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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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16th Mar 2019, 2:29 pm | #21 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,636
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Re: Ampro Stylist projector
I think we got off on the wrong foot here. The opening post unfortunately conveyed the impression that AmproStylist had much less experience than he actually has. We can only take that at face value, as we do get a lot of new members that do need safety advice and we'd be negligent if we didn't realise this.
However, AmproStylist just needs the correct schematic in order to solve his dilemma, and so far it seems to be elusive. The one linked to doesn't really help unfortunately. |
16th Mar 2019, 3:08 pm | #22 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,549
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Re: Ampro Stylist projector
I have not yet seen a snap shot of a mains dropper section in this thread however I can fix that.
The mains takes two paths that split between the heater chain and the supply to the HT rectifier. The projector has discreet resistors in series however a good idea can be had from the diagram of a small radio with the resistors in one single unit that is taped off. |
16th Mar 2019, 9:24 pm | #23 |
Octode
Join Date: May 2009
Location: Stevenage, Herts. UK.
Posts: 1,515
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Re: Ampro Stylist projector
Found it and finally managed to get it to upload!
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16th Mar 2019, 9:45 pm | #24 |
Nonode
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 2,034
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Re: Ampro Stylist projector
Thank you for uploading this- it's rather heart-warming to see such a nice example of the earlier form of component symbols in use
Guy |
16th Mar 2019, 10:59 pm | #25 |
Retired Dormant Member
Join Date: Mar 2019
Location: Horsens, Denmark
Posts: 16
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Re: Ampro Stylist projector
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16th Mar 2019, 11:52 pm | #26 |
Hexode
Join Date: Nov 2006
Location: Near Lincoln, UK.
Posts: 481
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Re: Ampro Stylist projector
Only just spotted this thread!
Can I ask the OP what the state of the actual Stylist Projector is, please? These are a lovely looking projector and can work very well. I have two, one an 'antique gold' kind of colour and the other silver. I've spent some time in making the former work to a good standard (both picture and sound) and it is one of my favourites. Both the models that I have are this 'educational' variety without a separate transformer. They are compact, reliable and quite decent for what they are. The amplifier is nothing to write home about, but it does the job and with a decent photocell, sounds quite reasonable. I actually traced the circuit of the amplifier out a while ago, so it's great to see an 'official copy'! I wonder how many more of these projectors are still 'out there'? Best regards, Paul M |
17th Mar 2019, 2:13 am | #27 | |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,518
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Re: Ampro Stylist projector
Quote:
Well done that man. Also chuffed to see my guesses about the supply side weren't far off
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17th Mar 2019, 9:12 am | #28 |
Octode
Join Date: May 2009
Location: Stevenage, Herts. UK.
Posts: 1,515
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Re: Ampro Stylist projector
New Educational here. Belonged to a late friend of mine, also called Paul, and I like to use it occasionally as a kind of memorial.
As PaulM says they actually work pretty well. Biggest problem with mine has been sourcing a drive belt, not helped by Ampro using two different sizes. Modern one's aren't made of rubber and do not have much give. The 'correct' size was just too tight, so ended up using the larger size and dropping the motor. Selenium rectifiers were weak and bypassed with silicon diode and resistor chosen to restore HT voltage to correct level. Regards, Yet another Paul! |
17th Mar 2019, 10:03 am | #29 |
Hexode
Join Date: Nov 2006
Location: Near Lincoln, UK.
Posts: 481
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Re: Ampro Stylist projector
Yes indeed, Paul, the drive belt is a weird size. I didn't know that there's two types. I managed to find one that works in my 'assorted belts' boxes. Heaven knows what it was off.
Also bypassed the rectifier with modern. You have to be pragmatic. Picture attached of my 'antique gold' one on a very rugged 3 leg period projector stand. Best regards, Paul M www.becg.org.uk www.projectvivat.co.uk www.golden-agetv.co.uk |
17th Mar 2019, 12:02 pm | #30 |
Retired Dormant Member
Join Date: Mar 2019
Location: Horsens, Denmark
Posts: 16
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Re: Ampro Stylist projector
Mine is a silvery color.
It is (was) in good working condition I think. It could spin at least some things, not sure if all parts moved correctly. I had no film to test it and I bought it for the purpose of guitar amplification. I'll take some pictures of the parts that I don't need. A cup of coffee and shipping costs and I'll be willing to ship them to someone who can use them. What are the benefits to bypassing the selenium rectifier and using diodes instead? P.S. They really are beautiful to look at. Much pretty than old Bell & Howells |
17th Mar 2019, 2:03 pm | #31 |
Octode
Join Date: May 2009
Location: Stevenage, Herts. UK.
Posts: 1,515
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Re: Ampro Stylist projector
Selenium rectifiers often weaken with age leading to sagging HT. They can also fail with a foul smelling cloud of smoke.
You cannot bypass with just a diode. There has to be a resistor in series with the diode to mimic the losses in the old rectifiers and keep the HT at the same level. |
17th Mar 2019, 4:06 pm | #32 |
Retired Dormant Member
Join Date: Mar 2019
Location: Horsens, Denmark
Posts: 16
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Re: Ampro Stylist projector
Sagging voltage might actually be desirable for guitar. But if I decide to do diode resistor, do you have any recommendations of components?
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17th Mar 2019, 4:18 pm | #33 |
Octode
Join Date: May 2009
Location: Stevenage, Herts. UK.
Posts: 1,515
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Re: Ampro Stylist projector
Diode the ever popular IN4007, try 220R as a starting point for series resistor and move up or down in value as necessary. I didn't completely bypass my selenium but 'topped it up' with the diode/resistor.
Resistor will need to be a decent wirewound and it will get pretty hot. |
17th Mar 2019, 4:34 pm | #34 |
Retired Dormant Member
Join Date: Mar 2019
Location: Horsens, Denmark
Posts: 16
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Re: Ampro Stylist projector
Thank you.
Since I gutted the projector I actually have one of those big green resistors I could use. It is 250R, a bit on the high end though. |
18th Mar 2019, 5:28 pm | #35 |
Heptode
Join Date: Mar 2017
Location: Cedar Grove, Wisconsin, USA.
Posts: 823
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Re: Ampro Stylist projector
Now that the proper schematic is furnished, things look a bit more promising!
I looks like they're pushing the 35L6's to the maximum, 216 on the anodes and 110 on the screens, so it's good for about 6 watts. I never seen a 6BR7 valve used here! I would be tempted to eliminate the 50C5 tube and eliminate the high wattage heater dropper resistor and use a cap dropper. Of course the heater drop has to be recalculated because of 50 volts less in the heater chain. Also, increase the size of the smoothing and storage capacitors to at least 50mfd because of the 50CY mains. |
19th Mar 2019, 9:01 am | #36 |
Retired Dormant Member
Join Date: Mar 2019
Location: Horsens, Denmark
Posts: 16
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Re: Ampro Stylist projector
I'm still too much a beginner to really understand what all these changes would do for the sound?
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19th Mar 2019, 9:57 am | #37 |
Octode
Join Date: May 2009
Location: Stevenage, Herts. UK.
Posts: 1,515
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Re: Ampro Stylist projector
As you don't need the exciter lamp he's suggesting you remove the 50C5, but this requires altering the heater circuit to suit. A capacitive dropper can replace a resistor dropper. It eliminates the heat, but requires careful selection of capacitor type and value.
Upping the smoothing caps will reduce hum levels and decrease sag on transients, but I wouldn't do this unless a diode has been fitted. The elderly selenium rectifiers may not cope with the higher peak current. Fwiw the Ampro is not very hummy by cine projector standards. I'd suggest playing the amplifier as is for a while and see how you like its tone etc. Some, or all of the above could be implemented at a later date, but do watch output anode and screen voltages. |
19th Mar 2019, 2:14 pm | #38 |
Octode
Join Date: May 2009
Location: Stevenage, Herts. UK.
Posts: 1,515
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Re: Ampro Stylist projector
PS: Some heat would be saved if your isolation transformer can do 230v in 205v out.
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27th Mar 2019, 11:35 pm | #39 |
Retired Dormant Member
Join Date: Mar 2019
Location: Horsens, Denmark
Posts: 16
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Hum after installing an isolation transformer
So.
I have an Ampro (Stylist) New Educational projector that I am in the process of converting into a guitar amp. As with most of my other projects so far, that involves installing an isolation transformer so I don't get fried. No problems before this one. Now I have a hum when the amp is turned on. You can easily hear it when the volume is all the way down. When I turn it up. It goes much louder. Any ideas to what is happening? It's worked before installing the transformer |
27th Mar 2019, 11:49 pm | #40 |
Pentode
Join Date: Mar 2019
Location: Monmouth, Monmouthshire, Wales, UK.
Posts: 166
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Re: Hum after installing an isolation transformer
is the chassis earthed? probably one side of the isolating Transformer secondary needs grounding too?
just a thought. Also assuming it previously had no mains transformer there may be a cap from line to chassis. this could be removed and the earth wire taken directly to the chassis, signal ground should only be made off to mains ground at one point the input valve base or input plug. Last edited by Megatron; 27th Mar 2019 at 11:57 pm. |