Classic 60

[roberto]

Hola Chicos,

Just got from a dear friend for repair a Classic 60 power amp. The unit did not turn on. So the first thing that I did was to check the power fuse that it is located at the IEC power cord female connector. The fuse was totally smoked. Then I opened the bottom of the unit and my bad guess was the power transformer. I thought it was bad. Then I sent an email to Jeff asking for the power transformer, and he gave me a truly and great tip: disconnect all the secondary wounds and please measure the voltages, using first a VARIAC transformer. My Variac has a VU Amperes meter. I put a new fuse, and having the unit with all secondary wounds connected, and having only supplied 10ACV, the amps meter measure a measured of 5A!!! Then I follow Jeff suggestion, desolder all secondary wounds, and the short was gone...the power transformer is OK. The next thing that I did was to find the diodes rectifier bridges. I found two diodes in short like a bare wire.

IMG_8673.JPG (2.07 MiB) Viewed 5286 times

The diode number is F 08H60S. It is a super fast acting diode.

That was the problem, two blown rectifier diodes...Thanks Jeff for the great tip. And furthermore, I got the parts from Jeff and the packet was dispatched right away.

Thanks Jeff for all the help to this matter!

Happy listening!

[admin]

Nice. That would have been a much more expensive "fix" if the transformer would have been replaced,... plus it wouldn't have fixed the issue.

[roberto]

Yes Admin, and the look of the transformer wires, due to the short, looked kind of a smoked color. My bad guess. It was just that. And also the great tip from Jeff. Using a variac is the way to trouble shoot vacuum tubes...or shorts of any electronic component. The amps reading meter built into the variac is another great tool on hand.

Happy listening!

[roberto]

Here is another tip: having this variac tool with the amps meter, if the transformer is bad, then even disconnecting all the secondary wounds, the amps reading on the meter will be showing the short. When I disconnect all the secondary wounds, the short went away, telling that the power transformer is OK.

[admin]

Do you have a link to the Variac tool you used?

[roberto]

Well, the model that I have is an old model, I bought it at circuits specialists...now they have a better variac:

https://www.circuitspecialists.com/tdgc ... ransformer


And I remember that I paid about the same too...

[admin]

Excellent. A little expensive on the "just to have it on my amateur workbench", but may very well be worth the cost if you think you have a transformer problem and are considering sending the unit in for repairs.

[roberto]

Yes, variac is a clever tool to have, specially when a short arise. Just isolate the parts of the circuit and there you go.

Happy listening to all! And as RJ says, enjoy those fine tunes.

[Big Dog RJ]

Now that's outstanding service! From JF and his team.

All the negative things said about CJ were only short lived... this goes to show the true test of time, especially when it comes to CJ's competition, CJ is right up there, at the very top of the podium. There's no denying it.

Oh, for the love of tubes, that deserves a mighty WOOF!
Enjoy those fine tunes, RJ

[roberto]

Yes RJ,

Jeff really knows his goods. He knew that once I was going to disconnect the secondary wounds of the transformer, the short will not be present. He knew that it was another problem, not the transformer. so what I did is to connect each secondary and checked the short with the aid of the variac. When I connected the orange and white/yel wounds, the short was showed up. Measured the diodes and the short was there. My tester has an option for testing diodes and transistors.

Having good tools around really help to solve this kind of problems. I just unsolder the bad diodes and I am waiting the new components.

Of course I asked if they do have in stock the parts, and they did. I was an easy transaction, a very fair price and Immediate delivery to my courier service address at Miami. I do not have any complaints and I am grateful with the great help and support that I got from Jeff!

Happy listening!

[admin]

Really amazing.

Roberto, do you get a sense that CJ may be pulling back on the "internal repairs only" policy? It seems like their general policy has been not to send any parts or offer to much troubleshooting advice, instead leaning to "send us the unit so we can do the proper repairs." This seems like a potential shift.

[roberto]

Gee, I can't say that about the service and support. I have being receiving all the help that I needed and support from Jeff. I knew that Jeff had problems with some non customers, and specially from people that was counterfeit Conrad Johnson products.

He still does not send the diagrams and when you are asking for help, he tells you what to do to track the problem. Also because I am located away in Costa Rica, he knows that it would be very expensive to send the goods back there. Also, he knows that I have all the service tools necessary to provide a very good service. Jeff to me, he is a gentleman!

HAPPY LISTENING!

[SolderSlinger]

@Roberto, Thanks for the variac link. I like the digital readout of both current and voltage. I have a very old viriac with only an analog current meter. I use a DVM to measure AC. Not as handy.