65 RI Twin borrowed came back DOA, Help!

[bloozdude]

I borrowed my Fender 65 RI Twin amp to a friend for a studio recording and it came back DOA, I had just tested it out before lending it and it worked fine like normal, not more than a few yrs old, mint condition.

The jem light does not come on, there is good fuse, the power switch is tested good. I can hear a faint click and hum in the area of the first transformer but that's it.

It was cold like 10 degrees F the day they took it into studio so it was cold soaked. Could it be from turning it on cold? I wasn't there but no report of any smoke and no smell either.

Can anyone suggest the cause and nature of failure. The "friend" is feeling no responsibility for the malfunction and I'm now stuck with a non working amp.

Help.

Thanks, bloozdude

[Gtr_tech]

The lesson here: *ALWAYS* let the <insert gear here> warm to the temperture of the environment it is to be used in before powering it up. Bringing cold gear into a warm room causes condensation inside the chassis....so you need to let it warm so all the water evaporates. No less than an hour is my rule.

[izzybell2810]

Some Friend

I take it that you have checked the fuse and switch with a meter? If not then check with a meter. Especially the fuse! Is the power cord electrically and mechanically sound? Check for continuity. If all this is good, providing you are competent with a meter and know what to probe (if you don't, then don't, there are very high voltages inside that WILL kill you!) then check that there is voltage present at the secondary of the transformer.

Some friend you have there!

[Robert M. Martinelli]

The lesson here: *ALWAYS* let the <insert gear here> warm to the temperture of the environment it is to be used in before powering it up. Bringing cold gear into a warm room causes condensation inside the chassis....so you need to let it warm so all the water evaporates. No less than an hour is my rule.

Uhmm..... Another lesson here IMHO : NEVER lend your < insert gear here > to anyone; I've done it many times in the past and almost every time I ended up with a broken guitar and/or amp in my hands....when I was lucky enough to get my gear back.

Even if it has been already said, I would add a word of caution : when people say tube amps can be LETHAL they're not kidding! Unless you have an electric/electronic background, understand the risks you're facing and know how to safely operate on such devices, I would recommend to bring the amp to a qualified tech. If you feel yourself up to the challenge, here you' ll find all the help you might need, and even more!

Good luck!

Bob

[6267]

*If* I lend my gear to people, I always go with it, so that if something goes wrong, I know if there's someone to blame or not. Also so that my equipment doesn't take a walk. There have been too many times equipment gets hosed and no one knows who did what when...suddenly I'm paying for the replacement speaker. Conversely, there have been times that I messed something up in an amp build and if I hadn't been there watching the amp, I might've been forced to annihilate the innocent musician!

Also, make sure the pilot lamp isn't burned out!

[bloozdude]

Thank you all for the good advise, I will exercise caution in delving into this project. I have moderate experience and would like to try so will study into how to drain caps and then use my meter to do some checking.

Can someone recommend where I can get another transformer if it proves to be failed.

Thanks,

Bloozdude

[6267]

You will probably want to check the continuity from pin to pin on the power plug with the switch on (not plugged in). No need to drain caps. If there is no continuity, it is possibly a blown transformer or bad switch. If there is continuity, you'll need to open it up and see if it's a short somewhere (plugged in, the power cord would be getting hot...you might be able to use a wall plug power meter to see if there's a current draw with switch off). If there is no continuity, you need to make sure that the switch works, and that all the wiring is intact to the transformer.

I drain the filter caps using a big metal screwdriver with a plastic handle, some people like to use a resistor. I just hold the tip of the screwdriver to the + side of the cap and touch the shaft to the chassis. Big sparks are fun . When I worked in a comp. repair shop, we discharged the CRTs with a resistor attached to an alligator clip which had the other lead on a long screwdriver. We'd clip the lead to ground and touch the screwdriver to the anode.

Make sure to check if the tubes are glowing when plugged in and switched on, because the pilot light may have simply burned out (always fun). Is the pilot lamp driven from the mains or from the heater winding? Try a new fuse, and try a different power cord too. Also, if the guy who borrowed it really hates you, I've heard tales of people putting clear nail polish on power cords/IEC sockets...of course this may be what you want to end up doing to the bastard's guitar .

Hammond makes great power transformers, depending on if you have space for a non-exact replacement. A 50/60hz model will be more reliable than a 60hz alone model, since the transformers capable of 50hz are a bit larger. Heyboer, Weber, AES and others make exact replacements, but I can't recommend any specific vendor having not used them. Weber is generally great about customer support though. Don't replace a transformer until you are *sure* that it is the problem.

Good luck, I'm sure that there are lots of people here willing to help you figure this out, just take it slow and steady. It sucks when people wreck stuff and don't take responsibility. Here's hoping it's something simple!

[izzybell2810]

Make sure to check if the tubes are glowing when plugged in and switched on, because the pilot light may have simply burned out (always fun). Is the pilot lamp driven from the mains or from the heater winding?

The Pilot light on that amp is powered from the heaters if my memory serves me correct.

[Albert Kreuzer]

What 6267 said.

Within a few weeks I had:
an Amp (Marshall) with a burnt-out pilot light (owner didn't try for sound)
one with a broken power cord (red-knob Twin)
one with a faulty mains switch (135W Bassman)
and one with a shorted filter cap and a 20A mains fuse (so it worked for a short time while shown to the buyer).

Sometimes it's the simple things.

Good Luck!
Albert

[Enzo]

And when repairing something, just repair it. DOn't waste time trying to figure out WHAt your friend might have done to it. It all may just be a coincidence. A wire could have jarred loose on the ride home, who knows. However it happened doesn;t change the repair.

Transformers are the last thing on my list of suspects, not up near the top.

[Robert M. Martinelli]

Hi,
your amp's service manual can be found @ this link :

http://www.schematicheaven.com/fende..._%20manual.pdf

Having the schematic diagram at hand can be useful, you'll find all the operating voltages, so with a good DMM, some help and a little patience you'll surely manage to fix your amp.

Best of luck!

Bob