At 15:28 01.07.2004 -0800, H.C. Croon wrote:
I have the HM605 with schematic. Perhaps there is some similarity.
In the schematic of the 605 the fly back suppresionpuls is coupled to the cathode circuit of the CRT, which is at high negative voltage, by an opto coupler. The output of the opto coupler is amplified by a complementary pair (BF440 (PNP) and BF199 (NPN)) and given to the cathode.
It might be a similar circuit, but I haven't found ay PNP transistors in that area yet. Exchanging T606 helped a bit, I can now adjust intensity to a spot where the fly back is invisible and the picture is absolutely perfect. However, the beam still stays on while the scope is waiting for a trigger event, and I bet it's not meant to be this way (I haven't used this scope for the past 4 years).
I'd appreciate a scan of that page, and maybe the trigger circuit page, because there must be some link to the suppression circuit.
If anyone on this list has the schematic of a HM604, it would be even better.
As for the BF311, I just bought "any" that I could get (BF311 is *not* obsolete as some pages suggest), and soldered that in.
ciao, -- Jens Sch�nfeld
-- Author: Jens =?iso-8859-1?Q?Sch=F6nfeld?= INET: [EMAIL PROTECTED]
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