Re: WG6100 heat problem

From: Kevin Moore <talon.k_at_gmail.com>
Date: Thu Apr 12 2012 - 15:12:26 EDT

Alot of the Jap parts exclude some of the part number. So looking for a
361-2 might not get you anywhere, try adding 2n. Then look for a 2n3612
then you will find your germanium power transistor.

Looks like the MPS-U57 was rated at 2A 100v 30-65 hFE fT 50MHz
NTE-50 2A 100V 100-? hFE fT 150MHz
2n3612 3A 60V 35-70hFE fT 40MHz

Kevin

On Thu, Apr 12, 2012 at 11:12 AM, Pat Danis <patdanis@verizon.net> wrote:

> Well, I replaced Q606 just in case it was bad. I rechecked all components
> in the circuit and all tested good. However, Q603 (and Q703) were
> different transistors than anything I had come across in the past.
>
> I missed them on my first go around on repairs and noticed this time that
> they were TO-220 packages instead of the smaller MPS-U57/U07 variety. This
> particular transistor is marked 361-2 and on the bottom of the chip, the
> Motorola symbol and 926 and what appears to be a smaller font capital "L".
> These are mounted on the standard heat sink but have a cutout to
> accommodate the larger transistor. They appear to be some sort of factory
> replacement. Has anyone seen these before and could you shed some light on
> their tolerances? I could not find a datasheet on them. Here is a link to
> the photo of the transistor in case you are curious:
>
> https://picasaweb.google.com/**pdkomodo77/WG6100Transistor?**
> authuser=0&authkey=Gv1sRgCI--**nZejz7ickAE&feat=directlink<https://picasaweb.google.com/pdkomodo77/WG6100Transistor?authuser=0&authkey=Gv1sRgCI--nZejz7ickAE&feat=directlink>
>
> I went ahead and replaced Q603 with a spare from a parts board in case
> these are out of tolerance for the application. I left the Q703 as-is to
> see what happens there.
> Thanks for your help on troubleshooting this. I guess it was just a bad
> transistor stuck open. It seems to be running at normal temperatures now.
> I left it on all night just to be sure.
>
> Pat
>
>
> On 4/3/2012 2:45 PM, Patrick Danis wrote:
>
>> Thanks Bill. I will report back with my findings after I troubleshoot.
>> Wish I had stayed an EE major at school.
>>
>> Pat
>>
>> On 4/3/2012 12:23 PM, wboucher6@cogeco.ca wrote:
>>
>>> Unfortunately, there are several things that could cause Q606 to be
>>> stuck turned on. I'll assume that Q606 is in fact
>>> good and not leaking like crazy. Be aware that it might operate/test
>>> okay when cool and go into thermal runaway once it
>>> warms up enough. In that case, you'd also get a picture for a while and
>>> I assume you are not.
>>>
>>> Faults that will cause your described condition:
>>> - an open diode at D600, D601, or D602
>>> - an open R611
>>> - an open Q603
>>> - a shorted Q601
>>> - opens at any of R602, R604, Q602, R605
>>>
>>>
>>>
>>> Bill Boucher
>>> http://www.biltronix.com
>>>
>>>
>>>
>>> Been fixing 6100's for some time and this is the first time I have run
>>>> into this issue. I have a monitor that was brought to me with the
>>>> following problem. Q606 is getting extremely hot. So hot that the
>>>> transistor socket is turning black like burnt toast and the frame is
>>>> almost too hot to handle on the right hand side.
>>>>
>>>> Believe it or not, the transistor is still working. I have been through
>>>> the deflection board several times and found nothing. I did find both
>>>> power transistors bad so replaced those and the blown fuses and the
>>>> socket on Q606 and it still will not come up. I only spent a few
>>>> minutes on it as I had to leave town for business. I'm just curious
>>>> what would cause the transistor to get so blasted hot.
>>>>
>>>> I will be getting back to it on Saturday to troubleshoot some more.
>>>>
>>>> Pat
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>>>>
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Received on Thu Apr 12 15:12:35 2012

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