Peter, I don't have direct experience of this but typically an amplitude of 1V or so and PRF of 1kHz - 1MHz would be fine. The scope is looking for a well defined (in time) trigger point and comparing

My DC503 also has nothing connected at the lower of the two points in your picture. On my board there are four of these holes in a row with no wires or components attached, partky hidden by the shaft

The high ripple you measure on the 50V and 100+ Volt supplies is usually due to the large 'bulk' smoothing capacitors on those supplies drying out with age and simultaneously losing their capacitance

When you measure R331 in-circuit there is a parallel current path through U330 and R330 (1k) so you might well see a low value of resistance and it would probably be different if you reversed the pola

Stephen, You have (at least) two distinct issues with comments coming in which are relevant to one or the other and are randomly interleaved. 1. The LCD display does not scan so typically only one LED

Stephen, So is either C548 or C549 showing high leakage (low resistance) with one leg unsoldered? Roger

Stephen, If you have almost zero volts across C548 then the -22V regulated supply is at almost zero volts. The most likely culprits are C548 itself and C549 which sits after L549 to provide an additio

U340 is a 7447 BCD to 7 segment decoder, £1.50 plus postage on eBay. Are you sure that U340 is the culprit? U 340 drives the individual segments of all the 7 segment displays in parallel. A fault with

If the scren is glowing but there is no trace the beam is probably deflected way off screen and you see some reflected electrons from the walls of the CRT. The power light is driven by the +20V regula

Sorry for the mistype, the module is of course the DC503. Roger

Stephen, The DC502 has a lot of switches for counting interval, AB switching, totalling ... They are prone to give intermittent contacts with age and can usually be improved substantially by a lot of

Just looking at the pictures of the attenuator board in the manual, the relays appear to be from the same series that have been problematic in other 7k plugins. I don't know if some contact arrangemen

Colin, If you have a problem with the triangle wave symmetry then I would begin with that before looking elsewhere. The operation is well described in the manual but I need the big screen to look at t

Hi Siggi, I am very interested to follow this thread since I might well need to recalibrate a 2465B and I am not keen on removing the NVRAM without some better de-soldering tools. I have no problem in

Thanks for the eBay link to the button repair kits, I am intrigued by how they work since they have no knowledge of the geometry of the conductors that they have to bridge when the button is pressed.

Thanks for all the replies and suggestions. Colin, 48 years ago I described Aquadag properly in my PhD thesis, the minimum purchase was something like six 5lb jars of a very thick concentrate that had

I have recently acquired a TDS744A which is working fine but I have minor concerns about the front panel buttons. The 'clear menu' button needs a much firmer push than its neighbours around the screen

Colin, Glad to hear it is working OK, if there is no need to clean the cam switches then don't rush into it, there is advice around that says energetic cleaning with the wrong type of paper can remove

Colin, If there are intermittent segments on the LEDs then the 74(LS)47 7 segment decoder is the likely culprit and is probably socketed (it is on my DM501). Roger

Correction, I don't think the cam switches improve with use, if they are dirty they need cleaning with IPA and strips of paper. Roger