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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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8th Mar 2018, 9:23 pm | #1 |
Heptode
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Dynatron GR8 Carnival Off/On/Volume Switch
Have a Dynatron Record Player which is stuck permanently on. The switch (Off/On/Volume) clicks and the volume control works fine BUT it wont switch off. Any thoughts other than replacing the control.
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8th Mar 2018, 11:56 pm | #2 |
Dekatron
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
By far the easiest and cheapest option is to fit an in-line type switch into the mains lead.
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Edward. |
9th Mar 2018, 10:54 am | #3 |
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
I don't know what form the switch takes in this particular player, but some OFF/ON switches can be repaired.
https://www.vintage-radio.net/forum/...0&postcount=36
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
9th Mar 2018, 11:59 am | #4 |
Dekatron
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
Hi,
Maybe a squirt of switch cleaner would help? Sometimes these switches have a dab of grease within, that could have hardened. If I remember correctly, I've done this in the dim and distant past with positive results. Cheers, Pete.
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9th Mar 2018, 1:06 pm | #5 |
Heptode
Join Date: Jan 2008
Location: Southend, Essex, UK
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
Think I'll try the squirt of switch cleaner first Tractorfan but will have to remove the whole front to get at it as switch control panel attached to front. Will do anyway to remove a dent in the grill. Thanks for all replies.
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9th Mar 2018, 3:58 pm | #6 |
Dekatron
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
Can you not access the switch far easier by just removong the inside amplifier cover panel just in front of the record deck?
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Edward. |
9th Mar 2018, 4:14 pm | #7 |
Dekatron
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Location: Cottingham, East Yorkshire, UK.
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
In 2014 I restored a GR8 which had the same problem. No luck trying to dismantle and repair the old pot so I had to get a replacement. Luckily, the one that Bowood sold fitted fine. The front to back dimensions are fairly critical as the knob is an edgewise control and must line up with the slot in the panel. I've attached a pic of the old pot and the Bowood replacement before cutting the 1/4" (not 6mm) shaft to length (the style of which might have changed by now).
Also had to change ten of the 18 resistors which had drifted way out of spec, and eight caps, five of which are on the attached pic alongside the resistors. Although the amp gives an excellent account if itself, with two ECL86 triode/pentode valves and a much higher component count that simpler amps, the rudimentary PCB is a rather untidy layout with flimsy point-to-point wiring. Adequate, yes, but not Dynatron's finest hour. Luckily the reservoir/smoothing caps reformed nicely, and the contact-cooled rectifier was still putting out the required Voltage. The first pic shows the original switched pot, Second pic is the Bowood replacement, Third is of the replaced resistors plus five of the replaced caps. The last pic is of the underside and the circuit board. One possibility worth trying would be to carefully drill a 1mm diam hole towards the rear of the perimeter of the pot and squirting in some DE-Oxit or whatever, while switching the switch on an off a few time. If it works, you could seal the hole with say a blob on UHU. Good luck in your endeavours.
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9th Mar 2018, 5:53 pm | #8 |
Heptode
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
You can, but doesn't give you enough access to squirt accurately. I have now dismantled and given it an accurate good healthy squirt and if I get time later I'll see if been successful. I needed to remove the front to press back a good healthy dent in the grill and that manoeuvre has been successful.
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9th Mar 2018, 9:21 pm | #9 |
Heptode
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
So far so good. The dent remove and the switch just tested after the earlier generous but accurate squirt of switch cleaner and seems to be working fine. Not counting chickens yet as will test again tomorrow.
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9th Mar 2018, 11:27 pm | #10 |
Pentode
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
My late father 'inherited' the GR8 during its development when he joined Dynatron in 1961. I remember him saying that the amplifier circuit was a bit of a mess and didn't work very well, so he had to do some rather rapid reworking of it, using what he had to work with, just before production started. That may explain the poor PCB and component layout. I have a GR8 which has developed distortion, so will have to work through the amplifier. My father died just a year ago aged 92, so it waited for him to go before it went wrong! Incidentally, the GR8 shared Best Buy in Which? with the Bush SRP31, so he got it right.
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10th Mar 2018, 7:25 am | #11 | |
Heptode
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
Quote:
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11th Mar 2018, 10:01 pm | #12 |
Heptode
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
Thanks for all your replies. Managed to sort the player out and running A1 fine. Dents fixed as good as I can get, the off/on switch working well.
The deck needed a lube and removal of hardened grease and the idler wheel cleaning. One thing that had me foxed for a goodly time was the bottom part of spindle used for autodrop was not protruding as at some time it must have been bent ever so slightly. All cleaned up but a good result in the end. Perhaps the earlier version did not have The Royal Coat of Arms on the inside the lid, as maybe the company got that award after March 1963 when the WHICH report came out?
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13th Mar 2018, 1:41 am | #13 |
Pentode
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
If I remember correctly, Dynatron was awarded the Royal Warrant in 1965, so the GR8 tested by Which? wouldn't have had the transfer on the lid.
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14th Mar 2018, 9:36 am | #14 |
Heptode
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Re: Dynatron GR8 Carnival Off/On/Volume Switch
Thanks again forum members for all your input. Must admit this is a really nice animal and certainly deserved a top rating status by WHICH back in 1963. Moderator think probably time to close this thread. Thank you.
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