PYE Blackbox four speaker

[RoyceVM]

I recently bought a PYE Black box 4 speaker record player and love to have the schematics of it before I start working on it.
It is in great cosmetic shape and love to see it all working.

[Cobaltblue]

Hi and welcome to the forum.
There is more than one model black box.
So the first thing to do is establish which exact model you have.

There are service sheets here:
https://www.service-data.com/search....&search=Search

Cheers

Mike T

[RoyceVM]

Originally Posted by Cobaltblue

Hi and welcome to the forum.
There is more than one model black box.
So the first thing to do is establish which exact model you have.

There are service sheets here:
https://www.service-data.com/search....&search=Search

Cheers

Mike T

Thanks so much Mike!
In the service sheets section which one is for the 4 speaker Blackbox?
The BBH model schematics only show two speakers in the schematics.

[Michael Maurice]

Can you post up a picture or two and also give us the valve line up?

[RoyceVM]

See the one side of the 4 speaker system.

[Ed_Dinning]

Hi, I think this was the same as the 2 speaker version of the PCL83 valved unit, but one of each speaker pair was fed through a cap and was used as a tweeter.
The 2 and 4 speaker versions were all fitted with the same OPT with a 1.5R secondary

Ed

[Edward Huggins]

Was there ever a 2 speaker version of the PCL83 model? From my time there I don't recall a "Running Change" notificaton on this. But I can imagine a situation where a failed EL42 amplifier was replaced with the later unit.

[Nickthedentist]

This thread, compiled by our late friend Colin, will help you:
https://www.vintage-radio.net/forum/...d.php?t=137233

[Ed_Dinning]

Hi Edward, most of the amps with PCL83's have an output transformer designed for 1.5 ohms, but, that said, it should present no problems fitting the tweeters, which simply are capacitor fed.
It should be noted that this amp was re designed from the earlier EL42 type and was fitted with a nuch smaller output transformer.
From memory at least 3 feedback loops were fitted to the amp in an effort to "tame " it; this did not always work and it would "hoot" at about 50KHz.
This would manifest itself as increased background noise and is easiest seen with a 'scope. If not sorted it will lead to the output valves red plating and burnt out transformers.
I have seen these amps with increased value caps fitted in various positions as a "factory fix". I did a post some time ago when I suggested a fix of adding a small 22uH choke in the feed to the grid of the phase splitter. This worked for me.

I'm not certain if the 2 or 4 speaker versions were the worst for feedback problems, but I had believed that it was only the chinrawsiarie (?) box that was fitted with 4 speakers

Your comments and thoughts please Edward

Ed

[Edward Huggins]

The Chinoiserie "Black Box" version was only offered (in the UK) on the 2 earliest BBs (Triode and the UL connected) and not the later 1959/60 4 speaker version. As many have discovered there were various degrees of feedback problems with both the EL42 and PCL83 versions. From my recall, the PCL83 amplifier was introduced as it was felt that Bass and Treble controls (and Tweeters) would enhance its purported "Hi Fi" status. Such tone controls would need more stages of AF amplification via the PCL83 triodes. And by that time Pye had built up a huge stock of TV valves!

[RoyceVM]

I was wondering where I can get the schematics for this 4 speaker system. My father had this Pye Blackbox in way back in1966 and it sounded the best. That is why I wanted one so badly.

[RoyceVM]

I haven't received the PYE Blackbox yet but came to know this has got a later edition of the venerable Black Box amplifier, the BBA version circa 1958-it is a three valve design with two PCL83, one ECC82 and a Siemens solid state rectifier.

I am looking for the schematics of this 4 speaker system.

[Ed_Dinning]

From the ones that I've seen the only difference is the addition of tweeters that are capacitor coupled to the OPT. The OPT still sees the approx 1.5R of the speakers because the tweeter "coming in" via the cap is to some extent compensated by the rising impedance of the LF unit

Ed

[John10b]

From the information I have the model you require is BBA or BBTA. Hope that helps in your search.
John
I couldn’t find the service sheet, but other members may be able to help find it.

[Valvepower]

Hello,

If it helps, I have taken some photos of a set of speakers destined for PCL83 BB restoration project. Sadly, I need to hang on to these, but it shows what is used in the PCL83 BB I have here in the workshop.

I have found the PCL83 BB manual with four speakers on net, but for the life or me I can't insert the address in the post!

Anyway its on the radio - workshop site.

Terry

[RoyceVM]

https://www.vintage-radio.net/forum/...t=96202&page=3
https://www.vintage-radio.net/forum/...d.php?t=136602
It seems like the circuit below is the one for the 4 speaker version but I don't have details on the component values

[Edward Huggins]

That circuit takes me back. It shows all the pitfalls that can arise, over time, from out-of-tolerance components. One can certainly design a PCL83 PP amp more simplisticly than this - but they did sound good. Remember no BB had extension speaker options, they were designed to make the most of being used in a small enclosure and with smallish speakers.

[RoyceVM]

Sadly, the PYE arrived a little damaged. Today I opened the chassis to take pictures. I was looking for bad electrolytic caps and found Plessy red and black with yellow label saying 25mfd, 25V. I believe the red end is the +ive. In the schematics +ive end goes to the grids of the identical tubes. I couldn't find another electrolytic caps with almost the same value. The other caps are in the top can beside the valves and transformers.

[RoyceVM]

Here is the capacitor list.

[RoyceVM]

Circuit diagram is attached and C11 is the cap in red and black with a yellow label
valves ID also attached.

In the split diagram of valves how do you know the pins on it?
I am lost there....