Balboa Mach 2 EL2000 board with no voltage past the heater relays

[MilkManPower]

EDIT: See second post for my current system and the board I replaced it with.

3 weeks ago my hot tub stopped heating. I opened it up and found the jumper wire between 2 relays on heater 1 disintegrated. I removed both heater 1 relays, the heater 2 relay, the jumper wire and replaced them. This worked and my hot tub ran for 3 weeks. Unfortunately, it's no longer heating again.

I removed the board and found no new damage. All 3 relays pass power properly after applying 9v battery voltage. I also verified and reflowed my solder joints on the relays. The hot tub display shows no errors and the heating light is on. However, 2 heater relays remain in the open position. The voltage stops at the relays. The heating element tests at 11 ohms. All fuses are okay. The temperature on the display is accurate. I can run the jets normally.

For whatever reason, the hot tub is not passing the trigger voltage to 2 of the relays coils. I'm stumped at this point.

It's worth mentioning that I previously saw both D3 and D7 were running hot and darkening the board. However, the relay swap above resolved my initial issue. After the new issue, I replaced both diodes at D3 and D7, but it made no difference.

[MilkManPower]

I've been trying to find a compatible replacement board or even an entire spa pack. I would appreciate any suggestions. So far this is the only one I can find that also specifically mentions the Bullfrog brand. My top control panel is a Bullfrog branded panel. https://www.hottuboutpost.com/el2000-mach-2-1-circuit-board-59003-mach-2/?srsltid=AfmBOoq9eSbMsgatUUhllpL4eHF4WtzLLgeUJ4xtjCmmYzcyOij6USu8

I tried to find an even newer spa pack + control board but I can't really find confident statements of compatibility.

EDIT: For any future viewers, the replacement board above "EL2000 Mach 2.1 Circuit Board 59003 MACH 2" worked perfectly for my Bullfrog tub model listed below. Once it arrived, I confirmed all wires and jumpers matched the diagram on my existing metal spa pack panel. The only changes I made were to move the red wire that goes from W15 to J97 to instead be W15 to J98 and I matched my existing dip switch configuration. (You need to flip the A12 dipswitch to the on position for the first start up and then flip it back off (at any time) to reset and save the dipswitch memory) The sticker next to the chip on my new board is EL2000R1C    3A19. The main sticker says both 59003 and "BOARD BALBOA EL2000 MACH2".

My system below:

Tub Model: Bullfrog Model 552
System Part Number: 52847-04  (Located on metal box)
System Model Number: BF01  (Located on metal box)
Sticker on heater relays: Bulfrg BF01 Mach 2 EL200    53618
Circuit board stamp bottom right: EL2000 Mach 2 P/N 21862 REV B
Sticker on circuit board: BF01R1A 20041206
Heater element sticker: HT 5.5KW 240V 15" 825 M7 EL's    58105

The first picture is from before I initially replaced the relays.

[CanadianSpaTech]

@Spa Board Doctor

[Spa Board Doctor]

These boards have proprietary software which makes them difficult to replace with anything other than original however the board can likely be repaired.  I'm not questioning your repairs here but I'm curious about the voltage values of the diodes you replaced at D3 and D7?  If there are no error codes then the only thing I can think is that the relays are not receiving the correct coil voltage.  Unfortunately, the new relays don't have exposed coil pins like the old ones or you could measure the coil voltage from the front of the board.  I'd start with tracing down the coil circuit for the high limit (left and upper relay) as they are both turned on by the same circuit.  If the temp sensors are both good these two relays should turn on right after boot i.e. there should be 15VDC across their coils.

Addendum:  I've heard it mentioned that the internet says to use a 9V battery to test these relays.  I can't say that it doesn't work however I don't think it's the best idea because you have a 50% chance of applying power in the opposite polarity than the circuit is designed to work with.  Some of the components can probably take this mis application of voltage, but I wouldn't do it to my own board.

[MilkManPower]

On 11/18/2024 at 7:41 PM, Spa Board Doctor said:

These boards have proprietary software which makes them difficult to replace with anything other than original however the board can likely be repaired.  I'm not questioning your repairs here but I'm curious about the voltage values of the diodes you replaced at D3 and D7?  If there are no error codes then the only thing I can think is that the relays are not receiving the correct coil voltage.  Unfortunately, the new relays don't have exposed coil pins like the old ones or you could measure the coil voltage from the front of the board.  I'd start with tracing down the coil circuit for the high limit (left and upper relay) as they are both turned on by the same circuit.  If the temp sensors are both good these two relays should turn on right after boot i.e. there should be 15VDC across their coils.

Addendum:  I've heard it mentioned that the internet says to use a 9V battery to test these relays.  I can't say that it doesn't work however I don't think it's the best idea because you have a 50% chance of applying power in the opposite polarity than the circuit is designed to work with.  Most of the components can probably take this mis application of voltage, but I wouldn't do it to my own board.

Thank you for the ideas.

I was confident I had the polarity correct... and then I burned out chip SN75468 at U1 and maybe more that I can't see. The ground from both relays goes to this chip. The positive goes through I believe a few capacitors and on to voltage regulator LM7508C. I read the coil voltages and I believe it was 7v which is low but that was also after burning the chip. I didn't take measurements of the voltage regulator before pulling the board again. After burning the chip, the pump only runs when it thinks its heating. I can't turn on either jet manually. Still no errors on the display though.

It's tempting to start replacing parts. I could replace the chip with a cheap generic available online. I could start testing capacitors and the voltage regulator. I could swap the rest of the relays out. It's become an educational project at this point. Though I would have to finally buy a heat gun for the chip. It's a real debate if it's worth continuing or just replace the board/spa pack.