Toaster Kenwood TTP102

I found this toaster a couple of weeks ago, with the main cord cut: here is the “disemboweling”!

The Toaster
The manual is here (from ManualsLib).
It is a simple, 2 slice toaster, with "600-800 W", vertical positioning and some controls which I’ll describe later.
It seems to be out of sale in some places (Amazon-UK, Amazon-DE, Kenwood-DE, Kenwood-PAK, Kenwood-ES) but it is available elsewhere (IND, UK, MasterSparesOnline, PAK, ebay-DE).










The Operation
The device is relatively simple, with 5 “controls”:
- the slice lowering lever,
- the variable "browning control",
- the cancel, defrost and reheat buttons (illuminated).


The Inside
The electrical parts are organized in 4 elements:
- the power switch, with a solenoid,
- the variable resistor (“browning control”),
- the 3 heating panels, and
- the control PCB (with the cancel, defrost and reheat buttons and the timers).

The following pictures show the sequence of opening the toaster.

There seems to be a market of spares for this unit, mostly in the UK (PartMaster, 4Kenwood, BuySpares, eSpares).

The Power Switch and Solenoid
Lowering the slices with the main lever closes a switch, that feeds a solenoid. The lever is then attracted to the solenoid and when the power supply to the solenoid is open, a spring in the lever makes it jump-up, with the slices.

The solenoid is labelled “TA8018”. It is fed from the control board, which supplies it with DC current.
The switch is mounted on a board, with no fuse.

The Variable Resistor
It is a linear variable resistor, labelled “B200K” and I have measured from 300 to 200 kohm. One of the bands on the sides of the support is conductive, the other resistive.




The Heating Panels
There are three heating panels, connected in series. One of them is connected with a single wire to the control board.



I have measured about 25 ohm for the ones on the sides, and 30 ohm in the central one. The heating power is therefore 600 W at 220 V (not 800 W).
Based on the length of the wire, the unit resistivity is approx. 150 ohm/m.
The support is a sort of micaceous paper.
The panels are labelled “TA8018M”.


The Control Board
The control board is connected to:
- the power switch for line,
- the end of the wire at the first heating panel for “neutral”,
- the solenoid, and
- the variable resistor (the “browning control”).



The board supports three push buttons with light, but its core is a chip: TN0841B2 A0201D, which I described here.
The board is labelled as “TA8018GS-D-11”, "E123995", "KB-3151" and “2006-7-15 REV:A”, for which I have not found any reference.

The schematics is as follows:

At the connector:

- 1 is for the "ground" at the heater,

- 2 and 4 are for the solenoid, and 

- 3 is for the AC line.

(The pins of the chip are not correctly identified).

Toaster Controller A0201D

1. Description
I found few days ago a toaster on a street. I normally do not pick this type of gadgets because I feel that somebody else may use them for better - but this time I got the electronics.

Because I only got the control board, I do not know the model: it was a toaster for two-slices, with independent selectors and three operation buttons: "reheat", "cancel" and "defrost".

For each slice-heater there is a control, with two boards each: for the timer/controller and for the buttons. 

Pictures of the control board and buttons:

 

 

The boards are 80*50 mm and 105*20 mm.

They are connected by 5 cables, and they have the following marks:
KT-223-MAIN for the main board,
and
KT-223-KR or KT-223-KL for the button boards (right & left).

The main board has two additional connector sockets: one with two pins, which is for the relay activating the heating AC side, one with three pins, which is the DC power supply for the board.


2. ICs for Toasters
The IC at the core of this board is labelled as:
A0201D
TN1430G3C+

I have not managed to get the datasheet of the IC A0201D - this is probably related to an intelectual property issue, at least this is what I asume.

This youtube upload is titled A0201D, and clearly talks about a toaster (model Aurora AU 153). It also mentions IC PT8A2511. Unfortunately it's ... in Russian!

This other webpage has the European certificates and tests on a toaster. The certificate mentions two suppliers for the control board, and the use of A0201D for certain models from one manufacturer, and PT8A2511 for the same models made by the other manufacturer.

Here, somebody asks for the equivalent subtitute of the A021D IC on a Kenwood TTP112 toaster (no reply was provided). Here some German guys were fighting with another toaster using this same IC (in German!). And there are also some Hungarians having fun/troubles with the toaster and the IC, and quoting pages in Chinese!

(In this Babel Tower I'm only missing the Finns!)

The A0201D chip is not unheard of: it is possible to find it on sales pages (f.eg: here or here), but no way to find the datasheet...

At least, for what seems to be an alternative IC, the PT8A2511, a datasheet is readily available (see here). As per the Hungarian blog mentioned above: "The Russians dare to believe and 99.99% certainty that the IC is the same as the PT8A2511".

In this page, which may be a/the manufacturer of the A0201D, the supply voltage is mentioned to be 3.5-5.5 V (other sources mention 12 V for the control board of toasters).

So, all in all, I have managed to collect the following:

- The "EMC Emission Test Report" for an electric toaster in whose control board, for some models, is installed the A0201D IC, as well as the PT8A2511. (The document is skimmed of what is no relevant here). The following scheme is of special interest:

- The PT8A2511 IC datasheet. This is a "CMOS LSI chip designed for toaster", presented in DIP8 package and working at 3.5-4.5 V. It includes few more information besides this scheme:

- The GA5210PH IC datasheet. This is also a DIP8 IC for toasters. The document is mostly in Chinese, mentions a standard range of 9-12 V, and includes the following scheme (among others):

Despite the apparent differences, all schematics share the pin utilization of the IC:
PIN 1 : DEFROST
PIN 2 : REHEAT
PIN 3 : RELAY / OUTPUT
PIN 4 : VCC
PIN 5 : RX
PIN 6 : OSC / RC
PIN 7 : CX
PIN 8 : GND

As per the PT8A2511 datasheet, the PIN operation is as follows:

3. Schematics

The circuit is modeled in QUCS, and can be found here.
A snapshot of the schematics:

Remarks:
1. The IC A0201D is not a sub-circuit, it's only a "box" without functionality. On this regard the schematics is "useless".
2. The lights at the button board are not LEDs (or at least their resistance is equal in both directions...)
3. The power supply (6 V) is just a figure: as mentioned above, I'm not sure of the required voltage.
4. The switches at the button board are actually of the push-button type (momentary, they remain open unless they are kept pushed).


4. Operation
The board is powered from connections S3_3 (VCC) and S3_1 (GND).
The coil is powered through S2_2, but only activated if the transistor T1 is closed, whose base is controlled by  PIN3.
Pushing puttons DR1 or DR2 closes the circuit through ground to PIN1 (a negative pulse). Similarly, pushing puttons RR1 or RR2 closes the ciruit through ground to PIN2. These negative pulses, according to the previous table, activates the DEFROST or REHEAT timing, resp. Once the function is activated, PIN3 activates the AC relay.
Once PIN1 or PIN2 are activated, they generate a positive voltage which keeps on the lights in the button board (DEF and REH).
If the main board is powered, the POW light is on through the direct VCC-GND circuit, regardless of the position of CR1/CR2.
If CR1 or CR2 are closed, in addition, a branch is closed through the base of the transistor Q1. Whether the voltage at the base is enough to overcome the transistor resistance will depend on specific values, but if it can, then it will also activate the coil which controls the heating of the slices.
VCC to PIN4 is constant.
The variable resistors VR1&2 control voltage at PIN6, and then the frequency of the oscillating system and the duration of the pulses at PIN2 and PIN3.
PIN5 and PIN7 are likely starters for the time counter controlled by the oscillator.