Ever Ready Sky Master problem.

[gary_crutchley]

Hi all,

I am looking for some advice please. I have an Ever ready Sky Master which was working okay until a few days ago, although it did appear to have the infamous AF117 "tin whisker" issue. Giving the AF117's a tap or a flick would get the set working again for a while, however, one of the AF117's leads has parted company with the transistor body.

Could someone advise me on a suitable replacement for the AF117's please, I would like to change all three?

Also I was wondering if anyone has worked on this set, and could advise on how to go about this task please? Also how tricky it is?

Thanks in advance.

Regards,

Gary

[crackle]

I think the AF127 is a reliable transistor by all accounts.

Mike

['LIVEWIRE?']

You could also use the Russian 'GT'(?322?) transistors, usually available for about £1 each on eBay (Sorry, I've forgotten the type number, but it is mentioned in another thread in this section

[AC/HL]

Type AF117 in the search box above. There have been many threads on this subject, which is common to most UK transistor radios of this age, not specifically EverReady.

['LIVEWIRE?']

The Russian Transistors I mentioned in post #3 are type GT322b, just to set the record straight.

[gary_crutchley]

Hi all,

That's brilliant thank you, I will also take a look at the other posts.

Has anyone worked on a Sky Master? I heard they can be a little tricky?

The other question I have might seem a bit basic. I've not changed any transistors before, how do I identify the leads please?

Regards,

Gary

[TrevorG3VLF]

Get a circuit diagram and note which lead goes where.
The AF117 has four leads; emitter, base, screen, collector. There is a teeny weeny bit of extra space between screen and collector.

Most transistors go emitter, base, collector but they can be any order, perhaps with the collector in the centre. It would be best to get documented connections of any replacement but some meters will give a measure of gain if connected correctly.

[Sideband]

Originally Posted by gary_crutchley

I've not changed any transistors before, how do I identify the leads please?

In that case be careful! The AF127 is an exact replacement for the AF117 BUT the lead-outs are in a different order. As suggested above, you need to obtain the lead-out info on the transistors. Simple....all you do is put the transistor numbers into Google and you'll probably find many sites that show the lead-outs.

[60 oldjohn]

Before fitting ANY metal cased transistor, I would advise checking there is no circuit between case and CBE. I put one probe on CB & E together other probe to case.
I have only recently started doing this since having a "Right run around" With a Hacker & AC127s. When I checked 5 out of 7 of my NOS were shorted out to case. One AC127 was mounted on the common heat sink, luckily its paired with an OC81 so no damage was done as the OC81 is a glass cased transistor (OC81D) with a metal case slipped over to help with heat dissipation.

John.

[gary_crutchley]

Originally Posted by TrevorG3VLF

Get a circuit diagram and note which lead goes where.
The AF117 has four leads; emitter, base, screen, collector. There is a teeny weeny bit of extra space between screen and collector.

Most transistors go emitter, base, collector but they can be any order, perhaps with the collector in the centre. It would be best to get documented connections of any replacement but some meters will give a measure of gain if connected correctly.

Thanks Trevor, that's great advice. I have the circuit diagram.

Originally Posted by Sideband

In that case be careful! The AF127 is an exact replacement for the AF117 BUT the lead-outs are in a different order. As suggested above, you need to obtain the lead-out info on the transistors. Simple....all you do is put the transistor numbers into Google and you'll probably find many sites that show the lead-outs.

Thanks I'll remember to get the lead out order. I might be back for further advice once I get the transistors.

Originally Posted by 60 oldjohn

Before fitting ANY metal cased transistor, I would advise checking there is no circuit between case and CBE. I put one probe on CB & E together other probe to case.
I have only recently started doing this since having a "Right run around" With a Hacker & AC127s. When I checked 5 out of 7 of my NOS were shorted out to case. One AC127 was mounted on the common heat sink, luckily its paired with an OC81 so no damage was done as the OC81 is a glass cased transistor (OC81D) with a metal case slipped over to help with heat dissipation.

Thanks John, great advice.

Gary

[gary_crutchley]

Hi all,

By way of an update, I ordered three AF127's (eBay) to replace the problematic AF117's in my Sky Master, we made the replacement today. I've had the set running on test all afternoon, it is working very well indeed. If anything the set is a little louder, and sounds better than with the original AF117's, although I suspect the latter weren't working to the optimum.

Just for information, we opted to solder to the existing leads rather than remove the chassis. There was enough insulation on each connection to cover the joints, so apart from the smaller size of the AF127's it quite looks reasonable. I've retained the AF117's, at some point I will remove the contents of the cans and fit the cans over the AF127's to improve the appearance.

Many thanks for all of your help.

Best regards,

Gary