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Perdio Portarama

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sideband
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After some years of searching, I've just bought one of these early transistor portables off eBay. I don't pick it up until next week but it's all arranged.

 

There seem to be plenty of these around but this is the first one I've seen within reasonable striking distance of home at a reasonable price and in good condition. The image isn't the one I'm picking up but still reflects the general condition. Once I have this in my possession I'll be adding to the thread during its revival/restoration. Hope the tube is good.....!

 

Portarama.jpg

 
Posted : 19/03/2017 6:25 pm
PYE625
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Well done!  

I had my eye on it too, but pleased it still remains "in the club" on here so to speak welld_gif

Looking forward to reading all about it wink

To understand the black art of electronics is to understand witchcraft. Andrew.

 
Posted : 19/03/2017 6:47 pm
crustytv
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Hi Rich,

Great little sets, pleased you finally nabbed one.

I've just uploaded the service data to the Data Library for you, some light reading prior to getting your mits on it. I look forward to you sharing the story. One thing to be wary of is the presence of a notorious AF117 in the video output stage. The cathode follower TR106(Af117) emitter output is fed to the Video output transistor TR107, so tin whisker trouble might cause that stage to shutdown.

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Posted : 19/03/2017 7:13 pm
sideband
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Chris said
One thing to be wary of is the presence of a notorious AF117 in the video output stage. The cathode follower TR106(Af117) emitter output is fed to the Video output transistor TR107, so tin whisker trouble might cause that stage to shutdown.  

I have a small supply of AF127's as replacements. Any of the AF11x are regarded with suspicion and with luck I'll have suitable replacements for any of them.

 
Posted : 19/03/2017 7:41 pm
crustytv
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Another thing to be careful with is the channel selector and fine tuning ring. Invariably these are always somewhat cracked or broken, they seem to get very brittle with age. You may be lucky and yours has no damage, just something to note when you come to operating it.

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Posted : 19/03/2017 7:46 pm
occiput
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I had one of these about thirty years ago. I got it working, but then moved it on, which I've regretted ever since.

 

They're a nice set, of typical Perdio build quality.  If my experience is anything to go by, the line output stage is fragile, and won't stand having any liberties taken.

709379

 
Posted : 19/03/2017 10:23 pm
sideband
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Well thanks to Chris, I've now downloaded the circuit. First time I've looked at it and there is nothing complex about it....all very conventional.

 

Thanks for the info re the line output stage. It's an early circuit and it was at the edge of transistor technology at the time....particularly for line output devices. Those AU101's didn't like spikes at all so I expect many fell foul of careless servicing or EHT recs deciding to flash over. I've got a few AU101's and most of the other transistors. 

 

Next I'd like to secure a Philips 11TG190. I had one many years ago but gave it away......dunce_gif

 
Posted : 19/03/2017 10:53 pm
sideband
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It's here!!

 

Went over to Laughton early this morning and collected it. Lovely condition, all the knobs and even the channel change and fine tuning work. It doesn't have the telescopic aerial or any cables but these are only minor problems on what is otherwise a very nice example.

 

Even the M25 was reasonably clear with only a few queues and I managed to get to the seller before 9am. All-in-all, well worth the effort of going there.

 

Can't wait to get it on the bench!read04dmm_gif

SAM_1071.JPG SAM_1072.JPG

 
Posted : 23/03/2017 10:50 am
Lloyd
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Looks like you got a good'un there! Mine is also missing it's aerial, but on top of that it's also missing all it's knobs, and the battery cover.

Regards,

Lloyd.

 
Posted : 23/03/2017 11:36 am
Marc
 Marc
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That does look tidy, nice find. smile

Marc.

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RSGB call sign 2E0VTN

 
Posted : 23/03/2017 11:39 am
sideband
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I couldn't resist having a quick look inside. The channel knob was something of a challenge to remove but eventually it released it's hold on the tuner shaft enabling me to remove the cabinet.

It all looks tidy with nothing amiss. There is a sticker inside dated 1968 that says AU101, 1000uF 25V and D87 (possibly 187) rectifier so it appears to have had at least one repair in it's life. Other than that it all appears to be untouched. I've found a proper mains connector for it and may also have a battery connector. I've seen at least one of those nasty torpedo type capacitors but all the rest are either the Philips 'mustard' types or ordinary ceramics so there shouldn't be too much trouble with those.

Later today I hope to be able to do some basic checks including a check of the CRT heater.

 

'Will Sideband be able to revive this neglected TV? Will the set present a number of challenges that puzzle and confuse? Stay tuned folks for the next exciting episode'

SAM_1074.JPGSAM_1075.JPGSAM_1076.JPGSAM_1077.JPGSAM_1082.JPGSAM_1084.JPG!  

 
Posted : 23/03/2017 1:06 pm
PYE625
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I'll be following with great interest as I now have a Portarama too.

(More on mine later  wink)

To understand the black art of electronics is to understand witchcraft. Andrew.

 
Posted : 23/03/2017 1:26 pm
crustytv
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Sideband Said

Later today I hope to be able to do some basic checks including a check of the CRT heater.

I doubt you will have any problems with your CRT but if you do, I have a good Mullard AW21-11 with scan coils in the loft.

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Posted : 23/03/2017 2:18 pm
sideband
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Well I spent a few hours on the set this evening. The idea was to assess the general condition of electrolytics and to see if the CRT heater was OK. Well in general all the main electrolytics seemed fine according to the ESR meter. I did notice an interesting 'repair' on the IF/frame board....the frame lin pot seems to have been replaced by a couple of fixed resistors. I can only assume that a replacement 100 ohm pre-set was not available so some experimentation with fixed resistors was carried out!  After removing the audio PCB I was able to remove the CRT base and check the heater....it was fine but I left the base disconnected for the moment until the supply voltage was measured. The heater is connected across the 11.6V supply so if the supply is high, it could ruin the tube. Some checks around the mains input showed an open circuit across the input terminals. Fortunately I found the on/off switch wasn't working but some switch cleaner seemed to sort that out. I made up a mains lead using the connector I found and then applied mains.

Immediately there was a faint hiss from the speaker. I found a convenient place to measure the 11.6 volt supply was at the audio amplifier. It measured 11.06 volts which I thought was pretty close seeing as the set probably hadn't been used since 1985 (405 switch-off in the London area). Now although the CRT base was disconnected, that wouldn't stop the EHT rectifier (DY87) from lighting up. It was decidedly dead and there didn't seem to be any line whistle (I can still hear that....just about). I decided to do a few voltage checks around the line timebase board and soon established that there was no 11V supply. Seeing as it was present at the audio stage, it had to be a resistor or a fuse. It turned out to be the latter. The same fuse also feeds the line output stage.....New fuse fitted, switch on and the new fuse failed instantly. I could see where this was heading so decided to try and confirm my fears about the line output transistor. Fortunately this is the later version of the set and the AU101 line output transistor is mounted on the main chassis...it's still a pig to change though probably necessitating removal of the CRT and LOPT.

Disconnected two leads on the lower tag of the line output transformer which feeds the AU101. Measured the resistance between the collector and chassis which is the same as collector to emitter...5 ohms one way, around 20 ohms the other way. That doesn't seem right even taking into account the diode across the junction. Left the transistor disconnected, replaced the fuse again and applied mains. The fuse didn't blow and I now had an 11.6 volt supply to the line timebase. There also appears to be some line drive.

So now I have the task of replacing the AU101. There is also an efficiency diode AY100 across collector emitter junction. That's as far as I've got tonight. I have a nice new AU101 waiting to go in but I want to check the oscillator and driver stages first as I don't want my AU101 to go into the bin!

There is also a familiar odour coming from the selenium bridge rec....puke

 
Posted : 24/03/2017 12:02 am
mendipviews
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If you need any spare bits  I have a scrap set which is complete but is cosmetically marked and some cracks in the plastic.
Rather it was some use to someone than go in the bin

Cheers
Luke

 
Posted : 24/03/2017 9:56 pm
sideband
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Thanks Luke! I may well need some parts.

We have FIRST LIGHT! After some further investigation around the line output transistor I found some very dodgy wiring. This set is the later version with the transistor mounted on the chassis. After removing the line lin coil assembly, the AU101 is easily accessible. What's more it has connectors on the base and emitter connections that just pull off. With the leads removed, the transistor measured fine as did the efficiency diode. The wiring left a lot to be desired so I tidied it all up with the result that I then had sensible readings on the transistor. I fitted yet another fuse, switched on and was rewarded with a line whistle and heaters in the DY87. I next refitted the CRT base and tried again. After around 20 seconds a scan of around half an inch high with full width appeared. I plugged in the aerial feed from the Aurora (having previously set the tuner to Ch9) and with a twiddle of the fine tuning and the contrast control, had good sound and some sort of video clearly showing. At least it proves that a lot of the signals side is working.

Next I hinged out the signals/frame-timebase board to do some quick checks. First I noticed that TH100 in the emitter of the frame oscillator TR111 had fallen to bits. No idea of the value and it's only given a type number in the Trader sheet of VA1057. I've temporarily fitted a 500 ohm thermistor in there but still don't get any frame scan. I then noticed some 'interesting' replacement components had been fitted at some point. R140 for instance in series with the height pot should be 5.6K and a 10K has been added in series with it for some reason. This together with the lin pot being replaced by two fixed resistors tells me that some bodgery has gone on so I decided to leave it for tonight and next session, start to restore the circuit back to how Perdio designed it! I may have to blow the dust off the 'scope and see what's what. 

Anyway it's all rather encouraging and the tube looks to be a cracker so with luck, once the frame scan is sorted, I'll start to see some good results.

SAM_1095.JPG

Line output transistor easy to get to

once the line lin assy is removed

SAM_1096.JPG

First light!

SAM_1097.JPG

Thermistor fallen to bits.

 
Posted : 24/03/2017 11:59 pm
PYE625
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Excellent news, and it's looking to be a good set.  welld_gif

I'm not sure whether to start a new thread on my portorama or wait until you have finished your's Rich.  

Is it good to have two together, or more polite to wait ?

I'm stuck and can't decide !duno_gif

To understand the black art of electronics is to understand witchcraft. Andrew.

 
Posted : 25/03/2017 7:25 am
crustytv
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Sideband Said

First I noticed that TH100 in the emitter of the frame oscillator TR111 had fallen to bits. No idea of the value and it's only given a type number in the Trader sheet of VA1057.

va1057.jpg

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Posted : 25/03/2017 7:39 am
sideband
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Thanks Chris. I really must get down to sorting out some data on these obsolete components.

So it's basically a 2.2 ohm.....probably why I still don't get any frame scan. I erred on the high side reasoning that it wouldn't be any higher than 500 ohms and intended to fit a small pre-set in the emitter and reduce the resistance until the oscillator started.

 

Anyway now I know the value, I can work from there. I can have a look through my box of thermistors to see if I have something that will do or can fit a 2.2 ohm resistor for now just to get things going.

 
Posted : 25/03/2017 8:18 am
PYE625
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The beauty of it being a low value means that something modern should be available if stock of vintage parts proves not to have the right type. 

(Actually, many varying values are available)  

To understand the black art of electronics is to understand witchcraft. Andrew.

 
Posted : 25/03/2017 8:37 am
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