Видео 51
Просмотров 117 405

Repair of a Cyrus 3 with volume control issues.

13:01

KT88 Valve Power Amplifiers

20:52

KT88 Valve Power Amplifier Design and Build

15:01

Repair of a Cyrus Power Amplifier that's lost its Marbles!

16:40

Linn Kairn Pre-amplifier backup battery replacement

5:04

Service/Upgrade of a Linn Kairn Pre-amplifier

25:20

Repair of a Bowers & Wilkins PV1 Sub-woofer

This sub had sustained some physical damage and was blowing mains fuses on power up. This thing is 20 something Kilos so was a bit of a handful but we get it opened up and extract the boards. A shorted FET in the power factor correction circuitry of the power supply is the main problem. With this and all the low level capacitors replaced we can feel the bass again.
Doing this unit was more of a project. Packing and shipping these units is unrealistic and they are too time consuming to make economic sense unfortunately.

Видео

Repair of a Cyrus 3 with volume control issues.

13:01

Repair of a Cyrus 3 with volume control issues.

Просмотров 7073 месяца назад

Here is a Cyrus 3 Integrated Amplifier that had issues on one channel where there were some DC pops at certain volume increments. We look at the circuitry involved and trace the problem down to a leaky analog switch.

20:52

KT88 Valve Power Amplifiers

Просмотров 1,1 тыс.5 месяцев назад

In a previous video we looked at the design and build of these amplifiers. Here we power them up, do some detailed testing and have a listen. They are sounding sweet and there are still a few refinements to be made. Note that at this point I'm not making these amplifiers available. ruclips.net/video/JD-7UXszlUI/видео.html ruclips.net/video/ujluV4mYZ8g/видео.html ruclips.net/video/9ASrvZkeqk0/ви...

KT88 Valve Power Amplifier Design and Build

15:01

KT88 Valve Power Amplifier Design and Build

Просмотров 3,3 тыс.7 месяцев назад

Looking at the design and build of a valve power amplifier. This design is loosely based on the Claus Byrith 4-30 and features some custom building blocks that we looked at previously. A further custom PCA is designed for the input, phase splitter and bias circuitry. ruclips.net/video/uwOKJMj3pCs/видео.html ruclips.net/video/ujluV4mYZ8g/видео.html ruclips.net/video/9ASrvZkeqk0/видео.html

Repair of a Cyrus Power Amplifier that's lost its Marbles!

16:40

Repair of a Cyrus Power Amplifier that's lost its Marbles!

Просмотров 2,2 тыс.8 месяцев назад

Here we have a Cyrus Power Amplifier model 'Power'. One of the early stereo/mono amplifiers. It wasn't powering up and had been to a repair house previously. We find that its been butchered and has multiple problems including a dead micro-controller(marbles). This would normally be terminal but in this instance I decided to re-create the function of the controller using an Arduino. Some further...

Linn Kairn Pre-amplifier backup battery replacement

5:04

Linn Kairn Pre-amplifier backup battery replacement

Просмотров 79910 месяцев назад

Replacing the backup battery in a Linn Kairn Pre-amplifier.

Service/Upgrade of a Linn Kairn Pre-amplifier

25:20

Service/Upgrade of a Linn Kairn Pre-amplifier

Просмотров 1,8 тыс.10 месяцев назад

Servicing of a Linn Kairn Pre-amplifier. There was a suspicion that there was a noise problem with this amp but it turned out that its just got a bit higher gain than your average pre-amp. A modification was made to the amp to give a lower level output that will be better suited to power amplifiers with more gain than a Linn. There is a backup battery that needs replaced in these units and the ...

Cyrus MonoX300 MC-Bus Issues and Accessory Testing

8:41

Cyrus MonoX300 MC-Bus Issues and Accessory Testing

Просмотров 49611 месяцев назад

Whilst working on my trigger accessory it became clear that the Cyrus MonoX300 amplifiers MC Bus operation is decidedly flaky. Here I make some changes to my accessory code to try and overcome the Cyrus shortcomings. A simple automated test is then developed to run some repeatability tests and spit out the results. ruclips.net/video/9hA3p_PAR4g/видео.html

MC-Bus Trigger Accessory for Cyrus Power Amplifiers

17:39

MC-Bus Trigger Accessory for Cyrus Power Amplifiers

Просмотров 751Год назад

Looking at the Cyrus MC-Bus. This is a data bus that's used to power up and control Cyrus units from a main controller unit. But what if we want to control this bus and trigger our power amps to turn on from some non Cyrus source? Not so easy, but we come up with an accessory to do the job. ruclips.net/video/Ez6l_Zfqfhk/видео.html

High Voltage (HT) Power Supply for Valve Power Amplifiers

16:01

High Voltage (HT) Power Supply for Valve Power Amplifiers

Просмотров 2,4 тыс.Год назад

Looking at a design of a high voltage or high tension (HT) power supply for valve power amplifiers. We look at the traditional method of smoothing out the hum causing mains ripple and then look at a capacitor multiplier implementation. A dedicated PCB is then made that includes cascaded capacitor multipliers for the various voltage rails required in a valve amplifier. We also take brief look at...

DC Heater Supply for Valve Power Amplifiers

19:17

DC Heater Supply for Valve Power Amplifiers

Просмотров 2,3 тыс.Год назад

Looking at a design for a DC valve heater (tube filament) power supply. An off the shelf switching supply is modified and additional circuitry employed to clean up the supply and add a true soft start function. There are other circuit arrangements that do similar things, a current limiter is the obvious one. Current limiter circuits come with extra losses however, probably near 3 watts in this ...

Repair of a Trio of Cyrus DAB 8.0 Receivers

15:41

Repair of a Trio of Cyrus DAB 8.0 Receivers

Просмотров 878Год назад

Three Cyrus DAB 8.0 receivers with different issues. One is completely dead and has a detached power button. The other 2 have display issues and all 3 needed a re-cap. The display issues consisted of a back-light that was not being driven hard enough. The contrast was also non optimum. Usually with displays like these there is a variable resistor that is set in the factory to give optimum contr...

Repair of a Motorola Car Radio for a Classic 1960's Daimler

22:07

Repair of a Motorola Car Radio for a Classic 1960's Daimler

Просмотров 454Год назад

This radio powered up but there was no output. It looked like there was a power amplifier problem but that turned out to be a curious bias architecture leading me astray. Once we get passed this and some loose wiring its clear that the radio section is not working. The age of this radio means that it uses Germanium transistors which have a notorious reputation for 'Tin Whiskers'. We find that t...

Repair of a Cambridge Audio CXA80 with a 'sticky' problem

8:07

Repair of a Cambridge Audio CXA80 with a 'sticky' problem

Просмотров 2,3 тыс.Год назад

Another faulty Cambridge Audio CXA80. This unit has a fault code that says there is DC present on the output. This unit had previously been looked at by Richard Sounds who reported that they had changed the main board without result. When we look inside we find that this is not the case and we see that there is some adhesive that's gone a bit wrong and corroded a bunch of parts. Board cleaned u...

Repair of a Bowers & Wilkins A7 Wireless Speaker

20:47

Repair of a Bowers & Wilkins A7 Wireless Speaker

Просмотров 7 тыс.Год назад

This B&W A7 was completely dead and this seems to be a common report with these units. There is some adventure in taking it apart but with some gentle persuasion and a hammer we get there and confirm there is a power supply problem. A bit more adventure to get the power supply out and its clear that something has gone drastically wrong. Investigation shows that the power amp supply section has ...