3 months ago I obtained an old Serviscope s31 in a non working condition. See photos.
There was also a Goldring G99 turntable and an AKAI 910 valve Reel to Reel tape deck.
I have finally got it back to working condition.
But, the schematic available on the internet does not exactly match what is and I cannot find a revision.
Is there anyone who can show me the correct wiring of C27 trimmer cap in the time base & horizontal amp on page 26 of the manual.
I removed this early on in the restoration because it was wrong according to the schematic.
In the schematic it is wired with the other caps c27-c31 in parallel but in reality it is not it is on the selector side of the switch in series going back to v7A anode.
I have left it out for the moment.
It can be seen in the circuit photo halfway up on the left, looks like a small can made of aluminium.
The previous owner had also removed other parts of the circuitry and miss-wired elsewhere. He was TV tech from the 60's and died about 5 years ago at 80.
So far I have replaced all the molded paper caps, v10, R107, R108, MR1-3, NT1-3, CR1, C43,C41,C41,C19, a multitude of resistors and some small caps.
v10 was acting like a Van der Graaf generator.
I replaced the Selenium rectifiers with a 1N4007 and a 100 ohm 1 watt resistor inside the original casing
The Germanium GD5 Crystal diode with a 1N5711 schottky diode, it was open circuit.
The Neon tubes with NE2 90v bulbs, all the leads were corroded through at the base
Other errors in the schematic include NT3 being joined to junction of R127 & R128 in Power Supply, I have not done this.
CA = C1, CB = C2, RA = R1 in Horizontal Amp.
Most frustratingly there are no voltages noted anywhere. This caused a small problem with replacing the Selenium recifiers.
By experiment with resistors and the 1N4007 diodes I now have 1250v after MR3 and the controls all work on the CRT. ie Astig, brightness, focus.
With the Selenium rectifiers I was only getting 900v.
Still waiting on some parts on the slow boat from China.
I am going to try some 1600v metalized film caps to replace the C49 and C48 0.5uf 1500v paper caps.
I ordered these
https://www.aliexpress.com/item/Free-Shipping-5pcs-CBB-105J-1KV-1uF-P25mm-Metallized-Film-Capacitor/32381712753.htmland was going to put them in parallel to give me .5uf.
There seems to be some fluctuations, random spikes in the power supply.
So hard to find high voltage caps today.
If anyone can send me more specs/tips etc. it would be much appreciated.
I included the service manual pdf as an attachment.