Try pressing the yellow button on the upper left while in diode/continuity mode.
Anonky
Kenwood KR-9600 / Pioneer SX-950 / Sony STR-GX10ES
That just holds the reading. I actually whipped out the manual and that reading is in mV so 0.8V. Is that ok?
Maybe it is for that meter. All the ones I've used are in the neighborhood of .5-.6 volts.
On my Fluke you use the yellow button to change from continuity mode to diode test mode. Couldn't see the label on the left hand button in the pic.
Anonky
Kenwood KR-9600 / Pioneer SX-950 / Sony STR-GX10ES
For what it’s worth I used another meter and got .73 V. Let’s assume it’s ok for now. I’m going to pull those other transistors you initially mentioned and test them too. So I’ll have checked TR609,611, 613 and 615. Will update shortly.
cademan
Lunatic Member
If your meter has a separate diode test mode, use it. None of my meters has diode test so I use the ohms setting. They have never let me down.
Either way, if you know what the readings mean, you will know if the transistor is shorted or not even when compared to a good one.
EDIT: Here's the deal. 9 times out of 10, you have one maybe two blown transistors in one channel only. It is rare to have a shorted or bad transistor in both channels.
Find which channel is the good channel and usually both transistors in the good channel will read the same.
One in the bad channel will read the same as the one's in the good channel while the other one will read completely different than the other 3.
Got any pics? Are we talking 4 output transistors altogether?
Either way, if you know what the readings mean, you will know if the transistor is shorted or not even when compared to a good one.
EDIT: Here's the deal. 9 times out of 10, you have one maybe two blown transistors in one channel only. It is rare to have a shorted or bad transistor in both channels.
Find which channel is the good channel and usually both transistors in the good channel will read the same.
One in the bad channel will read the same as the one's in the good channel while the other one will read completely different than the other 3.
Got any pics? Are we talking 4 output transistors altogether?
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Anonky
Kenwood KR-9600 / Pioneer SX-950 / Sony STR-GX10ES
OK readings are below for the four transistors TR/Q609, 611, 613 and 614.. I’ve put each reading based on the diode measuring guidance. Positive lead was probed to the first letter (B-base, E-emitter, or C-collector) while the second letter was probed with the negative lead.
TR609:
BE: 0.8v
BC: 0.8v
EB: - (no reading)
CB: -
CE: -
TR611 (this is PNP so I had to flip everything as I understand)
EB: -
CB: -
BE: -
BC: -
EC: 0.003v (continuity indicator was sounding?)
TR613:
BE: 0.23v
BC: 0.23v
EB: 0.23v
CB: 0.23v
CE: 000v (no volts but continuity indicator was sounding)
TR615:
BE: 0.18v
BC: 0.18v
EB: 0.7v
CB: 0.7v
CE: 000v (no volts but continuity indicator was sounding)
Based on the guidance in the post about measuring diodes/transistors, my untrained eye tells me TR611 is bad, and likely 613 and 615 as well. Is this correct? Thoughts? Next steps?
Correct. It's a good idea to print out the section of the schematic you're working on, and mark what you find wrong. This can help trace the path of destruction:
Check R633 too.
Attachments
Anonky
Kenwood KR-9600 / Pioneer SX-950 / Sony STR-GX10ES
R633 5.8 ohm so about spot on. Are those transistors as far upstream as the problem likely goes? I can place an order for replacements whenever we are to that point
Maybe. Check further back. For instance, TR611 was bad; check TR605, which is directly connected to TR611. And should TR605 test bad, test R629. TR607 is connected to both TR609 and TR611, and both of those are bad, so check it too.
The key here is to test until everything else in the area tests good. That will delineate the damaged area..
cademan
Lunatic Member
Honestly, I would forget about testing the collector and just test them like diodes between base and emitter whether using diode mode or ohms. I can tell when one is blown by just testing between these two points.
Now I'm dying to know how the OP took the pic in post # 20...
Anonky
Kenwood KR-9600 / Pioneer SX-950 / Sony STR-GX10ES
Ok ok my secret is I had my old girl come and snap the pic lol somehow she hasn’t tossed me to the curb yet. Going to test those additional components after while here. Will update later tonight!
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Anonky
Kenwood KR-9600 / Pioneer SX-950 / Sony STR-GX10ES
TR607 is bad (getting continuity in both directions from collector to emitter and 000v), TR605 is good. To be safe, I also checked R629 and it was good as well.
OK, that's probably the extent of the damage. The resistors before those components are high enough in resistance to limit current from damaging anything further back toward the front end of the amp.
After replacing these parts bring it up on the dim bulb first.
Anonky
Kenwood KR-9600 / Pioneer SX-950 / Sony STR-GX10ES
Can you double check that these are suitable replacements? Also, having difficult finding one for the last transistors.
2sc828–>KSC1845
2sc2003–>KSC2316
2SA954–>KSA1220
2SD586–> ???
2SD586 is the output transistor right? I'd suggest changing both it and it's companion with a complimentary set. Using two different transistors is probably going to behave poorly. Not sure what the preferred sub is these days, last few times I needed TO-3 transistors I used an MJE15003/MJE15004 pair.
Gadget73 is spot on, and I should have mentioned this: whenever you have a bad output transistor you need to changed them all on that channel.
Anonky
Kenwood KR-9600 / Pioneer SX-950 / Sony STR-GX10ES
So to be clear what all exactly should I replace?