Hey all
I’m doing a repair of a Juno-60, in which the resonance part of the filter on one of the voices is not working. The repair is bordering on what my capabilities amount to (I’m a bit of a newbie), but I think I may have found what’s causing the problem, but would like to hear your opinion on my conclusion before I continue.
I’ve been measuring the components in the filter circuit, on both the malfunctioning voice and the functioning voices to compare. What I’ve found is that a transistor (TR1 – i will attach a schematic of the filter) in the first part of the filter on the faulty voice, behaves strangely.
When I measure the functioning voices, I get Ve ≈ 0.6V, Vc ≈ -15V og Vb ≈ 0.2V (measured to ground).
When I measure the faulty voice, however, I get that Vc and Ve ≈ 0.6V and the junction seems to be shorted, according to my meter.
From this I conclude that the transistor must have burned out. It’s a 2SA1015, so I’m thinking I could replace it with something like this http://www.mouser.dk/ProductDetail/Fairchild-Semiconductor/KSA1015GRTA/?qs=%2fha2pyFaduiRU154msXApaj9mdvB9oNiGUYnp86d4b0%3d
Could you guys give me your opinion on wether my conclusion about the transistor being dead is plausible, or should I do some more testing before continuing? As I said, I'm just starting to do my own repairs, so I'm not too confident yet.
Cheers,
Mikkel
I’m doing a repair of a Juno-60, in which the resonance part of the filter on one of the voices is not working. The repair is bordering on what my capabilities amount to (I’m a bit of a newbie), but I think I may have found what’s causing the problem, but would like to hear your opinion on my conclusion before I continue.
I’ve been measuring the components in the filter circuit, on both the malfunctioning voice and the functioning voices to compare. What I’ve found is that a transistor (TR1 – i will attach a schematic of the filter) in the first part of the filter on the faulty voice, behaves strangely.
When I measure the functioning voices, I get Ve ≈ 0.6V, Vc ≈ -15V og Vb ≈ 0.2V (measured to ground).
When I measure the faulty voice, however, I get that Vc and Ve ≈ 0.6V and the junction seems to be shorted, according to my meter.
From this I conclude that the transistor must have burned out. It’s a 2SA1015, so I’m thinking I could replace it with something like this http://www.mouser.dk/ProductDetail/Fairchild-Semiconductor/KSA1015GRTA/?qs=%2fha2pyFaduiRU154msXApaj9mdvB9oNiGUYnp86d4b0%3d
Could you guys give me your opinion on wether my conclusion about the transistor being dead is plausible, or should I do some more testing before continuing? As I said, I'm just starting to do my own repairs, so I'm not too confident yet.
Cheers,
Mikkel
