69sixpackbee
Well-Known Member
Board has been out. Hooked up my Hakko 808 and I will report back.
Thanx!
Bw
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Thanx!
Bw
Sent from my iPhone using Tapatalk
Starting To Dive Into an SX-1250
- Thread starter 69sixpackbee
- Start date
69sixpackbee
Well-Known Member
Okay. Nothing conclusive. I pulled EVERY transistor and checked them. No shorts. I lifted EVERY resistor. All are within spec. Again, I did this to all diodes as well as the STV-3H's. Again, all is well. The e-lytics are all new as is Q1 & Q2 and both pots. No cold solder joints. Header pins clean and tight. No broken traces.
What should I try next?
Thanx
Bud
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What should I try next?
Thanx
Bud
Sent from my iPhone using Tapatalk
transistor shorts aren't the only possible defect, I NEEDED that transistor data. 6 lines per transistor, cut and paste the pnp or npn from post 11's examples as indicated, and edit your results onto the end of each line. I REALLY hope you wrote them down as each was done, that's the only way to methodically sort them out.
the transistor testing is new to you, correct? something could have gotten by you. plus with all the components testing good, and the outputs are ok, we are running out of things to go wrong. I don't want to end up chasing my tail on a cockpit error.
edit:
q1 and q2? what are they and did you do them.
plus I gotta be sure you know your transistor basics and symbol - success on the power supply is a possible indicator, but i need some sort of reassurance.
Last edited:
69sixpackbee
Well-Known Member
I will get you the readings. I referenced them from B to C, B to E, C to E and in reverse order as well. Also with reference to PNP as well as NPN and their location within the circuit.
Edit: Q1&Q2 were on the BOM of recommend replacement parts.
They were HFE matched prior to my installing them.
Transistor testing is old school for me as is the basics of electronics and I am pretty comfortable with troubleshooting and schematic diagrams are no problem. I am not a noob but I am fairly new to the vintage stereo scene as far as repair and function. I have some good quality test equipment inclusive of a Tektronics scope, Sencore SG-165, Fluke counter and a Thurlby signal generator. I am set up pretty well so I am just dangerous enough to cause major damage!
Thanx for taking the time to help me, Mark!
Bud
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Edit: Q1&Q2 were on the BOM of recommend replacement parts.
They were HFE matched prior to my installing them.
Transistor testing is old school for me as is the basics of electronics and I am pretty comfortable with troubleshooting and schematic diagrams are no problem. I am not a noob but I am fairly new to the vintage stereo scene as far as repair and function. I have some good quality test equipment inclusive of a Tektronics scope, Sencore SG-165, Fluke counter and a Thurlby signal generator. I am set up pretty well so I am just dangerous enough to cause major damage!
Thanx for taking the time to help me, Mark!
Bud
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I feel better. and worse, because the solution recedes from grasp.
Ok, I trust you enough to set up something technical for different readings.
We need the feedback path in place. Plus the power for the drivers and pre-drivers comes in through the transistor connectors and back on the heat sink the collectors are perpetually energized, the emitters are tied together through one ohm (and we NEED the feedback connection), and all we need is the wrong base current to happen.
There is a bit of a way around it, only pins 12 and 15 on the inner ends of the connectors (the pin with the larger gap from the other three) should be connected, the connector should be angled so only that pin (in each) gets power, the emitters will be isolated and the bases will be isolated, so no current should flow. The emitter resistors back on the board will be free floating so they will not interfere with the feedback system.
At this point, it will be hard to get readings, I attach wires to my measuring points, LONG wires, and take them out to a piece of cardboard, drawn with a schematic and the test points coming through at the corresponding schematic point. Makes it easier to understand, with a bit of preparation.
the points are pins 2 and 3 regulated +/- 65 volts ground referenced
pins 12 and 15 +/- 70 volts ground referenced
q5 q6 emitter, (pin 2 +65v regulated reference)
q6 collector q4 collector ground referenced
q7 q8 emitters ground referenced
q9 q10 emitters ground referenced
some of the voltages will be referenced to ground, some will be referenced to pin 3 +65v regulated.
Ok, I trust you enough to set up something technical for different readings.
We need the feedback path in place. Plus the power for the drivers and pre-drivers comes in through the transistor connectors and back on the heat sink the collectors are perpetually energized, the emitters are tied together through one ohm (and we NEED the feedback connection), and all we need is the wrong base current to happen.
There is a bit of a way around it, only pins 12 and 15 on the inner ends of the connectors (the pin with the larger gap from the other three) should be connected, the connector should be angled so only that pin (in each) gets power, the emitters will be isolated and the bases will be isolated, so no current should flow. The emitter resistors back on the board will be free floating so they will not interfere with the feedback system.
At this point, it will be hard to get readings, I attach wires to my measuring points, LONG wires, and take them out to a piece of cardboard, drawn with a schematic and the test points coming through at the corresponding schematic point. Makes it easier to understand, with a bit of preparation.
the points are pins 2 and 3 regulated +/- 65 volts ground referenced
pins 12 and 15 +/- 70 volts ground referenced
q5 q6 emitter, (pin 2 +65v regulated reference)
q6 collector q4 collector ground referenced
q7 q8 emitters ground referenced
q9 q10 emitters ground referenced
some of the voltages will be referenced to ground, some will be referenced to pin 3 +65v regulated.
69sixpackbee
Well-Known Member
I had a slight setback today. Right as i was leaving my workbench I accidently dropped the friggin thing onto the floor and it hit hard enough to yank the guts out of C15 rendering it useless. I am really pissed !!
Okay, before we get much further, here are the readings from the transistors pulled and recorded.
**ALL readings are read with reference to the base taken with a Fluke 87 DMM**
Q1 PNP-- black lead on base:
B-C .674V
B-E .682V
E-C. 0V
Leads reversed all "0"
Q2 PNP --black lead on base:
B-C .673V
B-E .683V
E-C. 0V
Leads reversed all "0"
Q3 NPN. --red lead on base:
B-C .681V
B-E .691V
E-C. 0V
Leads reversed all "0"
Q4 NPN --red lead on base:
B-C .684V
B-E .693V
E-C. 0V
Leads reversed all "0"
Q5. PNP-- black lead on base:
B-C .630V
B-E .662V
E-C. 0V
Leads reversed all "0"
Q6. PNP-- black lead on base:
B-C .623V
B-E .650V
E-C. 0V
Leads reversed all "0"
Q7 NPN ---red lead on base:
B-C .672V
B-E .680V
E-C. 0V
Leads reversed all "0"
Q8. PNP-- black lead on base:
B-C .653V
B-E .677V
E-C. 0V
Leads reversed all "0"
Q9 NPN-- red lead on base:
B-C .573V
B-E .576V
E-C. 0V
Leads reversed all "0"
Q10 PNP-- black lead on base:
B-C .564V
B-E .572V
E-C. 0V
Leads reversed all "0"
Q11. NPN. red lead on base:
B-C .668V
B-E .684V
E-C. 0V
Leads reversed all "0"
Now I have to scrounge up a couple of caps.
Sent from my iPhone using Tapatalk
Okay, before we get much further, here are the readings from the transistors pulled and recorded.
**ALL readings are read with reference to the base taken with a Fluke 87 DMM**
Q1 PNP-- black lead on base:
B-C .674V
B-E .682V
E-C. 0V
Leads reversed all "0"
Q2 PNP --black lead on base:
B-C .673V
B-E .683V
E-C. 0V
Leads reversed all "0"
Q3 NPN. --red lead on base:
B-C .681V
B-E .691V
E-C. 0V
Leads reversed all "0"
Q4 NPN --red lead on base:
B-C .684V
B-E .693V
E-C. 0V
Leads reversed all "0"
Q5. PNP-- black lead on base:
B-C .630V
B-E .662V
E-C. 0V
Leads reversed all "0"
Q6. PNP-- black lead on base:
B-C .623V
B-E .650V
E-C. 0V
Leads reversed all "0"
Q7 NPN ---red lead on base:
B-C .672V
B-E .680V
E-C. 0V
Leads reversed all "0"
Q8. PNP-- black lead on base:
B-C .653V
B-E .677V
E-C. 0V
Leads reversed all "0"
Q9 NPN-- red lead on base:
B-C .573V
B-E .576V
E-C. 0V
Leads reversed all "0"
Q10 PNP-- black lead on base:
B-C .564V
B-E .572V
E-C. 0V
Leads reversed all "0"
Q11. NPN. red lead on base:
B-C .668V
B-E .684V
E-C. 0V
Leads reversed all "0"
Now I have to scrounge up a couple of caps.
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69sixpackbee
Well-Known Member
Well, I have the new replacement caps coming due to my own stupidity. 
As soon as I get them in my hot little hands we'll get back to my dilemma..
Thanx for bearing with me:thmbsp:
As soon as I get them in my hot little hands we'll get back to my dilemma..
Thanx for bearing with me:thmbsp:
69sixpackbee
Well-Known Member
No prob.
1969 1/2 Dodge Super Bee A-12. Factory 440 six-pack. Dana "60" rear w/4.10 gears. About all that is "stock" is the sheet metal. I have extensively modified the mill. 10.85:1 CR (to run on pump crap) 440source "stealth" aluminum heads thoroughly CNC ported. 1.6 roller-tip rockers. A homologation of my own "el Cheapo" Chinese "CAT" units which are actually pretty strong. I junked out the roller bearings (you DON'T need these on hardened common shafts) and machined my own bearing inserts from SAE-660 bronze and with "banana grooving" the oil passages. Forged TRW slugs with Chevy ".990" rods. Forged crank and all reciprocating mass balanced within .001gm. Still using the old school Mopar .509 "Purple Shaft" hydraulic cam and Crane anti-pump up lifters so I can run this on the street. Otherwise I swap in a Racer Brown .610" cam for the track. I have enough valve relief in the piston tops to acomodate this and still get a .028" quench and 77cc's of chamber volume. The carbs have been treated to some extensive rework and jetting/passage way mods. One could look at this engine and swear it is all OEM....until I hit the starter.
You can check out a Youtube vid here;
http://youtu.be/fJoxZAaHiI0
The 727 T'flite is fully modified and race prepped & with a 10" Munsinger converter. The subframe is fully boxed. I run a 6061 T-6 aluminum shaft. The rear is hung with super stock springs (same as OEM with the offset leaves L - R) and the pumpkin is snubbed up to the floor.
I even fitted the interior with some new components from Legendary Interiors (seat covers and carpeting) although, for the most part, it is all original.
There is a lot more but this is the jist of it. I bought this car in '84. I did ALL of the work to it myself, paint, body, trans, heads, carbs, frame mods, any welding, etc..etc, with the exception of the engine block machine work (boring, honing, etc). It has been a "work in progress" but for the most part it took about seven years to complete.
I could take up a lot more time but this is, afterall, a Pioneer thread
Enjoy....
Bud
1969 1/2 Dodge Super Bee A-12. Factory 440 six-pack. Dana "60" rear w/4.10 gears. About all that is "stock" is the sheet metal. I have extensively modified the mill. 10.85:1 CR (to run on pump crap) 440source "stealth" aluminum heads thoroughly CNC ported. 1.6 roller-tip rockers. A homologation of my own "el Cheapo" Chinese "CAT" units which are actually pretty strong. I junked out the roller bearings (you DON'T need these on hardened common shafts) and machined my own bearing inserts from SAE-660 bronze and with "banana grooving" the oil passages. Forged TRW slugs with Chevy ".990" rods. Forged crank and all reciprocating mass balanced within .001gm. Still using the old school Mopar .509 "Purple Shaft" hydraulic cam and Crane anti-pump up lifters so I can run this on the street. Otherwise I swap in a Racer Brown .610" cam for the track. I have enough valve relief in the piston tops to acomodate this and still get a .028" quench and 77cc's of chamber volume. The carbs have been treated to some extensive rework and jetting/passage way mods. One could look at this engine and swear it is all OEM....until I hit the starter.
You can check out a Youtube vid here;
http://youtu.be/fJoxZAaHiI0
The 727 T'flite is fully modified and race prepped & with a 10" Munsinger converter. The subframe is fully boxed. I run a 6061 T-6 aluminum shaft. The rear is hung with super stock springs (same as OEM with the offset leaves L - R) and the pumpkin is snubbed up to the floor.
I even fitted the interior with some new components from Legendary Interiors (seat covers and carpeting) although, for the most part, it is all original.
There is a lot more but this is the jist of it. I bought this car in '84. I did ALL of the work to it myself, paint, body, trans, heads, carbs, frame mods, any welding, etc..etc, with the exception of the engine block machine work (boring, honing, etc). It has been a "work in progress" but for the most part it took about seven years to complete.
I could take up a lot more time but this is, afterall, a Pioneer thread
Enjoy....
Bud
69sixpackbee
Well-Known Member
Well, I have not got the caps to put back in the RH power amp board yet but I am pretty sure I know what the problem is.
I looked at the schematics and all I can say is, I hope the outputs are robust. It seems that in my haste when reassembling the heat sinks it looks as if I transposed the transistors. I really feel like a dumb ass. What a rookie mistake.
This is how I have it.,,
...,and this is how it's supposed to be
Now I REALLY feel like a putz
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I looked at the schematics and all I can say is, I hope the outputs are robust. It seems that in my haste when reassembling the heat sinks it looks as if I transposed the transistors. I really feel like a dumb ass. What a rookie mistake.
This is how I have it.,,
...,and this is how it's supposed to be
Now I REALLY feel like a putz
Sent from my iPhone using Tapatalk
Attachments
be very careful from side to side, I'm not sure if they are mirror images.
The ULTIMATE indicator of polarity is WHERE the collector/case is connected to, the big positive voltage cap's plus or the big negative voltage cap's minus.
plus goes to the collector of the NPN transistor
minus goes to the collector of the PNP transistor.
The ULTIMATE indicator of polarity is WHERE the collector/case is connected to, the big positive voltage cap's plus or the big negative voltage cap's minus.
plus goes to the collector of the NPN transistor
minus goes to the collector of the PNP transistor.
Last edited:
69sixpackbee
Well-Known Member
Nope. They were in bass-ackwards. I too "ASS"umed that the heat sink assemblies were mirror images but in reality they have the same configuration going from the front to back. That is where I made my mistake. I checked the schematics and followed the pinout s from the power amp boards and I definitely had the PNP's where the NPN's needed to go and vice-versa. I rang them out on the DMM and they still check out good.
Maybe I got lucky.
Note to self: check the pictures I took of the unit BEFORE I reassemble it!!
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Maybe I got lucky.
Note to self: check the pictures I took of the unit BEFORE I reassemble it!!
Sent from my iPhone using Tapatalk
69sixpackbee
Well-Known Member
It's alive!!!
Got it dialed in. Voltages are rock solid and stations are spot on.
Now time to sit back and enjoy it
Thanx again for all of the help!!
Bud Weaver
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Got it dialed in. Voltages are rock solid and stations are spot on.
Now time to sit back and enjoy it
Thanx again for all of the help!!
Bud Weaver
Sent from my iPhone using Tapatalk