-> not stable, case closed and a few times off/on -> first "m" for mV disappeared while "?" was ok, then "V" changed to "S", then again "4", "500V", ... appeared.
I consider, resoldering all solderings on the board, but big effort as brute force method.
Max
toggle quoted message
Show quoted text
--- In TekScopes@..., "max_3289" <max_3289@...> wrote:
Hi Albert, Jerry,
first i measured:
TP2119: -14,94 VDC with 3,75 mVAC ripple
TP2117: 4,96 VDC with 3,45 mVAC ripple
TP2115: 15,05 VDC with 9,94 mVAC ripple
-> ok.
Then, while thinking how to change the connections for Albert's proposal, i saw the characters all correct!
Obviously i touched some device while measuring the voltages (i have moved out and in all socketed transistors long before without success...), perhaps a bad soldering somewhere.
I will observe for the next days, by good luck the problem was gone and no IC affected.
Thanks a lot for your help!
Max.
BTW: is it possible to get email notification only for dedicated topics?
--- In TekScopes@..., jerry massengale <j_massengale@> wrote:
Hi,
There are 3 power test points on the readout board. Make sure all 3 voltages(+/-15V and 5V) are ripple free and stable with the 5V reading 4.8V or better.
Jerry Massengale
-----Original Message-----
From: max_3289 <max_3289@>
To: TekScopes <TekScopes@...>
Sent: Sun, Jul 22, 2012 12:14 pm
Subject: [TekScopes] Re: 7633 readout problem, advice or hints needed
Hello Albert,
backplaneboard A1, J2 contact A37 to readout board A13, U2190 pin 12 -> low ohmic
backplaneboard A1, J2 contact A38 to readout board A13, U2190 pin 11 -> low ohmic
backplaneboard A1, J2 contact B37 to readout board A13, U2180 pin 12 -> low ohmic
backplaneboard A1, J2 contact B38 to readout board A13, U2180 pin 11 -> low ohmic
aAll the diodes on the protection circuit board of A13 are ok.
Connections are ok, connectors are all clean.
After cooling down over night, there were seen some false characters again for some time.
Any ideas?
Max.
--- In TekScopes@..., "Albert" <aodiversen@> wrote:
Hi Max,
This makes contacts A37 and B37 suspect.
Remember this is a first check. The fault could also be in a readout board channel selector IC for instance.
Albert
Hi Albert,
thanks a lot; just tested the following:
I have 2 pcs. 7A22, 1 pc 7A26, 1 pc 7B53A, 1 pc 7B85.
The 7A26 in left position shows both channels ok, in centre position only CH2 (bottom middle position readout) ok, CH1 (top middle position) no readout.
7B53A and 7B85 timebases show no difference (except additional 7B85 readout bottom right).
It seems to be the problem of the backplane-connector you mentioned.
Did you read the other readout problems thread, concerning a R7903?
not yet; have not known it yet.
Max.
