[TechAssist] Re: HELP! Goldstar VCR Model #GHV-1233M - Correct PS cap orientation?
- From: "al m" <ampm@xxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Thu, 10 Jul 2003 09:01:16 -0400
Positive lead should go to positive voltage. You have it in backwards.
al marquardt
ampm@xxxxxxx
Al Marquardt Electronic Repair
206 W Main
Girardville Pa. 17935
----- Original Message -----
From: "Don Cohen" <bond007d@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Wednesday, July 09, 2003 11:55 AM
Subject: [TechAssist] HELP! Goldstar VCR Model #GHV-1233M - Correct PS cap
orientation?
> Hello,
>
> This is an old 1986 model that customer really likes and wants fixed=
> regardless of cost (to a point). Left side deck gears (looking from
front)=
> were broken, so I replaced the whole deck with one from a newer model=
> junker with same deck - gears looked fine. I did all the usual
maintenance=
> and also replaced 3 caps on the power supply board. When I plugged unit
in,=
> it looked like it was doing a reset operation, but something seemed=
> binding, with the mode motor continuing to turn when it should have shut=
> off. After about 5 seconds, there was a horrific pop and one of the caps
I=
> had replaced blew up. There was no previous problem with VCR other than=
> maintenance and broken gears. That cap was C112 on the power supply
board=
> and is a 100uF/16V. I tested it before I put it in with an ESR meter and
it=
> tested fine. Since the whole outer case blew right off, I am not able to=
> check to make sure I even put it in correctly (polarity), but I am
pretty=
> sure I did, as I always check that before finishing. I did not make note=
> when I pulled it out if the part marking matched the silk screen info. I=
> know that sometimes they are marked wrong. The silk screen on board says=
> that the + leg goes to the center pin of IC102 (positive 9 volt
regulator=
> AN78M09). That pin is ground. Also according to the silk screen, the=
> negative leg is supposed to go to pin 1 of IC102, which is Vin. On the=
> newer unit that I robbed the deck from, the power supply is designed=
> differently, but the same regulator and cap are there (except the
voltage=
> on the cap had apparently been upgraded to 25v) and the orientation is=
> reversed for the cap - neg leg of cap to center IC pin and positive to
pin=
> 1. That is what I would expect.
>
> So, does anyone have an old schematic or service bulletin that they could=
> verify that the silk screen info is indeed wrong? If not, does it sound=
> correct that the cap's + leg should not go to the IC's (and board)
ground=
> pin? Obviously I could just try to put another in again the way the silk=
> screen says and assume I somehow put it in backwards, but I would rather=
> not keep blowing parts and possibly doing other damage till I figure out=
> what the issue is.
>
> Much thanks to anyone that can help out here.
>
>
> Don Cohen
> DC Electronics
> Shinglehouse, PA=20
>
>
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