also, something is also wrong on DSP due no display.
Case 2 : mCOM IC 242 ... difficult to test due is opposite side but I will manage somehow to test ... it easy to test on std-by power, difficult to test with all main transformer voltages on ... anyway, for IC242 main tranformer does not exist due myself I by-passed power relay ...
For case 2: what to start with ? how to check the state of this mCOM with no display? all protections are triggered by main transformer voltages but IC242 is click-on-click-off no matter main transfomer connected or not.
I mean, IC 242 to be tested with or without main tranformer voltages ?....
Also, based on my experience, rarely to have 2 distinctive problems on same unit same time but here we are, STK 404 found shorted and still remain at least 1 problem ...
# Dear Azeem, below it is what I wrote after reading your last post:
Agree with you, should be a "protection situation" on IC 242.
1."clone the "ON" signal and inject it into Q371 base - already done safely by-passing power on relay. By this method Q371 and IC 242 not "touched" by injection.
2. some sort of heat/smoking possibly - not the case, no overheated semiconductors or resistors etc
3. "align grounds" , shortly , what does it means ? I'm not a native english speaker but maybe I've already done it but in other words ...
4. so , your opinion is to try checking protections directly with all voltages on board. I hoped to work with main transformer disconnected but maybe will be not enough information for IC 242 to have a complete picture...