SX-525 Refurb

[33&athird]

Another thing to check is if any source plays throught the headphone jack, that would narrow it down, I think. As goat67 mentioned, the DC voltage should be checked first.

According to the manual, at no signal, the B1 ouput from the PS board should be 50volts at 60mA. The other ouputs from the PS board are; B2 which is 25volts, and 24mA to the head amp, and 3mA to the control amp (B2 goes to both). B3 is 12volts at 60mA (again, all these are at no signal).

Everything lighting is good, and a slight pop is good, however everything not so much. I would double-check the output transistors, especially the legs. Look up the datasheet to be sure, since there are replacements that don't use E-B-C layout (however, if someone on here suggested it, it's probably fine).

I think a voltage check is first order, if something's not right there, it's not right anywhere...

 

[markthefixer]

Download the zetex data sheets, mine (zetex transistors in hand) have lettering on BOTH sides, and zetex references the CURVED side as the frint to get your EBC left to right, so some zetex transistors could be in backwards.

I don't remember recommending the zetexes, but if I did rtecommend the zetexes and didn't mention to check the datasheets carefully, I'm sorry....

 

[Rockmore]

I'm not getting any readings out of B1 B2 B3. Either I'm a moron and not measuring correctly, or...

Fuses all check out for continuity.

NO audio from headphone jack with headphones.

Replacement transistor on the PS is a 2sd313 from Parts Express.

Replacements transistors from Mouser are:
6- 512-KSC2383YBU FAIRCHILD BIPOLAR
NPN EPITAXAIL SIL

2- 512-KSA1013YBU FAIRCHILD BIPOLAR
PNP EXPITAXIAL SIL

4- 512-KSA992FBU FAIRCHILD BIPOLAR
PNP EXPITAXIAL SIL

2- 863-TIP41GC ON SEMI BIPOLAR
6A 100V 65W NPN

2- 863-TIP42CG ON SEMI BIPOLAR
6A 100V 65W PNP

I replaced all the transistors with the exact same pin orientation as the originals...

On the PS- replaced the diodes with same direction orientation with:

3- 1N4004FSCT-ND 400V 1A DO41
1- 1N5242BFSCT-ND 12V 500MW DO-35 ZENER



This may be a dumb question, but on the PS board with power off the two flameproof 1 and 3 w 330ohm and 390ohm resistors check out. With power on, 330 is ok but get a -1068 reading from the 390... ? Part is 71-CPF3-G-390-E3 3W 390OHM 2% from Mouser.

"...Now you know why it is suggested to do one thing at a time and check functionality as you go..." . I couldnt exactly do that, as had all the wires all clearly marked and off the PS, and the same on the main amp. Had to get the replacement caps and other parts first and get 'em in and get the wiring all soldered back to get any power to any of the boards. Couldnt get to any of the boards to replace the transistors, caps, etc with the wiring still attached.

 

[Rockmore]

Download the zetex data sheets, mine (zetex transistors in hand) have lettering on BOTH sides, and zetex references the CURVED side as the frint to get your EBC left to right, so some zetex transistors could be in backwards.

I don't remember recommending the zetexes, but if I did rtecommend the zetexes and didn't mention to check the datasheets carefully, I'm sorry....

Thats for g@d d@md sure........ man... what a mess... dont even know where to start now. As I said I replaced all the transistors exactly as the originals. If half of them are in backwards, this means i am going to have to completely desolder and unwire the amp and remove it to be able to check each and every transistor, and then rewire it again to check voltages to start? I STILL havent been able to figure out how to check the transistors with power on with my little DMM.

Where in the heck to I download these Zetex data sheets?

 

[markthefixer]

Thats for g@d d@md sure........ man... what a mess... dont even know where to start now. As I said I replaced all the transistors exactly as the originals. If half of them are in backwards, this means i am going to have to completely desolder and unwire the amp and remove it to be able to check each and every transistor, and then rewire it again to check voltages to start? I STILL havent been able to figure out how to check the transistors with power on with my little DMM.

Where in the heck to I download these Zetex data sheets?

In the parts descriptions in the mouser catalog.

Could you kindly repost any transistor original/replacement posts I would have done, which should show the originals. I can't find it.... It would have most of what I will ask for below:

Did you even use any zetexes? If not, then there's far less of a problem. I don't see any on the previous post. Did you keep notes on what came out of where? I ask because the info we have is woefully inadequate, and purchasing a paper manual from rick at stereomanuals.com would have made things a whole lot easier.

To help you I need to know exactly which transistors you removed, and try to figure out what their original lead arrangement was, and what the replacements had. Usually in the hand holding process I manage to communicate the differences in the lead arrangements from the original to the replacement.


On the larger cased transistors that are replaced with like cased transistors, the lead arrangements are the same.

 

[33&athird]

I'm not getting any readings out of B1 B2 B3. Either I'm a moron and not measuring correctly, or...

don't try to measure current to start with, just voltage. Put it on DC volts, in the correct range. The black lead(negative) can be attached to the chassis, since this unit has chassis ground. Then the red lead can be placed on the pins, be careful not to short any together. That will tell you the voltage output. With no voltage, nothing would work regardless (the lights have their own circuit).

This may be a dumb question, but on the PS board with power off the two flameproof 1 and 3 w 330ohm and 390ohm resistors check out. With power on, 330 is ok but get a -1068 reading from the 390... ? Part is 71-CPF3-G-390-E3 3W 390OHM 2% from Mouser.

No trouble there, as resistors are not supposed to be tested under power, turn it off to test them for value. You could measure the voltage across the resistor, and with a current reading, could determine active resistance. However, that's alot of trouble, just test when off, and keep in mind it may not be accurate in-circuit, as many things can act on it.

 

[Rockmore]

In the parts descriptions in the mouser catalog.

Could you kindly repost any transistor original/replacement posts I would have done, which should show the originals. I can't find it.... It would have most of what I will ask for below:

Don't know what you mean. I replaced the transistors from your recommendations in this and other posts, and as stated in post #23 above. Dont think you ever stated this is what you have, only replacement part numbers.

Did you even use any zetexes? If not, then there's far less of a problem. I don't see any on the previous post. Did you keep notes on what came out of where? I ask because the info we have is woefully inadequate, and purchasing a paper manual from rick at stereomanuals.com would have made things a whole lot easier.

To help you I need to know exactly which transistors you removed, and try to figure out what their original lead arrangement was, and what the replacements had. Usually in the hand holding process I manage to communicate the differences in the lead arrangements from the original to the replacement.


On the larger cased transistors that are replaced with like cased transistors, the lead arrangements are the same.

I replaced every transistor shown on AWH-006 with what I stated in post #23.

 

[Rockmore]

don't try to measure current to start with, just voltage. Put it on DC volts, in the correct range. The black lead(negative) can be attached to the chassis, since this unit has chassis ground. Then the red lead can be placed on the pins, be careful not to short any together. That will tell you the voltage output. With no voltage, nothing would work regardless (the lights have their own circuit).

OooKkk. Will try. Dont know what the difference is testing using leads from source to what it's wired to, and from source to chassis ground, but will try chassis ground.



No trouble there, as resistors are not supposed to be tested under power, turn it off to test them for value. You could measure the voltage across the resistor, and with a current reading, could determine active resistance. However, that's alot of trouble, just test when off, and keep in mind it may not be accurate in-circuit, as many things can act on it.

As I said, no problems with the resistors with no power. Just want to test them since I was in there because most guys couldnt even tell me what they were in the first place, and since I determined they both were 1-3w flameproof and then what I chose to replace them with. There was also no voltages across them with power- only the - 1038 I got across the 390ohm (so far).

 

[Rockmore]

Another thing to check is if any source plays throught the headphone jack, that would narrow it down, I think. As goat67 mentioned, the DC voltage should be checked first.

According to the manual, at no signal, the B1 ouput from the PS board should be 50volts at 60mA. The other ouputs from the PS board are; B2 which is 25volts, and 24mA to the head amp, and 3mA to the control amp (B2 goes to both). B3 is 12volts at 60mA (again, all these are at no signal).

Everything lighting is good, and a slight pop is good, however everything not so much. I would double-check the output transistors, especially the legs. Look up the datasheet to be sure, since there are replacements that don't use E-B-C layout (however, if someone on here suggested it, it's probably fine).

I think a voltage check is first order, if something's not right there, it's not right anywhere...

From source to chassis ground:

B1 52 vdc
B2 9.42 vdc
B3 5.88 vdc

Switched over to 200m on by DMM and blew it. DMM wont work at all now.

 

[33&athird]

As I said, no problems with the resistors with no power. Just want to test them since I was in there because most guys couldnt even tell me what they were in the first place, and since I determined they both were 1-3w flameproof and then what I chose to replace them with. There was also no voltages across them with power- only the - 1038 I got across the 390ohm (so far).

Okay, no voltage on a resistor is probably not normal. Have you checked the voltage going into the PS board?...check the voltage that goes into AC3 and AC4 on the board. The other AC1 and AC2 have no fuse, and would only fail if a wire were damaged. As mentioned, the lamps have their own circuit, which has a 3A fuse (no that it matters, but hey...)

If it's not the input voltage, it's a device on the board. I have had one occurance of a lead-switch on a replacement device, had some of the same issues (it was a little mono chip-amp), but not quite the same. If you need to know anything (like numbers) from the manual, I can help out...Also, I have a factory fresh (not a good thing at this point) unit, so if anything is amiss, I can check it on mine.

From source to chassis ground:

B1 52 vdc
B2 9.42 vdc
B3 5.88 vdc

Switched over to 200m on by DMM and blew it. DMM wont work at all now.

That's not good...two things. For one; the meter, is the 200m volts or amps?, there may be a fuse in the DMM, I hope there is, meter's are cheap, but it's not a good thing to have one die (where you checking volts or amps?). Other thing is, B2 is around 15volts low, and B3 is really low as well... It could still be other devices, creating a higher load on the power supply:scratch2:.

 

[goat67]

I'm not getting any readings out of B1 B2 B3. Either I'm a moron and not measuring correctly, or...

Fuses all check out for continuity.

NO audio from headphone jack with headphones.

Replacement transistor on the PS is a 2sd313 from Parts Express.

Replacements transistors from Mouser are:
6- 512-KSC2383YBU FAIRCHILD BIPOLAR
NPN EPITAXAIL SIL

2- 512-KSA1013YBU FAIRCHILD BIPOLAR
PNP EXPITAXIAL SIL

4- 512-KSA992FBU FAIRCHILD BIPOLAR
PNP EXPITAXIAL SIL

2- 863-TIP41GC ON SEMI BIPOLAR
6A 100V 65W NPN

2- 863-TIP42CG ON SEMI BIPOLAR
6A 100V 65W PNP

I replaced all the transistors with the exact same pin orientation as the originals...

On the PS- replaced the diodes with same direction orientation with:

3- 1N4004FSCT-ND 400V 1A DO41
1- 1N5242BFSCT-ND 12V 500MW DO-35 ZENER



This may be a dumb question, but on the PS board with power off the two flameproof 1 and 3 w 330ohm and 390ohm resistors check out. With power on, 330 is ok but get a -1068 reading from the 390... ? Part is 71-CPF3-G-390-E3 3W 390OHM 2% from Mouser.

"...Now you know why it is suggested to do one thing at a time and check functionality as you go..." . I couldnt exactly do that, as had all the wires all clearly marked and off the PS, and the same on the main amp. Had to get the replacement caps and other parts first and get 'em in and get the wiring all soldered back to get any power to any of the boards. Couldnt get to any of the boards to replace the transistors, caps, etc with the wiring still attached.

Mark this is from the other thread this was your first parts recommendations
the info I posted was your second recommendation

A's and B's are pnp,
C's and D's are npn

TO-220, on this type case lead designations don't change.
2- 2SA489 pnp 70v 4a 30w 40-240hfe 3mhz
2- 2SC789 npn 70v 4a 30w 40-240hfe 3mhz


512-KSB596OTU pnp to-220 bce 80v 4a 30w 3mhz 15-240hfe $0.62
512-KSD526O npn to-220 bce 80v 4a 30w 3mhz 15-240hfe $0.62
or
863-TIP42CG pnp to-220 bce 100v 6a 65w 3mhz 30-75hfe $0.70
863-TIP41CG npn to-220 bce 100v 6a 65w 3mhz 30-75hfe $0.64


4- 2SA726 pnp bce to-92 50v 0.1a 0.2w 500hfe 100mhz
512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea

2- 2SA720 pnp ecb to-92 50v 1a 0.625w 85-240hfe 200mhz
512-KSA1013YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17

6- 2SC1318 npn ecb to-92 50v 1a 0.625w 85-240hfe 200mhz
512-KSC2383YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17

Advice given from EW on purchasing parts from Parts Express

Parts Express sells crappy Chinese remarked transistors. I buy a lot of stuff from PE, but NOT transistors.
Pretty much every transistor in that receiver has been out of production for at least a decade & 1/2. This is rarely a problem, as there are good modern substitutes for 99.9% of them. If there's something you're looking for, tell us where it is used, what the number is, and identify the form factor, and myself or someone else will recommend a replacement.

I would look at two things the PS transistor get one from Mouser

Q1 2SD313 bce
512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54

Second verify the 512-KSA992FBU transistors as the pin layout is different from originals

You first need to get the Power supply to output the correct voltages.

 

[markthefixer]

Thanks goat67

yes I agree.... from Rock's descriptions, I suspect the 992's went in backwards.
seeing the zetexes mentioned threw me.

get some reliable readings on the p.s.'s d313 EBC ground referenced in circuit and then B1 B2 B3.

edit:
OK, I just opened up and LOOKED IN the 525 on the shelf, and the boards DO have transistor symbols marked on them, so just have Rock describe the orientation of the 992's on the power amp board, and talk him through a reinstallation.

Never mind the power supply as long as the to-220 went in facing the correct direction, rock's attention to detail should have gotten that right.

Plus rock sounds frustrated by the DMM, get the model number, look it up, and use the info for a dmm driving lesson, to find any lurking holes in rock's understanding of the thing.

You have the conn, number one..... make it so.....

 

[Rockmore]

Goat, Mark, 33- thanks!

A Lot.

Finally used an old reliable analog dial MM to try and get any or similar dcv readings (first), and got something. Looks like my crappy two other DMM are going in the trash. Batteries and fuses all fine- just that old Harbor Freight quality...

I will post what I find about the transistors and everything else as soon as I can.

Goat- thanks for pulling the info and assimilation from the other thread!

geeze... I am Jonathan Frakes now?!? LOL thanks for the grin. Frustrated is correct.

Mark- what did you say or recommend to use for the quick connects to all the wiring posts and wires on the different boards? All this un soldering and resolding of the wires to the posts is getting ridiculous, plus all the heat that may be going to all the components.

 

[markthefixer]

Uh, goat67 is Frakes, rock... I was letting him know his assistance is most welcome.

IIAC, the problem (miswired 992's) lies in the amp card, which has access from below - no more desoldering of wires with insulation, if I interpreted the question correctly.

The REST of the transistors on the cards behind the front panel should be ok. They were direct 1:1 lead arrangements.

 

[goat67]

Ok Picard (Mark)
I have the conn

What we want to do is verify the installation of Q1 - Q4
The originals lead configuration are bce the replacements are ecb
So you need to get the data sheets to confirm the pin layout.

You always want to verify that you put the transistors in correctly.

Using your DMM you can determine the pin layout if you do not know how let me know and I can explain or search for the instructions from EchoWars

About the DMM if you plan on working on this stuff good tools make life a lot easier.

What is the status of the DMM are you going to get another?

Using the analog meter is fine to get the following measurements

from AWR-007 power supply
B1 to ground should be 48v
B2 to ground should be 25 v
B3 to ground should be 12v

Q1
Emitter to ground should be 32.0v
Base to ground should be 31.4v
Collector to ground should be 40.5v

Lets see what you get

 

[markthefixer]

for testing

http://www.audiokarma.org/forums/showthread.php?p=432830#post432830

for the symbols

 

[Rockmore]

t
h
a
n
k
you.

was able to confirm BOTH my DMM's were faulty today from somebody else, so on top of everything else that didnt help all this mess.
got a new heavy duty tank of a DMM and will post answers, results, and findings especially on my transistor orientations as soon as i can, when i can find some more time. the old hand build analog mm i have just doesnt cut it. picard and riker (L..O..L..). thanks for the pics, recent info, hands-on time, etc. --AND-- for trying to make it simple(r) procedure wise. i dig the HUGE pic mark- even though i fully know transistor and diode orientations (polarities). All the recommend transistors i replaced were bi-polar you know... but...

BTW- 33 is Data you know.... :thmbsp:

 

[goat67]

t
h
a
n
k
you.

was able to confirm BOTH my DMM's were faulty today from somebody else, so on top of everything else that didnt help all this mess.
got a new heavy duty tank of a DMM and will post answers, results, and findings especially on my transistor orientations as soon as i can, when i can find some more time. the old hand build analog mm i have just doesnt cut it. picard and riker (L..O..L..). thanks for the pics, recent info, hands-on time, etc. --AND-- for trying to make it simple(r) procedure wise. i dig the HUGE pic mark- even though i fully know transistor and diode orientations (polarities). All the recommend transistors i replaced were bi-polar you know... but...

BTW- 33 is Data you know.... :thmbsp:

Rock
The highlighted portion does not make sense transistors are not bi-polar???

Anyway take your time and get back to it when you can

 

[xlbee]

goat67

I think you should read this:

http://en.wikipedia.org/wiki/Bipolar_junction_transistor

 

[33&athird]

Rock
The highlighted portion does not make sense transistors are not bi-polar???

Anyway take your time and get back to it when you can

goat67

I think you should read this:

http://en.wikipedia.org/wiki/Bipolar_junction_transistor

:yes: Bipolar is in regards to the junction, which differentiates it from mosfet (metal–oxide–semiconductor field-effect transistor), and other devices. It really refers to how it operates, not from a layer (npn, pnp) standpoint, but how it transfers electrons, through both electrons and "holes". I have a decent understanding (thanks Paul Turner!), but the wiki article has alot more on it.

~And to rockmore, i'll have some more stuff up in a little bit :thmbsp:.