Adcom GFA555II Amp. One channel out. Could not duplicate the custormers concern. It worked great!
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- čas přidán 17. 03. 2023
- An Adcom GFA-555II that came in with the complaint of no audio on one channel. I could not duplicate the customers concern. I did adjust the bias (idling current) After I returned it to my customer he determined that the input cable he had was defective.
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Email me at NorCal715videos@gmail.com - Věda a technologie
Faulty cables/plug connections are a common but relatively inexpensive problem to solve. A quick clean and adjustment, no parts required this time. The result: a fully working amp and presumably happier customer. If only all service jobs were this easy!😇
I love your leaf blower techniques for removing dust.. I remember a customer bringing in a CRT TV that was so full of cockroach shells it stunk, so I sprayed the TV with a water hose and waited a week before working on it.
Thank you...
Great work!
@ 4:30 odds are, you have a C-E leaky, but not fully shorted, power transistor since you can't adjust / null the offset out and the bias readings are identical between channels. You would need to pull each power transistor and check for a reverse junction C-E leak at a high enough voltage to read it, as it probably wouldn't show just using the "diode test" function of most DMM's The component at fault hasn't fully broken down yet, and hopefully it won't let go with a set of expensive speakers connected to it.
200 watts per channel into 8 ohms.. bought mine in 1991 still running and used almost daily for10+ hours! great video Steve👍👍👍 P.S. This was designed by Nelson Pass.
This was the video that just kept on giving!!!
Thanks!
Thank you Alan!
@NorCal715 No thankyou so very much !
I have this exact amp. What a power house!! Q: With all the dust and the previous factory low settings found in the bias pots, though you did not do it, should these pots be cleaned with the Deoxit Fader F5 along with scrubbing them as you performed? Thank-you
You are asking for that weeding ring to be welded to your finger
Would there be a downside to mounting a fan in that chassis to exhaust the heat it generates?
hello sir , i bought the blue esr meter(because of you :() , and i also have te capacitor wizard wich is analog , when i tested a 0.47 micorfarad cap out our circuit
the blue esr show 9.2 ohm and the capacitor wizard show 7 ohm , also there a big difference when checking on board caps , how can i know wich one is accurate ?
thank you very much
Simple test is to use a low value carbon or metal film resistor, to check, and see that the resistor value is displayed correctly. But with 0.47uF electrolytic ESR can be pretty high, and the reactance will also influence the reading. In any case a 0.47uF film capacitor is not that much bigger in size, at least at 100V with green mylar, and will probably last a lot longer. with electrolytic capacitors any value below 10uF is going to show a difference, but with 100uF most will agree within a few tenths of an ohm. In circuit some meters are better than others, but none will be accurate due to stray paths through other components.
It could be the test frequency that the 2 units (Blue vs. Capacitor Wizard) uses to determine the capacitor ESR. The higher the frequency the lower the displayed ESR will be (usually). As SeanBZA said, use a low value resistor to make a final determination on which one is fibbing. I know on the Blue ESR tester you use an included resistor to align the meter when building it.
@@norcal715 thank you , i did not get align resistor i got it build up from tha company , i tested other resistor and there are the same value with the 2 tester , the test frequency are both 100kh sine wave , when i test like 10uf 50v , get 2ohm on the blue esr and 1.5 on the capacitor wizard
what do you think ?
thank you for you timr and help i love your videos