Greetings Sir Jewells . . . .
Let’s see if we can get that FAVORITE little puppy of yours all up and being fully functional again.(Comment 1)
As a principal technical aid I am placing its schematic referencing with this post, with it consisting of select schematic snippets of your unit, giving what I certainly think will be the specific points of suspicion and interest
In the troubleshooting of the unit..
Also, since you displayed some degree of skepticism on parts familiarity, on that relay that you are hearing, its photo is being “PINK “starred on a photo at the bottom (also on the schema, but there it is split up as its coil
on top and its contacts just below.).
That photo is being from a Technics 650 series, but it will show you the basic size and rectangular profile of its relays case, which may be of yet another case colorization.
ALSO, I will tell you now, that the relays function, using its internal dual contact (DPST ACTION) assemblies, are to disrupt connection of your speakers to the POWER output section of the amp.
A major malfunction in the AUDIO POWER OUTPUT stage(s) can result in ~42V at a peak of up to 2 amps, being sent to your speakers voice coil . . .you can then read that result as “Smoke City”
You need covers pulled in order to get visual access to the PCB of the unit, and then you can’t miss seeing a massive heat sink assembly, used for the audio output power portion of the amplifier.
This unit is sophisticated enough to be using potted power amplifier output “modules” for your audio power output section . . . .so at its manufacturing time it was quite cutting edge technology . . . .while other makers
designs were using a hand full of discrete transistors, diodes, resistors and mid-size cased driver transistors and large sized power output transistor pairs.
That type of potted power output unit is now being the norm/standard in power amplifier design . . . with insiders usually giving them the nickname of STK units.
Your particular two units are STK8040’s, along with it’s Puny-sonic proprietary custom prefix/identifier of SVI.
The internal design is chock full of safety and corrective circuitry of keeping the internal circuitry balanced, since stages are directly DC coupled. It has overheating protection and shifting bias correction and assures that
the +42 and – 42 DC supply levels applied across the internal final POWER output semiconductors, are being balanced to a null of mere millivolts at their common node which is what feeds out to the speaker(s).
Heck . . . . it even detects the input audio level and keeps the amp working in class A for the first 5 or so watts of output level, then shifts to a subtler , less current HUNGRY, AB operating class as you demand upwards
to its then ~40 watt max power level, as per your volume adjustment.
Looking back to pictorial referencing, I have RED STARRED the STK’s in the photos and on the schematic and assigned them designators GREEN/YELLOW boxed F and G
The photo also shows your relay which I have assigned GREEN/YELLOW boxed C and on the schematic is the same with an additional PINK STAR on the schema in two places, since it s shown split up with the coil at the top,
and its tandem set of contacts just down below.
To date I know absolutely nothing of your capability of interpretation of the “hen scratching” on the schematic, so I will initially walk you thru its initial points of interest.
The start would be at the top right corner, where you see that I initially have used a GREEN/YELLOW boxed A for the power transformer area of the unit .I used a very fine red line, such as to not encroach upon schematic
lines in showing that sections boundaries.
Hoping that the primary connection to the AC line being shown is the same as yours, as I am unsure of your country, but suspicion that 120 or 220 is being used. There are 1 1/4 and 2 1/2 Amp fuses and two thermal breakers associated with input
power, but those will be all right, since your power is staying up long enough to detect multiple relay latching . . . ATTEMPTS.
The next section of interest is the GREEN/YELLOW boxed B area which contains a full wave bridge rectifier with D403-4-5 and 6 and main raw DC filter cps C403 and C404. These get your POWERFUL ~ +42 and -42 supplies
for the amps main POWER section, along with a few minor tap offs to feed other sections, such as the -15 and + 18 busses at the very top of the page, with them feeding left to circuitry.
They placed heavy black marking for the + 42 buss, and then INITIALLY started on the - 42 buss, but I have added on multiple periodic enhancements using BLUE RECTANGLES.
Next area to check is GREEN/YELLOW boxed D area which is the watchdog protection section which will provide drive for your relay. Its utilizing a TA7217 9 pin IC for driving that “C” Relay (RL-1).
(I had spare room on the page for its design application data at the far right center of the schema.) It works In conjunction with voltage data being fed to it from interfacing with discrete transistors Q601-02-03 and 04, along with steering diodes
D601-03-05 and 06. Those discrete devices are contained within the GREEN/YELLOW boxed E confines. They are voltage sampling to see if voltage level and current parameters are NOT being exceeded.
In your case it is doing a timely initial sampling of those points and finding fault, thus your relay never latches and then times out until the start of another test cycle, where it then also fails.
Soooooo we then go to the wisdom of Sir Colin Mitchell wherein he states . . . . . it’s NOT the relay . . . . per se . . . . BUT . . .its cycling IS trying to tell you something !
ASIDE technical interjection:
As a time related factor, the internal deterioration of electrolytic capacitors, in their exhibiting capacitance decline, can certainly be another potential fault possibility as they are very relevant to either the proper voltage build up level or some time delay
characteristics of the sample voltage nodes levels..
The sets relevant / associated electrolytic capacitors are being C601-02-03-05-06-07 and 08.BUT we will delay any potential judgement on those, until the units power output circuitry is initially evaluated.
Continuing:
GREEN/YELLOW boxed F and G were assigned for the POWER output STK’s photos and schematic placements.
GREEN/YELLOW boxed H is used to locate the larger insulated air wound copper wire HF choke coils in the bottom left photo and on the schematic as items L301-02 on both of the STK’s audio output terminal 3’s. The audio output STK’s from pin 3 passes
thru them, enroute to the individual contacts of the RY-1 relay, then the conjoining contacts route to the speaker terminals . They (H) are easy to spot and will be close to the sets RY-1 relay ( Where’s Waldo ? ) and also will be not too far from the speaker
terminals, since that interconnecting is being a high current path.
If you will power up ye olde unit and put a thumb atop suspect relay and then see if activation attempt sounds agree with your thumbs senses . . . . .then . . . EUREKA you has just o-fish-ully founded-ed RY-1 ! . . . all by yerself !
Next . . . . . using the sage safety advice coming forth from The Honorable and Esteemed shrtrnd ( Short and Round ) ? ? ? ? ? .DON”T GO STICKINGS YER FINGER IN NO ELECTRICAL-A-MA-TRICITY SOCKETS !
I would like you to measure the sets ~ Plus 42VDC and Negative 42VDC supply lines. If metering at the pins 1 and 5 of the STK’s back off to a common point on the same feed trace where there is no chance of probe shorting and touching an adjacent trace.
HINT . . . my probe tips are needle pointed, being done either with a Dremel tools cut off wheels side or a common file. It bites into the solder and stays in its prick.
Then set the units volume control to minimum and then move on to individually monitor the pin 3’s of the STKS to see if any DC voltage comes during that short test duration of the protective cycle.
This may be problematic, if using a DVM as they have a sampling time lag , so the voltage may come up and drop off even before the meter can respond.
An old style Simpson 260 or Triple-it 630 can respond quicker, but you will need to reverse leads or the polarity switch on the meter to test for both a + and – voltage polarity presence.
Of course, not that you will have it, but a scope in DC coupled mode can detect > than 50 millisecond presences (shorter times are too dim).
FLASH ! ! !
Utilizing a FULL implementation of Po’ Boy Test Instrumentation Technology, one could use a Red LED with a series current /limiting-voltage/dropping resistor soldered to one LED lead.
Ergo about a 4700 ohm resistor in series should about drive a 10 ma LED from a full 42 volts application.
One needs to reverse the LED test end and resistor test lead end in order to check for both + and - voltage polarities presence.
If it seems to light dim, shunt a second 4700 across the first one . . . . to halve that resistive value but what we are really wanting to see is, that there is being NO sustained voltage level at those STK’s pin 3’s.
UNLESS there is a crashed power semiconductor within those STK’s which could result in a very worst case full - 42 or + 42 VDC coming out of either STK’s output pin 3’s.
In which case Mr. Protector and Mr. RY-1 relay say OH NO YOU DON”T ! ! ! . . . .Do you get the operational /functional principle now ?
I’m standing by now until I hear back on your views and perceived degree of techno-comprehension.
BTW I see that there is just enough space at the right side of the page to include an “undressed” version of those STK power module of yours.
The RED markups are potential power and driver semiconductors that could bring on disaster upon their failures of opening up or shorting.
WHAT TESTING ANALYSIS IS COMING UP ?
If the fault analysis info seems directed towards a STK related failure, to either or both, the use of wet rosin supplemented Solder Wick and /or /plus using a Solder Sucker Pump to pull ALL, and that’s very heaveee on the ALL, of the solder from around both STK pins 1 and 3.
So that the pins FLOAT from making any connection to the copper connecting pads.
Then a powering up of the unit, which assuredly will result in no activation of the protective circuit.
Then a powering down and the bleeding down of the + and – 42 V supply lines with an ~ 100 ohm power resistor.
Then selecting one of the STK’s and a re soldering back of its two power input pins.
One then expects the unit to either do the same relay cut out procedure OR pass audio in a normal manner thru that then one working channel
If it happens to work, them solder suck all of its pins and completely pull That STK and take the other questionable STK, pull it and put it in its place on that then working channel, expecting it to now go into cut out protective mode if the subbed STK is bad.
THE ALTERNATE POSSIBILITY:
Was that with your VERY first STK test, it was resulting in the unit going into protective cut out with the relay cycling.
Bleed down the +42 and -42 V supplies with the resistor. ( ACTUALLY . . .Do this EVERY time that you have any STK pins floating from solder sucking . . . before then powering up the unit.)
Unsolder the 1 and 3 power pins of that first tested STK with the suck/wet wick procedure until the pins are floating and then reestablish that the pins are REALLY floating.
THEN . . . you move over to the other STK and solder flow in pins 1 and 3 to get +- 42 VDC power buss connectivity again.
If you are lucky that will be a working channel, then you do the same cross testing/swapping of STK’s to ascertain a bad unit, when a prior GOOD working channel, then goes into protective cut out mode.
That then gives you a working “schematic” of its components and voltage readings of a then evaluated good channel to compare the other one against.
I am yet unsure of how I can post a schematic to show FULL size on this page as an earlier test seems to have reduced the size of the illustration a bit, where I done went and showed everyone how to test a fuse.
As per my posting of:
https://www.electronicspoint.com/attachments/fuse-tester-png.21518/
Let’s see if we can get that FAVORITE little puppy of yours all up and being fully functional again.(Comment Deux)
THEN you can again fully experience:
Hotly Linked as :
(However . . . . my music option would have been their Money for Nothing or Walk of Life ).
Test of the placing reference schematic on THIS page:
(Didn’t work but will work on it later)
Sooooooo . . . . just use this HOT LINK . . . . as I will then be hosted elsewhere, off this site.
This URL just below is another option for the schematic image, in case the one above is microsized down:
http://i.imgur.com/zr6L8qu.jpg
(Left mouse click on it, in case of it’s being dinky sized)
Addenda:
I just now see from above, that you are in France . . .but of English derivation.
I spleekee the Englee also . . . .velleee well !
73’s de Edd
