Nad 705 repair
- Thread starter Eastham
- Start date
Eastham
More Class-A than ever!
Eastham
More Class-A than ever!
After finding no bad or obviously shorted parts I decided to throw the positive side output transistor in. All voltages are back to normal and the amp came out of protection! Looks like I just need the 2SC3519.
Eastham
More Class-A than ever!
Decided to make my own LED conversion using some left over Fuse style LED lamps I had from old projects.
Removed the little end caps by heating them up with my soldering iron to melt the solder, then attached some leads I snipped off some capacitor.
Don't look to bad installed.
Very nice. I may cut open an old LCD screen for it's diffuser try and make the dispersion more even. What you see in the picture is exactly how it looks in real life. The incandescents used to give off a slightly green tinge, now it's a perfect blue with perfect white charecters.
Removed the little end caps by heating them up with my soldering iron to melt the solder, then attached some leads I snipped off some capacitor.
Don't look to bad installed.
Very nice. I may cut open an old LCD screen for it's diffuser try and make the dispersion more even. What you see in the picture is exactly how it looks in real life. The incandescents used to give off a slightly green tinge, now it's a perfect blue with perfect white charecters.
Eastham
More Class-A than ever!
Yup, hopefully I won't run into any oscillation issues. Modern transistors seem to be better matched than older ones so I think I'll get away with it, if not I'll just order a matched pair. Just got my tracking number for the other 705. Looks like it'll be here by the end of the week. Can't wait to get it, then I'll be able to play with my nads at the same time!
Eastham
More Class-A than ever!
The other one was listed as used but after reading the listing I noticed the seller said the tuner just tunes static. So I guess I'll have a little tinkering to do with that one aswell.
Eastham
More Class-A than ever!
Indeed. I think it may need an alignment.
Eastham
More Class-A than ever!
That and sometimes people like to screw the adjustment screws all the way in... I got my 75ohm antenna in the attic to test it with.
Eastham
More Class-A than ever!
New fuses arrived today and as a matter of luck I was looking through my parts tub the other day and found a 2SA1386A with a matching 2SC3519A I bought for an old TEAC amp I was going to repair, So I've just popped them in and powered it up on my DBT, all was great, bulb was dim, set the idle current, flicked the switch I have on my DBT that bypasses the bulb annnnnnnd POP, BZZZZZT, FLASH, two blown fuses and a blown 2SA1386A. I never believed in luck before but now I'm starting to believe that either me or this amp is cursed or that I'm just a tool... Found the point of failure to be the emitter resistor R143 touching R151... I still have the original 1386A, I'll pop that in later and try to find the cause of this 7v DC offset. For now I'm gonna listen to some up beat tunes while I drown my sorrow in cheap wine and self pity... Only without the wine part...
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Eastham
More Class-A than ever!
Indeed, I got the 2SA1386A in last night still seem to have 7v on the emitters. I would have been working on it tonight but I got caught up watching the blues brothers... My other 705 should be here tomorrow!
Eastham
More Class-A than ever!
I will. I might invest in a pair of matched transistors for this one as soon as I find out what's causing the 7v on the emittiers.
Eastham
More Class-A than ever!
Will do!
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