kempy Posted May 19, 2015 Share Posted May 19, 2015 Thought I'd start 1 thread with the different bits and pieces I work on from. Starting with... Here's a Playtape I found last week, it was covered in cigarette smoke residue so I stripped it down and cleaned it inside and out. Originally it was so covered in nicotine that it was yellowish Playtape machines are like small 8 track tapes (but with 2 tracks), they were only released for about 2 years when the format was made redundant. I have a 2nd machine that needs a bit more work but I should have that working as well in a few days 2 Quote Link to comment Share on other sites More sharing options...
Popular Post kempy Posted May 19, 2015 Author Popular Post Share Posted May 19, 2015 8 track machines I picked up 4 machines recently, 3 that can record and one that is play only, in addition to this there were several boxes of tapes including some still in box new tapes. 2 of the machines were working, but again they were a mess and covered in nicotine residue. Internally they are all pretty good and most of the work required was just cleaning, lube, removing labels that had come of tapes and munched up in the mechanism and a couple of dodgy capacitors The exterior of all 4 were sticky Buttons needed a good scrubbing with Jif All clean and ready to go. One is an older version and still needs a bit of work, the bottom 2 are going sweet. 11 Quote Link to comment Share on other sites More sharing options...
kempy Posted May 19, 2015 Author Share Posted May 19, 2015 I have a limited supply of 8 track blank tapes if any OS'ers have an 8 track machine in their car and want some music they can actually listen to. 1 Quote Link to comment Share on other sites More sharing options...
Paulluap Posted June 4, 2015 Share Posted June 4, 2015 Nice. What do you do with them once you have finished? This is what I use in my shed. Akai Amp AA-1150 and a Mitsubishi automatic 7 x cassette player with a programmable record player. 2 Quote Link to comment Share on other sites More sharing options...
kempy Posted June 5, 2015 Author Share Posted June 5, 2015 I'm building up a bit of an analog recording facility, just for interest. Reel to Reel, Tape, 8 Track etc. Nice 7 tape unit, haven't seen one of those in ages. Quote Link to comment Share on other sites More sharing options...
Paulluap Posted June 5, 2015 Share Posted June 5, 2015 I'm building up a bit of an analog recording facility, just for interest. Reel to Reel, Tape, 8 Track etc. Nice 7 tape unit, haven't seen one of those in ages. That's cool. Never seen the 8 track before. Just before my time I think .They sort of look like Mini Disks. Yes I love motorised stuff. You can put 7 tapes in it, then it will play both sides of all 7 tapes. About 7 hours . 2 Quote Link to comment Share on other sites More sharing options...
kempy Posted June 10, 2015 Author Share Posted June 10, 2015 Here's another little project on the burn, I found 2 Pye Mozart amps a while ago and it's time to bring them back to life. They are what is called an integrated amplifier which means the pre-amp (volume/tone/input selectors) is integrated in the same chassis as the Amp. When they were sold in 1958 they retailed for approx. 33 pounds each. I was lucky enough to find a pair of them in reasonable condition Here's a rear view of the amp, plenty of dust from 50+ years of life in shelves and sheds. If you take a close look you'll see 1 large valve ( Vacuum Tube) lying on it's side, the model is what is called a "single Ended" amplifier. What does single ended mean? Strange that you should ask, but ok, I'll try to explain. I'll do my best to without making too many eyes glaze over , single ended means that the one tube is biased to the mid point (with no input) and it performs the whole output section with one tube instead of 2, sound confusing? Lets look at a normal situation using a complimentary pair of output devices, I'll use an example most can relate to; Car Batteries! If we had 2 x 12v batteries and we connect a volt meter lead to the jumper lead that connects the two batteries together, in this specific example that connection point is called the mid point or "0v". - [12v batt A]+ --- 0v --- - [12v batt B] + If we connect the other meter lead across bat "A" then it would read -12v If we connect the other meter lead across batt "B", then it would read +12v (if we put a meter across the 2 batteries (end to end) we would get 24v) The same logic applies to an amplifier, If I had 2 output tubes (or Transistors) 1 tube would handle the -V side of the sine wave, the other would handle the +V side on the sine wave, with them both connecting to each other at the "0v "point, put in a complimentary pair they do the job nicely and allow for very high outputs if reqd. However for a single ended tube we have only 1 output device, so if the maximum output swing was 24v, we artificially "bias" the tube so it sits at the mid point (0v in our battery example), and it can swing up or down 12v to make it do the job Hope that wasn't too confusing. The output tube is an EL34 and this model about 9 watts output at 0.3% distortion @1Khz, which was pretty good for back then. Here's another view with the cover off and the output tube removed, and a quick wipe 3 Quote Link to comment Share on other sites More sharing options...
kempy Posted June 10, 2015 Author Share Posted June 10, 2015 Next job is to dismantle the amps without damaging it further. The knobs are a snug press fit and the front is easily scratched, so a bit of thin plastic to slide under and pull works well. Front and knobs off The main offenders are the 2 large aluminium can type capacitors, the black plastic looking capacitors and the smaller aluminium type capacitors on the board However to do this I need to unsolder the capacitors from the other side of the board and to do this I have ti unsolder all of the wires going to the 2 transformers on the other side of the chassis. Here's one of the offenders They're a brand of capacitors made in the UK back in the 50's and 60's called "Hunts", most technicians renamed them by removing the "H" and replacing it with a "C", sums it up pretty well.. 2 Quote Link to comment Share on other sites More sharing options...
Popular Post kempy Posted June 10, 2015 Author Popular Post Share Posted June 10, 2015 With the board unsolder-ed from the transformers, I can now start the re-capping process. First up will be the black "Hunts" capacitors as I have suitable replacements in stock. I'm lucky to have a good stock of old "mullard "capacitors to replace them with, they hardly ever fail and are hard to get, also quite desirable to guitar amp builders. They are also can be named "Mustard " capacitors because of their colour. I'm using them as they don't look out of place unlike the new yellow ones either side of them. last one for tonight, Here's the "Hunts" capacitors removed. You can see from the picture that some look a bit worse for wear, they also fail testing on my ESR meter. 12 Quote Link to comment Share on other sites More sharing options...
pusherman Posted June 11, 2015 Share Posted June 11, 2015 Man id love to know how to do this. Very interesting mr kempy 1 Quote Link to comment Share on other sites More sharing options...
kyteler Posted June 11, 2015 Share Posted June 11, 2015 You're such a nerd, kempy. It's fucking great. 1 Quote Link to comment Share on other sites More sharing options...
cubastreet Posted June 12, 2015 Share Posted June 12, 2015 That pcb is a work of art Quote Link to comment Share on other sites More sharing options...
johnnyfive Posted June 12, 2015 Share Posted June 12, 2015 This is awesome. Do you do this or similar for a living or purely for an awesome hobby? Pretty darn cool Quote Link to comment Share on other sites More sharing options...
kempy Posted June 12, 2015 Author Share Posted June 12, 2015 Jonnyfive, Just a hobby, keeps me off the streets at night Pusherman drop in, happy to share a few tips if you have a live project. 1 Quote Link to comment Share on other sites More sharing options...
tortron Posted June 12, 2015 Share Posted June 12, 2015 I love the ood akai stuff must get another set up when ibreturn 1 Quote Link to comment Share on other sites More sharing options...
Popular Post kempy Posted February 6, 2016 Author Popular Post Share Posted February 6, 2016 Another moment of stupidity and I'm now the owner of a 32 channel Calrec S analog mixing desk. I figured it's a winter project with the assumption that it's going to freeze over for the next decade and I'll then emerge with a 3ft beard and a completed desk. The unit came with tons of spares, reportedly cost upwards of $750k when purchased in the early 2000's and there won't be a person here that hasn't heard the results of this desk. Its both a bit of NZ broadcasting history and also an interesting project to add to the collection and help to kit out my retro analog sound room/studio when it's completed. In it's current naked state What it's supposed to look like. It takes a truckload of cards like this 13 Quote Link to comment Share on other sites More sharing options...
xsspeed Posted February 6, 2016 Share Posted February 6, 2016 Long whistle 6 Quote Link to comment Share on other sites More sharing options...
chris r Posted February 6, 2016 Share Posted February 6, 2016 So cool 1 Quote Link to comment Share on other sites More sharing options...
Paulluap Posted February 6, 2016 Share Posted February 6, 2016 Awesome!! I love buttons. The more the better. 1 Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted February 6, 2016 Share Posted February 6, 2016 woooooooooooooooow my eybrows have been raised. 1 Quote Link to comment Share on other sites More sharing options...
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