Crown CE1000 channel 2 problem/fault indicator -diagnosis

Thread Starter

wolf1419

Joined Nov 1, 2008
117
Hello Ron,

So you can confirm there is no short from L102 / L202 to ground.
So we have to find out what other problem channel 2 has.
There are several temperatures checked.
And there are connections to the transformer.
Do channel 1 and channel 2 have seperate transformers?

Greetings,
Bertus
L101/L102 not shorted to gnd
1 large power supply(p37), which also shows in one of the attached pics inside the amp in an earlier post.....
The wires from the secondary side go to the bridge rectifier, and there are 4 smaller wires that show connector(p14) also in photos..
 

bertus

Joined Apr 5, 2008
22,120
Hello Ron,

Can you reach the point 1 and 2 in the drawing I posted here?



I expect that point 1 is high ( almost 15 Volts ) at channel 2 and 0 Volts at channel 1.
For point 2 it can be the same or different for the channels.

Greetings,
Bertus
 

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wolf1419

Joined Nov 1, 2008
117
I can gain access to U105(pins on top-super tight-close together-this should be interesting-this is like micro-surgery, especially powered-up).
Anyway, I downloaded the data sheet but my opamp has no "key", or "dot" for reference for pin 1....it does have the #'s etc..stamped on top, so I would assume bottom left corner(if reading text as normal on top) would be pin#1, then proceeding counterclockwise to last pin#8.....(chk'd pin#5=gnd).....is that correct..?
U105(CH1) Pin#7 = -14.8V
U205(CH2) Pin#7 = +14.0V
The fault points are unclear at this time...I'm still searching how to find and get access......
 
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bertus

Joined Apr 5, 2008
22,120
Hello Ron,

The So package seems to have a rimm on one side.
This side has the pins 1 to 4.



I expect pin 7 to be high on the wrong channel.
Pin 1 wil be switching the led on the wrong channel.

Greetings,
Bertus

PS did you notice the status change , You have become a senior member now.
 

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wolf1419

Joined Nov 1, 2008
117
Senior member....how did they know I was so old...Ha Ha.....
I feel a "little" smarter, thanks to your teachings, but I know it's that I just ask so many darn questions..my post count is higher than the average guy.
Wow....that ridge is almost undetectable, even under my super high-power glasses, but it does bear out my figuring of that opamp(pin#5=gnd for chk).....pin#1 was by accident..oops! I figured out the channels...
U105(CH1) Pin#7 = -14.8V
U205(CH2) Pin#7 = +14.0V

Pnt2 ......Will opamp U5, pin#2 give us what we need...? If so Pin#2 = + 13.6V
I can't find this point for CH2 in the schematic....a little lost there......
(All the little arrow bullets that say either fault, or mute.....that's what gets affected....correct..?...these schematics are very difficult to follow....they seem to be many bits & pieces that supposed to connect, but not clearly from my view....
 
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bertus

Joined Apr 5, 2008
22,120
Hello Ron,

The fault signal comes from the U 102 / U 202 pin 1.
In the schematic it is located near the input circuit.

The + 13.6 on pin 2 of U 5 for channel 1 seems to be OK.

Greetings,
Bertus
 

Thread Starter

wolf1419

Joined Nov 1, 2008
117
XFMR feeds D1-D4, which supplies 24V to U1/U2 which supplies +15V/-15V rails, which is the supply intended each time the schematic shows +15V, or -15V......which is connected even though it doesn't show the individual "lines or rails" in the schematic, as there would be too many to show(thus invisible lines)........correct...?

U105/U205 pin#1, respectively, are opamp outputs, supplied by that +15V rail(invisible supply lines mentioned above), thru R161/R261, E102/E202(Fault LED's), R160/R260 feeding input Pin#2, and feedback thru R162/R262 to input Pin#3 which compares voltages in this circuit.....:confused:.......exactly how to visualize what's truly going on is the challenge, because there are an unlimited # of processes also going on everywhere virtually at the same time........there are many circuits comparing voltages to decide when the startup procedure is done, or: the system either stays in startup/fault mode, or will later go into fault mode when excessive heat, or short, etc.. is detected..........SO either:
1) We have a bad component/components(short, open, or defect)* in a circuit(CH2) that will not allow the output to complete the full circuit as it should to amplify my signal.......
2) We have a bad component/components* falsely sensing heat incorrectly(CH2)-because there is NONE on startup.......
3) The component/components* that switch from startup to working mode are just not operating....keeping us in startup mode(CH2), which was where we started, but we have the upgrade that eliminates that previously known issue...
Let me know where I am way off base...........:eek:.....I can take it...;)
 

Thread Starter

wolf1419

Joined Nov 1, 2008
117
Hello Ron,

The "invisible" feed lines are shown on the right bottom corner of the page
for the connections of the individual opamps on that page.

The opamps U105 / U205 make some relaxation oscillators:
http://en.wikipedia.org/wiki/Relaxation_oscillator

Did you have a chance to measure the point I asked (U102 / U202 pin1) ?

Greetings,
Bertus
I see the "invisible" feed lines for the opamps & bypass capacitors, these and other ones I was referring to are the +15V, -15V, etc.. that show up all over the schematic(ex: "invisible" feed at +15V to R161, E102, etc....), which all hook to that same supply rail....correct..?

Ah.... that "relaxation" oscillator....the circuit around U105, C122 charges and quickly discharges to create the flashing of E102 in the startup and fault mode....so that's working and triggered by whatever is triggering my fault status.

U102 pin#1 = +14.96V
U202 pin#1 = +12.56V
 
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bertus

Joined Apr 5, 2008
22,120
Hello Ron,

The "FAULT" voltages are about the same, I think both channels are OK for this.

I looked at an earlier measurement (U105-7 / U205-7) measuring -14.8 and +14.0 Volts.
For a working channel we need the - 14 Volts on the pins 7 of U105 and U205.

I looked at the chain connected to U105/U205 and drawn some expected voltages.



You can confirm them by checking both channels.

Greetings,
Bertus
 

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Thread Starter

wolf1419

Joined Nov 1, 2008
117
OK...we have some matches...good!!
U104 pin#4 = -3.7V, U204 pin#4 = -3.7V
U104 pin#8 = -1.2V, U204 pin#8 = -1.2V

Now the mismatches(CH2)*
U104 pin#5 = +0.8V, U204 pin#5 = -5.0V*
U104 pin#1 = +7.8V, U204 pin#1 = -14.9V*
U105 pin#7 = -14.9V, U205 pin#7 = +14.0V*
U105 pin#6 = +7.1V, U205 pin#6 = -13.5V*

I wasn't clear on the only + point(U104/204 pin#1), or (U105/205 pin#6), so I gave both.....and CH2 was - on both anyway(not good)*
 

bertus

Joined Apr 5, 2008
22,120
Hello Ron,

I think (I can be wrong) that we have a problem with the temperature sensors.
Please check the voltage at R190 near U106 (LM234).
Do this also for R290 near U206.

I attached the datasheet of the LM134 / LM234.
On page 6 ia described how it works as a temp-sensor.

Greetings,
Bertus
 

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wolf1419

Joined Nov 1, 2008
117
You "may" just be right, as this was also one of my 3 scenarios posted earlier...that this thing "may" think it's overheated before it even gets going due to a faulty sensing circuit(could be any element of that circuit that controls or sends the message, I suppose...I'm pretty sure it'll be something simple, in the end, that is just so difficult to pin down exactly and takes a lot of theory and testing to find it)...:)

Thanks for the data sheets, links, pics, redlining, patience, and continuing support................I've got some real studying to do....components to locate, gain access, etc..........and I might have lost a few brain cells in "electronics land"......but I am having fun working with you from such a great distance, and it's like you're right here working with me.......I hope I'm not burning you out....I know this must be a lot of brainwork for you and time from your needs............tell me any time that you just need a "break"...........:rolleyes:...........and I'll try to make you proud again.....You need to pat yourself on the back for getting me through the Marshall 8100 and the Fender Princeton Chorus treble issue.....I wish I could help you ......:D.....APPRECIATION is what I have to give.... it's yours!!
I finally found U106/U206, R190/R290 and there is no access without dismantling the whole amplifier to get under the board.....OK forget my "simple" scenario....Wow!!....I "may" be getting in over my head....I don't have any of the torquing tools to get it back together to specs, if we find and repair the causes......Major surgery....could be Fatal!!......any ideas before I attempt that?.....

NEW THEORY - I just reviewed section 3.8.2 and knowing that it has muted the CH2 output, if it is due to a CH2 heat detection error, it should turn on the fan(thinking it's overheated)......but it doesn't, so that "may" point us elsewhere(not heat related)...output circuit fault instead(not related to fan)......heat faults alter fan speed/output not muted.........BUT, output circuit problems will cause fault light/muted output/no fan alterations.......these are the symptoms(CH2) of this amp...........make sense..?
 
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bertus

Joined Apr 5, 2008
22,120
Hello Ron,

When I look at the values for the U104 / U204, wich are +0.8 and -5.0 Volts,
this can be translated to a temperature.

I have putten the found values in the schematic:



As you can see a temperature of -99C is rather low.

Is it possible to measure the resistance from U104 / U204 to - 15 Volts, to see if the resistors R190 / R290 are OK ?
(Of course the amp is switched off for that).

Greetings,
Bertus
 

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Thread Starter

wolf1419

Joined Nov 1, 2008
117
-99C is like a subfreezing temp....:eek:.....obviously bad data....correct...?
That is a "false signal voltage" supplying U204, supplying "false signal voltage" to U205 and triggering fault light E202......:(......fan does not need to come on due to temp way too low...no trigger in this false state.

Now the muting of CH2 would be the "false signal voltage" also supplying U204, affecting mute 2(not sure where that connects)....:confused:

I'm also assuming that the " short signal voltage"(if we had a short) supplies U204 pin#4, which is confirmed at -3.7/-3.7(match-no short in output), but the feedback there from the incorrect temp voltage is also affecting that opamp, and also Q229, affecting K200 and the switching circuit that we discussed earlier....(arrow just above K200), which is the actual muting cutoff point, and why CH2 is in mute condition(false trigger voltages).....is that right....?

Since the amp is still together, and operable, I would like to trace that "false signal voltage" thru these components and compare with CH1 to see the similarities or differences, mostly as a learning exercise, and confirmation until we get matching #'s as we work our way away from this falsely affected portion of the circuit(s)....we could discuss certain circuit sections as we go.....:D.....the actual repair will probably have to wait until I get comfortable with the learning of this particular problem and try to confirm if anything else "may" be affected as well........;).....we have a match at XFMR at U204 pin#8(-1.2/-1.2).....so that's helping to isolate the areas of concern...and eliminate other parts.
 
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bertus

Joined Apr 5, 2008
22,120
Hello Ron,

Walking over the page I saw there are some "reference" voltages accross it.
Could you check if these voltages are correct?



One of the voltages is important for the temp sensing fault circuit (6.07 Volts).

I will have a look at the others parts of the schematic.

Greetings,
Bertus
 

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wolf1419

Joined Nov 1, 2008
117
I started checking voltages
WP#1 = +84.5V
WP#3= -84.5V
U1(out) = +14.5V
U2(out) = -14.9V
Now checking U2(in)probably didn't even need it, but I wanted to check everything, following trace chk points, but too "tight"....BANG...:eek:......SHORTED something at U2.. "sparks, burning smell", CH2 heatsinks get HOT right away, fan comes on...heat detector worked..?..turned right off...:mad:

Before I realized it was a blown cap, I turned on again to see if it was dead....:eek:......"sparks, etc"...fan on, no normal startup check....I shutoff......visually found Cap C5 is now blown(exploded top).......SHE's Blown and needs to be dismantled after all....no choice!!...:mad:

I don't believe I had access to the 6.07 at the resistors anyway....now I have a "real repair job".....I don't know how many more parts may have been affected.....Now comes the REAL FUN...maybe $$.......let's hope all these protection circuits saved a major disaster of # of parts blown....:rolleyes:

Well, Charlene says...Everything happens for a reason....I guess I need to get knee deep into a major repair to learn more and be more careful trying to get in tight spots with those probes...at least I'm ALIVE....:D
 

bertus

Joined Apr 5, 2008
22,120
Hello Ron,

You are not lucky at that moment.
If C5 is blown also check the diodes D1,D2,D3 and D4.
They probably can be checked when J2 is taken of the board.
Those might also be affected by the "blow".

I do not see any fuses near the diodes. Are the none?
Or are they on the other side of J2?

Greetings,
Bertus
 

Thread Starter

wolf1419

Joined Nov 1, 2008
117
Hello Ron,

You are not lucky at that moment.
If C5 is blown also check the diodes D1,D2,D3 and D4.
They probably can be checked when J2 is taken of the board.
Those might also be affected by the "blow".

I do not see any fuses near the diodes. Are the none?
Or are they on the other side of J2?

Greetings,
Bertus
NO fuses...with J2 still attached presently/C5 blown.....D1-D4 effectively a bridge rectifier by design, checked in diode mode D1 & D2 are shorted(bad)..., D3 & D4 appear open both ways(bad), and one side of D3,D4 are shorted to D1/D2....so 6 points are shorted to gnd, 2 points open(one side of D3 & D4)....I know this is not good....but I do remember the Marshall 8100 bridge rectifier measured as shorted while in circuit, but it turned out to be TR8 & TR10 that were shorted, showing a short back at the BR.....probably not the case here, but worth mentioning just in case of interaction of other components.

The good news is that the flyback diodes D114, D115, D214, and D215 are not shorted, which "may" be good news for the output section being saved by the protection curcuits.

I'm trying to find IN4004 rectifier diodes(1A, 50V-1000V specs), but no suppliers, my typical supplier has this:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=1N5408%20%20%20%20%20%20%20%20%20&FTR=rectifier%20diode&CFID=10514020&CFTOKEN=47776107
Will this one work properly for my purposes....it was searched as a rectifier diode...
**then I found this:
http://www.parts-express.com/pe/showdetl.cfm?&DID=7&Partnumber=1N4007
I'm assuming the 1A is better protection for other parts in the amp, 3A being overkill and won't burnout when needed..

Only 470mf cap available is 25V vs. 35V specified.....will this still be sufficient...or just too minimal to deal 24V?
http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=020-1736&ctab=1#Tabs
**More searching.....I think this is it:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=020-1168

I just reviewed the LM134 datasheet and wondering if the resistor that controls the current may be at fault, especially since the fan did come on, meaning LM134 may be functional, but external resistor is throwing it off......
 
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bertus

Joined Apr 5, 2008
22,120
Hello Ron,

About the diodes:
The 1N4007 is a higher voltage version of the 1N4004.
That will work fine in the amp.

About the capacitor:
The working voltage must be the one stated in the schematics.
The 35 Volts can be used. A 50 Volts version may even be better.
(I am in favour for the High temp types).
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=020-1670
Perhaps change C4 too, that is of the same age.

I alway use a capacitor that is rated 1.5 times the working voltage or higher.

About the LM234:
I asked to check the 57.6 K (R190 / R290) resistors before, but the 226 Ohms resistors can be checked too.
(you said you had no access).

Greetings,
Bertus

PS Digikey and Mouser are also very good part suppliers:
http://www.digikey.com/
http://www2.mouser.com/Home.aspx
There you will also find a lot of SMD parts.
 
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