Toss another kit on the barbie....

My kit arrived today so I will be building it over the weekend. Watching 
the comments closely.

  -Bill-


On Friday, May 21, 2021 at 5:14:24 PM UTC-7 gregebert wrote:

> I have an Aneng UT61e; cheap but quite good. One of my scopes has a pair 
> of 100x probes that lets me look at a few kV, but I was too lazy to bring 
> it up today. If I run into problems I'll post some screenshots.
>
> After installing the diff-amp transistors and Q1, current-drain increased 
> to 360mA.
>
> I suggest you bench-test your power-supply board by itself first; 
> disconnect all cables, and jumper J5-4 and J5-5 together to enable the HV 
> supply. Make sure all generated voltages are correct, especially the 300V 
> supply (should be around 305V per the instructions).
>
> On Friday, May 21, 2021 at 4:10:55 PM UTC-7 John Snow wrote:
>
>> Paying full attention - what model DMM do you have if you can't directly 
>> connect it? I have an 87V I'm happy to connect as it's rated for 1KV.
>>
>> On Friday, May 21, 2021 at 11:38:27 PM UTC+1 gregebert wrote:
>>
>>> UPDATE 1: I built the power supply/driver board and completed some basic 
>>> testing. I installed all components EXCEPT the transistors for the diff-amp 
>>> that drives the CRT. The standby current at 12V is zero. The HV supply can 
>>> be enabled by grounding the POWER_ON signal; that causes the inverter to 
>>> run and the current is 170mA. The neon bulb is on and it's supply is 306V; 
>>> the +5 and -5 supplies also work. The filament supply voltage on my scope 
>>> is about 500kHz, somewhat sinusoidal, and about 17V pk-pk, which is about 
>>> 6.3 Vrms for a pure sinusoid. The HV is beyond the range of my DMM so I had 
>>> to put a 10meg resistor in-series to double the range (inaccurately, 
>>> because it's a 10% resistor) and measure around 1270 VDC.
>>>
>>> Next step is to build the other board. Stay tuned.
>>>
>>> On Thursday, May 20, 2021 at 7:34:52 AM UTC-7 John Snow wrote:
>>>
>>>>
>>>> I've been checking over solderjoints, hoping to find a Q or U with a 
>>>> solderbridge, no luck.
>>>>
>>>> Ah, I hadn't made the connection - I found your build guide before, 
>>>> it's what made me decide to order one. It's been useful for making A or B 
>>>> comparions for anything standing out.
>>>>
>>>> I've also been checking over the circuitboard hoping to find a Q or U 
>>>> inverted, but they're all following the soldermask guides.
>>>>
>>>> There's no breakout for and ground VCC_300 to easily probe? 
>>>> On Thursday, May 20, 2021 at 8:10:06 AM UTC+1 Paolo Cravero wrote:
>>>>
>>>>> John,
>>>>> pictures of my build are here: 
>>>>> https://ik1zyw.blogspot.com/2020/10/kit-oscilloscope-clock-8sj31j-review-3.html
>>>>>
>>>>> The code on the HV board is the same. I think I reversed a 79Lxx, but 
>>>>> the smell of it burning was too obvious and I cannot tell what the effect 
>>>>> was on the CRT.
>>>>>
>>>>> I do get intermittent failure probably caused by a cold joint at a 
>>>>> ground point that was not designed with thermal relief and it took me a 
>>>>> while to solder.
>>>>>
>>>>> Paolo
>>>>>
>>>>>
>>>>> On Thu, May 20, 2021 at 12:49 AM John Snow <[email protected]> wrote:
>>>>>
>>>>>> Hi Paolo,
>>>>>>
>>>>>> no filament glow after one minute powered on,
>>>>>>
>>>>>> both fuses continuity checked, they've not blown
>>>>>>
>>>>>> I'm getting 60V across the indicator bulb.
>>>>>>
>>>>>> Which voltage regulator did you reverse?
>>>>>>
>>>>>> -- 
>>>>>>
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>>>>> To view this discussion on the web, visit 
>>>>>> https://groups.google.com/d/msgid/neonixie-l/3f6e2a4a-ed6d-485d-9ccc-a0dfc157b451n%40googlegroups.com
>>>>>>  
>>>>>> <https://groups.google.com/d/msgid/neonixie-l/3f6e2a4a-ed6d-485d-9ccc-a0dfc157b451n%40googlegroups.com?utm_medium=email&utm_source=footer>
>>>>>> .
>>>>>>
>>>>>

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