The drive circuit is probably OK.
In the future when you post asking for help, include the make/model number of the amp and include good quality photos (in focus, no flare from the flash...) for the area in question. It's also better if you clean the board with acetone and a toothbrush before taking the photos.
In the future when you post asking for help, include the make/model number of the amp and include good quality photos (in focus, no flare from the flash...) for the area in question. It's also better if you clean the board with acetone and a toothbrush before taking the photos.
Yes sorry I just had light issues this morning. I did give the board a bit of a clean but ran out of alcahol but thank you very much for you're help and appreciate you're patience with me also learning to use the scope . I kind of came to the conclusion the driver was ok because the waves were consistent across the board fets in vs fets out. Frequency and volatge was all spot on. Nothing looked burned and the buffers were not shorted or blown. I just wanted to make 100% sure before fitting new mosfets and also learn a bit along the way... So can u use this cap trick in the output ? (For future refrence?)
This configuration is odd. Most amps that have this many transformers have a set of drivers for each bank of FETs. For those, you have to test every bank with a load. You cannot rely on what you have on other banks.
You can use a loading cap in the output section as well.
You mentioned a value of 265 ohms. That's not a common value. They are likely 270 ohms unless they have 5 color bands.
You can use a loading cap in the output section as well.
You mentioned a value of 265 ohms. That's not a common value. They are likely 270 ohms unless they have 5 color bands.
I don't understand why you're stuck on having a 6 in the value. The other resistors are clearly violet.
Just an app I have in my phone if I put those colours in comes up as 260ohm. Nevermind I have trusted you're opinion and ordered 270ohm as some were measuring 267ohm. I don't understand colors. If I need 200ohm resistors I just order them never bother looking at the colours. The app on my phone may be incorrect
I still don't understand why you entered blue when there weren't any blue bands on the other gate resistors.
Oh I get you now. Yes I must have confused blue with volet so yes 270 ohm is correct. That's what I ordered. None of my local shops stock the 1/4w only the 1/2w yes I know they would have worked but as I'm only replacing the gate resistors on the blown banks I wanted it to all look matching . The owner wants to keep the repair semi cheap as he is only selling it so no point taking the time to replace all gate resistors. Only going to replace the bad fets which will be fine using different batch as they are all parallel . And also that bad exploded cap made me think change them all from the blown banks even though the rest look ok
I have no way to test caps my meter will only test tiny ones so just swap them out .
I have no way to test caps my meter will only test tiny ones so just swap them out .
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Are you referring to anything in the output section? If not, you're mixing terms used for the output section.
What I ment was even though there are only 2 NPN and 2 PNP buffers I think it's ok to use different batches as it's not going to directly interfear with each other just as long as u don't have 2 different batches in the same bank of that makes any sence
There are 4 FETs in two banks per transformer. The FETs in each bank need to have the same date code. The banks don't have to have matching date codes.
I don't understand what you mean about the drivers (buffers).
The gate resistors appear to be 1/8w. Measure them with a dial caliper.
I don't understand what you mean about the drivers (buffers).
The gate resistors appear to be 1/8w. Measure them with a dial caliper.
Yes so 4 blew out on 1 transformer and 4 off the other. So I thought it would be ok to just replace 4 from 1 bank and 4 from another.
Or u think it would be wise to pull some good fets as there all the same batch and group them together in 1 side then replace the whole other side? I only ordered 10 fets however.
Or u think it would be wise to pull some good fets as there all the same batch and group them together in 1 side then replace the whole other side? I only ordered 10 fets however.
The only information I have is what you posted and I didn't see more than 4 missing. The same thing applies if 8 failed for two transformers.
4 and 4 . Sorry uploading photos here has been a bit difficult this morning. All the rest of the remaining mosfets are fine and amp is powering up ok as of right now. Obviously I have not attached a load yet. I was going to remove the rectifiers when I fit new fets just too check amperage draw but don't think I'll need too. Everything seems ok.
