Ultra 6020

[ekjdm14]

Definitely not just valve amps that give trouble. In fact I think most valve issues are actually caused by other things out of tolerance rather than the valves themselves.

The problem with germanium transistors tends to be tin whiskers, hence my thought of cleaning the cans out if replacements weren't easily available.

I was thinking it's worth replacing the remaining 'lytics as a matter of course anyway (it's more my way of doing things than testing/reinstalling nearly half century old ones, on someone else's gear anyhow. I admit I like the way the old Callins/Elco/Hunts ones look but there's no way they can be in tolerance by now). Either way, looking forward to having a look at it now. It's almost nice to have something with an actual electronic problem/symptom to work with rather than mechanical or recapping which is about all that's needed with my current stash of kit. (this may change tomorrow though as there's a few lots at auction I have an eye on!)

[BUSHVHF]

Well, I have to be honest the guy who did this player for me did say that he thought it was these "whiskers" that were forming from the germanium to the metal can of the transistor, but as I said this very young guy in Preston is very well regarded, I took him to a radi swap meet last year and he is well known, but I wont be going back as there are so many conflicting things that he is telling me, he told me he bought transistors for this player early in january, he has had it since december and as my plan was to take it back to The Netherlands I had to force the issue and just told him I would collect it anyway even if he cant fix it, which to be fair he did do partly but as it is a 70 mile round trip I just wont be going back, he's not cheap either. he did say that he replaced one cap and the others were showing good readings so I dont really know, you can see the sound is quite good on my little youtube vid but the hissing is terrible. I did have a Bush SRP31C with a fantastic valve amp but it has a Garrard 210 deck that was nothing but trouble so I sold that one. Laurence

[ekjdm14]

It depends on how he's tested the caps, there's more than one test for electrolytics & they can show good on one but not another. I don't have a proper old-school cap tester just my multimeter and ESR meter so I tend to err on the side of caution for what replacements cost, it's up to you though if you wanted them replaced. Any components I replace I'll do my usual thing & bag the originals up and fix them inside the machine anyway.

It's good that this other guy is young, at least it shows there's still some interest in the "game" even if he is financially motivated currently (and I'm not saying that is his reasons) it's the kind of thing that gets under your skin as I have found! The reason for conflicting ideas might be a case of youthful enthusiasm, at least that's what I try to tell myself when I get excited and bounce from pillar to post on what something could be )

Anyway must fly, there's an auction begging for my attention!

[BUSHVHF]

Yes to be fair this guy started when he was about 11!! I think his grandfather taught him, I think he is 19 now and he is a musician, he plays organ on most of his youtube vids and he has some very extensive restoration vids of old radiograms and radios, so he seems to know his stuff, I dont think he is too "mercenary" really but I think he is just doing too much and he has this rather annoying habit of TOTALLY IGNORING you, both to emails/texta,phone calls, and alot of things dont tally when you ask him about them, like when he told me early jan. he bought new transistors for this amp but in the end just said that he thought it was the whiskers in the old transistors that caused this awful hissing (but what happened to the transistors he "claims" he bought?? I did give him a £40 deposit for this player and the deck was very siezed up at first so he has got that free-er running and OK on autochange, he changed the cartridge and put a BSR one with a flipover ST8 lp/78 stylus. I dont know what to think really but I have decided I am not going back to him, as I recommended another guy to go to him and he has totally ignored this guy, whcih looks bad on me, so I told him about my problems and that now I have the player back from him I wont be going back and this guy told me he wont now either. This young guy is very very self assured, a real "salesman" type, but this business of not keeping in touch or giving a breakdown on what he has done does rub me the worng way, he knows my situation I wanted to take this player to The Netherlands, and the way it went if I left it with him it wouldnt get done for months - You seem to know what youre doing and I am sure you will get to the bottom of putting it right, I dont think it is irrepairable as the amp plays so well in all other respects. Laurence

[ekjdm14]

Auction done & dusted, didn't get the main object of my desires (A Decca Sound Compact2) but came away with a modern ('90s) Matsui stack system cheap & a lovely Ekco valve radio to restore.

I think you're probably right he might have taken on a bit much and is struggling to prioritise. Not sure on the transistor thing though, maybe he thought he had a source and told you he had them a bit prematurely before then finding out he couldn't get them or they were no good. Whatever the case a bit of honesty wouldn't hurt though, if nothing else it's doing him out of business which is a bad thing if he's trying to make a living at it.

I do a fair impression of knowing what I'm about haha, still on a learning curve really but electronics/electrics have always been a hobby since I was a kid, second only to mechanical work. Certainly don't think the amp would be irrepairable, the way I like to look at things is pretty much everything is able to be repaired if you go about it in the right way.

[BUSHVHF]

Yes, this was the problem, I didn''t feel I was getting an honest appraisal, no follow up, ignoring all my mails, texts, even on his youtube channel, funnily enough someone else came on to me via his youtube channel over a similiar problem this guy was having with money paid and then NOTHING (I didn't get involved in it) but after this guy made this post he was MIRACULOUSLY Repaid!! So yes, problems there, which I don't intend to repeat, especially with a 70 mile turnaround just to take things and wait months to collect them. I have a good feeling you will get this Ultra going for me!! Laurence

[ekjdm14]

OK, thank you for bringing the set for me to have a play with Laurence. Have had a quick preliminary inspection this evening & pulled the chassis to examine/compare to the 6024 schematic which it appears to match closely thus far.

First impressions are, I don't feel the capacitors have been tested properly since the solder joints are quite obviously the factory job. Further, the one cap which was replaced has a dry joint and the track is starting to lift (no criticism of the previous guy on that count, this is a danger with older PCBs but the dry joint won't be helping matters any.) Also have changed the 13 amp fuse for a 3 amp which should be more than enough!

I'll do some further checking against the schematic tomorrow hopefully and when I'm happy that it matches what's in front of me I'll quickly check some voltages and then move on to removing and checking the remaining Hunts electrolytic caps. For how many there are (7 total, 6 if the admittedly good quality Vishay your man fitted is good) I'd suggest it'd be worth replacing them anyway seeing as they're Hunts brand in the main, along with the big Daly and a couple of Callins.

One thing I have just this minute noticed different to the schematic I have, the bias stabilising Ge diode is specced as AA129 when the unit has AC169 fitted, the output transistors match the schematic but then the AF amp and driver differ slightly too.

Will look further into what this means when my eyes are fresh but may be of little consequence. Whatever the score I believe I can source any of the transistors that may be suspect, either as fitted or as specced in the schematic. I'll hold off on any of that until I know the rest of the circuit is in spec and behaving as it should though.

Give me a shout on what you think re: testing/keeping any good caps or replacing them all, Cheers for now, Dan.

[Herald1360]

Originally Posted by ekjdm14

.....13 amp fuse for a 3 amp....

Nice touch, there

[ekjdm14]

OK first interesting point, the AC169 in the bias stabiliser diode position is in fact (according to Cricklewood, whose list I would trust) a transistor, although it's definitely only got 2 legs visible/in circuit and appears original.

Could this be a case where they've lopped a leg off a transistor and utilised it as a diode when the correct part was not in stock? Or am I missing something?

As to the fuse change, most of the kit I have seen comes ill-equipped with 13A. Scary really but must be a common thing. If I had a 1A I would have fitted that to be honest since I doubt this player is capable of using anywhere near 240W at nominal line voltage.

[ms660]

Transistors used as diodes in that circuit position was common place.

Lawrence.

[Herald1360]

Don't forget that the plug fuse function is to protect the cable, not the appliance. That should be internally protected if required.

Some equipments (especially those with a mains transformer) will take switch on surges which can be tens of times above normal running current for a few cycles of the mains- this may make the best choice of fuse the largest one safe for the cable size, rather than the one best matched to the normal running current.

Anyone who's tried running a Farnell H60/50 from a 13A supply will know all about this!

[ekjdm14]

Don't forget that the plug fuse function is to protect the cable, not the appliance.

This was my first thought when I opened the plug to verify the terminations, this player has a lovely dark green mains cable (in great condition) which matches the cabinet, I imagine would be impossible to find nowadays not to mention the risk if it were to melt.

Re switch-on surge, that is a good point and the 3 amp is likely a fair choice here. I don't have any 1 amp but if I do get some may experiment with those and see if they handle things. I can't see the surge being huge on this, the shaded pole motor has a secondary winding to produce the amplifier's 18vac supply so it's not a big transformer by any stretch.

Thanks Lawrence for the tip on the transistor junction as the diode. I'll go and have a look over the voltages shortly and see what's what then onto cap testing. Cheers, Dan.

['LIVEWIRE?']

I have sometimes fitted 1 Amp fuses in 13Amp plugs, most recently to the mains plug on a Pioneer PL12 turntable, and have run it several times since so doing without the 1A fuse failing. Perhaps, with hindsight, it would be better if a 3 Amp plug fuse was fitted. The PL12 has no internal fuse, though no doubt one could be fitted if required.

[BUSHVHF]

thanks Dan, I have PM'd you.

[BUSHVHF]

You may as well replace all the caps if you think its necessary! At least they won't be failing in the future if they all get replaced with a modern version.

Thanks Lawrence.

[ekjdm14]

Hi, just finished lunch & finished stripping the chassis/removing the caps. I can confirm that they were certainly not tested correctly and there are 3 definitely faulty (basically acting like resistors more than caps) and one suspect that hovers around 60 meg.

The 3 "maybe good" ones for reference are the large Daly reservoir cap (1500uF, measured at 1730uF), Callins (2uF showing 3.2u) and the Vishay fitted by the previous guy (220uF showing 208uF) but in the absence of a high voltage cap tester I can't say 100% they wouldn't be leaky too.

I agree it's best to replace the lot on this basis, and since there's no pattern of maker or body type being better or worse, I'll retain the originals in a bag for possible future restuffing. Even the "new" one I think should go as it's rated for 63v and only has 16v across it (generally slightly higher working voltages are a good thing but I think 63v is a bit excessive and may cause the cap to not function as intended.)

Anyhow enough rambling on from me now, I'll make a start checking out the resistors to see if any are way out of spec, and will add the appropriate capacitors onto my list to order and get back on with diagnosing the amp when they are installed.

Cheers, Dan.

[BUSHVHF]

Great, thanks!! hope it all gets rid of the terrible hiss!! it was playing quite well really apart from that but with all those caps replaced it should sound much better, laurence, funny site this, the PM I sent you doesnt show, only up till friday.

[ekjdm14]

I still feel there may be noise in the Ge components, but one thing at a time & having the caps in spec can't hurt things. It did indeed have a good sound to it, nice and clear with plenty of volume.

I'm hoping my oscilloscope (only a cheapie, in kit form) arrives fairly soon so when the amp is together with new caps etc I can hopefully trace down which stage the noise is getting in at, assuming it is a transistor.

I'll have a look at my inbox, nothing showing at the moment though

[BUSHVHF]

its very strange this PM system, I sent you a load of links to my youtube channel with those vids on there. but my "sent" messages only show till Friday 1st march. i dont think this amp was looked at as thoroughly as you have done it! thanks

PS I will PM you now with something personal.

[ekjdm14]

OK no worries, I have a PM notification now.

Just finished checking the resistors, all are up in value as I expected but I have to ask some help from the experts here. All the resistors are 10% tolerance but very few remain within this & some quite far outside.

Which areas (if any) would be the most sensitive to resistors higher than tolerance? Apart from the hiss/white noise issue the amp appears to work pretty well so I'd be tempted to leave all but the worst 2
(680k measuring 890k, voltage was a little low in that area too, 1.6v where schematic calls for 2.5 on the base of TR1, and a 470k measuring 630k which is between the cartridge pickup & C1 so amp likely would have even better volume on records with this replaced).

Unless I hear differently then my plan for the moment is to replace the caps as mentioned & these 2 resistors & then see where we are with the transistors when all the voltages are where they need to be.