Texas Star DX 350 HDV Issue

[Phantom43]

I've just dusted off my old 2950 and Texas Star but seem to have a slight problem. I had these when I lived in Missouri and never had an issue but the Texas Star doesn't appear to be working right.

The amp powers up and output is fine, a 1W dead from the radio is giving about 90W out the amp so I believe output is fine. The problem I have is with receive, as soon as I turn on the amp it's as if an attenuator is switched in, signals drop by a good S5-S7. The pre-amp button is also not doing anything. It's been a good 12 years since this was powered up, was hoping someone might be able to point me in the right direction.

Richard

[MDYoungblood]

It sounds like the relays are stinking and that would be since it is sitting so long. I haven't been inside a TS in quite a while but I think the caps on the relays will pop off and spray the contacts with some good cleaner. I like DeoxIT D5 and then use canned air to blow out any residue. Let it dry before using the amp.

3's

Greg

[Phantom43]

Thanks for the response, after a little research I checked the keying transistor and that was short circuit which I think would explain the relay switching in as soon as power is on. The pre-amp transistor is the same and looked okay so I swapped it over (no shops to buy transistors, need to order some). Has slightly different symptoms now, with delay switch on it acts as before immediately switching the relay on when pressing power or pre-amp switch. With delay switch off pressing power or pre-amp seems to move the relay but not fully engage it.

Will continue investigating but if anyone has seen similar symptoms let me know.

Thanks

Richard

[Phantom43]

I'm thinking maybe the delay capacitor is short circuit, that might explain the difference with delay switch on or off.

Can someone confirm for me that the keying circuit is RF sensing, so the relay should not engage without an RF signal present?

This was my understanding but doubting myself a little now.

Richard

[Phantom43]

Hmmm.... I might need to admit defeat and seek professional help.

Been on this a fair few hours today and apart from finding a faulty transistor I haven't made much progress. Took the delay capacitor out but that didn't test short circuit.

I don't have a problem paying a good shop to fix this for me, it's just a pain sending it back to the States and the time that will all take. I doubt there is anyone in the UK with experience of Texas Star amps.

I'm all ears if anyone has ideas on the problems or recommendations for a really good repair shop.

Thanks

Richard

[Phantom43]

I've ordered a load of caps for the amp and a replacement relay just in case, no doubt it will take some time for all of that to arrive so I had another look at the amp today anyway.

Removed all the caps from the keying circuit, they all tested okay so re-used them and put new transistors in for the pre-amp and keying circuit. The amp fired right up and is now working as it should.

So I'm very pleased with that, just need to spend more time operating now.

Thanks

Richard