TOA BG-130 Amplifier power supply fuse blown

[fuxxy]

Re: TOA BG-130 Amplifier power supply fuse blown

So I checked the main power transistors (attached to the heatsink) using the "Diode" function on my DMM.
The results are a little confusing.

The first two D2059 transistors have similar results.

Pins 1 & 2 = .538
Pins 1 & 3 = .541

Pins 1 & 2 = .540
Pins 1 & 3 = .542

I get no other readings ("OL") using any other polarity or pins

The second two B1367 transistors are wildly different from each other

B1367 #1
Pins 1 & 2 = .523
Pins 1 & 3 = .525
No other readings using opposite polarity, like the D2059's.

B1367 #2
Pins 1 & 2 = .027 (Both polarities - odd!)
Pins 1 & 3 = .463
Pins 2 & 3 = .459 (Didnt get this read on the other B1367!)

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D110 is a "15b2" silkscreened label
Reads "OL" one polarity, 0.650v the other way

D109 is a "15b2" silkscreened label
Reads "OL" one polarity, 0.642v the other way

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R179 i can't identify. I've included a pic so you guys maybe can read what exact colors those might be
It reads 0.664 kOhm with my multimeter.

[Andrew F. Ali]

Re: TOA BG-130 Amplifier power supply fuse blown

Looking like a 1K resistor and something is wrong with that 2nd 2SB 1367 PNP Transistor. These reading were taken in or out of circuit??

[R_J]

Re: TOA BG-130 Amplifier power supply fuse blown

the diodes would be 15 volt zeners, they seem to be in series, so thats around 30 volts, Not sure what the voltage is on the main filter but i would guess aroud 40-50 volts, I suspect the resistor is ok, it is discolored but my guess is 680 ohm
I would remove that #2 2sb1367 and check it out of circuit, I suspect its bad,
It looks like the 2 npn outputs are driven by one driver, through its own base resistor and the 2 pnp's are driven a similar way
I bet the BG-115 only has on each npn & pnp and this being the 30 watt version uses 2 transistors in parallel, I know what I would do to check the amp
I suspect you found the problem, those readings are enough to cause the amp to draw too much current but not being a dead short did not blow the 3 amp dc fuse, thats my guess,

[fuxxy]

Re: TOA BG-130 Amplifier power supply fuse blown

All those components were tested out of circuit.

Output of the primary transformer is right at 40v

Would I be able to run this amp with one complementary pair of transistors, and the other set removed?

If I can't find a source for the KEC B1367, can I replace it individually with the NTE equivalent - or would I need to replace both in the pair?

EDIT:
I'm showing the NTE replacement for the D2059 is NTE54, and the B1367 is NTE55 - Do you guys agree?

[R_J]

Re: TOA BG-130 Amplifier power supply fuse blown

I'm sure you can run it without the one set of transistors, would be the 15 watt version. The problem with the nte is you need mounting hardware to insulate the tab (collector) I would find an alternative that had the isolated case
UTsource has the ktb1367-y for $1.51 each, and ktd2059 for $1.67
there are eb sellers that have them also, one even has 2 of each for $16.95

[petehall347]

Re: TOA BG-130 Amplifier power supply fuse blown

mje are a good replacement .. bd for drivers . eg bd139 140 ..mje15003 15004 ... top of my head thinking there so check the specs before proceeding .... these should be in stock from reputable dealers ... sack nte ..

[fuxxy]

Re: TOA BG-130 Amplifier power supply fuse blown

FIXED!
Thanks guys!

Since I was fixing this for free, I just wanted to get it over with.
I purchased a single complimentary pair of transistors from Fry's (NTE54 & NTE55), and installed them, replacing both in the pair of the side that went bad.

Reinstalled the zeners, and the resistor, and it powers on and works now!

[madan1]

Re: TOA BG-130 Amplifier power supply fuse blown

did you check the emitter resistors? usually they fail with the transistors.

[Andrew F. Ali]

Re: TOA BG-130 Amplifier power supply fuse blown

Good job!!!