On 1/7/2022 2:35 PM, Nigel Johnson Ham via cctalk wrote:
I told the chief engineer that the problem was the same thing that
caused planes to crash, and he suggested maybe the cargo door had fallen
off! (that puts it in 1972 since it was AA Flight 96 that had just
happened!)
My uncle worked
> The terminal posts are aluminum, and can develop an oxide
> layer that prevents good contact.
>
> Removing and replacing them might improve the contact.
I have experienced this personally with TO-3 regulators, too. I had a bunch of
triple voltage Power One linear supplies that would intermitten
On 1/7/22 2:21 PM, Rob Jarratt via cctalk wrote:
Weirdly, the whine has disappeared. This is after I put the suspect capacitors
back in. Because I had previously removed them for reforming, I wonder if one
of them was not properly screwed in?
The terminal posts are aluminum, and can develop a
-
From: cctalk On Behalf Of Jay Jaeger via
cctalk
Sent: 07 January 2022 16:02
To:cctalk@classiccmp.org
Subject: Re: Source for replacement caps in H744 regulators
On 1/6/2022 7:03 PM, W2HX via cctalk wrote:
My 2c. I am not familiar with a "whine" but certainly a "hum." So
t; cctalk
> Sent: 07 January 2022 16:02
> To: cctalk@classiccmp.org
> Subject: Re: Source for replacement caps in H744 regulators
>
> On 1/6/2022 7:03 PM, W2HX via cctalk wrote:
> > My 2c. I am not familiar with a "whine" but certainly a "hum." Sometimes if
>
On 1/6/2022 7:03 PM, W2HX via cctalk wrote:
My 2c. I am not familiar with a "whine" but certainly a "hum." Sometimes if a power
supply has seen a lot of heavy load over its lifetime, the heat generated can begin to do things to the
transformer. And once that heat has done its "thing" to the tra
On 07/01/2022 02:39, Jon Elson via cctalk wrote:
> Yes, the 2nd unit is running at 5 KHz, clearly explaining the noise.
> Possibly there is a bad flyback diode, or something causing the
> different waveform.
>
That would be D5 I guess? I did do some checks in this area but I can't
remember if I s
On 1/6/22 6:04 PM, Matt Burke via cctalk wrote:
Quiet regulator: http://www.9track.net/posts/h744/h744_ba11_q2e.png
Noisy regulator: http://www.9track.net/posts/h744/h744_ts11_q2e.png
The yellow trace is the emitter of Q2 (input of L1) and the cyan trace
is the output of L1. Q2 seems to be swit
On 2022-Jan-06, at 4:04 PM, Matt Burke via cctalk wrote:
> On 06/01/2022 12:59, Jonathan Chapman via cctalk wrote:
>> That said, it's not like replacing them with new will *hurt* -- it just
>> might not fix the whine.
>
> I suspect that it won't fix the problem. Slightly hijacking the thread
> he
ay, January 6, 2022 7:05 PM
To: cctalk@classiccmp.org
Subject: Re: Source for replacement caps in H744 regulators
On 06/01/2022 12:59, Jonathan Chapman via cctalk wrote:
> That said, it's not like replacing them with new will *hurt* -- it just might
> not fix the whine.
I suspect that it
On 06/01/2022 12:59, Jonathan Chapman via cctalk wrote:
> That said, it's not like replacing them with new will *hurt* -- it just might
> not fix the whine.
I suspect that it won't fix the problem. Slightly hijacking the thread
here but hopefully in a semi-helpful way.
I have two of these regula
It would be a lot easier to replace the large circular regulator if you're
taking the shotgun approach, and much more likely that the regulator is a
source of faults. and it's cheaper. For the h744, 45, 54. BUT measuring
things is the best way if you can do it. Pull the values from the
backpla
On 1/6/22 2:52 AM, Rob Jarratt via cctalk wrote:
I think I may need to replace the two output capacitors in some of my H744
regulators. These are screw terminal 6,000uF 10V parts. I have looked on
Mouser, Farnell and Digikey and there don't seem to be any available, and
any that are listed are re
> -Original Message-
> From: cctalk On Behalf Of Peter Coghlan
> via cctalk
> Sent: 06 January 2022 12:16
> To: General Discussion: On-Topic and Off-Topic Posts
>
> Subject: RE: Source for replacement caps in H744 regulators
>
>
> >
> >> --
> -Original Message-
> From: Jonathan Chapman
> Sent: 06 January 2022 13:00
> To: r...@jarratt.me.uk; Rob Jarratt ; General
> Discussion: On-Topic and Off-Topic Posts
> Subject: RE: Source for replacement caps in H744 regulators
>
> > One of the H744 regulator
>
>> -Original Message-
>> From: cctalk On Behalf Of Christian Corti
>> via cctalk
>> Sent: 06 January 2022 10:02
>> To: General Discussion: On-Topic and Off-Topic Posts
>>
>> Subject: Re: Source for replacement caps in H744 regulators
> One of the H744 regulators whines
FWIW, none of mine are silent under load. If they're not being loaded (e.g. on
a test bench, with no dummy load, or if you have all the boards out) they can
whine excessively due to no minimum load.
> it seems higher than the expected values printed on the me
> -Original Message-
> From: cctalk On Behalf Of Christian Corti
> via cctalk
> Sent: 06 January 2022 10:02
> To: General Discussion: On-Topic and Off-Topic Posts
>
> Subject: Re: Source for replacement caps in H744 regulators
>
> On Thu, 6 Jan 2022, r...@
Rob,
The voltage rating is just an absolute maximum. For PSU capacitors the other
critical rating is ripple current. Lower voltages are
The capacitance value won't be too critical either. At the time that was
made typical electrolytic tolerances were -50/+100%
So your 6,000uf could be anywhere be
On Thu, 6 Jan 2022, r...@jarratt.me.uk wrote:
If I can't find 10V rated ones, then, generally up to what sort of voltage
rating can I go? Of course, physical size will be a factor, but electrically
can it affect operation of the regulator if the rated voltage is too high?
If you need to ask thi
On 06/01/2022 08:52, Rob Jarratt via cctalk wrote:
> I think I may need to replace the two output capacitors in some of my H744
> regulators. These are screw terminal 6,000uF 10V parts. I have looked on
> Mouser, Farnell and Digikey and there don't seem to be any available, and
> any that are liste
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