12-05-2011, 12:52 PM
While hunting for an avatar image, I found that I had lots of older images on this computer. Then I realised that I could cobble together a “success story”, which might be a nice way to start on here...
This is one of the first Hacker sets I bought, from our very own ppppenguin last year. To this day, it's probably my favourite of all the Hacker sets; the RP37A tended to use the Elac loudspeaker with the large ceramic magnet which gives them an edge over the electrically equivalent Sovereign IIs that used Goodmans or Celestion speakers.
This set worked perfectly, but had modified by a former owner (not Jeffrey!) to run from mains. Now, I completely understand why one would want to do that – PP9 batteries are expensive for the general public, and we tend to forget that accessing “trade” outlets like CPC was much harder 20 years ago. But while I get the motive, I normally question the execution of these sorts of conversions. I've seen many now, and they are generally pretty scary in safety terms.
But apart from safety, It's a shame how sets are often damaged irreparably in the process. A hole is needed to let the mains in – understandably so – but unfortunately this set also had an LED mounted on the front panel!
Starting with the mains lead, this had been drilled in the side panel. Luckily, the placement of this hole was reasonably sensible; later Sovereign II sets had a DC input socket mounted in much the same place. So although none of the Heralds were ever fitted with a DC input from new, it made sense to fill this hole with a suitable socket. After a tip-off from a good friend on the Yahoo Hacker group, I selected CPC part number AV15144. These are panel-mount, and require a 14mm hole, which neatly covered the hole drilled by the previous engineer.
As many of you know, Hacker always use plugs and sockets for everything (if only everyone did!), so I didn't want to stray from this philosophy. There are of course many ways to achieve this, but I ended up with a neat solution; I had a standard 3-way Molex connector that is meant to be mounted on a PCB, but this was the 90 degree version. The longer pins were straightened out and formed to meet with the tags on the back of the DC input socket. Very neat. But, best of all, the nut belonging to the socket was big enough to fit over the completed assembly. Perfect!
Unfortunately the previous engineer had cut short the existing battery leads and lost the PP9 battery snaps, so I robbed them from a scrap Sovereign II (another from Jeffrey, but actually it is no longer scrap and is nearly finished – but that's another story!). These were connected to the Molex plug and neatly attached to the chassis, and a 1N400x “idiot diode” was discretely mounted on the back of the volume control. Lovely...
The final detail was to scan in the label fitted to later sets and print it out on card. From a distance, it looks pretty convincing.
But what about the hole in the front panel? I could have left the LED in place, or fitted a nicer one, but it just seemed wrong. I could have replaced the front panel, but scrapping a good set also felt wrong. Perhaps replace the Rexine? Not a job for the beginner, even assuming you could find something that matched the rest of the set. So the only option seemed to be to patch the hole. I stole a small section from a scrap set with a torn rear cover, and put a new blade on the scalpel. I started by making the hole in the front panel a perfect circle, then cut a circle of Rexine to fill the hole. Another scrap of Rexine was placed on the rear to hold the patch in place, and the whole lot was glued with PVA. It's not perfect, but worked amazingly well as I hope the photos show...
Of course, being a 1960s Hacker, the foam padding had disintegrated. Given that I had to remove the Rexine to fix the hole, fitting new padding was the obvious next step. I spent ages looking for suitable padding, and the best I could find at the time was 6mm foam from the local market. It's a bit too thick, and although the final results are pretty good, it does look a bit “bloated” from certain angles. Really you need 3 or 4mm, and I'll tell you where I found some when I do the next success story...
Tips for repadding? Really concentrate on getting the corners right. Pay attention to how they were originally, and do your best to replicate this when reassembling. Any mistakes are really obvious, unfortunately. Also, pay attention to the piping when you glue this back in place – especially along the top panel. In fact, if you can, leave this alone if you can - I undo the sides and bottom. That said, you might choose to leave the areas attached around the grille.
When removing the Rexine, warm air from a hair dryer will soften the glue. I use a decorators tool for this - I think they're meant for applying filler – a 2 inch wide blade with a nice wooden handle. Earlier sets were made from good quality plywood, and these are easy; however later sets used nasty particle board of some sort, and flakes of this will come away with the Rexine. It's worth cleaning this up, and in some cases it's worth using wood filler on the panel. Otherwise, the end result will be uneven, and the white piping will highlight this nicely...
I use PVA to glue the Rexine back. The secret is to realise that there is a lot of “open time” with this stuff, so you can re-position it at will. It helps if you've had the glue a long time, because it goes off quicker – otherwise you need to wait for quite a while before it starts to grip. But your patience will be rewarded!
The rear grille is a pain because the pins fall off. I've used 2mm machine screws and nuts here, and this would be much better if the screws were black. Another option is to glue the screws to the rear of the grille – this depends on how much you trust the glue. Also, you would need to remove the cloth on the inside of the rear panel to make adjustments - I have to do this once, and use fairly weak spray-mount glue to secure it back in place. Just in case.
Next, the chassis. Electrically it was pretty good. As is often the case, the amplifier was very noisy – this is normally caused by T1 (BC148). I've found these to be pretty unreliable – a BC109 is a better replacement, but for now, I'm using up my childhood stocks of Lockit BC149s in this position...
I always strip down the chassis to clean it thoroughly and lubricate the tuning drive. But the other Achilles Heel of Hacker sets – again caused by foam – the scale paint fell off in a number of key places. Luckily most of the small text was OK, but the “HACKER” and “VHF” print was damaged. Using Humbrol paint, a tiny brush, a scalpel and an eyeglass, I was able to recreate the print. I realised afterwards that my success here was helped by the paint being 20 years old and partially set – making it easy to apply in a thick and well controlled manner.
I've had lots of these over the last year, and some can be restored easily. If you're lucky, no print will be affected, just the background and border. Sometimes, the black paint reacts with the foam, but the white print is completely untouched. Occasionally, the scale is a write-off. It's just luck...
Once the paint has been repaired, it's time to polish the front of the scale. These come up like new with patience, and even quite deep scratches can be removed. Metal polish works best for me, sometime in conjunction with a power sander (very carefully!). Oh, and it's worth changing the grille cloth - front and rear. The original material fades badly over the years...
So, while not a “how to”, there are hopefully some useful tips in here. These really are lovely sets, and I can't recommend them highly enough. It's the one I use most, and I think it's one of Hacker's best sounding sets. Like the Hunter, but with better bass and better sensitivity. Without the boomy bass that Sovereign IIs can sometimes have. Enjoy!
Mark
This is one of the first Hacker sets I bought, from our very own ppppenguin last year. To this day, it's probably my favourite of all the Hacker sets; the RP37A tended to use the Elac loudspeaker with the large ceramic magnet which gives them an edge over the electrically equivalent Sovereign IIs that used Goodmans or Celestion speakers.
This set worked perfectly, but had modified by a former owner (not Jeffrey!) to run from mains. Now, I completely understand why one would want to do that – PP9 batteries are expensive for the general public, and we tend to forget that accessing “trade” outlets like CPC was much harder 20 years ago. But while I get the motive, I normally question the execution of these sorts of conversions. I've seen many now, and they are generally pretty scary in safety terms.
But apart from safety, It's a shame how sets are often damaged irreparably in the process. A hole is needed to let the mains in – understandably so – but unfortunately this set also had an LED mounted on the front panel!
Starting with the mains lead, this had been drilled in the side panel. Luckily, the placement of this hole was reasonably sensible; later Sovereign II sets had a DC input socket mounted in much the same place. So although none of the Heralds were ever fitted with a DC input from new, it made sense to fill this hole with a suitable socket. After a tip-off from a good friend on the Yahoo Hacker group, I selected CPC part number AV15144. These are panel-mount, and require a 14mm hole, which neatly covered the hole drilled by the previous engineer.
As many of you know, Hacker always use plugs and sockets for everything (if only everyone did!), so I didn't want to stray from this philosophy. There are of course many ways to achieve this, but I ended up with a neat solution; I had a standard 3-way Molex connector that is meant to be mounted on a PCB, but this was the 90 degree version. The longer pins were straightened out and formed to meet with the tags on the back of the DC input socket. Very neat. But, best of all, the nut belonging to the socket was big enough to fit over the completed assembly. Perfect!
Unfortunately the previous engineer had cut short the existing battery leads and lost the PP9 battery snaps, so I robbed them from a scrap Sovereign II (another from Jeffrey, but actually it is no longer scrap and is nearly finished – but that's another story!). These were connected to the Molex plug and neatly attached to the chassis, and a 1N400x “idiot diode” was discretely mounted on the back of the volume control. Lovely...
The final detail was to scan in the label fitted to later sets and print it out on card. From a distance, it looks pretty convincing.
But what about the hole in the front panel? I could have left the LED in place, or fitted a nicer one, but it just seemed wrong. I could have replaced the front panel, but scrapping a good set also felt wrong. Perhaps replace the Rexine? Not a job for the beginner, even assuming you could find something that matched the rest of the set. So the only option seemed to be to patch the hole. I stole a small section from a scrap set with a torn rear cover, and put a new blade on the scalpel. I started by making the hole in the front panel a perfect circle, then cut a circle of Rexine to fill the hole. Another scrap of Rexine was placed on the rear to hold the patch in place, and the whole lot was glued with PVA. It's not perfect, but worked amazingly well as I hope the photos show...
Of course, being a 1960s Hacker, the foam padding had disintegrated. Given that I had to remove the Rexine to fix the hole, fitting new padding was the obvious next step. I spent ages looking for suitable padding, and the best I could find at the time was 6mm foam from the local market. It's a bit too thick, and although the final results are pretty good, it does look a bit “bloated” from certain angles. Really you need 3 or 4mm, and I'll tell you where I found some when I do the next success story...
Tips for repadding? Really concentrate on getting the corners right. Pay attention to how they were originally, and do your best to replicate this when reassembling. Any mistakes are really obvious, unfortunately. Also, pay attention to the piping when you glue this back in place – especially along the top panel. In fact, if you can, leave this alone if you can - I undo the sides and bottom. That said, you might choose to leave the areas attached around the grille.
When removing the Rexine, warm air from a hair dryer will soften the glue. I use a decorators tool for this - I think they're meant for applying filler – a 2 inch wide blade with a nice wooden handle. Earlier sets were made from good quality plywood, and these are easy; however later sets used nasty particle board of some sort, and flakes of this will come away with the Rexine. It's worth cleaning this up, and in some cases it's worth using wood filler on the panel. Otherwise, the end result will be uneven, and the white piping will highlight this nicely...
I use PVA to glue the Rexine back. The secret is to realise that there is a lot of “open time” with this stuff, so you can re-position it at will. It helps if you've had the glue a long time, because it goes off quicker – otherwise you need to wait for quite a while before it starts to grip. But your patience will be rewarded!
The rear grille is a pain because the pins fall off. I've used 2mm machine screws and nuts here, and this would be much better if the screws were black. Another option is to glue the screws to the rear of the grille – this depends on how much you trust the glue. Also, you would need to remove the cloth on the inside of the rear panel to make adjustments - I have to do this once, and use fairly weak spray-mount glue to secure it back in place. Just in case.
Next, the chassis. Electrically it was pretty good. As is often the case, the amplifier was very noisy – this is normally caused by T1 (BC148). I've found these to be pretty unreliable – a BC109 is a better replacement, but for now, I'm using up my childhood stocks of Lockit BC149s in this position...
I always strip down the chassis to clean it thoroughly and lubricate the tuning drive. But the other Achilles Heel of Hacker sets – again caused by foam – the scale paint fell off in a number of key places. Luckily most of the small text was OK, but the “HACKER” and “VHF” print was damaged. Using Humbrol paint, a tiny brush, a scalpel and an eyeglass, I was able to recreate the print. I realised afterwards that my success here was helped by the paint being 20 years old and partially set – making it easy to apply in a thick and well controlled manner.
I've had lots of these over the last year, and some can be restored easily. If you're lucky, no print will be affected, just the background and border. Sometimes, the black paint reacts with the foam, but the white print is completely untouched. Occasionally, the scale is a write-off. It's just luck...
Once the paint has been repaired, it's time to polish the front of the scale. These come up like new with patience, and even quite deep scratches can be removed. Metal polish works best for me, sometime in conjunction with a power sander (very carefully!). Oh, and it's worth changing the grille cloth - front and rear. The original material fades badly over the years...
So, while not a “how to”, there are hopefully some useful tips in here. These really are lovely sets, and I can't recommend them highly enough. It's the one I use most, and I think it's one of Hacker's best sounding sets. Like the Hunter, but with better bass and better sensitivity. Without the boomy bass that Sovereign IIs can sometimes have. Enjoy!
Mark
