[Premium-Rx] CUBIC-CDR-3250-LF-HF-DSP-COMMUNICATION-RECEIVER

[jrusgrove at comcast.net]

Peter

Interesting on the glue blob issue. I didn't mention that earlier thinking it was probably a one off 
with the unit I was working on.

Same here ... it was under the 220 uF / 35 v electrolytic. Trace was intact but fiberglass was 
charred. Dug out all charred material and applied a mixture of epoxy and fiberglass 'milling 
powder'. Once harderened I touched up the area with a green conformal coating repair pen. That was 
the only glue blob that had a problem but, like you, I removed all other signs of glue when 
replacing the other electrolytics.

Thanks for the confirmation that this isn't wasn't a one off situation!

Jay W1VD


----- Original Message ----- 
From: "Peter Hamilton" <lists at g4vlc.net>
To: <premium-rx at mailman.qth.net>
Sent: Friday, January 01, 2016 6:44 AM
Subject: Re: [Premium-Rx] CUBIC-CDR-3250-LF-HF-DSP-COMMUNICATION-RECEIVER


>I had two PSU failures out of four. Symptoms not identical to yours, the
> restarting was intermittent. I didn't need to trace out the schematic as
> the worst one had failed dramatically and I just had to follow my eyes /
> nose.
>
> (NB, this was the 31xx - but probably similar / identical to the 32xx)
>
>
> One of the electrolytic capacitors, C10 (220uF, 35V) has a top-side track
> running close to it. There is no solder resist on the top side. The C had
> been fixed to the PCB with blobs of glue, big enough to cover the nearby
> track and soak under the C. The glue in the failed PSUs had decayed with
> heat/age and was brown and slightly sticky. Decayed glue can be conductive,
> but to make matters worse the Cs had leaked some electrolyte which had
> seeped under the glue to the adjacent track. In the worst PSU this had
> clearly cooked for a long time, leaving the board charred to about half its
> depth.
>
> The second PSU in that unit had the same decayed glue and capacitor
> leakage, but there was no charring.
>
> Both PSUs worked some of the time (until the worst one died in a puff of
> smoke), but would intermittently shut down and restart.
>
> The second, more recent, 3130 used different glue, possibly cyanoacrylate,
> which was still clear and brittle.
>
> To be safe I updated all four PSUs by removing all glue, replacing all the
> electrolytics with 105deg long-life ones, and removing the offending track
> and replacing it with an insulated wire link. They've now been on soak at
> 260V for a couple of weeks without problems.
>
> If anyone's interested I have a "shopping list" of >=105deg, >=5000Hrs
> electrolytics with Farnell/Newark order codes.
>
> Not sure whether the list supports attachments, but I also have some pics.
>
>
> --
>
> Peter (G4VLC)
>
>
> On 31 December 2015 at 22:15, VK3XYZ <VK3XYZ at wia.org.au> wrote:
>
>> Hi all,
>> Given it looks like there's a few of these receivers about ...... would
>> anyone have reversed engineered the schematic for the power supply (would
>> save me some effort)? I have a couple that continuously cycle between
>> startup and shutdown. I suspect the obsolete ML4811 switch mode IC is dead
>> but if anyone else has come across this before and found a solution I'd be
>> very interested.
>>
>> If it is the controller IC, again to save some effort, would anyone have
>> already designed a form fit replacement?
>>
>> Thanks
>> Greg
>>
>> -----Original Message-----
>>
>>
>> Today's Topics:
>>
>>    1. Re: CUBIC-CDR-3250-LF-HF-DSP-COMMUNICATION-RECEIVER
>>       (Peter Hamilton)
>>    2. Re: CUBIC-CDR-3250-LF-HF-DSP-COMMUNICATION-RECEIVER (Rick Vesny)
>>    3. Re: CUBIC-CDR-3250-LF-HF-DSP-COMMUNICATION-RECEIVER
>>       (Peter Hamilton)
>>    4. Re: CUBIC-CDR-3250-LF-HF-DSP-COMMUNICATION-RECEIVER (W4NJ)
>>    5. Re: Cubic CDR-3250 (Tisha Hayes)
>>    6. Re: CUBIC-CDR-3250-LF-HF-DSP-COMMUNICATION-RECEIVER (Ed)
>>
>>
>> ----------------------------------------------------------------------
>> End of Premium-Rx Digest, Vol 109, Issue 9
>> ******************************************
>>
>>
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