Author Topic: one woofer pump_ground issue?  (Read 5254 times)

Offline data

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Re: one woofer pump_ground issue?
« Reply #20 on: October 12, 2014, 02:34:19 PM »
 :o

Hmm...looks looks like a dumpster dive tonight  :D

LOL
Probably buried under a heap of crap by now, oh well....weren't going to suit what I needed them for anyway. But thanks for that heads up all the same, Steve.
« Last Edit: October 12, 2014, 02:45:44 PM by data »

Offline omodo

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Re: one woofer pump_ground issue?
« Reply #21 on: October 12, 2014, 06:16:57 PM »
wow binned them, that's a bit drastic!!  :-[

only one was bad? wouldn't a single replacement would be around the same $ as a pair of Jupiters?

Offline data

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Re: one woofer pump_ground issue?
« Reply #22 on: October 12, 2014, 07:13:18 PM »
The other was still allowing over a half volt of DC pass (0.68v), not acceptable when there are no blocking caps on the input of my amp....or is it?

Still might dive in and see if I can get them out, luckily It's Sunday so may not be difficult or messy :)

But with my plans, and these being 1.5uf I doubt I'll use them unless I go with a SS player or DAC.......not likely for myself.

Edit: Ah bugger it, can't bring myself to dumpster dive to get them back.
« Last Edit: October 12, 2014, 07:31:55 PM by data »

Offline omodo

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Re: one woofer pump_ground issue?
« Reply #23 on: October 12, 2014, 07:44:25 PM »

Offline Rob181

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Re: one woofer pump_ground issue?
« Reply #24 on: October 12, 2014, 07:44:48 PM »
Edit: Ah bugger it, can't bring myself to dumpster dive to get them back.

Jeez I would...its Sunday & I wouldn't care anyway...

Offline data

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Re: one woofer pump_ground issue?
« Reply #25 on: October 12, 2014, 09:58:30 PM »
OK...Ok, went down and had a go.

First I would like to say that I'm about to have a very thorough shower shortly, but have them back, only an extra issue now with one, fishing them out and one has a leg snapped off at the body...maybe from the ompact of when they went in  :D

I don't even know if it is the better one or not.

Offline Rob181

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Re: one woofer pump_ground issue?
« Reply #26 on: October 12, 2014, 10:50:01 PM »
OK...Ok, went down and had a go.

First I would like to say that I'm about to have a very thorough shower shortly, but have them back, only an extra issue now with one, fishing them out and one has a leg snapped off at the body...maybe from the ompact of when they went in  :D

I don't even know if it is the better one or not.

That's better...

Once you have showered...relax...& enjoy some music...

Offline data

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Re: one woofer pump_ground issue?
« Reply #27 on: October 12, 2014, 11:17:37 PM »
Oh god, Rob, the things we do for audio parts, even dodgy ones ;)

Had a shower and did a.......repair of the leg as best I could, so now they go in the cupboard until and if i have a use  ::)

They look worse for wear....as expected after being in and out of a few different builds, and a dumpster also.

Offline zenelectro

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Re: one woofer pump_ground issue?
« Reply #28 on: October 13, 2014, 12:33:58 PM »
The other was still allowing over a half volt of DC pass (0.68v), not acceptable when there are no blocking caps on the input of my amp....or is it?

Still might dive in and see if I can get them out, luckily It's Sunday so may not be difficult or messy :)

But with my plans, and these being 1.5uf I doubt I'll use them unless I go with a SS player or DAC.......not likely for myself.

Edit: Ah bugger it, can't bring myself to dumpster dive to get them back.

Data,

You should really just get a tech to check it out, anyone who knows what they are doing will have the problem diagnosed very quickly.

If you are measuring DC on the OP of the pre amp this can be purely because there is no ground reference resistor at the OP to pull it to ground.
There should be a resistor -after- the OP cap going to ground but some equipment don't always have one,  they rely on the gear that the
pre is feeding to have an IP ground ref resistor which will pull it to ground. 

If there is no resistor to ground after the OP cap, solder a 1 meg R there to gnd and re measure.

If you have a decent size OP cap and the OP resistor is also large say >1.0uF and 1 Meg R then you may measure some
DC there that is constantly slowly hunting around because of very low frequency drift. But it will be 'hunting' around zero going + and -
to some small degree - this is normal.

Other causes of DC offset are a leaky grid on the IP tube that connects to the 'wiper' of the volume pot - assuming the vol pot
is right at the IP feeding the first tube.

There are some cases where a high frequency oscillation can measure as a DC offset with a multi meter and where the oscillation can
actually cause some DC offset, however this is not common and since you don't have an oscilloscope lets doubly hope so. :)

In the end you are better off just getting someone who knows what they are doing to check it out, you will save a lot of time.

cheers

Terry 
 


Offline data

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Re: one woofer pump_ground issue?
« Reply #29 on: October 13, 2014, 02:59:23 PM »
Wow!

Some stuff to take in, but very good stuff!

Thanks, mate......I'll look into those things and if need be I'll look for someone to have a look at it.

I wish you were local ;)

Thanks again
Ian

Edit: the Schamatic shows a 220k resistor to ground.
(Sub ECC83 with 6SL7)

« Last Edit: October 13, 2014, 03:09:41 PM by data »

Offline data

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Re: one woofer pump_ground issue?
« Reply #30 on: October 13, 2014, 06:00:41 PM »
OK, I'm going to search out a competent Tech' to look at this pre. I didn't like that he had the circuit ground tied directly to chassis as from reading up this is not a safe practice? but if I put a C/R in between (.047 & 39ohms) it has no music and DC pulses on the left channel  >:(

Anyone know of a good tube tech' in Brisbane?

Offline Jehuty

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Re: one woofer pump_ground issue?
« Reply #31 on: October 13, 2014, 07:36:57 PM »
OK, I'm going to search out a competent Tech' to look at this pre. I didn't like that he had the circuit ground tied directly to chassis as from reading up this is not a safe practice? but if I put a C/R in between (.047 & 39ohms) it has no music and DC pulses on the left channel  >:(

Anyone know of a good tube tech' in Brisbane?

Paul Baker. He's near Gold Coast though....But he's always worth a visit  8)
Not all that matters can be measured, not all that can be measured matters.

Offline data

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Re: one woofer pump_ground issue?
« Reply #32 on: October 13, 2014, 07:53:48 PM »
Cheers mate :)

Will need to wait a few weeks to engage him for the job, but this thing is a POS, taking everything back to how it was and worked and still a pulse in the left channel and no sound.

I might even just scrap the home made PBC and just go without and rebuild the bloody thing in a better case, as It's not that complicated a circuit......I think his layout/build on this PBC is part of the problem.

But who knows.

Offline Jehuty

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Re: one woofer pump_ground issue?
« Reply #33 on: October 13, 2014, 08:06:33 PM »
If you want a nice case, Paul Baker can get you a very nice one like this (borrowed pic from gamve):
Not all that matters can be measured, not all that can be measured matters.

Offline data

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Re: one woofer pump_ground issue?
« Reply #34 on: October 13, 2014, 08:19:27 PM »
Looks cool  8)

I'll have a think about things and work out what fits my budget, and when... before deciding what way to go.

Edit: My bad!
A ground wire that looked connected was actually broken :(

Working again..........silly me, as usual the problem was me  ;D

Will still rebuild the thing in the near future. It's also a good thing that I can laugh at my own mistakes.
« Last Edit: October 13, 2014, 09:06:56 PM by data »

Offline data

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Re: one woofer pump_ground issue?
« Reply #35 on: October 27, 2014, 03:25:37 PM »
Damn it! had to try the Duelunds one last time, and one leaks far too much.

But I definitely need more (maybe RS) as they cream the Russian PIOs  >:(
 :D

Offline stevenvalve

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Re: one woofer pump_ground issue?
« Reply #36 on: October 27, 2014, 11:32:58 PM »
Damn it! had to try the Duelunds one last time, and one leaks far too much.

But I definitely need more (maybe RS) as they cream the Russian PIOs  >:(
 :D
It's a problem, Duelunds are usually the only game in town.

Offline klackto

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Re: one woofer pump_ground issue?
« Reply #37 on: October 28, 2014, 07:10:23 AM »
Has anyone tried the RS series?

Offline data

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Re: one woofer pump_ground issue?
« Reply #38 on: October 28, 2014, 09:11:40 AM »
It's a problem, Duelunds are usually the only game in town.
Seems so Steve, I'll wait and get some in the new year.
8)

Offline data

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Re: one woofer pump_ground issue?
« Reply #39 on: October 28, 2014, 09:14:05 AM »
Has anyone tried the RS series?
Mike Lenehan has been using them I think.

Maybe Bill has hear them...