[time-nuts] 8 kHz problem in Wavetek/Rockland 5135A synthesizer

gandalfg8 at aol.com gandalfg8 at aol.com
Wed Sep 19 05:49:24 EDT 2018


I remember your DDS problems with the 5120A, and of course it was our conversations that led to the notes I mentioned that discussed board similarities.
When looking those notes out I came across a previous comment expressing surprise at the small C&K mains switch that often seem to give problems.
Whilst there's no doubt those switches can be a cause of problems it was only last year when working on a 5120 with a faulty power supply that I realised they aren't switching mains voltage, the power supplies are live as soon as mains is connected and the switch is actually an On/Standby switch and seems to operate at -12.4V to control the outputs.

I see also I referred to the PTS 160 DDS option, and have since acquired a PTS160 with an obviously functional fine resolution DDS option that's marked as option J on the serial number plate, with a brief description in the PTS3200 manual but still with no schematic:-(


Looking back again, I suspect it will be the PTS310 manual that might be closest to what you need.
I'm not sure but it seems it should be closer than the 160/500 etc with all their DM modules.
I see Murphy's law is still up and running well, I'm glad your problem seems to be resolved but also hate those faults that end up fixed without knowing why.
Re your comments about poor soldering etc on the 5120A, I've always considered the PTS series to have exceptional build quality but a PTS160 that failed in transit for no obvious reason took quite a bit of tracing to identify a small blob of solder that must have been shaken out of one of the modules and into its edge connector socket. Fortunately it only shorted a signal line and not power!

Nigel, GM8PZR

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