HM504-2 rotary encoder problems

[Hydrawerk]

The timebase knob on my Hameg HM504-2 started developing problems in late 2014.
The video works fine, do not mind the grey color at preview.

I should replace it in future. The scope can still be used, though. The scope was manufactured in 2007 and bought in 2008 in a sale in a second-hand store. The warranty is gone.
The scope was not used very often, just a few times in a month. 

[Fraser]

I used to sell Hameg oscilloscopes in the late 1980's. They were always happy to help with problems and they still provide schematic diagrams upon request. Things may have changed under R&S management but you could ask customer services about obtaining a replacement encoder. You may be pleasantly surprised by their response.

I have an oscilloscope that suffered from intermittent push button operation. I was very pleased to see the switch manufacturers part no. next to each switch on the schematic  diagram. It was then easy to find the exact replacement part. Worth checking to see if Hameg have used a COTS encoder from ALPS or BOURNS.

Aurora

[Fraser]

I have just taken a look at my similar HM2005 oscilloscope schematic and have attached the relevant part as a PDF. Sadly the schematic set is slightly too big to attach.

The Timebase encoder is shown as a 'STEC16B04' on the schematic. Very helpful of Hameg to provide that detail. I note that there are two types of encoders used on the scope STEC16B03 and the STEC16B04. On my scope the Y channels and Time base use the same encoder type. The only difference between the '03' and '04' is whether a click action detent is present.

The STEC16B04 is an ALPS part and costs less than $5 It would be worth buying some spares at that price !

http://www.distrelec.ch/de/Encoder-24-24-%C3%B8-6-mm-abgeflacht-Alps-STEC16B04/p/13584673

Datasheet attached. Thankfully these are not hard to find parts 

You need to confirm that my scope uses the same part as yours but it is very likely that Hameg do use a part like this across their range.

Let me know how you get on 

Aurora

[Hydrawerk]

Thank you for your advice. I do not have much time now, so I will repair it in two months or so.

[Fraser]

At least you now know that the encoder is likely to be a nice common ALPS type and nothing custom, or hard to source

It is worth an email to Hameg Customer services to request your units schematics. They have never disappointed me but they do not seem to provide service manuals.

Aurora