>
> I think that a good thing is to ramp up the input voltage slowly. Use a
> bench PSU to supply the Vstart voltage and then use a variac with
> insulation transformer to feed the rest if the supply. Use some small
> loads on the 5V and 12V outputs. Now you can safely probe the PSU and
> monitor
On 2022/11/27 1:21 a.m., Rob Jarratt via cctalk wrote:
I have done a little more probing around. I have found that the 7812 regulator
that drives Vstart on sheet 1 of Tony Duell’s schematic is shorted, so I will
have to replace this too. I have not found anything else that looks obviously
susp
> On 27 Nov 2022, at 10:21, Rob Jarratt wrote:
>
>
> I have done a little more probing around. I have found that the 7812
> regulator that drives Vstart on sheet 1 of Tony Duell’s schematic is shorted,
> so I will have to replace this too. I have not found anything else that looks
> obvio
I have done a little more probing around. I have found that the 7812 regulator
that drives Vstart on sheet 1 of Tony Duell’s schematic is shorted, so I will
have to replace this too. I have not found anything else that looks obviously
suspicious. I can’t test the output rectifiers for shorts wit
> -Original Message-
> From: Will Cooke via cctalk
> Sent: 26 November 2022 19:12
> To: Rob Jarratt via cctalk
> Cc: wrco...@wrcooke.net
> Subject: [cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power
> Supply
>
>
> I'm not at all famil
> On 11/26/2022 12:47 PM CST Rob Jarratt via cctalk
> wrote:
>
>
> Just trying to decide what to replace the failed diode with, and looking at
> the UF400x series, as suggested by Mattis. It seems to me that as long as the
> PIV is 200V or higher it should be fine from that point of view,
nd Off-Topic Posts
>
> Cc: Peter Coghlan
> Subject: [cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power
> Supply
>
> It is often possible to infer the component ratings needed from the other
> components around them. A component in the base circuit of a transisto
It is often possible to infer the component ratings needed from the other
components around them. A component in the base circuit of a transistor is
likely to experience lower currents and voltages than one in the collector
circuit.
In this case, we can see from Tony's diagram that there is a 2.7
Tony Duell has reverse engineered the following schematic.
http://www.bitsavers.org/pdf/dec/rainbow/duell_schematics/psu.pdf
I will go with the 1000V as you suggest anyway.
Thanks
Rob
From: Mattis Lind
Sent: 25 November 2022 07:12
To: r...@jarratt.me.uk
Cc: General Discussion:
> On 24 Nov 2022, at 22:45, Rob Jarratt wrote:
>
>
> Thanks for the suggestion Mattis. The UF4007 has a PIV of 1000V, I had a
> suggestion that the PIV should be 200V. Not sure what rating I should be
> going for here?
Given that I didn’t have a schematic and this is on the primary side I
You’re right, I superimposed the number.
That certainly doesn’t help at all.
Don Resor
Sent from someone's iPhone
> On Nov 23, 2022, at 10:50 PM, Don R via cctalk wrote:
>
> The data sheet lists H5892 through H5899 and H5900 through H5911.
>
> Don Resor
>
> Sent from someone's iPhone
>
>
Thanks for the suggestion Mattis. The UF4007 has a PIV of 1000V, I had a
suggestion that the PIV should be 200V. Not sure what rating I should be going
for here?
Regards
Rob
From: Mattis Lind
Sent: 22 November 2022 07:54
To: r...@jarratt.me.uk; General Discussion: On-Topic and Off-T
The data sheet lists H5892 through H5899 and H5900 through H5911.
Don Resor
Sent from someone's iPhone
> On Nov 23, 2022, at 4:32 PM, Peter Coghlan via cctalk
> wrote:
>
> Don,
>
> Does the url suggest you may have searched for a H5901 rather than a H9501?
>
> Regards,
> Peter Coghlan.
>
Don,
Does the url suggest you may have searched for a H5901 rather than a H9501?
Regards,
Peter Coghlan.
>
> NTE seems to turn up these possibilities for a H9501.
>
> https://www.nteinc.com/search/search/search.php?ss360Query=H5901
>
> Don Resor
>
> Sent from someone's iPhone
>
>> On Nov 23,
This data sheet may prove to be more useful.
https://www.nteinc.com/specs/5800to5899/pdf/nte5892_99.pdf
Don Resor
Sent from someone's iPhone
> On Nov 23, 2022, at 1:00 PM, Don R wrote:
>
> NTE seems to turn up these possibilities for a H9501.
>
> https://www.nteinc.com/search/search/search.
NTE seems to turn up these possibilities for a H9501.
https://www.nteinc.com/search/search/search.php?ss360Query=H5901
Don Resor
Sent from someone's iPhone
> On Nov 23, 2022, at 12:04 PM, Antonio Carlini via cctalk
> wrote:
>
> On 21/11/2022 21:45, Antonio Carlini wrote:
>>
>> I have two m
On 21/11/2022 21:45, Antonio Carlini wrote:
I have two more I can open up and look at, but I cannot get to them
tonight and I'm probably out tomorrow too. But I think I can get to
those other two supplies on Wednesday. Hopefully at least one of them
will be readable! Otherwise I can desolder
On 20/11/2022 21:03, Rob Jarratt via cctalk wrote:
> The location of the diode is arrowed on this picture:
> https://rjarratt.files.wordpress.com/2022/11/img_20221120_205802-arrowed.jpg
>
> You can also see the heatsink where the transistor used to be.
The component you refer to as an inductor is
Hello Rob!
>
> Given that before the transistor blew up there had clearly been another
> failure somewhere else, I tried to find the original failure. There were no
> obviously damaged parts, so I just probed around near the transistor for
> any
> parts that were open circuit or short circuit. I
On 20/11/2022 21:03, Rob Jarratt wrote:
Thanks Antonio,
The location of the diode is arrowed on this picture:
https://rjarratt.files.wordpress.com/2022/11/img_20221120_205802-arrowed.jpg
You can also see the heatsink where the transistor used to be.
This is mine:
https://drive.google.com/f
t;
> Thanks
>
> Rob
>
> > -Original Message-
> > From: Peter Coghlan via cctalk
> > Sent: 20 November 2022 18:50
> > To: General Discussion: On-Topic and Off-Topic Posts
> >
> > Cc: Peter Coghlan
> > Subject: [cctalk] Re: Identifyi
cctalk
> Sent: 20 November 2022 20:38
> To: Rob Jarratt via cctalk
> Cc: Antonio Carlini
> Subject: [cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power
> Supply
>
> On 20/11/2022 17:40, Rob Jarratt via cctalk wrote:
> > The H7842 PSU in my Rainbow failed yesterd
On 20/11/2022 17:40, Rob Jarratt via cctalk wrote:
The H7842 PSU in my Rainbow failed yesterday. At first the machine just
powered down and there was a slight burning smell, I wasn't next to the
machine when this happened, so I didn't see or hear anything to tell me
where the problem might be. No
Rob
> -Original Message-
> From: Peter Coghlan via cctalk
> Sent: 20 November 2022 18:50
> To: General Discussion: On-Topic and Off-Topic Posts
>
> Cc: Peter Coghlan
> Subject: [cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power
> Supply
>
>
Hi Rob,
I'm only guessing here. I think the sequence may have been that the
main switching transistor failed first as it would be under more stress
than a diode in the base circuit. If the transistor shorted E-B-C then
the HT would become connected to the circuitry at it's base which would
be co
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