Pure Evoke 2S, Pure Evoke 1S, Avanti Flow, Evoke Flow radio problems

[rh100605]

I thought I would share my experience of repairing 5 of these radios
The Evoke 2s is mains driven as it is capable of 20watts of audio. It has the same radio board (Bachmann) as the Evoke 1S, Evoke Flow and Avanti Flow. Even the later model Tempus 1S has the same board . Each are populated differently depending on wifi/battery/audio amplifier being present or on another board.

All use the Austrian Micro systems AS3654 audio / power controller chip (https://media.digikey.com/pdf/Data%20Sheets/Austriamicrosystems%20PDFs/AS3654.pdf )
This 100 pin BGA takes 6 Vdc in via a switching regulator to produce 4.2V (lithium cell voltage). The 4.2Volt rail is used by 4/5 switching regulators to produce 9V (audio) 3.3v and 1.8V (logic) and 12volt (oled display). The circuit diagram in the application note is almost exactly that used by Pure only the Mosfet numbers vary.

A common source of failure in both Early Tempus 1s and Evoke 1S(square usb connector) is failure to power up due to the AS3654 failing to switch the primary regulator MOSFETs .
The Evoke 1s will normally function on battery and I have used a TP4056 5V 1A Mini/Micro USB 18650 Lithium Battery Charger Board Module and USB MCP73871 DC Solar Lithium Ion Polymer Charger 3.7/4.2V Battery Module from Ebay to power the radio and charge the battery simultaneously.

The OLED displays fail with time but are still available on Alibaba ( Jack Chan) and are relatively easy to replace (except for the Avanti flow which is mechanically difficult).
The Evoke 1s and 2s use 128 x 22 displays. The early ones ( square USB port) are an Osram Pictivia (OS128022PR24MY0C10) part number (You need to remove a screening can to replace this) and later a RIT display number (3003321501001) was used. Both use the SSD1305 controller but the Osram part has an early controller version that has a different starting offset when writing . So older radios will work with the later displays but 8 pixels are missing off the rhs of the display. Most 128 x32 24 pin OLED displays also work as RIT part replacements but obviously have smaller characters.

The Fdg313 (6 pin SC70)MOSFET with 100 microhenry choke producing the 12V OLED supply fails as does the pass mosfet (FDV 302) that controls the brightness. You will need to remove the screening can to get at these take care not to lever this off as this can damage several 0402 surface mount capacitors.

Other common faults in the Evoke 2s and Avanti flow are:-
There are Four 1000 mfd electrolytics inside the class D audio screening cans. They get hot and fail, which can cause the TI amplifier (TAS5706B) to pump and fail .
The sot 23-5 3v3 regulator supplying both analogue and digital 3v3 to the TI amplifier from the 4.2v suppled over the connecting flat cable, also fails. I replaced with MC5219. Watch out as drawing too much current on the 4.2v line damages the ferrite bead in the tuner can that feeds pin 7 on the flat cable. This leads to the radio powering up but the audio not coming on due the high resistance of the ferrite bead and replacing the audio can makes no difference......

The Avanti flow uses the same board/can with a further Class D chip (MP8042 from monolithic power systems) for the woofer. It too has 1000mfd smoothing capacitors that burst and fail, often after the Schottky clamp diodes( 30v 1amp) fail.  I bought on a replacement MP8042 on AliExpress, the circuit is almost the Monolithic Power example circuit  ( Evaluation board EV8042DF-00B from monolithic power) Removing this chip needs heat from the underside as well as top just like removing the TI TAS5706B use CHIP QUIK solder on the leads first to lower the melting point of the solder on the connection pads. Do not use force.

The bass/treble is handled by the TI PCM1870 chip(marked 1870) in Avanti flow and Evoke 2s.

The mains powered 20v / 6vpower supply is also in a can in both Avanti flow and Evoke 2s and has both 1000/680 10v and 1500 mfd 35V capacitors that fail. There is also a surge limiter and pcb fuse in the AC input that fail. I have seen the TIP 32C series transistor burn up twice. In the worst case the rectifier diodes fail causing the fuse to blow.

The Evoke 2s has a 6800 mfd 35v electrolytic on its own separate pcb which smooths the 20v audio supply. I have seen two go short.

Hope all this helps....

[bouncingboffin]

I've been fixing Pure Avanti Flow radios for some time, giving them away to friends and family. So far, so good.  I had one with a blown fuse and a dead rectifier diode and apart from that it was fine and I used that one for music on my indoor rower. I didn't change out the rubbish Chinese capacitors... The history of this one: it was used for a few months until a thunderstorm.... and then left in its box for a couple of years. It was like brand new, remote, bright screen etc

Today, oh dear, a weird smell, over and above sweat and grease. Then the music started getting garbled and it sounded like there was a rat chasing a canary inside, then silence apart from a pop-pop-pop from the speakers. The display went blank too. Opened it up and the PSU was too hot to touch, taking out the front panel and subwoofer, I could get at the three cans inside, also still hot to the touch. I ended up binning it and taking another working one in worse cosmetic condition.

I used to repair them, but they're practically worthless these days, eBay for pennies with the usual broken screen. The sound is good, but the power supply is overdriven and the OLED screen dies (I leave it off in the settings)  It takes me about two hours to replace the electrolytics in the amplifier and PSU I didn't bother and it bit me (eventually) As for Pure or as it was back then Imagination Technologies, I'd never buy one of their products after this product's bulls**t specification and lousy components.

A good writeup of the function of the various bits, I never saw the innards of the other Pure brand radios, so thanks for enlightening me 

[rh100605]

Hi,
The audio board that you sent a picture of is quite usual. Nearly burst 1000mfd capacitors and probably a schottky diode blown next to the woofer Driver ic. The problems are mostly heat, the cans are also heatsinks putting Electrolytics inside the can was foolish in both the audio amplifier and PSU.

I would be interested in the pcb you photographed as I have one where the TI chip has set fire to the fibreglass....do you still have it ?
Regards
Rob

[rh100605]

Hi,
Have you still got the board in the photo
Rob

[CJR]

Hi  I have just found your post and hope you might be able to help.  My Avanti flow screen was fading and then the unit just died - thought it was the display so got a new one from Jack Wan and fitted it. However it does not power up. Checked the power unit and seem to get 20v and 6v on some pins but nothing is working. Any advice for a newbie on where to start looking? 
Thanks Chris

[rh100605]

Chris,
I usually start by checking the power supply which has three connectors (Radio 6V =gnd, Ipod dock 6v+gnd  and Audio 19 to 20 v and ground) while connected to the radio. I normally replace the electrolytic capacitors in the PSU as a matter of course.

Then check voltages again at the front on the boards to check the connectors.

Next remove power to the audio can and power up the radio, the display should show "avanti flow" and then freeze. Remove and examine the flat cable between the two cans, it will go in back to front ( blue plastic to pins will not work) and is very easy to damage causing shorts/opens but is replaceable on Ebay.

Try powering up with flat cable between the cans removed making sure that the video (narrow cable) to the front panel has not been disturbed and is correctly inserted, The display should come alive and freeze. The reason this may work is that 4.2v and 3.3v to the audio can are carried on the short flat cable and if the audio can has a short it will stop everything.

If  the screen came alive and the flat cable is ok, next is opening the audio can which is tedious and has to be done with solder wick and gentle leverage as many components are very close and possibly replacing the TAS5706 chip..... Let me know how far you get, I am happy to give more advice

Happy debugging

[webkai]

A common source of failure in both Early Tempus 1s and Evoke 1S(square usb connector) is failure to power up due to the AS3654 failing to switch the primary regulator MOSFETs .

Hi,

I have two Tempus 1S's, both of which do nothing at all when powered up.

I have checked the power supply, it's fine, and 6V is getting as far as the main PCB. I've stripped them both down as far as possible, removing the can over the AS3654 and the other can next to it. I've had a good look with a magnifying glass, no sign of anything fried or burnt out.

I'm guessing it might be the problem Rob mentioned with the AS3654 and the MOSFETs. If that's the case, is there anything I can realistically do to fix them?

Thanks for any help (and thanks Rob for the original post!).
Kai.