Hi all,
So a Citation 16 just came to me with one channel not working. The seller has provided me 6 transistors, the Motorola MJ13333. I just looked at the service manual and it states using the original RCA1B04 or 05, the MJ15024 is a modern replacement equivalent. Is the MJ13333 ok or no go? I believe there are some already on the bad channel side and I think a few on the good channel.
Any insights?
So a Citation 16 just came to me with one channel not working. The seller has provided me 6 transistors, the Motorola MJ13333. I just looked at the service manual and it states using the original RCA1B04 or 05, the MJ15024 is a modern replacement equivalent. Is the MJ13333 ok or no go? I believe there are some already on the bad channel side and I think a few on the good channel.
Any insights?
Ok thanks for that. So I can use the MJ13333 still or do I have to make the transition over to the 15024. There is about 8 transistors per side (2 on each side are different). Channel A is working fine (with the light indicator on front emit) but channel B is a no go. Need to pop off the panels and see what's wrong.
Also is the case of the 024 to be isolated from the heatsink or ? There are Aavid Thermalloy plastic isolation covers for all the transistors. One seems to be broken off on the bad channel.
Also is the case of the 024 to be isolated from the heatsink or ? There are Aavid Thermalloy plastic isolation covers for all the transistors. One seems to be broken off on the bad channel.
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Yeah well just popped off all the transistor isolator covers. 3 RCA 2928A transistors on channel B (faulty channel) rest are all MJ13333's and all 10 transistors on channel A are Mospec MJ13333's. Channel B light indicator does not come on. Popping off the bottom cover reveals the slowblo 2A fuse for Channel B blown. Swapped fuse for new one and it blew again. So something is wrong on Channel B.
Can't be transistors overdrawing current because I just replaced all the MosSpec and RCA's with new Motorola MJ13333's the seller provided me with. I looked inside the driver board to the heatsink and nothing looks burnt or damaged.
On the bottom though there is 2 universal jumper switches connected to some fresh looking 1N4007 diodes on a tag strip (both channels) routed back to a bunch of wires near the power trafo. Both universal jumper switches are set to 240VAC.
Had a look at the service manual supposedly Q11-12 are NPN driver transistors (doesn't indicate model) and the other 8 are RCA1B04's (substitutable for MJ15024's). Can Q11-12 have 15024's used in its place as well, seeing it's just a higher rated NPN for what Q11-12 driver transistors are.
Any other ideas as to what might be blowing the fuse for channel B?
Any other ideas
Can't be transistors overdrawing current because I just replaced all the MosSpec and RCA's with new Motorola MJ13333's the seller provided me with. I looked inside the driver board to the heatsink and nothing looks burnt or damaged.
On the bottom though there is 2 universal jumper switches connected to some fresh looking 1N4007 diodes on a tag strip (both channels) routed back to a bunch of wires near the power trafo. Both universal jumper switches are set to 240VAC.
Had a look at the service manual supposedly Q11-12 are NPN driver transistors (doesn't indicate model) and the other 8 are RCA1B04's (substitutable for MJ15024's). Can Q11-12 have 15024's used in its place as well, seeing it's just a higher rated NPN for what Q11-12 driver transistors are.
Any other ideas as to what might be blowing the fuse for channel B?
Any other ideas
Some pics (no the thermal paste mess is not from me).
Channel A:
Channel B (faulty):
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Channel A:
An externally hosted image should be here but it was not working when we last tested it.
Channel B (faulty):
An externally hosted image should be here but it was not working when we last tested it.
"The MJ13333 is a superb switching transistor. Some 20Amps at 450Volts."
High voltage switching transistors have no SOA for linear use, and so cannot be used for audio.
I have a box of 600 pieces of 2N6277's that originally cost $44 each (180V, 50A, 30Mhz), worthless for audio.
2N6277 pdf, 2N6277 description, 2N6277 datasheets, 2N6277 view ::: ALLDATASHEET :::
Note the whopping 15W SOA at 100V.
High voltage switching transistors have no SOA for linear use, and so cannot be used for audio.
I have a box of 600 pieces of 2N6277's that originally cost $44 each (180V, 50A, 30Mhz), worthless for audio.
2N6277 pdf, 2N6277 description, 2N6277 datasheets, 2N6277 view ::: ALLDATASHEET :::
Note the whopping 15W SOA at 100V.
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