SANSUII BA-3000 PROBLEMS

[pppoffice]

OK, here are these voltages I think you were waiting for. I just didn't catch it. The positive side of C17 I measured +1.687 VDC, on the negative side of C18 I measured -0.328 VDC, on the positive side of C15 I measured -0.707 VDC (YES, negative voltage), and on the negative side of C16 I measured -84.4 VDC. I have everything ready to put both bricks back together with the old power transistors. It won't take me 5 minutes to have the right side ready to go back in the amp whenever you tell me to put it in.

 

[pppoffice]

Mike, are you wanting me to get the voltages off of these same caps again. This is the only thing that I can think of that you want. I will go get these voltages again but I doubt they have changed as nothing I can think of has been done to cause a change. I will get back to you in a short period of time.

I will take the time to read the thread you sent to me one night when I can't sleep. I have a laptop over in my bedroom to turn on when I can't shut my brain off.

 

[pppoffice]

I will take the time to read the thread you sent to me one night when I can't sleep. I have a laptop over in my bedroom to turn on when I can't shut my brain off.

I am getting ready to go home for an early dinner with my wife. After dinner I will be back to work late in the night and I will check to see what you have for me to do next.

 

[vigman]

If these are still correct : I thought you changed some parts....
Lets focus on the 35....
Print out the 2508 schematic and mark what has been replaced ( hilighter ) and current measurements

+/- 35 volt
On the positive side of C17 I got 1.675 VDC <<Tell me what you have on the collector of TR-03 ( should be about 50 VDC )
On the negative side of C18 I got -0.331 VDC<< Tell me what you have on the collector of TR-03
Tell me the voltage drop across ZD-02
Pull and test TR-13
Pull and test TR-12 and once all back together tell me the voltage on the base

+/- 60 volt supply:
On the positive side of C15 I got +0.685 VDC
on the negative side of C16 I got -84.5 VDC<<<<<< Thinking TR-10 is shorted

 

[vigman]

I guess the obvious question is have ANY of the semi's been replaced on the 2508 or all they all OE?

 

[vigman]

While you are waiting, I would pull each and every resistor ( 1 leg ) out of circuit and verify the values, and if I'm still not in sync with you time wise, same with the semi's
Note sometimes the silk screen is WRONG on the PCB... verify the polarized caps match the schematic...

 

[vigman]

I'll check back ~ 1 hr 3:37 PST BEEP

 

[pppoffice]

If these are still correct : I thought you changed some parts....
Lets focus on the 35....
Print out the 2508 schematic and mark what has been replaced ( hilighter ) and current measurements

+/- 35 volt
On the positive side of C17 I got 1.675 VDC <<Tell me what you have on the collector of TR-03 ( should be about 50 VDC )
On the negative side of C18 I got -0.331 VDC<< Tell me what you have on the collector of TR-03
Tell me the voltage drop across ZD-02
Pull and test TR-13
Pull and test TR-12 and once all back together tell me the voltage on the base

+/- 60 volt supply:
On the positive side of C15 I got +0.685 VDC
on the negative side of C16 I got -84.5 VDC<<<<<< Thinking TR-10 is shorted

Since we have been working on this amp the only part that has been changed is the fried 10 ohm resistor. When I replaced it I gave you voltage readings after it was replaced. Since that 10 ohm resistor was changed, I have not changed any parts. I have read back all the way thru this thread and I can't find where I didn't give you a reading you asked for. I can see how you might have not seen my reply to a request for a reading but I am pretty sure that I have replied to every question you have asked. Since I have owned this amplifier a good many transistors have been changed for OEM style transistors and also paying attention to the letters after the part number to be sure they were of the same series. Over the course of the time I have owned these two amps I have gone thru my stash of OEM transistors and I am starting to run out of them so I have stocked up from Mouser Electronics a pretty good stash of the recommended cross reference parts that was listed here on audiokarma on another thread. I either have the original OEM style parts in stock OR the parts that were shown in the cross reference list that was on another thread about the BA-3000 Amps. Right now I will go over to the shop and first try to get you these readings FIRST. Then I will check the values of all the resistors on the 2508 board. I was always careful (but I have made mistakes in my life) to install the new caps the same way the old one came out. If I saw the the original cap was not in as the board was marked I would always check to see what the schematic showed and make sure it was installed per the schematic. Just prior to me asking for help here on Audiokarma I had pulled EVERY transistor on the 2508 board and checked it using my little transistor tester AND with an my HP 3401A Multimeter I also used the conductivity test that I always use to use to test a transistor for a short. I will pull every transistor on the 2508 board again and test it with my little transistor tester. I can also pull every diode and test it with this little tester too plus with my HP3401A. After I get you these readings you need I will be a very busy person for a while pulling all of these parts and testing them one at a time but I will check back from time to time to see if you have any other information you need.

 

[vigman]

Well something has been missed.. and I KNOW how frustrating this can be. We have to go thru it ALL AGAIN, because NOTHING is even close. and at this point I would not put the other 2508 in..It will just confuse matters.. Please do a marked up schematic so I can follow closely and not mis read your data, so I do not send you on a wild goose chase.
Possibilities are : a replaced transistor might not pin out EBC ( or however the OE transistor was ) as far as the pin out goes, so something to watch out for..
Lets back up 1 step on the +/- 35
What are the voltages at: Neg side to ground BTW what are you using as ground?
the junction of R-05 & R11
The base of TR-03
The base of TR-04
the junction of R-06 & R14

I'm REALLY trying to get a clear picture of the failures....

 

[vigman]

OH OOPS I just checked the COMMON for the 85 V supply doesnt show a connection to CHASSIS, so your COMMON needs to be where C-01 NEG and C-02 Positive join.. the GND silk screen on the +/- 85 2512.. this supply ( without boards in ) FLOATS

 

[pppoffice]

Ok, before I start testing all the resistors, transistors, and diodes here are the readings you asked for. The collector of TR-03 is +17.5 VDC, You then asked for the same collector voltage so in hopes that I give you what you intended to ask for the Collelctor voltage of TR-01 is +5.1 VDC, the collector voltage of TR-02 is -85.9 VDC, and the collector voltage of TR-04 is -15.2 VDC. I pulled and tested TR-13 and it regisered hFE=418 and Vf-787 mV. TR-13 is a Fairchild C1845-FTA which is cross ref. off of the transistor list found here on audiokarma. I pulled and tested TR-12 and it registered hFE=69 Vf=758 and this transistor is a C1735-C. Then you said you thought that TR-10 might be shorted and bad so I pulleld and tested it and it registered hFE=169 Vf=704 and it is a D381-K. I think I answered all of your readings and other questions. I will now go over to my shop and start pulling and testing parts.

 

[pppoffice]

Well something has been missed.. and I KNOW how frustrating this can be. We have to go thru it ALL AGAIN, because NOTHING is even close. and at this point I would not put the other 2508 in..It will just confuse matters.. Please do a marked up schematic so I can follow closely and not mis read your data, so I do not send you on a wild goose chase.
Possibilities are : a replaced transistor might not pin out EBC ( or however the OE transistor was ) as far as the pin out goes, so something to watch out for..
Lets back up 1 step on the +/- 35
What are the voltages at: Neg side to ground BTW what are you using as ground?
the junction of R-05 & R11
The base of TR-03
The base of TR-04
the junction of R-06 & R14

I'm REALLY trying to get a clear picture of the failures....

In regards to a transistor being put in wrong that is the MAIN reason I rely on the little transistor tester is because it tells me what each pin is so that I can be sure that I am installing the transistor correctly. Before I got this little transistor tester I had to go to the Internet and print out the specs on every transistor so that I could see what each pin is. Now this little tester shows me exactly what each pin of the transistor being checked is so that I can be sure to solder it into the board correctly. I pay VERY close attention to this especially now that I am starting to run out of my stash of OEM transisors and having to use the list found here on audiokarma for a cross ref. Yes, as I have worked on these amps when I did find a bad transistor and I was out of my OEM stash I used the cross referenced transistor found on the list. I didn't pay any attention to what each pin is and rely entirely on this little transistor testor to let me know that information.. It would probably be easiest for me to just make up a list of all the transistors on the 2508 board and list what transistor is in it so you can see where an alternate transistor is being used. Trying to get all the data scribbled on a copy of the little schematic in the service manual and than scan it or take a picture of it and send it to you I think is going to be a waste of time because I don't think you will be able to make heads or tails of it when it is done. It is cleaner and easier for me to just make up a Microsoft Excel or Word document with all this information in it and get that to you. Let me know your thoughts. I will certainly do what you want but I am just trying to make sure that you can read the information when I present it to you.

 

[pppoffice]

OH OOPS I just checked the COMMON for the 85 V supply doesnt show a connection to CHASSIS, so your COMMON needs to be where C-01 NEG and C-02 Positive join.. the GND silk screen on the +/- 85 2512.. this supply ( without boards in ) FLOATS

I have been taking all of my readings using chassis ground. I didn't even think about the possibility of a floating ground. I guess you will just have to tell me any time that I need to take a reading where the chassis ground won't work and what to use as the ground.

 

[pppoffice]

Well something has been missed.. and I KNOW how frustrating this can be. We have to go thru it ALL AGAIN, because NOTHING is even close. and at this point I would not put the other 2508 in..It will just confuse matters.. Please do a marked up schematic so I can follow closely and not mis read your data, so I do not send you on a wild goose chase.
Possibilities are : a replaced transistor might not pin out EBC ( or however the OE transistor was ) as far as the pin out goes, so something to watch out for..
Lets back up 1 step on the +/- 35
What are the voltages at: Neg side to ground BTW what are you using as ground?
the junction of R-05 & R11
The base of TR-03
The base of TR-04
the junction of R-06 & R14

I'm REALLY trying to get a clear picture of the failures....

I am really confused by this request. I totally understand your concerns that a transistor could be put in wrong but I just explained to you why I love this little transistor tester and how it tells me what each lead is so that I can install ALL transistors correctly whether it is an OEM or a cross ref. transistor. Could you ask again what readings it is that you want me take are so that I can go get that information for you right now. Be sure to let me know if I need to use a ground other than chassis ground.

 

[pppoffice]

Well something has been missed.. and I KNOW how frustrating this can be. We have to go thru it ALL AGAIN, because NOTHING is even close. and at this point I would not put the other 2508 in..It will just confuse matters.. Please do a marked up schematic so I can follow closely and not mis read your data, so I do not send you on a wild goose chase.
Possibilities are : a replaced transistor might not pin out EBC ( or however the OE transistor was ) as far as the pin out goes, so something to watch out for..
Lets back up 1 step on the +/- 35
What are the voltages at: Neg side to ground BTW what are you using as ground?
the junction of R-05 & R11
The base of TR-03
The base of TR-04
the junction of R-06 & R14

I'm REALLY trying to get a clear picture of the failures....

OK, here are these readings TAKEN TO CHASSIS GROUND. The junction of R-05 & R-11 = + 86.2 BDC. The base of TR-03 = +85.3 VDC. The base of TR-04 = -85.3 VDC. And last but not least the junction of R-06 & R-14 = -86.3 VDC. I hope this is what you wanted and it helps. I am getting ready now to go home and to bed. I haven't had a particularly good day today. I have had on crisis after another around here today. I live on 10 acres of land that has my home, my little machine shop (with everything I need to make what I need), my old company offices (where my computer is with stereo room upstairs), and my old company warehous (Ham Shack & electronics workshop) and it seems that there has been spmething wrong going on in every building on my property that has needed attention. I am a bit worn out. Make me a list of what you need for me to do in the morning. I usually get up at about 10 AM Central and get over to my office (where I am now) by 11 AM Central.

 

[vigman]

1) use this ground "COMMON needs to be where C-01 NEG and C-02 Positive join.. the GND silk screen on the +/- 85 2512.. this supply ( without boards in ) FLOATS"
retake the measurements

 

[pppoffice]

1) use this ground "COMMON needs to be where C-01 NEG and C-02 Positive join.. the GND silk screen on the +/- 85 2512.. this supply ( without boards in ) FLOATS"
retake the measurements

I will go back over to the shop and retake them right now.

 

[pppoffice]

I will go back over to the shop and retake them right now.

I tacked a lead at the junction of C-01 Neg and C-02 Pos with a clip on it so I could clip on to my negative meter lead. The readings I got this time are The junction of R-05 & R-11 read +86.9 VDC, the base of TR-03 is +85.8 VDC, the base of TR-04 is -85.7 VDC, and the junction of R-06 & R-14 is -86.9 VDC.

 

[Overundr1]

pppoffice, admire your ability to provide accurate readings when asked, not as easy to do on a forum as working side by side on a bench
Anyways been reading along (too many cooks etc etc) however suggest replacing ZD02 (or at least measure across that zener) and then measure from each leg to ground.
Oh, btw, better not visit those folks over in the tube forum or we will lose you in the Sansui forum, the force is strong over there
-Lee

 

[vigman]

Ok I have these for you .. and now I will note your measurements to date... and send a copy so I can SEE what you are seeing