Giscours malfunction
 

Hi Guys,
woke up this morning and only had music on left channel. checked cc80's and swapped cables around it appears to definitely be the pre-amp.

all six valves are glowing and i have a green light infront of each WE tube.

see pics for evidence. Anyone have any ideas or experience or further diagnostic thoughts or is it back to the factory.

Giscours purchased second had from AA member, been working fine for nearly a year, serial number 003 and after email with shindo san (upon purchase) no service was recommended.

Only change to the set up was the swapping in of some different kt88's in the cc80 (two months ago). Had not got round to biasing the amps, could that affect the pre-amp????

thanks in advance for any help,
Paul. :tears:

Paul,
Sorry to hear of your troubles. I too have had Shindo malfunctions. Best bet is to send it back to Shindo. Although they are very reliable, like anything else
they can have issues from time to time.
Dale

Same here Paul, sorry for the troubles you're having. I would reach out to JH. He should get back to you on Monday. This is not my area of expertise, so other users please back up my following thought. How about just taking those WE tubes, and swapping channels.
Both volume controls on your amps are turned all the way up, Right?

fjn04

good answer:thumbsup:

Sorry to read this Paul.

Swapping the right and left tubes is a good idea but I would swap all of them, not only the WE tubes.
Does this happen no matter the inputs you are using ? Did you try swapping the cables between your source and the Giscours ?
Having a bad bias on a CC80 won't affect the preamp.
If the KT88 come from Shindo, you may not have to adjust the bias.
We have a fabulous Shindo expert in Paris.
If you need service It could be simpler to send him your Giscours than sending it to Japan. Just let me know by PM if you need him.

Just BE VERY CAREFUL WHEN REMOVING AND INSERTING THE TUBES. THE SOCKETS ARE VERY VERY TIGHT.

I assume that by checking cables you also swapped the connections to the amps at the pre?

I assume this is happening both with phono and another source? This would eliminate something in the phono stage as the issue.

If so, then the easiest trouble shooting is to swap the positions L/R of the valves, one set at a time, powering off in between. Start with the rectifiers, then the tubes in the line stage. If you hear the failure switch channels, you know that tube is bad.

If after doing this the problem doesnt flip channels, and all the cable connections are not bad, you know you have another part failure in the line stage that you will have to seek out a reliable repair for. Probably the best place to start with that might be A23.

That's the exact procedure I would follow.
Keith Aschenbrenner will not service a Shindo piece not imported by himself. He has been very fair to stop imports when they became forbidden by RoHS regulations so he does not accept to work for the ones who do not share the same respect for the law.

Guys,

Thanks for the support, group answer in one go!

I only have one source - my MSB DAC but i will move it to another pre-amp input..

Im thinking about the tubes switch.....

I agree with Jerome regarding Keith's view point - i think the real answer is in Japan not A23

Paul,

Sending your gear to Japan will be very expensive. PM me if you want to talk about my technician, I will give you his web site and phone number. He is fabulous. He is also a designer and maker of High end tube amps and cd players, pretty well known in France. Sending your Giscours from Switzerland to Paris won't cost a fortune if it really needs service.
And I bet you that Shindo has no mystery for him. :D
But of course, swap cables and tubes first !!!

I assume that by checking cables you also swapped the connections to the amps at the pre?

I assume this is happening both with phono and another source? This would eliminate something in the phono stage as the issue.

If so, then the easiest trouble shooting is to swap the positions L/R of the valves, one set at a time, powering off in between. Start with the rectifiers, then the tubes in the line stage. If you hear the failure switch channels, you know that tube is bad.

If after doing this the problem doesnt flip channels, and all the cable connections are not bad, you know you have another part failure in the line stage that you will have to seek out a reliable repair for. Probably the best place to start with that might be A23.

** If I may just ad one precaution. After you power down the Giscours, I would wait like 5 minutes before powering back on. So following Gortnippers procedure above, also give the preamp that rest before powering back up. So I would shut down, let the tubes cool a few minutes, put 1st set back to original position, flip second set, power back up....

Thanks fnj04,
Im going to try this tomorrow might once i locate my hex screw drivers!

Regards,
Paul

Paul,
be patient. It takes a lot of time to unscrew all of them :D !

Thanks Jerome,
Im very protective of my little green beasts, and i want dont want to scratch or ruin a thread, extra care is called for! I also has a spare rectifier set that the previous ower was kind enough to give me so fingers crossed!

Geez- Wouldn't that be cool if it were those rectifiers. I believe the Allen size you need is 2mm. Make sure to drink Chamomile before you start the process. :-)

Frustration continues...

Started the task of carefully removing all 26 2mm hexagon screws from the top of the unit, after removing 25 i came to the last screw which, in pre-purchase activity has developed a worn/stripped head and i cannot remove it, tried the rubber band over the screw driver trick but cannot get it to move. The head of the screw is close to circular!

25 down and one to go is really frustrating and it looks like tube swapping across the channels is not going to be achievable by myself, scratching head time, looks like this needs to go to somebody more qualified than me since i cant think of removing without marking the green beastie.

This happened to me once with a Copland CD player. Very frustrating !
Sorry Paul.
I would drill the screw out, with a dental bur if I had your unit on hand, or I would grave a new cross in the screw to grab it with a cross screwdriver.
It is not very tough to pull out a screw with a damaged head. Maybe you can ask your carpenter....or your dentist :) !

Some more suggestions I found...this one involves something like super glue..of course if I recall the darn screws are really tiny...

Use JB Weld or equivalently super strong “welding” adhesive to attach a nut to the screw head. Pick a nut that is about the same size as the screw head or at the least such that the diameter of the hole in the middle of the nut is smaller than the diameter of the hole in the screw. Now place the nut centered on top of the screw. Fill the hole with JB weld, being careful to not let it run everywhere. If the nut is flush on the screw, this shouldn’t be a problem. If it can’t be flush, use some sort of quick drying temporary gasket or the like to seal around the edges so that the JB weld doesn’t get everywhere, but rather just stays in the hole. Now let it dry the recommended time. Once it has hardened up, use a socket wrench on the attached nut to remove the screw.

Read more at The 12 Best Ways to Remove Stripped Screws

I was wondering if this would happen.

No, this wont work - . I tried that. The best thing to use is a screw extractor - Screw extractor - Wikipedia, the free encyclopedia

Get one that fits into the stripped hole and you can do it gently by hand. They work well.

If there is still a bit of grip in the screw (you might try a non-metric size allen head or a different shape head if you have a set of screwdriver tips) and have someone assist you by gently lifting the top plate of the pre and rotating it counter-clockwise to "help" the screw out.

Thanks, I stand corrected...sometimes the best laid plans of mice and men....damn I should have gone with the screw extractor (item #3).

Awesome !
Thank you !

Put the amp back into the rack today and reconnected everything up and started to research getting a screw extractor in switzerland.

10 minutes later whilst hunched over the laptop i started to hear music coming from the music room. Wife had assumed i was finished and she powered everyhing up and started playing music - both channels miraculously working!

The good news is that the amp is working again! The bad news is i dont know why and I still have a screwed up screw!!!

Great news Paul !
IMHO it looks like you had a cable connection problem. This is what I thought from the beginning. A tube usually dies slowly. Not in a blink of an eye.

I think your right Jerome, and all the tubes remained lit up (as you cn see from the piccies).

More fiddling required!

Good deal Paul. I would still casually rectify the stripped screw, so it's done and over. I had an OTL amp some time ago that stopped working. I drove it to Canada (sneaky-sneaky) where the factory was located. They put it on the bench, or whatever it is they do. Needless to say, he said nothing was wrong. I returned home, and it worked fine.
I guess sometimes there's no good explanation...!

So, it does sound like a cable connection issue. Good!

But, I would fix that screw. After it is out, take out all the tubes and clean their pins with a small wire brush. Reinsert them and pull them back out a couple of times. This way, you get a good, fresh connection with the tubes in the sockets, and any oxidation effects might be minimized.

Paul,
Do you have a cat ?
I would check if nothing pushes up or down a RCA plug. They are very fragile, and not only the Switchcraft used by Shindo....

No cat Jerome, but agree with gortnipper and yourself and will be addressing the screw and will clean put the inside and reseat the tubes .

Thanks everyone for the support (emotional and technical know how!)

this is ridicolous

?

OH? A quote from a very well respected tube seller who rebuilds Citation gear: audioasylum.com/cgi/vt.mpl?f=tubes&m=253369

"I have been deluged lately with people asking about issues with their tube gear that they have decided for whatever reason must be the tubes. Occasionally it is, but at least 75% of the time in my experience it is not. So I wanted to make a few points and pass along a few tips to help people out.

1. The #1 cause of noise problems with tubes is poor contact between the tube pins and the socket. There are a wide variety of possible causes, dirty pins and/or sockets (in the case of a noisy new tube the socket is the PRIME suspect), socket contacts that have been stretched out or worn out and don't make good contact, or in a few cases, bad solder joints on the socket itself.

A tube socket - even really good ones - are not sophisticated, high reliability connectors. You won't see tube sockets in critical applications because they simply are not reliable enough.

Do yourself a favor - clean the tube pins and sockets every time you change tubes. A bottle of DeOxit D5 and a handful of good old fashioned pipe cleaners works great for octals and other large pin sockets; for the miniatures, D5 and the little tiny dental brushes for cleaning between your teeth (another drug store item) do a solid job. BTW, D5 is good to 400F - so don't lose sleep over it because of something you read on the "Hi-Fi Hysteria" forum. And it doesn't gum up either. Spray some in a paper cup and let it evaporate - you'll be able to see for yourself.

Sometimes you swap a tube and the new tube is okay. so the tube you removed must be bad, right? NO! Sometimes the scraping action of removing and reinstalling a tube in that socket is enough to temporarily restore contact - and fool you into thinking you have a bad tube! KEEP YOUR SOCKETS CLEAN!!

Honest - only a few % of the tubes I get back for noise are bad. Most go on to play fine in another socket."

Gortnipper,
This sounds like good advice, once I get that pesky screw out! :-)

Hi
I am new on this forum

I'm looking for someone who has pictures of the inside of a Petrus 349A and a 349A Giscours to compare my Giscours CV391

Best regards
Joscad

What are you trying to compare?

joscad... Welcome to AA! :wave:

Thanks ;)
Joscad

Giscours 391
 

what changes are necessary to use 349A in my Giscours
Regards

Joscad

You can't use the 349A in your Giscours. Its designed for the 391. Please don't try to modify or alter art. Its a wonderful preamp, enjoy it!
Jonathan

Giscours
 

Hi
Do you think 391 is in this Giscours is better or identical 349A?
Regards
Joscad

Its is different, not better or worse. Think of them as different vintages of the same wine. Don't get hung up in the audiophile comparison game, just play some music. The best thing you can do for your Giscours is use it to the fullest. Proper amp, speakers, cables, sources, transformers etc. 99% of people never hear half of what Shindo can do from mismatched speakers and associated cables and accessories.
Where did you purchase this Giscours? Hopefully your dealer can help you get the most from it.

Jonathan