[time-nuts] Re: Z3801A questions

[Bob Camp]

Hi

Each time I’ve had a Z3801 fail, a fuse in the front end (ahead of the internal supplies) has been the issue. 
Replace that fuse and they go back to normal function for a number of years. Obviously, a blown fuse is
open circuit and we’re looking at a short in this case. 

It does bring up the question: What about that fuse? 

1) The cap you “lost” is ahead of the fuse. Not sure there are many in that category …

2) The fuse is defective. 

3) The fuse was replaced with a short at some earlier repair point.

4) It’s also possible that there multiple versions of the 3801 and some do and others don’t have fuses. 

Something more to consider.

Bob

> On May 22, 2023, at 7:26 PM, Mahlon Haunschild via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Ed,
> 
> I think my 48V golf car battery bank is stiff enough for this :)
> 
> Seriously, that is what I always intended to try first.  Fed through a suitable fuse/circuit breaker, of course.  Will give it a go and report back later.
> 
> Best regards
> 
> Mahlon -N4ZK
> 
>> On May 22, 2023, at 2:19 PM, ed breya via time-nuts <time-nuts at lists.febo.com> wrote:
>> 
>> Before doing a bunch of mods to the Z3801A PS, it would be wise to try running it from a linear supply with enough V and A to launch. SMPSs usually have a hard time with load startup surges. In PS experimenting on my 24V unit, I found that SMPS units of seemingly adequate size - even two paralleled - could not fire it up from cold. Neither could a linear one, unless rated for much higher output current - it would fold-back and stall.
>> 
>> The bottom line is that you need substantially more than nameplate current to get these puppies up and running. They were built to run from telecom battery bus supplies, which can handle those critical few
>> seconds at startup.
>> 
>> An old-school unregulated transformer/rectifier/capacitor supply is the closest match. This kind of setup can be sized (VA-wise) close to the normal running power needed, but is forgiving enough to handle the startup surge - use a slow fuse sized about right for steady-state VA.
>> 
>> Ed
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com
>> To unsubscribe send an email to time-nuts-leave at lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe send an email to time-nuts-leave at lists.febo.com