Re: G05 HV troubles

On 08/23/2013 5:16 AM, Jeffrey Matthews wrote:
> Andrew;
> Did you check/replace D904 leading to the anode cup?
> I had a R901 cooking and found that to be the culprit.
> Jeff
>
Indeed, the HV diode can cause all sorts of overheating problems. I see
that they are still being made by a few people and available from a
couple of suppliers:

http://hvstuff.com/high-voltage-diodes-and-rectifiers

And:

http://www.americanmicrosemi.com/products/search/index.php

Look for the 2CL73, 2CL74 and 2CL75

John :-#)#
>
>
>
> On 8/23/2013 4:56 AM, Andrew Welburn wrote:
>> hi all..
>>
>> I've been fighting with a HV box from hell recently, and i've held
>> off posting to vectorlist until i was really stuck. I'm at that point
>> now.
>>
>> Its a G05-802...
>>
>> Right now, R901 is smoking up. I'm only getting 7.2kv at the anode,
>> and the HV adjust pot does not change the hv. I can only have it
>> running for 10 seconds before R901 really starts to cook off.
>>
>> The flyback was actually bad, as the HV was bouncing around from
>> nothing up to 7kv very erratically before, so i swapped that from a
>> known-good v2000 hv box. Now i get a steady HV, albeit low and r901
>> still burning up. (R901 was cooked crispy before the flyback swap
>> anyway)
>>
>> I have subsequently swapped _every_ diode and transistors in the
>> box, and it still acts the same, no improvements. I also changed the
>> electrolytics, and the HV adjust pot itself (R905).
>>
>> Can anyone think of a scenario that would let R901 burn up? any
>> pointers as to where i should be looking harder?
>>
>> thanks..
>>
>
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