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Old 10th Jan 2018, 2:26 pm   #41
12jslater
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Default Re: Pye B18T found, how did I do?

I went through the set last night and checked all resistors (never bother with checking the caps they are nearly always bad) but out of all of them only 2 resistors had drifted from their original rating enough to result in them needing to be replaced.
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Old 10th Jan 2018, 10:39 pm   #42
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Default Re: Pye B18T found, how did I do?

Jake I wouldn't go mad and replace all the caps in one go, unless the set has been ravaged by damp and is in a really poor and dangerous state. After a good clean I'd carry out a few straightforward checks such as making sure the chassis is complete and any obvious poor connections are remade. Look at the condition of all the big smoothing cans and the power supply area to establish if its safe enough to be powered up. Your meter is your best friend so check this area carefully for dead shorts and open circuits. You'll enjoy the process more and be less likely to make mistakes if you avoid blanket replacing components. You also don't learn anything by doing this!! best of luck though and I look forward to seeing your progress

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Old 10th Jan 2018, 11:09 pm   #43
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Default Re: Pye B18T found, how did I do?

Sorry I should have stated that my usual mad go at the capacitors only applies to the wax type caps, where as the metal caps/cans have been checked and are only being replaced as necessary.

while im waiting for my capacitors to come I shall start the bit of work on the cabinet and replace the grill cloth as it is covered in very small holes.
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Old 14th Jan 2018, 12:47 am   #44
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Default Re: Pye B18T found, how did I do?

Capacitors have arrived but before I started work (this will sound stupid) I couldn't figure out how to work around the transformer under the chassis to fit a new mains lead?

I feel very stupid for asking this but I only looked at around 23:15 and I don't want to start any work this late.
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Old 14th Jan 2018, 4:01 am   #45
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Default Re: Pye B18T found, how did I do?

Can't you connect the mains lead to the on/off switch, perhaps disconnecting the pins for the original mains connector for safety?

Beware though, it's common for the fuse(s) to be before the switch, don't inadvertently bypass them.

I don't have a circuit of this set for reference, I'm just going off the pictures in this thread.
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Old 14th Jan 2018, 7:36 am   #46
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Default Re: Pye B18T found, how did I do?

I take it that the original mains lead has been cut off?
If it has not, there is no reason to replace it as it is a PVC lead and should be perfectly safe to use.


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Old 14th Jan 2018, 11:45 am   #47
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Default Re: Pye B18T found, how did I do?

One particular cap worth changing even if it tests O/K is the line drive coupling cap (C26a) that feeds pin 5 of the PL38 via a grid stopper resistor. it is in some sets a silvered mica type and can produce the same effect as an intermittent LOPT, changing width rapidly and changing EHT The value of the cap is0.02uF, a very high value for a silvered mica type, a suitably rated styro should fit the bill. I restored my receiver about 15 years ago and is still going well with the original tube and valves. The tube has an ion burn but is not too bad on anything but a full bright screen.
Good luck.
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Old 16th Jan 2018, 12:42 pm   #48
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Default Re: Pye B18T found, how did I do?

Well the heaters are on now that the bad caps have been replaced the set i didn't get much further than this last night as a college essay was due for today so this is a good sign that the set is beginning to awake after many many years.
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Old 16th Jan 2018, 10:05 pm   #49
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Default Re: Pye B18T found, how did I do?

After opening the LOPT the Cossor su61 has no heater life it appears, and if im right in saying I believe probably the easiest replacement is an EY51?

And when I get the valve how do I know which way to solder it or does it not matter?
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Old 16th Jan 2018, 10:43 pm   #50
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Default Re: Pye B18T found, how did I do?

Hi Jake, the heater will only be lit if you can hear the line whistle, it may be very dim anyway. An EY51 is a direct replacement and the heater wire can go either way around.
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Old 16th Jan 2018, 10:44 pm   #51
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Default Re: Pye B18T found, how did I do?

Jake are you saying the SU61 has no heater continuity?
If so an EY51 is fine as a replacement. It doesn't matter what way the pair of lead out wires are connected.
Before you do this you need to establish if you are you getting any line drive or EHT? do you have any line whistle? The SU61 heater will not light unless there is EHT present. Check also the heater winding for continuity.
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Old 16th Jan 2018, 10:59 pm   #52
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Default Re: Pye B18T found, how did I do?

I am currently getting a spark jumping from the lead to a screwdriver a couple of mm. and the heater is reading open.

Sorry, its a bad habit I do need to be more clear on posts in the future.
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Old 16th Jan 2018, 11:15 pm   #53
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Default Re: Pye B18T found, how did I do?

Quote:
Originally Posted by 12jslater View Post
I am currently getting a spark jumping from the lead to a screwdriver a couple of mm. and the heater is reading open.
It looks like you have found the reason why the set was retired all those years ago.
EY51's are cheap and plentiful. Even NOS ones.

Can you hear any static etc. on the sound if you plug in an aerial?
A metre or so of wire.

Don't be surprised if the large smoothing capacitor fails
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Old 16th Jan 2018, 11:42 pm   #54
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Default Re: Pye B18T found, how did I do?

At the moment just a massive amount of hum from the can capacitor, so I haven't a clue unfortunately as I am currently waiting for some electrolytics to come so I can restuff the old can. (56uf to replace a 60uf and a 120uf for the original 120uf both at 450v)
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Old 17th Jan 2018, 12:17 am   #55
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Default Re: Pye B18T found, how did I do?

If you have a problem emptying the original can, you can make a new one easily, as I did with my Cossor.

I still have the original, if you get a good result, maybe I will try and restuff mine.

When you consider how tiny modern electrolytics are compared to the original cans, depending how much you care about originality, you could elect to wire them conveniently into the chassis.
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Old 17th Jan 2018, 10:17 am   #56
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Default Re: Pye B18T found, how did I do?

I don't really plan to do it for originality but i just want to try to keep the chassis as tidy as possible, i have also ordered a replacement valve so i may get 'first light' within the week.
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Old 17th Jan 2018, 11:15 pm   #57
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Default Re: Pye B18T found, how did I do?

What should the values be on the sets LOPT? I have removed it from the chassis as it is being a bit picky on whether it wants to work or not.

If it is faulty would a rewind or a replacement be cheaper?
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Old 17th Jan 2018, 11:31 pm   #58
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Default Re: Pye B18T found, how did I do?

The LOPT is very reliable in these, i would doubt a fault at this stage. Why do you suspect it.
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Old 17th Jan 2018, 11:55 pm   #59
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Default Re: Pye B18T found, how did I do?

No HT but I was getting a spark from the top of the SU61 on the LOPT but not anymore and the line whistle that had seemed a mixture between a whistle and a buzz now just a loud buzzing however all the input has not changed.

I have yet to check the LOPT coils as the PP3 has decided to die in my multimeter. However I thought that these were fairly bad signs so I'm not hoping for much, what should the various windings be?
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Old 18th Jan 2018, 1:36 am   #60
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Default Re: Pye B18T found, how did I do?

When a set has been in suspended animation for 50-60 years and you wake it up, components can work for a few tantalizing minutes and then fail, I am sure we have all experienced it.
It is probably something mundane, like a capacitor or resistor. You need to adopt, with our help, a methodical fault-finding approach. Pulling out major components on a whim is going to end in tears.

When you ceased getting a spark, did the line output valve anode start to glow red?
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