Sorry to learn the news. Unless you want a matching Tentec supply, I'd opt for
an inexpensive 12 volt supply.
I purchased a new switching supply which I found to be astonishing clean
radiation wise from Amazon for $20. It is a LED lighting supply rated at 12
volts @ 20 amps. I tweaked the voltage pot so I have 14.0 volts.
Bob, K4TAX
Sent from my iPhone
> On Oct 6, 2019, at 8:57 PM, Johnathon Allread <john.allread@gmail.com> wrote:
>
> Gents,
>
> It appears that the transformer is bad. There may be more bad components,
> I am not sure. While taking meter readings, my main fuse blew. I changed
> it and it blew again.
>
> I desoldered the 2 output connections to the power supply circuit and was
> only getting 2VAC from the output of the transformer.
>
> So it appears I need a power supply. If you have one, please let me know
> what you want for it shipped to 75077. Thanks!
>
> 73's
>
> John - NE5J
>
>
> Johnathon B. Allread
> john.allread@gmail.com
> 469-336-7763
>
> "The Road to Success is Always Under Construction" - Lily Tomlin
>
>
>> On Sun, Oct 6, 2019 at 9:19 AM Mike Bryce <prosolar@sssnet.com> wrote:
>>
>> gary,
>>
>> that supply is very simple.
>>
>> if you have 25 V AC from the secondary of the transformer yet no dc on the
>> cap, check the bridge rectifier. They have been known to go bad in that
>> radio. Most likely one or more of the diodes inside have opened.
>> Replacement is the best way to check, they’re not expensive or hard to
>> obtain
>>
>> the over trip circuit uses the voltage drop across a low value resistor
>> that when it drops an excessive amount, trips a scr that shuts the PS down.
>> It only controls the DC side of the power supply.
>>
>> when it trips, you would still see both ac from the transformer and dc
>> across the filter cap.
>>
>>
>> Mike, WB8VGE
>> www.theheathkitshop.com
>>
>>
>>
>>> On Oct 6, 2019, at 1:01 AM, Gary Follett <dukeshifi@comcast.net> wrote:
>>>
>>> Well I have a transformer for the C21 sitting right behind me if you
>> find that you need it.
>>>
>>> With the power switch on, you should see voltage across C1 regardless of
>> trip condition, as long as the power switch is OK.
>>>
>>> You should also see voltage across C2.
>>>
>>> If not, use an ohmmeter to measure transformer windings and power
>> switch. It is not unheard of for that switch to be bad. I may have one of
>> those too.
>>>
>>> Since it is ,not blowing the fuse, likely the diodes in the bridge are
>> OK but it would to hurt to test them for open. I doubt you sill find any
>> open though. Diodes usually fail shorted.
>>>
>>> Gary
>>>
>>> W0DVN
>>>
>>>> On Oct 5, 2019, at 10:15 PM, Johnathon Allread <john.allread@gmail.com>
>> wrote:
>>>>
>>>> Hello everyone,
>>>>
>>>> I recently purchased a digital version of a Century 21. Unfortunately,
>>>> when I received it, It will not power on. When I turn it off, it very
>>>> briefly powers on then off. I have verified 120VAC going to the
>>>> transformer from the switch and tried to verify 25VDC from the
>> transformer,
>>>> but I am not seeing a DC output across the capacitor C1. I did this
>>>> quickly, so I will recheck tomorrow. My question is, if there is an
>> issue
>>>> with the excess current trip shut down circuit, would it have any
>> impact on
>>>> the unregulated output of the transformer or just affect the regulated
>> side
>>>> of IC1? I am trying to understand the circuit, but my electronics
>>>> knowledge is limited when it comes to ICs and transistors. By the way,
>>>> this unit is spotless inside and does not look like it has been worked
>> on.
>>>> Lastly, If there was an issue with the transformer, where could I
>> purchase
>>>> a replacement? Thank you!
>>>>
>>>> 73's
>>>>
>>>> Johnathon - NE5J
>>>>
>>>> Johnathon B. Allread
>>>> john.allread@gmail.com
>>>> 469-336-7763
>>>>
>>>> "The Road to Success is Always Under Construction" - Lily Tomlin
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