STD4 endless selection repeat in UK

[Ron Rich]

Follow the "orange wire"--

[normantomlin]

Hi Ron,
Been trying that today with little success. After cleaning the PCB connector and refreshing all the solder joints on orange, it did work briefly on all bulbs, apart from duds obviously. Then orange sequence went off again after a few minutes. I then noticed that if I pull the plug to the lights on the lower front panel, all bulbs in the upper panel come on, but those connected to orange stay at about half brightness, but do not flash like the other four sequences. That sounds like a ground issue to me, what do you think?
regards
Norman

[Ron Rich]

Hi Norman,
My Guess woodbe-- a "plug issue", or a cold (dry) solder, issue-- coodbe a ground, but I don't think so ?? Ron Rich

[normantomlin]

Hi Ron,
Thanks for that. I think I'll park the lights issue until I get all the dud replacements bulbs replaced in case that is having an effect.
I have discovered another issue regarding the amp I think. Left hand channel is often dead, when I swap the outputs on the back of the amp right hand is dead. Occasionally the left channel will spring to life. However what is strange is that when both channels work there is often a really loud pop/bang when the selection ends and the channel is dead again. Could this be something to do with the mute/trip relay? I did 'adjust' the relay by bending the lower outer pins, as in your book. Might I have bent one too much?
Norman

[Ron Rich]

Hi Norman,
Check both Guides-- I think you have a problem with the cartridge socket, in the tone arm---I would advise purchasing the new black colored one being sold now on eBay (USA), before you monkey with the old, white one-- Ron Rich

[normantomlin]

I'll give it a good look over. Can't remember what colour or is to be honest.
Thanks again Ron

[Ron Rich]

Hi Norman,
I told you-- it's white (Nylon?)-- remember I am not always rite-er, write, ah, correct-- but I'z nevar rong !! LOL -- Ron Rich

[normantomlin]

Hi Ron,
Sorry I misunderstood. Yes mine is white
I swapped over the red and blue inputs to the amp and the problem did not switch sides. To me this suggests there isn't a problem between cartridge and amp. I swapped over the output wires and the problem did switch over.
I also have a spare preamp board, which I installed and there was no change in behaviour. I.e very quiet muffled bass from left hand channel whereas right seems normal.
I do have a cap kit for the amp which I haven't installed yet. Do you think this is worth trying at this stage?
Can transistors be checked in circuit, as I do have a simple LCR t4 tester.
Sorry this is such a ramble.
Norman

[Ron Rich]

Hi Norman,
I agree-- you have narrowed it down to the output section of the SHP-- Yes-- smaller transistors can be checked in circuit, but I doubt that will be the problem-- Check the interconnect plugs-- Yes--again- cap kit MIGHT help-- worth the try, IMHO--- Good luck-- Ron Rich

[normantomlin]

Hi Ron, thanks for the quick response. I'll get on with cleaning connectors and replacing caps.
Norman

[normantomlin]

Hi Ron,
I saw something on you tube about checking voltage between test point on the best sink and body of RCA transistors. Is this worth a try, before I get the soldering iron out?
Norman

[Ron Rich]

Hi Norman,
I'll refer you to the "Hi Newbies" post in our FAQ's above--- Ron Rich

[normantomlin]

Hi Ron,
Point taken re. You tube. Have been replacing caps on driver board and chassis and checking transistors as best as I can while in circuit. Not put it back together yet.
I was thinking about your comment on interconnects and was chasing down and cleaning connectors. I noticed that SN12 stereo network unit had plugs for amp and horns. Is it possible there could be a problem in there? Can find very little about this unit.
Norman
Norman

[normantomlin]

Hi Ron,
Back together now. Left hand channel still misbehaving.
Sounds a little 'brighter' but that could be my imagination.
Would it be worth trying the 16w output rather than 50w, to see if there's a problem with t5103?
Norman

[normantomlin]

Hi Ron,
I think cancel the thought about SN12. I followed the audio service diagram and disconnected the input to it. No difference except RH horn obviously off.
Norman