SINCLAIR Amps from c1972

[poynton]

HI.

Does anyone have any info / circuits for the Sinclair range of amps c1972.?

I think they were called the Z30 and Z50

Thanks

Andy

[poynton]

[rjb]

I have three pages of the stereo 60 manual which gives a preamp cct, Z30 cct, and PSU cct. No transistor types though.
Do you want scans emailed to you?

Ross

[poynton]

HI.

Yes, Please.

andy-dot-atherton-at-fsmail-dot-net

Many thanks

Andy

[rjb]

Anyone else want this info by email?

[Bo Hansén]

Andy,

I remember I have a little book, the "Sinclair Project 60"
that I have save from early 70`s.

And guess what, yes there was the schematic you serch for.

You can find it here:
http://web.telia.com/~u31641623/Sinc...Z30,%20Z50.jpg

--Bo

[poynton]

HI.

Excellent.

Many thanks.

I built a version of this when I was at uni.
My first pcb.
2n3055 for outputs and BC109s [I think] NOT Sinclair specials.
It oscillated on one half cycle when fed with sine and blew up !!
When fixed, I remember it sounded pretty good and was more reliable than the Sinclair pre-built version I copied.

Andy

[Peter Burney]

Hi Ross,

Just opened up a treasure trove of electronic goodies packed in a box in my garage for the last 30years and found a complete sinclair project 60 set that I would like to rebuild.
I spotted your last thread of a few years back and wondered if you still had any of those schematics you talk about below.
If so I wondered if you would also be willing to e-mail them onto me at peter@bridgeconsultants.co.nz
Any help greatly appreciated.
Cheers

Peter

Originally Posted by rjb

I have three pages of the stereo 60 manual which gives a preamp cct, Z30 cct, and PSU cct. No transistor types though.
Do you want scans emailed to you?

Ross

[John Hope]

I built many of the Sinclair systems for family and friends when I was a teenager in the 1970's. These included Project 60's (with the Linear Volume Pot!) and Project 80's (with the Coat Hanger Clip Pots).

I had a recurring problem with the power amp modules of the same vintage as the Project 80 - They were later ones than the Z30/Z50's, and may have been called Z40/Z60's. I seem to recall they used TIP42 output trannies. If left playing the whole day playing background music for merry housewives, the power amps would get warm, then get thermal runaway, then die, taking out the output trannies and the PSU fuse. This happened over and over again, despite very careful layout and grounding and reasonable heatsinking. I went through a sack of TIP42's

I did a brute force modification by replacing the output trannies with what we used to call Throffs (2N3055's) mounted on a huge heatsink, with the Z50 board tagged onto it. That seemed to do the trick.

I wrote to Sinclair about this and they replied with some embarrassment that there was a bias setting resistor for the output stage that was too low and they recommended I increase the value. 40 years on I can't remember the values (10 R to 15R??? it was about a 50% increase) but if someone posted a working link to a circuit of the Z40/60 it might jog my memory. Whether or not Sinclair later brought this mod to production I don't know.

Another Sinclair Wonder was the IC12 integrated 6W power amp. This worked quite well but was not short circuit proof. If the speaker leads were shorted it would die in a cloud of smoke and stink. I had a big sack of IC12 chips, too. I stand corrected, but I think the original Z30/Z50 amps may also not have been short circuit proof.

[Bone]

I have a pdf of the Sinclair stereo 60 manual if anyone wants it. Ive already sent it to Peter.
As far as I know none of the Sinclair amps were short circuit proof. They were made to a very low budget and things like protection were ignored. Biassing of the output stages was a bit hit and miss, and they very often destroyed themselves.

Tony.