18-05-2015, 07:49 PM
About 15 years back, I was offered a DM64 once - IIRC, the gent wanted just a tenner for it. I looked inside, and declined the offer 
I've been spoilt, having had a DM63 for 25 years. It's still my default 'scope - I like the form factor, which occupies less bench space than a convention "horizontal" 'scope. These days I have 2 or 3 of them in various states. Despite the small difference in model number, there is a massive difference in construction. You can really see the Tek influence on the DM63 (and D83, which is related).
Do you have access to another 'scope? With that, you should be able to break it down before diving in there. I assume you've downloaded the manual?
Is it a lack of sweep, or is it a faulty X-amp? Or is it a fault in the mode switching (external X or X-Y modes)? It might be that the trigger circuit is locked out, indicating a fault with the comparator or bistable. Can you get anything from the Gate and Sweep outputs? From what you say, I assume you have 1 or 2 spots? Are these at normal brightness, and where on the screen are they? Do they move when you alter the X-pos controls, the X5 magnifier, or press Beam Locate?
Usual generic Telequipment faults:
- Resistors failing high, especially in the power supply or EHT sections.
- Transistors failing - often MPS6518, but others as well. Especially if they are in a plastic TO92 package and run hot, but the MPS6518s fail for fun in any position (I replace them with BC327-25 as I have hundreds of them)
- Transistor sockets needing to be cleaned.
- Capacitors drying up. Not surprisingly... Probably not the main issue here, but expect to replace a few later on.
- EHT transformers failing. Luckily not seen that personally, but it happens.
All the best,
Mark
I've been spoilt, having had a DM63 for 25 years. It's still my default 'scope - I like the form factor, which occupies less bench space than a convention "horizontal" 'scope. These days I have 2 or 3 of them in various states. Despite the small difference in model number, there is a massive difference in construction. You can really see the Tek influence on the DM63 (and D83, which is related).
Do you have access to another 'scope? With that, you should be able to break it down before diving in there. I assume you've downloaded the manual?
Is it a lack of sweep, or is it a faulty X-amp? Or is it a fault in the mode switching (external X or X-Y modes)? It might be that the trigger circuit is locked out, indicating a fault with the comparator or bistable. Can you get anything from the Gate and Sweep outputs? From what you say, I assume you have 1 or 2 spots? Are these at normal brightness, and where on the screen are they? Do they move when you alter the X-pos controls, the X5 magnifier, or press Beam Locate?
Usual generic Telequipment faults:
- Resistors failing high, especially in the power supply or EHT sections.
- Transistors failing - often MPS6518, but others as well. Especially if they are in a plastic TO92 package and run hot, but the MPS6518s fail for fun in any position (I replace them with BC327-25 as I have hundreds of them)
- Transistor sockets needing to be cleaned.
- Capacitors drying up. Not surprisingly... Probably not the main issue here, but expect to replace a few later on.
- EHT transformers failing. Luckily not seen that personally, but it happens.
All the best,
Mark
