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Old 8th Mar 2018, 9:23 pm   #1
Ekcoman
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Default 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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Old 8th Mar 2018, 11:56 pm   #2
Edward Huggins
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Default 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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Old 9th Mar 2018, 10:54 am   #3
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Default 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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Old 9th Mar 2018, 11:59 am   #4
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Smile 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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Old 9th Mar 2018, 1:06 pm   #5
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Default 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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Old 9th Mar 2018, 3:58 pm   #6
Edward Huggins
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Default 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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Old 9th Mar 2018, 4:14 pm   #7
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Default 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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Old 9th Mar 2018, 5:53 pm   #8
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Default Re: Dynatron GR8 Carnival Off/On/Volume Switch

Quote:
Originally Posted by Edward Huggins View Post
Can you not access the switch far easier by just removong the inside amplifier cover panel just in front of the record deck?
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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Old 9th Mar 2018, 9:21 pm   #9
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Default 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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Old 9th Mar 2018, 11:27 pm   #10
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Default 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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Old 10th Mar 2018, 7:25 am   #11
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Default Re: Dynatron GR8 Carnival Off/On/Volume Switch

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Originally Posted by dalgwcobl View Post
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.
Interesting to note that this one had "Royal Approval" badge on the inside the lid but the one in the WHICH Mag doesn't so possibly different dates?
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Old 11th Mar 2018, 10:01 pm   #12
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Default 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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Old 13th Mar 2018, 1:41 am   #13
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Default 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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Old 14th Mar 2018, 9:36 am   #14
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Default 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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