• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

SX-1010 Recap ?

C

craxx6969

Well-Known Member
I am recapping and replacing the transistors on a friend's SX-1010. I have all of the parts for the main boards, etc. I do not see any posts that have the equivalents for the output transistors on the large heatsinks. They are NEC 2SD287b and NEC B539b.

Also what can I use for Q4 on the AWH-032 board. Lots of discussions indicating do not replace.

Thanks to all of the AK'rs...


JT
 
Register to hide this ad
Q4 2sb528 (bias circuit): to-202? bce 130v .8a 1/10w 55-300hfe ?mhz
512-KSA1381es x to-126 ecb 300v .1a 1.2/7w 150mhz 40-320hfe $0.27 ea
 
craxx6969 said:
I am recapping and replacing the transistors on a friend's SX-1010. I have all of the parts for the main boards, etc. I do not see any posts that have the equivalents for the output transistors on the large heatsinks. They are NEC 2SD287b and NEC B539b.

Also what can I use for Q4 on the AWH-032 board. Lots of discussions indicating do not replace.

Thanks to all of the AK'rs...


JT
Click to expand...

Generally on the 1010 if it's not one of the problem child transistors, or if it's not functioning, leave them be. In special cases, shotgun replacement is warranted. Specifically the POWER SUPPLY due to the excessive heat buildup that was designed in to the 1010 for the P.S. It can't breathe, gets overheated and parts break down.

Q4 on the AWH-032 isn't one of the "problem child" or wholesale replacement transistors. Having said that if you are dead set on replacing every transistor on the "BEAST" here's the info from one of my threads. There's so many 1010 rebuilds with parts lists, you are well served to use the latest one. HOWEVER I would advise to have it vetted by MARK the Fixer or MATTSD before ordering. They have taken the time effort and loss of income researching these and the manufacturers change the game rules every once in a while by substitution of parts.

[q]Q4 2sb528 (bias circuit): to-202? bce 130v .8a 1/10w 55-300hfe 70mhz
512-KSA1381es x to-126 ecb 300v .1a 1.2/7w 150mhz 40-320hfe $0.27 ea
[/q]
 
Quote:
Originally Posted by craxx6969 View Post
I am recapping and replacing the transistors on a friend's SX-1010. I have all of the parts for the main boards, etc. I do not see any posts that have the equivalents for the output transistors on the large heatsinks. They are NEC 2SD287b and NEC B539b.

Also what can I use for Q4 on the AWH-032 board. Lots of discussions indicating do not replace.

Thanks to all of the AK'rs...


JT
Generally on the 1010 if it's not one of the problem child transistors, or if it's not functioning, leave them be. In special cases, shotgun replacement is warranted. Specifically the POWER SUPPLY due to the excessive heat buildup that was designed in to the 1010 for the P.S. It can't breathe, gets overheated and parts break down.

Q4 on the AWH-032 isn't one of the "problem child" or wholesale replacement transistors. Having said that if you are dead set on replacing every transistor on the "BEAST" here's the info from one of my threads. There's so many 1010 rebuilds with parts lists, you are well served to use the latest one. HOWEVER I would advise to have it vetted by MARK the Fixer or MATTSD before ordering. They have taken the time effort and loss of income researching these and the manufacturers change the game rules every once in a while by substitution of parts.

[q]Q4 2sb528 (bias circuit): to-202? bce 130v .8a 1/10w 55-300hfe 70mhz
512-KSA1381es x to-126 ecb 300v .1a 1.2/7w 150mhz 40-320hfe $0.27 ea
[/q]


Thanks, I checked it using the EW diode sticky and it appears to be okay. I had read in many of the 1010 threads that this was usually not a problem transistor. On this amp, the receiver part was okay, just the amp was causing the protection circuit to cut in and out. I tried to dial in the bias & dc offset but only one channel was able to come in line. The other was way out of spec.

I have read in previous posts about the power supply and how it gets hot/darkens the board on this model. Lucky for this one the board looks fairly decent. I will be recapping & replacing the transistors on this board with new mica and thermal grease from Mouser.

Thanks to tsd71 and larryderouin for helping out on this one! Great bunch of AKr's!

JT
 
Update:

I finished recapping the AWH-032 boards on this receiver. I have some odd voltages on one of the boards. According to the SM the reading on pin 13 should be a -0.6 volts (this is off of the emitter of Q10 a 2sa740). On mine it reads a +12.97volts so I checked the reading before R28 (4.7K 2W) and the voltage is the same on both boards. Hmm I don't think a resistor can change a + voltage to a - voltage. AND I cannot set the bias in this channel. My new varistor has no effect. The only transistor in this area is the bias transistor Q8 2sb528.
Any input to my "issue" would be appreciated. I followed mattsd's recap and trans list on both boards.

thanks,

JT
 
SX-1010 question on Power Amp Board AWH-032 C version

craxx6969 said:
Update:

I finished recapping the AWH-032 boards on this receiver. I have some odd voltages on one of the boards. According to the SM the reading on pin 13 should be a -0.6 volts (this is off of the emitter of Q10 a 2sa740). On mine it reads a +12.97volts so I checked the reading before R28 (4.7K 2W) and the voltage is the same on both boards. Hmm I don't think a resistor can change a + voltage to a - voltage. AND I cannot set the bias in this channel. My new varistor has no effect. The only transistor in this area is the bias transistor Q8 2sb528.
Any input to my "issue" would be appreciated. I followed mattsd's recap and trans list on both boards.

thanks,

JT
Click to expand...


Okay some initial measurements have been done.

On Q8:
E = -1.9volts
C = 54.8volts
B = -1.357volts and descending

These were taken while on a dbt.
 
SX-1010 AWH-032 Power supply board issue

Update on some of the readings off the power supply board:

All measurements taken on dbt:

Right Channel:
Diode D4 - A neg. = 38.99, C = neg. 25.56v
Diode D8 – A = neg. 38.7v, C = neg. 39.4
Diode D3 – A = 1.815v, C = 37.04 (falling)
Diode D2 – A = 53.0v, C = 53.7v (sb 56)

Left Channel:
Diode D4 – A = neg. 040.9, C = neg. 1.751v
Diode D8 – A neg. = 38.9, C = neg. 39.52
Diode D3 - A neg. = 1.263, C = 37.85(falling)
Diode D2 – A = 53.2v, C = 53.7v (sb56)


Power readings from Pins still on the dbt:
S/B = should be
Pin 4 = 54.4v, sb/ 56v
Pin 3, 7 = -54.3v, s/b -56v
Pin 8, 9 = 41.4v, s/b 55v
Pin 11, 12 = -41.7v s/b -55v
Pin 10 = -2.516v, s/b 0.6v
Pin 13 = 13.02v, s/b -0.6v

any ideas where to search. I also have readings from the various new transistors that were install. I have checked the pin outs on the new transistors with the .pdf's that are available for download (ECB, EBC, BEC, etc) and all are installed correctly in both right channel board and left channel board.

The only transistors not replaced are the 2SB528 and the 2SD358 which are Q4 and Q7 respectively.
 
check to make sure none of the small signal transistors have a "C" suffix. Check the Datasheet for a small print sentence that states "C" = CENTER Collector. I got caught on a KSA 733 Saturday on my SX-939, and 2-3 years ago on my 1010 onthe amp. can't remember which one it was now.
 
larryderouin said:
check to make sure none of the small signal transistors have a "C" suffix. Check the Datasheet for a small print sentence that states "C" = CENTER Collector. I got caught on a KSA 733 Saturday on my SX-939, and 2-3 years ago on my 1010 onthe amp. can't remember which one it was now.
Click to expand...

Thanks for the update on the ECB pin out issue Larry. I have double checked the connections on the board and they are in the correct position. I compared the right channel to the left and they mirror each other.

When I started this recap, the left channel was not working, the pre amp section works great (separated amp from pre amp to check both sections). The trace on one of the transistors on the left channel was broken which I repaired. The transistor leg was long enough to reach the resistor pin that the trace led to so I soldered the leg of the transistor to the pin on the resistor.

I am going to take some readings off of the transistors and post the results.
 
power supply still misbehaving?

i tried to get AWAY from the a733 and c945 because of the ebc/ecb dichotomy

look for lists that use ?ksa1013? /?ksc2383? they are larger cases for more power dissipation, with gain and current drive but less speed - but that doesn't matter much on the power supply

if it is squirrely - look for cracks in the foils especially around the heat sink mounts
verify connections from lead to lead so the solder joint and foils are in the ohmmeters current loop.
 
Sx-1010

markthefixer said:
power supply still misbehaving?

i tried to get AWAY from the a733 and c945 because of the ebc/ecb dichotomy

look for lists that use ?ksa1013? /?ksc2383? they are larger cases for more power dissipation, with gain and current drive but less speed - but that doesn't matter much on the power supply

if it is squirrely - look for cracks in the foils especially around the heat sink mounts
verify connections from lead to lead so the solder joint and foils are in the ohmmeters current loop.
Click to expand...

mtf,

Thanks for the info on the a733 and c945, yes they are a PITA for pin outs. I have another issue. I installed new transistors on the channel that had the low volume yesterday evening, new a733 and c945, and now have a short somewhere, WTH, so back to square one in figuring out which board took the hit. I have both 1013 and 2383 for equivalents so I'll have to do some transistor pulling in order to find out what failed or shorted out. Oh well it's like I have nothing better to do (sarcasm):scratch2:
 
craxx6969 said:
mtf,

Thanks for the info on the a733 and c945, yes they are a PITA for pin outs. I have another issue. I installed new transistors on the channel that had the low volume yesterday evening, new a733 and c945, and now have a short somewhere, WTH, so back to square one in figuring out which board took the hit. I have both 1013 and 2383 for equivalents so I'll have to do some transistor pulling in order to find out what failed or shorted out. Oh well it's like I have nothing better to do (sarcasm):scratch2:
Click to expand...


Update:

Pulled output transistors - they are all okay (checked using EW's method). Checked transistors on the power amp boards, one was open (940) so I had an extra. I checked the balance of the transistors on both boards and they all checked okay (pulled them from the boards to check). In the process of cleaning the outputs transistors, regrease and reinstall them. I was glad to use the DBT when I fired up the unit after I installed one of those 945's on the board. Saved my outputs.

I also noted on the equalizer board I didn't replace C1 and C2 (small blue caps) so I pulled them out and put in new ones as listed in the latest cap list.

More to follow when I get reassembled and started on the dbtester.

Joe
 
sx-1010 recap

markthefixer said:
please define what you mean by short? DBT stays bright?
Click to expand...
@NYC

yes the DNT stayed bright. Luckily no output transistors were damaged. Been busy at night with other issues and did not get a chance to respond. I have one channel reassembled and will work on the other channel tomorrow. Big storm hammered us today so I will have a chance to work on it.
 
SX-1010 Recap

craxx6969 said:
It should be @mtf, not @nyc. Some of the time the phone adds or changes the words.
Click to expand...

We have music!! :music:

Regreased the output trans, reassembled the unit, checked for shorts at the outputs (none thankfully), I had one lead to long on a replacement transistor that I believe was touching the board retainer. trimmed the lead, checked for other dumb mistakes, none found. Okay now for true test, fired up on the dbt, goes bright then dim!!! We have no short, okay so now to check bias and dc offset. Again on the dbt, brought to zero (very close on BOTH channels) and set the bias at 50mv. Reset to zero and powered off the unit. Unplugged from the dbt and straight into the wall socket. Again, unit starts, relay clicks after a few seconds, lights are good, checked both settings, rezeroed and then set the unit to 50mv on both channels. We have a working 1010!
I hooked up my cheapo $20 pawn shop speakers and hooked up the FM dipole. We have music and both channels work, sounds great even on cheapo speakers. So now we have another great sounding vintage amp brought back from the brink.

Both main caps were okay so they were not replaced. I do have the caps in case she comes back. Hope not as this was a bear to get at some of the parts. The customer will be happy!
 
craxx6969 said:
We have music!! :music:

Regreased the output trans, reassembled the unit, checked for shorts at the outputs (none thankfully), I had one lead to long on a replacement transistor that I believe was touching the board retainer. trimmed the lead, checked for other dumb mistakes, none found. Okay now for true test, fired up on the dbt, goes bright then dim!!! We have no short, okay so now to check bias and dc offset. Again on the dbt, brought to zero (very close on BOTH channels) and set the bias at 50mv. Reset to zero and powered off the unit. Unplugged from the dbt and straight into the wall socket. Again, unit starts, relay clicks after a few seconds, lights are good, checked both settings, rezeroed and then set the unit to 50mv on both channels. We have a working 1010!
I hooked up my cheapo $20 pawn shop speakers and hooked up the FM dipole. We have music and both channels work, sounds great even on cheapo speakers. So now we have another great sounding vintage amp brought back from the brink.

Both main caps were okay so they were not replaced. I do have the caps in case she comes back. Hope not as this was a bear to get at some of the parts. The customer will be happy!
Click to expand...


Some photos of the unit. It needs cleaning but that is left to the customer.. that is the outside of the unit.
 

Attachments

  • 2013-03-26_10-23-59_984.jpg
    2013-03-26_10-23-59_984.jpg
    68.7 KB · Views: 40
  • 2013-03-26_10-23-47_265.jpg
    2013-03-26_10-23-47_265.jpg
    68.3 KB · Views: 31
Last edited:
You must log in or register to reply here.
Back
Top Bottom