GK1- one channel no longer working

fajimr · « **on:** 9 Jan 2008, 08:34 pm »

Happy new year fellow askafellas!

I have been happily listening to my GK-1 Platinum for the last few months with no problems... recently I moved and even though I packed the preamp carefully and carried it with me in my car, once I rehooked up my system I could not get any sound our of the right channel. I've already:
- switched the input wires from the CDP to make sure it wasn't the source
- switched the output wires to make sure it wasn't the amp
- checked the input wires
- checked the wires from my grayhill switch (silver wiring used for this)
- checked most of the other wires
- the tubes are working (or at least lit)

anything else I missed? any ideas for problem solving.

thanks
jim

AKSA · « **Reply #1 on:** 9 Jan 2008, 09:00 pm »

Hi Jim,

Does the signal get through from the sub-out RCA?

If yes, the tube is the problem, if no, the SS input section is the problem.

Is the LED glowing on the right channel?

If not, there's a power supply problem.

Try these simple tests, then get back to us!

Cheers,

Hugh

fajimr · « **Reply #2 on:** 10 Jan 2008, 03:24 am »

Quote from: AKSA on 9 Jan 2008, 09:00 pm

1. Does the signal get through from the sub-out RCA?

2. Is the LED glowing on the right channel?

thanks Hugh....

1. There is no sub out as I have the GK1 EL (? without the selector switch board) Both tubes glow - i am not sure if that is indication of anything. I did pack the tubes in their original boxes but put them inside the case so maybe they got jostled around a bit. but now i remember that I also switched the tubes so they should both be fine.
2. The LED is indeed working

jim

AKSA · « **Reply #3 on:** 10 Jan 2008, 03:27 am »

Jim,

On the right channel only, run a croc clip from volume control wiper arm to right channel output.

Now, with the amp, CD player and speakers all connected and running, do you get a signal.

If no, the problem is in the SS part of the GK1.

If yes, the problem is in the tube section of the GK1.

Moving right along......

Hugh

fajimr · « **Reply #4 on:** 10 Jan 2008, 04:56 am »

thanks hugh

will try tomorrow... too late now.

jim

Rom · « **Reply #5 on:** 10 Jan 2008, 07:48 am »

Hi Jim,

To add to Hugh, suggestion, also check the connetion on the Pot, It might be just one of the cable to the potentiometer. The cat5e solid copper wire has a tendency to break, brittle, or sometimes the solder also comes off overtime.

Cheers
rom

fajimr · « **Reply #6 on:** 15 Jan 2008, 10:11 pm »

Quote from: AKSA on 10 Jan 2008, 03:27 am

Moving right along......

or not... still unpacking, looking for the instructions so I know where to connect the croc clips...

still haven't learned how to be more organized after all these years

jim

fajimr · « **Reply #7 on:** 16 Apr 2008, 02:00 am »

Quote from: AKSA on 10 Jan 2008, 03:27 am

On the right channel only, run a croc clip from volume control wiper arm to right channel output.

Now, with the amp, CD player and speakers all connected and running, do you get a signal.

If no, the problem is in the SS part of the GK1.

If yes, the problem is in the tube section of the GK1.

hi hugh...

well i've finally emerged from a long winter's hibernation. luckily the sound of the naked LF was enough to carry me through but i would now like to resolve my problem.

I did the test you described- ran a croc from the R channel vol wiper to the right channel output (at the rca). No signal to the speaker.... I've done a visual inspection of all the connections to no avail. Where do you suggest i go from here?

thanks
jim

SuperMart · « **Reply #8 on:** 16 Apr 2008, 02:08 am »

Go to Jail. Do Not Collect $200........................Sorry, Hugh - back to you.

Cheers,

AKSA · « **Reply #9 on:** 16 Apr 2008, 02:56 am »

Hi Jim,

Problem is in the SS section.

Measure the two rails, should be between 14 and 15 volts, pos and neg. Measure + at top of R12, and - at bottom of R16.

We'll see if there is voltage available, if yes, the problem is in the circuit, if no, it's in the power supplies!

Cheers,

Hugh

kyrill · « **Reply #10 on:** 14 Jun 2008, 08:32 am »

hi
i dont see a follow up

may i assume it all worked fine , in the end?

AKSA · « **Reply #11 on:** 15 Jun 2008, 04:04 am »

Good question,

Jim, do you have it up and running now?

Hugh

fajimr · « **Reply #12 on:** 4 Jul 2008, 04:37 am »

hi kyrill, hi hugh

thanks for the follow-up.... to be honest I haven't had enough time to devote to problem solve this. it's been a pretty hectic winter, spring and now summer looks pretty busy too. doesn't help that i live in one country and my kids in another (and I am not talking western europe here).

so i've decided to put it on hold until I have more than a few hours here and there to properly go through it. i'll also use the opportunity to properly fit it into a chassis as I really wasn't that happy with my old set up. the great thing about the LF is that it sounds just fine naked- this emperor needs no clothing.

enjoy the rest of the summer everyone- i will check back in once I have it working again.

cheers
jim

AKSA · « **Reply #13 on:** 4 Jul 2008, 05:50 am »

Jim,

Thanks for the reply. You have my warm assurance that when you are ready to get stuck into it, I will be able to help you through, particularly if you get a good quality digital camera. I recommend the Sony T200, I have one, a corker, but they are all good these days.

These are not difficult circuits, and I have built and trouble shooted a few now, so I'm itchin' to go when you are ready......

Cheers,

Hugh

fajimr · « **Reply #14 on:** 14 Jul 2009, 09:02 pm »

Quote from: AKSA on 16 Apr 2008, 02:56 am

Measure the two rails, should be between 14 and 15 volts, pos and neg. Measure + at top of R12, and - at bottom of R16.

We'll see if there is voltage available, if yes, the problem is in the circuit, if no, it's in the power supplies!

hi hugh... how time flies- just pulled out the GK-1 to have a look and it's been over a year! summer vacation is much too short for me but i vow to get this figured out!

i measured as you suggested and have 14 and -14 at both R12 and R16, respectively. measured the left channel for good measure and have the same reading. looks like i need to go into the circuit. any advice?

jim

fajimr · « **Reply #15 on:** 14 Jul 2009, 09:58 pm »

hugh

just saw that you are at your mother's - wish you both the best. i'm obviously in no particular hurry here....

but i did follow your original testing protocol and got the following results within your tolerances:
across R8
ground- R12 (as reported above)
ground - R8
across R31
ground- R23
across R26B and R 27B

not sure if any of this helps...
jim

AKSA · « **Reply #16 on:** 14 Jul 2009, 11:41 pm »

Hi Jim,

Nice to hear from you again, let's try once more......!!

It seems to me that it's working in DC without problem. I would now be looking at the input and coupling caps, making sure that all are connected as they should be. There seems to be some blockage of the signal - the amp is ready to boogie, but the signal is not getting through.

If this is not successful, take a few pictures... I love to see the circuit close up, then I can see what needs to be seen.

Do you have 140V on the tube, BTW?

Hope this helps.

Cheers,

Hugh

fajimr · « **Reply #17 on:** 15 Jul 2009, 10:14 pm »

thanks Hugh....

I did do the 'platinum' upgrade and was a little concerned about C1 (I think was the large cap upgrade) but the connection looked o.k. Am i mainly looking for a bad solder joint? Is it only visual at this point?

jim

AKSA · « **Reply #18 on:** 16 Jul 2009, 02:03 am »

Hi Jim,

Yes, look for a bad joint, but you might find it's less subtle than that, like a wire or a pad which has come adrift.

My belief is that the signal is not getting through. With a cheap cap, 1uF approx, you could plumb a signal directly into the preamp input point on the analog board and see if it works... that's a powerful test and it will reveal a switching or bad contact issue earlier in the chain.

Hope this helps,

Hugh

fajimr · « **Reply #19 on:** 20 Jul 2009, 08:48 pm »

update:

everything is fine now... pretty easy, with the deft hand of hugh leading the way.

great... did i say great? to have the GK1 back in the system... everything is much more open now

mmmmmmmmm, rediscovering all my CDs again

jim