Help!!!!!!!!!!!!

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jestaudio
Posts: 654
Joined: Sat Mar 12, 2011 4:12 pm
Location: UK

Help!!!!!!!!!!!!

Post by jestaudio »

Some one please give me some direction before i go bonkers, i,m trying to test the voltage of a gz34 rec before i connect anything up, all i have is 6 v dc, got 290 on either ht when measured to eart, the centre tap is grounded properlly, the heaters are showing just over 5 v ac and the pin outs are correct, this is a brand new rectifier. Any suggestions please :cry:
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Phil_S
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Location: Baltimore, MD

Re: Help!!!!!!!!!!!!

Post by Phil_S »

Even though you tell us wiring is correct, I think we want to see a photo of the socket showing enough to identify the wiring for ourselves. I've done it myself where I'm so sure nothing was done wrong when it was. You have not much to lose and lots to gain, so give us a photo.

Assuming it is all wired correctly, either the tube is bad or there is a wiring error. Well, maybe something else, but can't imagine what, a bad cap? Exactly how are you going about measuring the 6V? Red probe where, black probe where?

Are your caps all oriented correctly? Are there any grounds made on the B+ rail that are unintended?
jestaudio
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Location: UK

Re: Help!!!!!!!!!!!!

Post by jestaudio »

Phil_S wrote:Even though you tell us wiring is correct, I think we want to see a photo of the socket showing enough to identify the wiring for ourselves. I've done it myself where I'm so sure nothing was done wrong when it was. You have not much to lose and lots to gain, so give us a photo.

Assuming it is all wired correctly, either the tube is bad or there is a wiring error. Well, maybe something else, but can't imagine what, a bad cap? Exactly how are you going about measuring the 6V? Red probe where, black probe where?

Are your caps all oriented correctly? Are there any grounds made on the B+ rail that are unintended?
no caps fitted measuring from the star earth to pin 8, just quickly wired up a silicon diode rectifier to check the transformer and got 409 volts dc,.
The keyway sits between the heaters, the heaters are working ok got a nice glow off them
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Luthierwnc
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Location: Asheville, NC

Re: Help!!!!!!!!!!!!

Post by Luthierwnc »

I have 2 UF4007s wired to a broken octal tube base to check rectifier functions in the spark testing phase of some builds. The diodes go from pins 4 and 6 to pin 8 and it is smothered with some big shrink tubing so it doesn't get too friendly with conductive neighbors (or fingers). I usually unsolder the 5v from pin 8 but probably don't have to. Course, you can't fully goose the SS rectifier unless the caps can handle it but on a variac you just bring it to the expected B+.

At 15 cents a piece for the diodes and nothing for the base it is a handy gizmo to have in the what's-it bin. You can buy them ready made too. sh
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rdjones
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Location: Music City, TN

Re: Help!!!!!!!!!!!!

Post by rdjones »

jestaudio wrote:Some one please give me some direction before i go bonkers, i,m trying to test the voltage of a gz34 rec before i connect anything up, all i have is 6 v dc, got 290 on either ht when measured to eart, the centre tap is grounded properlly, the heaters are showing just over 5 v ac and the pin outs are correct, this is a brand new rectifier. Any suggestions please :cry:
You need some capacitance to hold the DC voltage for measurement so it will measure low.
I would expect more than 6 VDC, though.

rd
Alexo
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Re: Help!!!!!!!!!!!!

Post by Alexo »

yes, it isn't exactly DC yet. Do you have any known good rect tubes you can sub in?
Life is a tale told by an idiot -- full of sound and fury, signifying nothing.

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jestaudio
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Location: UK

Re: Help!!!!!!!!!!!!

Post by jestaudio »

Alexo wrote:yes, it isn't exactly DC yet. Do you have any known good rect tubes you can sub in?
Unfortunatly not, i normally use diode rectifiers rather than tube, typical really i,ve got stacks of preamp and power tubes but no recs, i'm very much inclined to assume the tubes duff and see if my supplier will accept a return
jestaudio
Posts: 654
Joined: Sat Mar 12, 2011 4:12 pm
Location: UK

Re: Help!!!!!!!!!!!!

Post by jestaudio »

rdjones wrote:
jestaudio wrote:Some one please give me some direction before i go bonkers, i,m trying to test the voltage of a gz34 rec before i connect anything up, all i have is 6 v dc, got 290 on either ht when measured to eart, the centre tap is grounded properlly, the heaters are showing just over 5 v ac and the pin outs are correct, this is a brand new rectifier. Any suggestions please :cry:
You need some capacitance to hold the DC voltage for measurement so it will measure low.
I would expect more than 6 VDC, though.

rd
might it be worth hooking up a 450v cap as a resovoir to see what happens
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