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 Post subject: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Jan Sat 27, 2018 12:12 pm 
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Location: Christchurch, New Zealand
This set is one I purchased in a bulk lot some time ago and which ended up in storage and 'out of sight, out of mind'. Just before Xmas while moving house I decided I quite liked how it looked when I pulled it out to move it - and so it ended up on a hastily arranged bench, well before I'd finished moving properly :oops:

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I'm part way though the restoration at the moment and thought I'd document it since I've gone down the rabbit hole on this one - probably deeper than it warrants - but never mind... its just time and stuff and it should still look good when its done :) and if the sound is good (it generally is pretty good in these old sets) I'll also potentially add a hidden Bluetooth module as well...

"Rolls" was a brand name that appeared in the mid 30's and was produced by Radio Ltd (also known as Radio (1936) Ltd from 1936 onwards, due to a company reorganisation that year) in New Zealand. Radio Ltd's main brand was Ultimate - although there were many other names - all using virtually the same chassis as the Ultimate sets with similar or the same codes and just different dials. As best I can figure, the chassis in this set is labeled as a BBU in the Ultimate set and a BBR in the Rolls set - the schematic is labeled just as 1937 5-Valve which was a frustrating habit of Radio Ltd and means sometimes a little detective work is required to find the right schematic for a set.

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The other obvious difference between Ultimate (and other brands of Radio Ltd) and Rolls is the copper-coloured chassis. I looked at several options to recoat the chassis - but settled on a budget brand of copper-coloured paint which seems to be a very close match. It took weeks to cure properly, and even now its still a little bit soft... but it will do the job nicely given the state of the chassis its gone on to. I applied it in multiple thin coats around 20 minutes apart until it was looking good.

I did consider trying to repair the chassis - its been got at pretty well by rodents with weak bladders - I even considered folding up a new one... but after stripping it out completely and soaking it in rust converter for a day with occasional wire brushings to get the worst of it off I decided it wasn't too bad and decided the set didn't warrant it. It'll still look good.

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More to come...

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Jan Sat 27, 2018 12:45 pm 
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You can see how bad the rust is... and its got right into the seams and lifted the top panel in places... but soaking in rust converter has (hopefully) neutralised it for a good few years to come. It looks a lot better now. There were also a few coats of high-build primer under this to try and even out the mess, sanded between coats. There is only so much you can do with a sows ear though... no silk purse here :)

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And this shows the colour match between old and new

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I then got stuck into cleaning up the aluminium... some scotchbrite, then some fine (400 grit, wetted with some water) wet and dry, then a quick going over with some Autosol chrome polish. They're pitted and a bit rough so I just did the best I could - no 'see yourself' mirror finish for this one. I also rewired the IF coils while I was at it.

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On the matter of wiring... its quite difficult to figure out what colours were originally used... black, blue (sooo much blue!), yellow, tan, red with some kind of trace in it, green... I've tried to use the colours I found in the set - although the power wiring has an abundance of blue, which I'm not fond of... but I stuck with it. I'm in two minds about it though. I'll add a photo tomorrow showing the replaced wiring and it should be apparent that too much blue was used.

This is the underside before I began:

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And the beginnings of the rewire:

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And how its looking as I begin to reassemble it:

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You might just be able to see the pencil marks where I've marked the location of the valve shield base for the 2A6. before screwing that down I've scraped away the paint, back to bare metal so that they will earth properly. I considered re-rivetting the sockets, but I had some nice NOS brass screws that fitted nicely.

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All the while, the cabinet is sitting in a plastic bag in the freezer to kill any possible borer that it might have - it'll spend a week in there. That will get new grill cloth (because its glued in and I just can't see it coming off in one piece), stripped back, repaired as needed and re-lacquered with a little air-brushing around the slats as per the original.

Anyway, more to come tomorrow :)

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Jan Sat 27, 2018 7:03 pm 
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Very, very nice work. It's a nice looking cabinet and should look great when you're done.

Where did you get the red wire with the white markings on the insulation? It looks terrific. And all of the wire appears to have cloth insulation, correct?

Your comment about the rodents was hysterical.

-Kevin

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Jan Sun 28, 2018 10:52 pm 
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Cheers Kevin - yes its cloth covered vintage repro wire - I import it for sale to the vintage community here in NZ and have various different variations in trace colours to suit things like the green with white used in some older Philco speaker wiring etc.

I haven't made a huge amount of progress, but here is how I keep track of where I'm at. First, I don't just tear the set apart - I take a lot of photos from a lot of angles, and continue to do so as I take things apart. I also take comprehensive notes on where things were connected and draw myself diagrams showing what goes where, what colour wires were used etc.

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Then I find one photo which shows a good range of components and do something similar to Philco service bulletins and label as many components as possible / necessary, along with adding component labels to the schematic. I did get a little ahead of myself on this one and started the reassembly before I'd fully completed it - hopefully this won't come back to bite me, but it undoubtedly will at some point in the rebuild :) I then use the schematic and a coloured vivid marker to keep track of what wiring I've completed in the chassis. This is invaluable as a visual aid to keep me on track. I've shown this method before in the Philco 89B I restored a while back

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And this is about as far as I've gotten so far underneath... before and after - as you can see, sooo much blue. In hindsight I wish I'd just gone with conventional colours rather than sticking with the original... but I'm not that upset with it that I'm going to go back and start again.

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Oh, and one other thing - Radio Ltd seems to have shunned the use of the common tagstrip in favour of what appears to be short single-element candohm resistors... I've not seen them used in any other sets here in NZ or abroad - I don't know if they made them or imported them but they certainly had me scratching my head when I first saw them (and I must admit I thought at first glance they were resistors). You can also see here that they used spot-welded metal 'cups' as earthing points on the chassis as well - these are easier to solder to than I thought they would be - although there is no positive capture for the wires soldered to them other than the solder itself which I'm not a huge fan of... but then the wires on this set were still fairly solidly connected after 81 years... so they should do the trick

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More to come... slowly... unfortunately work is getting in the way of my fun.

Cheers

Steve

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sun 04, 2018 6:08 am 
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A little power supply progress today... I decided to not go down the track of putting both electrolytics side-by-side on the transformer, and instead fitted tag strips to the original cap locations (refitting the one original cap that was still in place, and replacing the missing one with what it would have had - the same thing, a Magnavox 10uf 475V cap. Both got a good polish from a scotchbrite wheel in the drill.

So this got a polish:
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...to look like this:
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And then this:
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...ended up looking like this...
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...and this:
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So progress is being made... slowly.

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Also, its worth noting that in the last photo above, the second electrolytic in the power supply circuit (which is on the far side of the chassis to the transformer) is not earthed in the schematic - but in this set it is. I thought this might have been a mod (either intentional or accidental) by a previous serviceman when replacing the electro... but when I tried refitting an original cap to the chassis I discovered the hole was slightly smaller than the other cap hole - so there was nowhere for the stepped insulating washers to go - indicating that it was earthed from factory. This is not the only anomaly I've found - there is a missing link in the schematic feeding the plate and screen grid of the 2A5 with HT as well.

Cheers

Steve

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sun 04, 2018 6:29 am 
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This is how I think it should look, with the second electrolytic caps negative side disconnected from the field coil and connected to earth, and the screen grid connected to HT. I'll fix this properly once I have it all working and iron out any other bugs in the schematic I find.
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Cheers

Steve

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Wed 07, 2018 10:38 am 
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A bit more progress this evening... and a bit of confusion on the schematic again... since the grid and plate of the oscillator section on the 2A7 are drawn back to front to how I would have expected them (presumably drawn in relation to where the cathode is drawn) with the plate on the far left end... took me a few minutes of scratching my head to figure that one out.

I've just been working through wiring, slowly (and pointlessly, but satisfyingly) replacing all the wire and getting the valve sockets back in place, and I started wiring the oscillator and RF coils back in as well.
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I apologise for the poor lighting in the photos, my service bench is in a bit of a state at the moment, and some of the lighting is out of action.
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And about where I got to:
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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sat 10, 2018 1:14 pm 
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A bit of work squeezed in tonight... finished the wiring for the RF coil, finished the heater wiring, fitted a few more components, soldered and finalised a few more terminal points. Also found one more variation from the schematic - the 50k resistor that is shown from the oscillator grid (2A7 pin 5) to ground was actually connected from the oscillator grid to the cathode (2A7 pin 6). This is where I've left it when I replaced it with a modern 47k 1W resistor (I always use 1W or higher to allow for the higher voltages in valve sets).

More wiring complete:
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Ant (RF) coil complete
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I also need to update my 'marking off' schematic on my wall behind the bench, because I got a bit behind with it... I'm further ahead than it shows - so I'll sort that tomorrow along with also trying to tidy up the little mess in the middle of the set around the 2A6... but things are on track. I also need to pull the cabinet out of the freezer and make a start on that...

Cheers

Steve

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sat 10, 2018 3:35 pm 
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Note that that is the less common PSU as it has the field in Negative and its "back biased". If you get Hum you may have to float the second filter cap. Not the worlds best circuit; I note the nomenclature on the grid resistor of the 2A6 & 2A5 & others . What looks like 2. and .5 Ohms are actually 2 meg & 0.5Meg: Beware you may get caught out.

Marc


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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sat 10, 2018 11:23 pm 
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Thanks Marc, yes Radio Ltd were one of those companies who used this reversed nomenclature on their schematics. I had a bit of a browse through the schematics I hold for them and it was quite interesting. They used this reversed system until around 1938 before bringing them into line with everyone else (well, actually they just showed the number of ohms right up to 500000, then switched to 1M from there on... no k-ohms to be found. It appears that around 1942 they started to adopt things like 0.25Mohms instead of 250000 ohms. By the war they had started using kohms. I wonder if this was company policy for the engineering department or if it came down to the draughtsman? I'd assume the former since many of their drawings show three separate signatures: Drawn, Checked and Approved (as do most other major NZ manufacturers schematics).

Fortunately I was aware of this reversed system before starting - although I'm sure its a head scratcher for anyone who hadn't seen it before. I'd be very interested to know the history of why it was done this way - and if this was the original way or if people just adopted their own greek letters before standardisation. They certainly seem to have carried it on much longer than anyone else I've seen using it - maybe because they didn't want to confuse their service agents who were used to seeing it this way?

I'm getting reasonably close to completion now - hopefully there is no hum but if there is then we'll see how we go - floating the second cap will be a fairly simple job in this set. This is a power supply they seem to have used commonly when browsing through their schematics - even through to the 40's: first cap -ve to the field coil, second to ground, so I wonder if floating the second cap was something they shifted to for the production of 1937 but found it less satisfactory? Having the caps as they are in the schematic for this set seems to be an exception to their SOP... unless it was just another error in the schematic

Cheers

Steve

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sun 11, 2018 12:17 am 
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In earlier times with colour codes & nomenclature it was Raferty's rules. Gradually things got internationally standardised, or standardised to a point. The German circuits tend to be the better ones for detail and their resistor symbols when drawn as a rectangle, actually tell you the wattage.

There really is not a standard power supply. Its a range of variations. One set of theories saw the field, or choke, placed in negative to take the stress off of the insulation & lower corrosion. Then of course some had two chokes & one was in Negative the other Positive & there is a HMV radiogram here where the OP tube (807) has its own choke. Having both negatives of the filters, as noted, above ground is not unusual.

Note: I am not a fan of 450V caps and I will not use them on an 80 / 5Y3, or anything that causes a surge like them (diodes) when combined with heater tubes.


Marc


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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sun 11, 2018 4:12 am 
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Electrically, we are nearing the end of the journey... just one decoupling cap, the tone circuitry and the mains wiring to go... maybe tonight if I get time.

I've tidied up most of the various bits that still needed doing - but also need to double check all connections as I'd left some unsoldered to allow for any further connections I still needed to make to them... I should probably get in the habit of noting which ones I've left in that state lest some serviceman in 80 years has to try and find an intermittent fault that I unwittingly left for him :)

Here's the schematic so far - as you can see there is very little left to do (whew!):
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And the top-side thus far:
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Reproduced audio signal wire from the volume control to the 2A6 grid (The old one was pretty manky and corroded):
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The chassis as it stands right now:
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And the replaced volume circuitry including a new pot as the old one was shot:
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Close! So close...

...then just hours and hours to spend on the cabinet :)

Cheers

Steve

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sun 11, 2018 4:55 am 
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I assume you have shields? The base plate of the two I see is the spigot for them. 58 reincarnated as 6D6 & 6U7 (different heaters, bases, but same bad habits) is about as stable as a bucket full of weeping Jelly, if it has no shield.

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sun 11, 2018 5:09 am 
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Marcc wrote:
...58 reincarnated as 6D6 & 6U7 (different heaters, bases, but same bad habits) is about as stable as a bucket full of weeping Jelly...

:lol: :lol:


Yes, the set came with one fitted and one missing but I have a tidy matching pair of Radio Ltd shields to fit once slightly modified to take the grid cap wires.

Cheers

Steve

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Mon 12, 2018 11:11 am 
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Its complete! Not perfect, and not 100% operational but its all together and its working. Nothing needed fixed, which is always nice - I appear to have it mostly right :mrgreen:

So from this:
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To this:
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And as an interesting aside, that first photo is dated 27 Dec 2017, and this one is 12 Feb 2018, so only 6 weeks or so - that might be a new record for me! :lol:

One thing I discovered as I was reassembling the set and checking, the primary of the output TX is open... so I cludged a mess together to get it running. I do have another Rola 2.5k field EM speaker but its in storage about an hour away... I'll get it later this week. What I did have was the field coil in the original speaker so the power supply will work, an old PM Rola speaker from a 50's radiogram, an old unknown output transformer, and several clippy leads... so the cludge looked something like this just to run it up and check things out:
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The sound quality is not great, nor is reception (which is just working from a short-wire aerial in my garage).. but then I'm probably 60km away from the nearest station, and further from most of the stations I can get... I'm rural... and this is just a 5-valve set. So I'll forgive it. So far.

The IF's were quite close, but the dial was way off... and it got better after a quick alignment - but the output is a bit hummy when the alignment isn't quite right, and it sounds 'fluttery' especially at the top of the dial... but given the bodge setup I've done here and the fact I've completely stripped this and replaced everything during reassembly I'm happy enough that it works straight up. I'll wait now until I have the replacement speaker and I'll also string up my long line (we've just moved into this place so nothing is set up properly yet... here's my excuse :) )

Happy :)

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Tue 13, 2018 10:04 am 
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Before and After:
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I believe its a slight improvement :mrgreen:

The only real problem, is that I've got quite a warble / flutter in the audio - I'll have to pick up my oscilloscope from storage later this week and see whats causing that...

I'll also have to work on the dial now, then the cabinet. I've got two weeks until the first meeting of my local vintage radio group, so there is a deadline for show and tell :shock:

Other than that its going really well now I have a decent aerial on it - Hay barns are so useful - at a guess its probably 30m of wire strung out from the house to the barn :)

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Fri 16, 2018 9:41 am 
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The warbly audio has been solved - it was a dodgy 58. I swapped it out with another set and it cleared up instantly... I know they can be a bit unstable (or 'stable as a bucket full of weeping jelly' I believe Marc described it as :lol: ), but that was an interesting one... not a symptom I recall having seen before. It sounds great now - so I'll start on the dial and the cabinet tomorrow - cabinet thread is here: viewtopic.php?f=7&t=336000

Its a pretty nice performer with a good aerial... I'm picking up quiet stations from other cities so I'm quite happy with that...

Next step might be a bluetooth module - I'll see what the audio quality is like when its back together. I did manage to get the original speaker working but the replacement one (a slightly later model of the same Rola 2.5k field em speaker) sounds much better on the bench so I'll probably go with that.

Cheers

Steve

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Fri 16, 2018 11:27 pm 
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Love looking at progress. Thats quite a awsome job you did.

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 Post subject: Re: New Zealand 1937 'Rolls' Model BBR Restoration
PostPosted: Feb Sat 24, 2018 11:06 am 
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Thanks Rich... last steps of the chassis now - and the cabinet is mostly done as well...

Pulled the dial apart this evening - glass, then black paper backing, then the frame, which is painted silver on the sides and back everywhere else. The frame is a bit rusty, so its had a bit of a wire brush-down and now its taking a cobbled-together bath (beer box, plastic bag and a can of CRC to take up the unused space) in evaporust for a day or two. Then I'll clean it up and repaint it before refitting it. Then replace the dial light wiring, add a period power cord and fit it back inside the cabinet.

Oh, the speaker needs cleaned up - thats also on the list.
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