dying v2

[fordy]

Help!

Well let me introduce myself first as its my first post. I've had a v2 for a few years now but hardly ever used it. Too shrill, hurt my ears. Then I discovered Pinkies mods over on the head-fi forum and rolled in some russian 6H23N valves. Eureka! Loved them ever since with my Senn 580's. Unfortunately I'd started to take no noticf of them again due to other things and left them turned on for a few months. Seems its not done them much good as it seems to have gone quite noisy in one channel. Its not the valves as I rolled the originals back in. Looking at the boards it looks like TR1 (ZTX653 NPN transistor) has stained the board underneath. Looks like it might have overheated. I'm no electronics expert (although I did succesfully make one of Pinkies PSU's for this amp). Question is, given the above whats the likely culprit? ZTX 653 looks to be hard to come by. Alternatives?

If I can get it going again I'll do the cap swaps. I had amassed most of the parts nearly a year ago but RS always seem to be out of stock of the pana caps and they screwed up my backorder. Twice. WIll order Pinkies set though to be sure if I can get it going.

Hopefully someone might have some advice Cheers all.

[PinkFloyd]

www.rapidonline.com part number 81-0226 no problems at all getting hold of a ZTX653

When you say "noisy" is the amp still actually working? (ie: sound coming out of both channels)

Fault finding on these guys is a bastard and it generally always turns out to be the least obvious that's causing the problem.

Noise in one channel.... what kind of noise? Is it a buzz, is it hum or is it high pitched? The type of noise may be able to narrow things down.

I was working on an X-10D yesterday and just couldn't find what was causing it to sound like a reverb unit. Eventually I got there, after replacing almost "everything" on the PCB.... The problem was the gold quad board mount phono socket, the ground tags had sheared off under the pads (due to age / stress) so the actual phonos were not connected to ground..... now I think of it, would have been a good first place to look but that never happens at the time you normally end up looking for dead components somewhere.

These little ZTX653 jobs either work or they don't, there's not really any "inbetween" state. Turn the amp on and measure each of them (base, collector emitter), if one is drastically different to the others then it may well need replaced.

I don't envy you, my head is still spinning after 7 hours trying to find the fault in that X-10D! You could also measure all the voltages across the components on each channel, set your meter to 200V DC and probe across things like capacitors and diodes. If you get totally different readings between channels then this will help pinpoint the culprit.

Basically what I'm saying here is "it could be anything" absolutely impossible to diagnose online and even with the thing in front of myr face (unless it's something totally obvious) it can take quite some time to find out what's going down.

For starters though we need to know the "type" of noise you're experiencing ie: "whoosh" "high pitched squeal" buzz" "Hum" etc.

All the best.

Mike.

[fordy]

thanks Mike,

WIll get hold of a ZTX653.

The noise in one channel is distortion. No whoosh, hum, buzz or squeal, just one channel with diminished volume and heavily distorted sound. The other channel works fine.

Interestingly, for a few months the amp would get turned on and off with the computer and I would often hear an odd sound coming from the headphones. Sort of like an electronic square wave buzz sound that would diminish in volume and finish on a squeal. Only when being turned off mind.

Might just have to start working away through components in the end I guess.

cheers
all.

[rickcr42]

i/2 of the triode is going south on you sounds like.does the amp come on clean sounding then diminish in quality the longer it is on ?

also,flip your left and right channel input cable to make sure the problem actually IS one amp channel.If the problem travels with the cable to the other channel then problem is not the amp but if the same channel remains the noisy one then yes,internal

[rickcr42]

troubleshooting flow charts

System Signal Flow :

www.avahifi.com/root/ordering_info/troubleshooting_flow_chart.htm

Internal :

www.curcioaudio.com/Troubleshooting%20Overview.pdf

[PinkFloyd]

A very "common" problem and one you should never overlook.....

The board mounted Quad phono socket.

The two earth (ground) tags will eventually part company with the PCB (in and out of the interconnects) you can spend "WEEKS" trying to pinpoint the culprit and get nowhere.... you'll be tearing your hair out.......

Happened to me "twice" and is now the first place I look. desolder the quad phono socket and just make sure the ground tags haven't broken..........

Change the "hot" tranny at the same time.

best I can come up with "online" very hard to diagnose from text only I'd need the old girl in front of me.

Mike.

[rickcr42]

Happened to me "twice" and is now the first place I look. desolder the quad phono socket and just make sure the ground tags haven't broken..........

you may be right on target there Mikester and why I NEVER use anything other than chassis mounts that can be cranked down as hard as I am able.I understand the "why" of this type of connector being used in commercial gear but still would never actually want one on the back of any of mine since i never leave shit alone and am always swapping cables in/out


i'd wreck the bitch in a day

Multimeter time dude ;D

[rickcr42]

Crackling, pffff noises
1) Possible poor internal connection in capacitors, resistors, etc. Many cheaper brands use poor quality internal termination's, resulting in noise. Remember: Holco terminations do require care in handling. Also take into account component deratings in high temp environments.
2) Possible faulty rectifier tube. Try a known good replacement.
3) Possible faulty input or driver tube. Try a known good replacement.
4) Possible faulty output tube. Some current production types can not operate at or near book spec, and will start making noise when used either under high voltage and/or high current conditions. Recent tests suggest at this point in time, derate most KT88 or 6550 types to 32-38 watts maximum, keeping voltage at 525 maximum @ 60ma plate dissipation in Ultra linear mode (EI KT90 excepted). Chinese 2A3 double plate types sound quite good, but are prone to noisy operation.
The 2A3B and C single plate variants have great promise.
5) Dirty tube pins or socket contacts.

from here

www.hndme.com/storetroubleshootingtips.html

kinda reinforces both Mike's and my own thoughts on possiblilities

[fordy]

:DVoila

It was the crappy pot. Replaced with the alps pot i've had waiting to go in and its fine. Once the amp was properly in bits I was fiddling with the RCA socket board to see if there were any broken grounds. I was holding the unit in my hands with the vol control and noticed it was cuting in and out and generally making a noise! Just got lucky I suppose. Desoldered the RCA socket board anyway to double check it but its fine despite having some big tight plugs in and out of it many times.

So now I can start the upgrades. Need some of them big old Pana caps now.

Woohoo.

Thanks for all the hints guys.

[PinkFloyd]

fordy said:

:DVoila

It was the crappy pot. Replaced with the alps pot i've had waiting to go in and its fine. Once the amp was properly in bits I was fiddling with the RCA socket board to see if there were any broken grounds. I was holding the unit in my hands with the vol control and noticed it was cuting in and out and generally making a noise! Just got lucky I suppose. Desoldered the RCA socket board anyway to double check it but its fine despite having some big tight plugs in and out of it many times.

So now I can start the upgrades. Need some of them big old Pana caps now.

Woohoo.

Thanks for all the hints guys.

The problems are generally things like loose / broken connections (in this case it was the pot) and they're usually the last place you look (if you look there at all!) I think I'll write up a diagnosis page listing some of the faults I've encountered over the years, it may be a handy resource.

Glad you found the culprit! Now go and get those caps in place

[PinkFloyd]

Woohoo.

I know that feeling! Great when you get a dead unit back on its feet isn't it?

[fordy]

Just to follow up this thread. Since the minor problem with the amp and uprade with the alps pot. I bought one of Mikes cap upgrade kits. Been a bit busy so only recently got around to fitting it up. Easy work though, maybe 2 hours max. Only concern is the ease in which some of the tracks lift if you leave heat on too long which requires careful soldering but otherwise no problems.

I left the amp on with various repeating CD's on for a week before I listened seriously.

Wow!!
I'm using Russian 6H23's, a homebuilt version of one of Mikes PSU's and Senn 580's from a Pink Triangle Anniversary TT and the sound is simply astonishing.

Its a lovely detailed sound with a nice fullsome bass and very relaxing. Now I know what the "out of the head" comments mean now. Ahh!

Anyway this is a little gem. I absolutley hated this combo when I first bought it years ago. Shrill sound that I couldn't listen to for more than half an hour. The amp sounds great on dem but its not a liveable sound. Then after not using it for about 3 years I discovered Rock Grotto. The valve swap got me likeing the amp alot. Its the single biggest change you can make really but the rest of the mods have made it a really complete little amp.

Great Stuff. Cheers Mike.

[PinkFloyd]

fordy said:

Just to follow up this thread. Since the minor problem with the amp and uprade with the alps pot. I bought one of Mikes cap upgrade kits. Been a bit busy so only recently got around to fitting it up. Easy work though, maybe 2 hours max. Only concern is the ease in which some of the tracks lift if you leave heat on too long which requires careful soldering but otherwise no problems.

The most vulnerable pads are the 100uF ones, you've got be in and out of there pretty quickly and don't want to keep the iron tip on for more than a second or two. If you do manage to lift a pad here and there it's not the end of the world, you can do one of two things.... first you can scrape the adjacent track down to the copper (use a craft knife) and then solder the leg of the component direct to the track. Secondly, you can simply solder the leg of the component onto the next component's pad and bypass the track altogether.

Lifted pads are a sign you're in the area too long but they're easily worked around. The trickiest little bugger is the potentiometer, the pads that it connects to are tiny, so you have to be very careful here.

fordy said:

Wow!!
I'm using Russian 6H23's, a homebuilt version of one of Mikes PSU's and Senn 580's from a Pink Triangle Anniversary TT and the sound is simply astonishing.

Nice one fordy, glad you like it, it gets even better with time

fordy said:

Great Stuff. Cheers Mike.

Thanks