Re: Tek 2247A [SN B029000] Recap and diode part list ?


Darren Ting
 

Hi Jerry,

Based on service manual for 2247A, I can't  find Tantalum cap, am I missing something?
Old thread mention my issues could be Q2209 and Q2210 C-E shorted, quick measures give me 100kohm and above for any test point on this two Qs.  so shorted C-E unlikely.

Measure on-board C2210 give  7.2uF rather  than  4.7uF.  Look very suspicious




From: "jerry massengale j_massengale@aol.com [TekScopes]" <TekScopes@yahoogroups.com>
To: TekScopes@yahoogroups.com
Sent: Sunday, 13 March 2016, 22:10
Subject: Re: [TekScopes] Tek 2247A [SN B029000] Recap and diode part list ?

  Darren,

I look for caps that show signs of heat, either a swollen top or a darkened case. Surface mount aluminum caps get replaced always. Tantalum caps that are used at greater than 50% of their rating get replaced.

I would not replace any diode without cause.

Jerry Massengale

-----Original Message-----
From: TING HENG CHING darren_ting_hc@yahoo.com [TekScopes] <TekScopes@yahoogroups.com>
To: TekScopes <TekScopes@yahoogroups.com>
Sent: Sun, Mar 13, 2016 8:38 am
Subject: [TekScopes] Tek 2247A [SN B029000] Recap and diode part list ?

Does anyone keep a list of parts for recap power supply board [A18] on 2247A ?

I toke out the power supply board [A18], but can not find any diode mark as ZM or ZS which known to have issue and recommended to replace as well.
All I can find is mark as Motorola instead, diode issue not applicable to B290000 and later?
My unit based on IC date code should be late in 1994.
It run fine but decided to recap before it fail, more than 20 years old caps sound really scary.
However, I found burn mark on my power board near area :- A18CR2228
A18R2255A18R2275A18R2254A18CR2227
Something went WRONG to my power supply board? FAN is running fine.

Could someone advise related to burn mark? should I worry? look scary to me





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