Toasted 400 still toast
- Thread starter roccus
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Did some checking out and looks like I did order the Central A42's and 651's. Back when I started this repair when I found a known bad part I woulld order some extra stuff that may be in question as I went through the board. Looks like those 2 parts were not in stock and obsolete so I took what was available. So what happens on this eventually Joe? Will you have to go to another brand, find an ON replacement, or do a whole new redesign for parts that are available??
Eventually Ray will have to find alternatives and qualify them. Was really sad when ON Semi discontinued TO-92 production, they are the best manufacturer out there. I have a lot on hand, I stock up very heavily when EOL notices are served by the manufacturers in cases like this.
I eventually had to move before on RevD to RevE when ST Micro discontinued production on 2 critical parts on that board. I still have a lot of service stock available for that too.
I eventually had to move before on RevD to RevE when ST Micro discontinued production on 2 critical parts on that board. I still have a lot of service stock available for that too.
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- Jan 14, 2011
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- Halfbiass...Electron Herder and Backass Woof
- Joined
- Jan 14, 2011
- Messages
- 74,826
- Location
- Gillette, Wyo.
- Tagline
- Halfbiass...Electron Herder and Backass Woof
Joe... the parts came in today, thanks very much for that. I put them in and everything looked good, 0V on outputs and bias looks good now, so I connected the DCP the points stayed closed as they should and all voltages still look good, then I put D9 and D10 back in and everything still good. I think that is it. I have it sitting here powered up to get good and warm to tweak the bias..... anything else you think I should look at before I connect an input and speakers??
Shotgun is a repair term. Where you just swap things out when they are suspect.
The 0.27V is an approximation Ray, the circuit regulates where it needs to be based on the global feedback loop. The important aspects are that the 3 readings are within 7mV of each other which means all 3 transistors are sharing quite equally and that you output offset is no longer suffering voltage sensitivity. You obviously had walking wounded in there prior.
The 0.27V is an approximation Ray, the circuit regulates where it needs to be based on the global feedback loop. The important aspects are that the 3 readings are within 7mV of each other which means all 3 transistors are sharing quite equally and that you output offset is no longer suffering voltage sensitivity. You obviously had walking wounded in there prior.