Tektronix 2445 Readout is no good , video included
in [Repair]
|
Prev: Avometer Model 8 repair
Next: sharp lcd 5 inch LQ5RB43
From: NetSpid3r on 14 Nov 2007 16:26 http://video.yahoo.com/video/play?vid=1466538 The readout looks bad , i can see jumpy dots ,instead of clear numbers as in the other 2445 . i replaced those 3 47uf caps on the A5 board (control board) , and it didn't helped . http://img110.imageshack.us/img110/2372/image015pn5.jpg
From: Jim Yanik on 14 Nov 2007 21:04 "NetSpid3r(a)gmail.com" <NetSpid3r(a)gmail.com> wrote in news:1195075563.961231.101880(a)57g2000hsv.googlegroups.com: > http://video.yahoo.com/video/play?vid=1466538 > > The readout looks bad , i can see jumpy dots ,instead of clear numbers > as in the other 2445 . > i replaced those 3 47uf caps on the A5 board (control board) , and it > didn't helped . > http://img110.imageshack.us/img110/2372/image015pn5.jpg > > 2445 non-B scopes have separate R-O boards. the signal from them feeds into the vertical on the main bottom board. try swapping the readout boards. IIRC,there's also a pot to adjust R-O crawl/jitter. see the cal procedure in your service manual. On "B" models,the readout is integrated to the A5 uP board. "B" model A5 uP boards are NOT swappable with earlier versions. -- Jim Yanik jyanik at kua.net
From: JW on 15 Nov 2007 05:36 On Wed, 14 Nov 2007 21:26:03 -0000 "NetSpid3r(a)gmail.com" <NetSpid3r(a)gmail.com> wrote in Message id: <1195075563.961231.101880(a)57g2000hsv.googlegroups.com>: >http://video.yahoo.com/video/play?vid=1466538 > >The readout looks bad , i can see jumpy dots ,instead of clear numbers >as in the other 2445 . >i replaced those 3 47uf caps on the A5 board (control board) , and it >didn't helped . >http://img110.imageshack.us/img110/2372/image015pn5.jpg I'll second what Jim has said with regards to the jitter pot. On very early serial numbers, the pot and a few passive components were tack soldered to U800 (An ECN I guess - I just replaced a U800 on a 2465 that had this). On later serial numbers, R805 was added to the A1 board. It couldn't hurt to give it a twiddle.
From: NetSpid3r on 15 Nov 2007 17:08 Jim Yanik wrote: > "NetSpid3r(a)gmail.com" <NetSpid3r(a)gmail.com> wrote in > news:1195075563.961231.101880(a)57g2000hsv.googlegroups.com: > > > http://video.yahoo.com/video/play?vid=1466538 > > > > The readout looks bad , i can see jumpy dots ,instead of clear numbers > > as in the other 2445 . > > i replaced those 3 47uf caps on the A5 board (control board) , and it > > didn't helped . > > http://img110.imageshack.us/img110/2372/image015pn5.jpg > > > > > > 2445 non-B scopes have separate R-O boards. > the signal from them feeds into the vertical on the main bottom board. > try swapping the readout boards. > IIRC,there's also a pot to adjust R-O crawl/jitter. > see the cal procedure in your service manual. > > On "B" models,the readout is integrated to the A5 uP board. > "B" model A5 uP boards are NOT swappable with earlier versions. > > -- > Jim Yanik > jyanik > at > kua.net tried play with jitter , didn't do the trick ... and you are right about A5 in the 2445 , the R-O is not on this board , i just did a swap with a good 2445 A5 and got the same jerky readout . what component is making the problem in the R-O of the 2445 ? caps ? or something else ?
From: Jim Yanik on 15 Nov 2007 23:57
"NetSpid3r(a)gmail.com" <NetSpid3r(a)gmail.com> wrote in news:19dc4e5b-d326- 4c17-9bc9-bb21fa6f033f(a)a28g2000hsc.googlegroups.com: > > > Jim Yanik wrote: >> "NetSpid3r(a)gmail.com" <NetSpid3r(a)gmail.com> wrote in >> news:1195075563.961231.101880(a)57g2000hsv.googlegroups.com: >> >> > http://video.yahoo.com/video/play?vid=1466538 >> > >> > The readout looks bad , i can see jumpy dots ,instead of clear numbers >> > as in the other 2445 . >> > i replaced those 3 47uf caps on the A5 board (control board) , and it >> > didn't helped . >> > http://img110.imageshack.us/img110/2372/image015pn5.jpg >> > >> > >> >> 2445 non-B scopes have separate R-O boards. >> the signal from them feeds into the vertical on the main bottom board. >> try swapping the readout boards. >> IIRC,there's also a pot to adjust R-O crawl/jitter. >> see the cal procedure in your service manual. >> >> On "B" models,the readout is integrated to the A5 uP board. >> "B" model A5 uP boards are NOT swappable with earlier versions. >> >> -- >> Jim Yanik >> jyanik >> at >> kua.net > tried play with jitter , didn't do the trick ... > > and you are right about A5 in the 2445 , the R-O is not on this > board , i just did a swap with a good 2445 A5 and got the same jerky > readout . > > what component is making the problem in the R-O of the 2445 ? > caps ? or something else ? > possibly caps,or a bad hybrid on the main board. Does it twitch in the vert or horiz direction,or both? signal trace solid,in both V and H axes? This may be where you have to scope every decoupled PS supply line. could even be some of those 0.1uf DIP caps that are all over every board. -- Jim Yanik jyanik at kua.net |