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Old 22nd Jun 2009, 4:52 pm   #1
dave.mycock
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Default hacker mayflower 2

I am trying to restore a mayflower, The output stage has been over running, I have changed the coupling caps. and the anode and cathode resistors along with assosiated decoupling caps. But I have the problem of R34 cooking it's self to death even though I have replaced C27. Anybody point me in the right direction please?
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Old 22nd Jun 2009, 5:00 pm   #2
Steve_P
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Default Re: hacker mayflower 2

Using the manufacturer's sheet, try C38, Pull V1 and see if it still overheats.

Cheers,

Steve P.
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Old 22nd Jun 2009, 6:01 pm   #3
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Default Re: hacker mayflower 2

I agree with Steve, almost certainly C38
Also possible is a short within the tuner assembly ( ie metal cover touching, if there is one ?? )
Forget that - I've just noticed that the HT supply resistors appear to be outside of the tuner head.
What does the C28 end of R34 to ground measure (ohms )
Also, what is the voltage across R34 ?

Andy
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Old 22nd Jun 2009, 7:09 pm   #4
dave.mycock
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Default Re: hacker mayflower 2

Iv'e changed C38
Volts across R34 = 77v it reaches a temp of 50 degrees C after about 5 mins.
Ohms to chasis junction C28/R34 rises in M ohms until my digital meter reads overload.
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Old 22nd Jun 2009, 7:23 pm   #5
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Default Re: hacker mayflower 2

Pull out V1 and see if it overheats then.

Change R34.

Cheers,

Steve P,
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Old 22nd Jun 2009, 7:25 pm   #6
dave.mycock
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Default Re: hacker mayflower 2

Scrub the bit about meter showing overload iv'e done it again and the resistance started at 112K but is very slowly going down the longer i have the meter conected
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Old 22nd Jun 2009, 11:02 pm   #7
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Default Re: hacker mayflower 2

From your measurements the current through R34 is only c. 11ma which seems reasonable for the tuner head.
Also, the power being dissipated, assuming R34 actually measures 6k8 is only just under 0.9 watts, so this doesn't look like a fault, as such. If double checking the measurements gives the same readings, you need a higher wattage resistor perhaps ??

Andy
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Old 23rd Jun 2009, 5:40 pm   #8
dave.mycock
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Default Re: hacker mayflower 2

I removed V1 and R34 was cool, Being a beginer what should removing V1 tell me?
I have a 2W resistor to replace R34, I will change it and see what happens
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Old 23rd Jun 2009, 5:43 pm   #9
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Default Re: hacker mayflower 2

Fit a 2W resistor like you said and you should be OK. Good sounding sets.

Cheers,

Steve P.
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Old 1st Aug 2009, 5:02 pm   #10
dave.mycock
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Default Re: hacker mayflower 2

Sorry it's taken so long to say thankyou to all that helped but I have been in France getting even more sets !!!
Dave
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