Today feeling a little bored and not really knowing what to do or what to have a stab at, I thought lets have a look at the yucky old Ultra and give it the first baseline evaluation. Well it has been a while since I had a Thorn on the bench and I know how some of you just love them so don't all groan at once
Here we go, I bought this set back in April along with an HMV 2725
and other than a quick peak inside to see the cobwebs, live spiders, gnawed front edge and mouse puke balls, pretty much left it to one side. That description should at least paint a picture that this set has seen better days but I've had worse on the bench.
The various modules look to be in fairly good condition with the PSU module looking a little on the tired side but I've had worse.
The Ultra's PSU module outwardly looks fairly OK, the most obvious first problem to address before power up is C607, this is in the 30V supply, no 30V rail means no 'Chopper' drive therefore no 'EHT', no 'Field scan' or 'sound' So the three rails 240V, 30V and 58-65V will all need to be checked out and to do this rather than using the set I use my Thorn test rig.
I guess on the 3000/3500 the single most troublesome module is the PSU, I've had no end of fun with these and having repaired four of them so far this year, I'm starting to get to grips with them as you can follow over here
. In fact I've spent so much time working on Thorn PSU modules I have a dedicated work bench with the test rig, relevant data plastered on the back wall and parts all to hand.
First job then is C607 but before I did that I wanted to see what the A56 120X is like and OH dear! what a disappointment. First of all I could hardly set the Cut-Off for the red gun, only managing to raise it to the required +1 division by having the G2 control at maximum rotation. Green and Blue Cut-off's were set normally. When emission tested well what can I say other than its pants!
I left it running on the B&K for an hour and then rechecked Reds Cut-Off, there was a slight improvement but very minor. The emission did not improve whatsoever. Next I tried clean and balance, this restored Red and blue but Green was having none of it.
So the only option open to me now was a rejuvenate of the Green gun. This achieved the desired result giving Green the lifty that was needed.
Well at least the repair is now viable and I should get something decent from the A56 120X. That's as far as I've got this morning, later this afternoon will see C607 replaced and then the PSU module loaded on to the test rig for first power application. Then the fun and games will truly start and as I said at the start I do apologise to those that are sick and tired of my Thorn 3000/3500 set repairs.