Even though the Beta Layout Reflow Controller (V2) has become obsolete, I wanted to perform a teardown of the unit for those planning on building a similar reflow oven controller looking for design inspiration.
There are numerous Reflow Oven controllers based on Arduino, Raspberry Pi and similar based hardware platforms. Most of these designs are Open Source hardware and software allowing for improvements not available on a commercially manufactured product.
Beta Layout Block Diagram
As a basic representation the block diagram below shows the Beta Layout V2 controller.
Beta Layout Block Diagram
As a basic representation the block diagram below shows the Beta Layout V2 controller.
 |
| Beta Layout V2 Controller Block Diagram |
Opening the Controller
The Beta Layout plastic case does not use fixing to hold the two part enclosure together. Instead there are a pair of opposing plastic clips on the lid and base, hidden by the ventilation holes, which were released using a screwdriver to gain access to the controller.
 |
| Beta Layout V2 Controller |
Inside the Case (Power Board)
Upon opening the case the power and logic boards are exposed. These are board names which I have assigned for the ease of this blog, not the manufacturer. Both boards are solder masked, immersion gold plated, untented vias and without component overlay possibly making servicing difficult.
The power board, shown in the lower part of the image above, features two IEC connections, AC transformer for logic board power, Solid State Relay (SSR), female 9 pin D connector and Thermocouple connector.
The power board, shown in the lower part of the image above, features two IEC connections, AC transformer for logic board power, Solid State Relay (SSR), female 9 pin D connector and Thermocouple connector.
 |
| Beta Layout Power Board |
The IEC connection (oven side) and SSR are protected with an M205 250V 8A ESKA sand filled fuse. Power for the logic board is provided from a 230V to 6V transformer with 300mA capability. The AC supply feeds a full wave bridge on the logic board.
Performing the control of the oven heating is the now obsolete Sharp SSR S216S02. This AC SSR was rather solidly rated at 240VAC 16A featuring zero crossing. For those in need of repairing a failed SSR, there were no direct replacement from Sharp at the time of writing this blog.
Connection for the RS232 was made with a panel mount D socket connector. The Thermocouple connector uses a two part design with what appeared to be standard hook-up wire, type TR-64, not dedicated Thermocouple wire. For reference regarding the proper cable see the IEC/ANSI details on this Omega sensor site.
Inside the Case (Logic Board)
The logic board is of a double sided design with the buttons, LEDs and crystal oscillator populated on the side facing the enclosure lid.
6VAC from the power board transformer is rectified and DC regulation is achieved with a 78L05. There appears to be an option on the connector with the AC power to drive the logic board from 5VDC directly. A single diode on one of the unused connector pins supplies the 5V rail on the board directly. At the brains of the operations is an Atmel 32A microcontroller. The thermocouple interface is made with an SPI K type thermocouple converter from Maxim - MAX6675. Lastly the TTL to RS232 is handled with a jellybean level translator from Maxim - MAX232.
Temperature Measurements
Out of curiosity the Beta Layout controller case was left open and a reflow cycle was performed. Close to maximum temperatures of some of the devices were captured. Firstly is the SSR which peaked a little over 65C however was captured using the Flir Camera when marginally cooler.
Summary
As was shown in a previous blog, the Beta Layout V2 Controller does the business for reflow soldering with off the shelf ovens. Some tuning of the reflow profile was required. From a hardware perspective the design would be considered outdated now, possibly the V3 controller with LCD interface addresses issues with controller connectivity and upgradeability.
The RS232 interface was possibly the only oversight at design time. USB 2.0 had been released in 2000 and this board was purportedly designed in 2008. Regardless with new technology there is an easy way to upgrade the Beta Layout V2 RS232 to USB using an Adafruit - CP2104, more in a coming blog.
Performing the control of the oven heating is the now obsolete Sharp SSR S216S02. This AC SSR was rather solidly rated at 240VAC 16A featuring zero crossing. For those in need of repairing a failed SSR, there were no direct replacement from Sharp at the time of writing this blog.
Connection for the RS232 was made with a panel mount D socket connector. The Thermocouple connector uses a two part design with what appeared to be standard hook-up wire, type TR-64, not dedicated Thermocouple wire. For reference regarding the proper cable see the IEC/ANSI details on this Omega sensor site.
Inside the Case (Logic Board)
The logic board is of a double sided design with the buttons, LEDs and crystal oscillator populated on the side facing the enclosure lid.
 |
| Beta Layout Logic Board |
Temperature Measurements
Out of curiosity the Beta Layout controller case was left open and a reflow cycle was performed. Close to maximum temperatures of some of the devices were captured. Firstly is the SSR which peaked a little over 65C however was captured using the Flir Camera when marginally cooler.
 |
| Beta Layout V2 Controller SSR Temperature |
The second device measured was the AC transformer which hovered at a steady 37C.
 |
| Beta Layout V2 Controller AC Transformer |
Lastly and unexpectedly the bridge rectifier rounded off the three warmest devices between the logic and power boards.
 |
| Beta Layout V2 Controller Rectifier Temperature |
The bridge like the SSR had temperature peaks depending on what part of the reflow cycle was active at the time.
Summary
As was shown in a previous blog, the Beta Layout V2 Controller does the business for reflow soldering with off the shelf ovens. Some tuning of the reflow profile was required. From a hardware perspective the design would be considered outdated now, possibly the V3 controller with LCD interface addresses issues with controller connectivity and upgradeability.
The RS232 interface was possibly the only oversight at design time. USB 2.0 had been released in 2000 and this board was purportedly designed in 2008. Regardless with new technology there is an easy way to upgrade the Beta Layout V2 RS232 to USB using an Adafruit - CP2104, more in a coming blog.
No comments:
Post a Comment