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Old 13th Nov 2021, 6:57 pm   #1
Pamphonica
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Default Pamphonic Pam 27 AM/FM Radio

A minor "success story" as this one proved troublesome, rather than technically challenging. These are just a few notes for anyone who is working on this set.

This simple ac-only AM/FM set from 1959 is not that common and I had been looking for one for ages, to fill a gap in my Pam radio collection lineup. It's a 4-valve early FM set (ECC85, ECH81, EBF89, ECL82 plus metal recifier). It's not very sensitive on FM.

Bought as "untouched, as seen" it of course turned out to already be "restored". However, it was in great cosmetic condition with a high-gloss cabinet and mint-looking speaker grill cloth, so I decided that it would become my new workshop radio once fixed, rather than just join the museum shelves. (Out went a nice Bush VHF81 to make room).

There is only one service sheet available, even on Paul Stennings fantastic depository. Just the two pages from the Radio & TV Servicing book for 1960-61 (pages 184-5). This was enough to do the job, though.

The previous repairs had involved replacing various caps, but left the volume control inoperative (incorrect wiring), and the HT supply incorrectly wired in one place. These were quickly rectified. Now the fun started, as I had endless crackles to deal with. After hours of cleaning switches and tweaking valve sockets to no avail, I gave in and undertook full replacement of 3 of the 4 valve sockets. A very tedious and fiddly job but all the crackles vanished as a result.

I did a cleaning job on the chassis, to remove the dirt but leave some "patina of age", and re-cleaned the main band-switch. I also removed a crude HT choke added by the last restorer in mid-air. Yes, the set does hum a bit as standard but not objectionably so.

A quick tweak of the 10.7MHz IF alignment (T3, T2, T1 in that order), and replacement of the ECC85 and EBF89 and the FM side came in much more strongly. Note - the FM coils of the dual 470kHz/10.7MHz IF transformers are located towards the front side of the chassis.

While I was about it, I applied the FM stability mod mentioned in the service sheet, (re-routing the earthing of the ratio detector decoupling caps, and re-terminating an odd decoupler from V3 screen). The new earthing point is the right-most terminal on the tag strip in the final photo.

Note that the wires to the output transformer (mounted on the speaker) are quite short so the chassis has to be partly withdrawn before un-bolting the speaker. The output transformer must be uppermost on the speaker or the chassis doesn't fit (guess how I found this out!).

So that's it - another set back in order. (Photos attached).
-Jeremy
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Old 13th Nov 2021, 7:05 pm   #2
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Default Re: Pamphonic Pam 27 AM/FM Radio

Very nice Jeremy, a great addition to the collection.

Peter
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Old 13th Nov 2021, 7:07 pm   #3
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Default Re: Pamphonic Pam 27 AM/FM Radio

Those Plessey electrolytics with red and black ends and a yellow label are a known source of issues; would suggest you put them on the component-replacement schedule too.
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Old 13th Nov 2021, 7:10 pm   #4
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Default Re: Pamphonic Pam 27 AM/FM Radio

The electrolytics actually tested fine for capacity and leakage, and seem to be doing their job, so I tend not to replace them on sight, unlike waxies and Hunts!
And sorry about the horrid radial capacitor bodge on the right-hand side by the volume pot (blame the last repairer).
-Jeremy
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Old 13th Nov 2021, 8:33 pm   #5
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Default Re: Pamphonic Pam 27 AM/FM Radio

With so much black sticky tar stuff down there, you sure it's not a Philips?

David
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Old 13th Nov 2021, 8:36 pm   #6
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Default Re: Pamphonic Pam 27 AM/FM Radio

Yes, I think that poor transformer had a hard time at some point. Now running cool but the tar has escaped a bit! No doubt a coupling cap went leaky and no-one noticed the hot smell.
I would be interested to know if this chassis appears in any other Pye/Invicta/Ekco sets.
-Jeremy
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Old 13th Nov 2021, 10:37 pm   #7
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Default Re: Pamphonic Pam 27 AM/FM Radio

That looks lovely, Jeremy. I can see you must have had a delightful and lengthy period replacing those valve sockets - they didn't leave much room for manoeuvre!
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Old 14th Nov 2021, 12:27 am   #8
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Default Re: Pamphonic Pam 27 AM/FM Radio

Nice little set Jeremy, is the front padded? I think whoever made Phillips transformers also did some for Pye/Pam.

Andrew
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Old 14th Nov 2021, 1:39 pm   #9
Edward Huggins
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Default Re: Pamphonic Pam 27 AM/FM Radio

The chassis in this could be a version of the Pye FM/AM "Piper" budget radio.
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Old 14th Nov 2021, 3:22 pm   #10
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Default Re: Pamphonic Pam 27 AM/FM Radio

Quote:
Originally Posted by Andrewausfa View Post
Nice little set Jeremy, is the front padded? I think whoever made Phillips transformers also did some for Pye/Pam.

Andrew
The front is not padded. The cloth lies straight over the front baffle, and the cream rexine is flat. As to why they decided to mount the speaker vertically, I can only assume that they originally may have wanted it horizontal, but the output transformer would have fouled some part of the rest of the gubbins. The speaker fret cutout is definitely vertical, but does obscure about 1cm of the speaker at the top.

By the way, in photo 2, the eagle-eyed may have spotted that the ECL82 is missing. I removed it to protect it as I manoeuvered the chassis back into the case. It lives just to the left of the main can cap in the photo.

-Jeremy
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Last edited by Pamphonica; 14th Nov 2021 at 3:43 pm.
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Old 14th Nov 2021, 5:30 pm   #11
Leon Crampin
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Default Re: Pamphonic Pam 27 AM/FM Radio

I have a P117 Pye Piper which is a minimal (reflexed) AM/FM set and probably just pre-dates Jeremy's set. The Piper must have been a nightmare to produce and align in the factory, as it has a great deal of hot switching in the AM and FM signal circuits and its gain is rather lacking on FM. It's also a live chassis set with a heater transformer, unlike the Pam 27.

I suspect Jeremy's set was a sucessor to this and, sensibly uses more conventional circuitry. The ECL82 seems rather hum prone in my set - perhaps the later set has a better layout. The build standard of both of these sets is rather poor though - a rat's net with some floating connections....

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Old 14th Nov 2021, 8:43 pm   #12
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Default Re: Pamphonic Pam 27 AM/FM Radio

I’m impressed Jeremy. Not a job for the feint hearted, most of those valve holders are almost completely obscured under the chassis and it looks as though you had to remove a mass of short leaded components in order to reach them. You also appear to have riveted them putting to shame those of us that cheat by using screws.

I would second the comments about those Plessey electrolytics, they look so pretty in red, black and yellow that it’s tempting to leave them but you will most probably end up having to replace them in the near future. The strain of having to work after decades of rest seems too much for them.

Len
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Old 15th Nov 2021, 3:10 am   #13
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Default Re: Pamphonic Pam 27 AM/FM Radio

Quote:
Originally Posted by Pamphonica View Post
The electrolytics actually tested fine for capacity and leakage,
I agree. A lot of folk say that those Plessey capacitors are known to be trouble, but I have to say that I haven't found this to be the case in radios and record players. I think the unreliability thing comes from their use in TV receivers, where they were a lot more stressed and did actually cause quite a few issues.
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Old 16th Nov 2021, 11:56 am   #14
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Default Re: Pamphonic Pam 27 AM/FM Radio

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Originally Posted by Tantanometer View Post
You also appear to have riveted them putting to shame those of us that cheat by using screws.
Len

Actually, the only new ceramic B9A sockets I had to hand with the central metal spigot were the types with in-built rivets, so I just inserted them and swaged the ends as best I could. If you look closely, one has bolts. That was because I inadvertently drilled out the NEW socket again when meaning to remove the next one for treatment - Duh!

As for the caps, maybe they should get replaced, but it's a simple job if they do fail, and they may be happier now they will be more regularly used.

-Jeremy
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