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Old 18th Jun 2006, 6:31 pm   #1
af024
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Default Bush VTR330 s/n 358A/15722 Now Working

Cost £7.50, Elvaston Castle.

This radio is now back in the land of the living.

There were four things wrong:-

R40 and R45 – suspected dry joints (re-made).

The Hfe of VT8 (AC128 audio driver) was down at 1 (yes, 1). Amazingly it metered ok out of circuit and in circuit, all voltages around it looked reasonable. I replaced it for one which had a gain of 60 (ish).

The on-off pot

Well what can I say about this? The thing didn’t switch on and even with the switch contacts bridged, the adjustment of the volume pot thumbwheel did absolutely nothing.

Bravely I decided to take the thing apart to see if there was anything that I could do. I have nothing like this in any of my bits – looks a bit special, so it was all or bust.

It’s certainly not for the feint-hearted or indeed a job for big-fingers, so only go there if you really need to – you have been warned.

I rapidly came to the conclusion that someone had already been there before me.
I’ve attached a photo of the innards (once I’d straightened things out – sorry I should have done an ‘as found’ but I forgot). The centre arm of the switch part was not originally engaged with the shaft and it was jammed up and under the ‘W’ shaped slider contact. The wiper of the pot had come off its locating lugs and was stuck in an out-of-sync position with respect to the switch. One part of the wiper was stuck between the ground end of the track and the wiper terminal with the other being bent but touching the carbon track a good way towards the ‘hot’ end. This explained why I couldn’t get any audio from the wiper and also explained that there wasn’t much level from the ‘hot’ end of the pot too. I couldn’t believe my eyes. What a set of coincidences! In my testing, I suppose I should have disconnected the hot end to see whether that made a difference (but I didn’t – this kind of problem never occurred to me). Anyhow, I straightened out the internal metal bits, gave them a good clean-up (including the carbon track), dabbed two tiny spots of glue on the locating lugs and affixed the wiper in the correct position and correctly oriented relative to the end stop and switch mech. I then re-assembled it (taking care to re-load the spring that pushed down on the ‘W’ slider contact). This took several attempts as just when I thought ‘time to close it all up’, the thing decided that it would fly apart. Needless to say I had to work out the relative positions of everything again and start all over – quite frustrating. Eventually I got there and was holding it all closed with two hands. The phone rang – no, seriously. I left it ringing.

Finally I managed to close the external tabs up to complete the fix (none of them broke off to my amassment). I then soldered the beast back into its small PCB and re-connected the wires.

At last, time to check it. Instantly I was rewarded with audio – and bags of it too. What a little cracker! All stations seem to be in their correct positions as well. I’m really glad about this since without alignment instructions I wasn’t going to attempt that. The pot doesn’t even crackle. Having said this, it’s not totally without the odd hic-up. Sometimes it doesn’t switch on. Perhaps I need to expand the loading spring a bit more (but I don’t think I’m going there again). Time to look for a new switch methinks.

I’ve posted some photos of the completed set. It even still has its original plastic battery bag!

I’m so glad I persevered with this one – I think it’s a cracking little set both in terms of performance and looks. I wonder when it was made? The chrome caps at the ends of the handle are a bit scuffed and there’s a little ding in the rear vent, but apart from that, the set looks brand new. I’m really pleased. I think I’m another VTR330 fan.

So thanks for your help Howard – excellent stuff. Much appreciated.

Another radio sings …


Andy
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Old 18th Jun 2006, 8:02 pm   #2
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

Well done Andy,

Youve done a grand job there and had quite a bit more work to do than I did too. It certainly came up nice and these VTR330s really do work well and play very loud !!

I think this model was introduced around 1972 at the same time as the TR230s but Im not absolutely certain, but it was one of the very last radios built by Bush in the UK.

Now is Colin going to complete his VTR330 as well so we have three VTR330s in Success Stories ....... I hope so cos these are getting few and far between.

Howard

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Old 18th Jun 2006, 10:04 pm   #3
GJR 11L
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

My black 330 had suffered the same problems with the switch, but I transplanted one in from a VTR174 mounted on a home-made bit of paxolin to allow for the different pin layout. BUT..... The switch is now at the wrong end of the scale due to the VTR174 donor having a switched tone pot!

It's interesting that all the sets of the type shown here have been the black ones, two of my VTR330s are tan in colour so I had assumed that the tan was the more common colour?
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Old 19th Jun 2006, 5:18 pm   #4
Colin
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

Quote:
Originally Posted by howard

Now is Colin going to complete his VTR330 as well so we have three VTR330s in Success Stories ....... I hope so cos these are getting few and far between.

Howard
Well done Andy, nice job. There are more and more 'pot doctors' meeting the challenge of repairing pots that would normally be in need of replacement. It's good to see that this stuff is 'do-able' if you've the patience and eyesight!

Howard, I've done both my Black VTR330's. If you recall I picked up a couple with the intention of making one good set from the pair. The 'Donor' set was in pretty bad shape but It's actually come up reasonably well. So now I have two, a complete set and another that needs a handle (as you can see in the picture the grille isn't too good either).

Both were 'non-working' but they had the same fault ... a dead AC128 driver. They both work really well now following the usual switch cleaner and the odd cap etc. I'm pleased the 'donor' set turned out to be okay as they do seem to be quite scarce.

Anyone got a spare handle?

Here are a couple of pictures.

rgds
Colin
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Old 19th Jun 2006, 7:52 pm   #5
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

Well thanks for the compliments one and all. I'm really glad that I stuck at it. It's a lovely set and sounds really good too.

If only I could get a new on-on pot.

Interesting that more than one of use have had AC128 driver and pot trouble too. Yes I can imagine that the switch could well be at the wrong end of the travel - how annoying. Has it gone log to lin as well? Someone somewhere has a warehouse full of pots ...

Have you noticed how warm the output stage gets - even on tick-over. I wonder if this is normal?

Oh, one question, is a piece of foam stuck under the push-buttons? Mine just has the remnants of something sticky, but that's about all I know.

It looks like mine has the worst black Bush writing on the chrome grille bottom. An obvious candidate for being scuffed off I guess. I wonder if I should get rid of it altogether? Maybe not.

Cheers,


Andy
And thanks again for the help - best regards.
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Old 19th Jun 2006, 8:13 pm   #6
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

Quote:
Originally Posted by GJR 11L
It's interesting that all the sets of the type shown here have been the black ones, two of my VTR330s are tan in colour so I had assumed that the tan was the more common colour?
Black is by far the commonest 330 and the tan ones are relatively rare. I don't know whether a red version exists though - I was once told they do but can't recall ever seeing one.
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Old 20th Jun 2006, 8:16 am   #7
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

Well done Colin,

It's good to see two more of these VTR330s working again.

Andy, there is a 1/4" wide strip of foam under the push buttons, I replaced it on mine and on both TR230s. I just used a piece of thin foam stuck on with double sided sticky tape, it cant be seen with the chrome cover in place.

I've never had the patience to dismantle and clean pots, I always imagined that it was a very fiddly job .... very useful to know how its done though.

My Mum had one of these many years ago and it kept on going for over 20 years. That one was black as well, the tan ones are rarer.

Howard

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Old 24th Jul 2006, 12:09 pm   #8
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

Nice job Andy

I picked up a black VTR330 at a car boot sale yesterday for £3. I thought I might have been a bit rash spending so much, but having read posts on this forum, I'm glad I rescued it.

It was incredibly filthy, but after a strip-down and soak in Maplins foam cleanser, it looks like new, albeit with one pushbutton missing and no handle. It works on FM, but not AM - that's the third set recently that's been the same. With the others it was just dirty wavechange switches, but this one hasn't responded to switch cleaner yet. The top part of the cabinet was covered with a brown varnish-like deposit, probably tar plus nicotine, and I think this may have penetrated the switches.

However, the main reason for posting was that the on-off switch is a bit intermittent, and I had thought about trying to fix it. So thanks for posting the photo of the dismantled switch. I'll have a go when I'm feeling brave.

Incidentally a good replacement for perished foam pads in sets like this is light-trap foam, intended for use in refurbishing old cameras. It comes in various thicknesses and has self-adhesive backing. Having said that, it's expensive and not easy to get hold of, but if you can beg, steal or borrow some from a camera enthusiast, it makes a very neat job.

Tom
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Old 24th Jul 2006, 8:44 pm   #9
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

Thanks for your posting Tom, it's nice to see that you've found another one of these sets. Shame about your switch and the loss of AM but hopefully you'll be able to get it sorted. The switch is a bit of a nightmare though (you need to be a small octopus and have fingers all over the place). The spring compression seems really crucial too. Since you've realistically only got one try to get it back together, I suggest you ensure that the spring has got lots of compression (not easy I know). I wish you the best of luck. I'd love to hear how you get on.

Regards,


Andy
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Old 28th Jul 2006, 5:22 pm   #10
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

Thanks for wishing me luck Andy.

I've just finished the job this afternoon. I wasn't going to bother, as the on-off switch has been working reasonably reliably, but the volume pot has been getting intermittent fits of pops and crackles, so I decided to pile in.

There's certainly some fairly challenging soldering to do in confined spaces, but I suppose that's all part of the fun. Fortunately my switch had not been molested by a previous visitor, and it was just a case of cleaning things up and buffing the on-off contacts with a fibreglass pencil. I didn't try to adjust the spring tension, but just re-assembled it as it was. I can see exactly what you mean about needing to be a small octopus!

I took out the tone control at the same time, as that was also erratic, but after a good soak with contact cleaner it seemed to be responding OK on a test meter, so I didn't dismantle it.

So while this was certainly a fiddly job, it's not impossible. My only real unscheduled problem was a 33K carbon resistor on the main pcb, which has two of the wires from the volume/tone controls soldered to one end of it. It promptly fell to bits as I unsoldered the wires. I wasn't applying any significant force, so I think it must have already been cracked. I don't carry many components around the house, but to get the job done I found three 100K miniature resistors which I soldered in parallel on the other side of the board, with the leads formed into a post to solder the wires to. Not especially elegant, but at least it works!

As indeed does the set. The switch seems to be OK, and the pots are nice and quiet. I agree with you that these are cracking little radios - very impressive sound for their size. I still don't have any AM, but I'll save that for another day. I can't cope with too much excitement all at once!

As I said before, thanks for posting the photo of the dismantled switch - it makes things that bit easier when you know what you are going to find inside.

Regards.

Tom
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Old 29th Jul 2006, 5:33 pm   #11
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Default Re: Bush VTR330 s/n 358A/15722 Now Working

Well done Tom!

You can now be added to the bravery list of pot twiddlers!

It's difficult to see how challenging it is until you actually go there yourself. I am really pleased that you've got it sorted.

Yes I know the fixed resistor that you refer to. I had trouble releasing the wires off mine too.

Glad you like the set. When I first got mine going I couldn't believe how good it sounded. Obviously you are impressed too.

Best of luck with the AM issue.

Best regards,

Andy
PS I know what you mean about the missing handle and button - I have another VTR330 with EXACTLY the same things missing!! Somewhere someone has a surplus ....
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