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WME_bill · 13th Jan 2018, 4:51 pm

Telequipment D54. Nice machine, dual trace, 10Mhz, with a very good Brimar tube D13-47. Worth getting going. I'd endorse what the others say.

But even more first, check out all the voltage rails. Should be within +-10% at this stage. As it appears to be largely working, leave electrolytics alone. They are often a higher grade in test gear than in consumer equipment.

The EHT resistor chain is a well known weak spot on later Telequipment (Tektronix) scopes (D63,D75,D83), but this one has a mains powered EHT, lower value resistors and less voltage stress across them. and you have a trace, so leave R302-305 alone.
You appear to have a Y trace.

Have you an external X trace: feed in the calibrator to get a horizontal line, and can you shift and expand it (X shift and X gain controls). That confirms the X Amplifier. Though the initial spot only moving half the screen suggests half the X amplifier has failed. Easy to identify, just check voltages across X amplifier loads R175,R179. Leave that for now and get the TB working first.

So now look at where the main trouble sounds to be: Trigger, or the Timebase itself.
Trigger is a traditional trouble spot with early Telequipment scopes, but this one appears a Tektronix design after the take-over, which are usually better.
Check control settings, Normal/Int with Y1 signal input, Y1 on, Y2 off, TrigCh1. Set Trigger Level to Auto and Stability to fully CW. Then try with Trigger Level central and play with Stability. Those should give a horizontal sweep.
If not, clean all Trigger and TB switches.
The negative voltages mentioned shouldn't be a problem on this model. It is not a separate feed from the EHT supply, as in some earlier Telequipment scopes, jsy off the -12v rails.

Transistors. I have found the Motorola pnp MPS6518 a bit unreliable. I have had much trouble with them in a couple of D67, where substitution proved a quick solution. Almost any small general purpose pnp eg. BC388/BC212/BC307 will do. It doesn't matter if it is not quite the same specification, as long a voltage rating is enough, as you want to get the thing working now.
wme_bill m0wpn

13th Jan 2018, 4:51 pm	#8
WME_bill Octode Join Date: Oct 2007 Location: Exeter, Devon, UK. Posts: 1,554	Re: New member and a Telequipment D54 Telequipment D54. Nice machine, dual trace, 10Mhz, with a very good Brimar tube D13-47. Worth getting going. I'd endorse what the others say. But even more first, check out all the voltage rails. Should be within +-10% at this stage. As it appears to be largely working, leave electrolytics alone. They are often a higher grade in test gear than in consumer equipment. The EHT resistor chain is a well known weak spot on later Telequipment (Tektronix) scopes (D63,D75,D83), but this one has a mains powered EHT, lower value resistors and less voltage stress across them. and you have a trace, so leave R302-305 alone. You appear to have a Y trace. Have you an external X trace: feed in the calibrator to get a horizontal line, and can you shift and expand it (X shift and X gain controls). That confirms the X Amplifier. Though the initial spot only moving half the screen suggests half the X amplifier has failed. Easy to identify, just check voltages across X amplifier loads R175,R179. Leave that for now and get the TB working first. So now look at where the main trouble sounds to be: Trigger, or the Timebase itself. Trigger is a traditional trouble spot with early Telequipment scopes, but this one appears a Tektronix design after the take-over, which are usually better. Check control settings, Normal/Int with Y1 signal input, Y1 on, Y2 off, TrigCh1. Set Trigger Level to Auto and Stability to fully CW. Then try with Trigger Level central and play with Stability. Those should give a horizontal sweep. If not, clean all Trigger and TB switches. The negative voltages mentioned shouldn't be a problem on this model. It is not a separate feed from the EHT supply, as in some earlier Telequipment scopes, jsy off the -12v rails. Transistors. I have found the Motorola pnp MPS6518 a bit unreliable. I have had much trouble with them in a couple of D67, where substitution proved a quick solution. Almost any small general purpose pnp eg. BC388/BC212/BC307 will do. It doesn't matter if it is not quite the same specification, as long a voltage rating is enough, as you want to get the thing working now. wme_bill m0wpn