Hi Guys,
I'm in the process of fixing a broken rotel power amp was hoping for some advice.
Both D606 1n4148 and Q606 2SC2362K-FG are damaged and will need replacement.
I intend to replace the 2SC2362 with a KSC1845FTA
Do I need to replace any of the other transistors at the same time? Or can I just replace the two damaged parts.
If I do this for on channel, do I need to do it for both channels?
Is there anything else that I've overlooked? Is there biasing adjustments or any kind of other process that I need to do to fix this amp?
My amplifier and electronics understanding is basic.
Thank you for your help!
Service manual
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I'm in the process of fixing a broken rotel power amp was hoping for some advice.
Both D606 1n4148 and Q606 2SC2362K-FG are damaged and will need replacement.
I intend to replace the 2SC2362 with a KSC1845FTA
Do I need to replace any of the other transistors at the same time? Or can I just replace the two damaged parts.
If I do this for on channel, do I need to do it for both channels?
Is there anything else that I've overlooked? Is there biasing adjustments or any kind of other process that I need to do to fix this amp?
My amplifier and electronics understanding is basic.
Thank you for your help!
Service manual
\
Attachments
From the components you describe, I would say that was a man made fault. Slipped with a probe maybe.
Have you found out why only one diode and the transistor failed? There is a 47k resistor feeding the base and the diode and a pair of transistors loading at low current, so it won't have died naturally!
Change all three transistors and both diodes. There will be no re-biasing to do.
I would use original type transistors.
Have you found out why only one diode and the transistor failed? There is a 47k resistor feeding the base and the diode and a pair of transistors loading at low current, so it won't have died naturally!
Change all three transistors and both diodes. There will be no re-biasing to do.
I would use original type transistors.
having difficulty reading the sch.
Are D606 and Q606 the CCS that feeds the input LTP?
If so then shorting the 47k would probably have damaged both the upper and lower CCS. replace the four diodes and the two transistors.
Then check whether the two LTPs are still performing and are quiet.
Sometimes the noise performance is the early sign of damage.
Are D606 and Q606 the CCS that feeds the input LTP?
If so then shorting the 47k would probably have damaged both the upper and lower CCS. replace the four diodes and the two transistors.
Then check whether the two LTPs are still performing and are quiet.
Sometimes the noise performance is the early sign of damage.
Yes, Q602/604. That is why I suggested replacing all three transistors along with the two diodes.
the four diodes are in a string across the supply rails. If one is damaged, then maybe all four are damaged.
So far I replaced all the diodes and the amp is working again.
The clipping light and protection light that were showing are now gone.
I will do a listening test and compare channels. If there's a noticeable difference I will go ahead and change all the transistors.
If so do I change both channels? I don't think I can find original parts and was going to use KSC1845FTA as a substitute.
Better schematic attached...
The clipping light and protection light that were showing are now gone.
I will do a listening test and compare channels. If there's a noticeable difference I will go ahead and change all the transistors.
If so do I change both channels? I don't think I can find original parts and was going to use KSC1845FTA as a substitute.
Better schematic attached...
Attachments
just change the channel that measured as damaged.
One channel has upper and lower halves. You may need to change both halves of that one damaged channel.
On that sch if you need to replace Q606 and Q612, do that and measure again before doing any of the LTP (Qs 602, 604, 608, 610).
Measure the output Offset and the output Noise+Hum with both the inputs shorted. Use the 20.00Vac and Vdc scales first, then move down to 2.000Vac & Vdc, before using the 200.0mVac & mVdc scales.
Do the two channels measure the same?
That will give a good clue to whether there is any further damage.
One channel has upper and lower halves. You may need to change both halves of that one damaged channel.
On that sch if you need to replace Q606 and Q612, do that and measure again before doing any of the LTP (Qs 602, 604, 608, 610).
Measure the output Offset and the output Noise+Hum with both the inputs shorted. Use the 20.00Vac and Vdc scales first, then move down to 2.000Vac & Vdc, before using the 200.0mVac & mVdc scales.
Do the two channels measure the same?
That will give a good clue to whether there is any further damage.
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