I’m trying to repair an Orion HCCA 2100. Upon removing the clamp bars I found several blown NDP7060. Digi-key says that model is discontinued and they don’t have any replacement models that match the amp and voltage ratings of the NDP7020s (60V/75A). So I’m looking for a replacement rated for 60V or higher and 75A or higher.
FQP85N06 is 60V and 85A so I’m tempted to go that route. But are there any other specs (other than physical sizes) that I need to match up? Am I sacrificing in other areas by increasing the amperage capacity of the transistors or is this just a more robust model?
FQP85N06 is 60V and 85A so I’m tempted to go that route. But are there any other specs (other than physical sizes) that I need to match up? Am I sacrificing in other areas by increasing the amperage capacity of the transistors or is this just a more robust model?
Attachments
The 85N06 will likely be OK. The IRF3205 (with 47 ohm gate resistors) has been the go-to FET for many power supplies.
https://octopart.com/irf3205pbf-infineon-65873333?r=sp
https://octopart.com/irf3205pbf-infineon-65873333?r=sp
I swapped in 28 FQP85N06 and have replaced all the AlumE caps except for the tiny 35V 10uf ones (will do them soon). When resistance testing the new FQPs across the outer legs (with no power applied to the amp) I noticed that one group of 7 FQPs has to “charge” or ramp up to the value of 110ohms which is where the other 3 groups of 7 FQPs and the original NDPs measured at with no ramp up. Any idea what would cause this or where I should focus my efforts? I’ve been testing resistors but so far they have measured properly while on the board.
I plan to verify which leg is shared on the BCAE website (base?) and try to test the components on that segment but am hoping for a push in the right direction while I study!
I plan to verify which leg is shared on the BCAE website (base?) and try to test the components on that segment but am hoping for a push in the right direction while I study!
Last edited:
Check the PNP driver transistor and confirm that you read 10 ohms from the collector of the PNP driver transistor to ground.
I checked the MPSA05 closest to the FQPs and got 10ohms from collector to the ground terminal. Same with the driver for the B+ side. I did not get 10ohms for the drivers placed next to the for-mentioned ones.
I’m touching the one that tested as 10ohm collector to ground.
I’m touching the one that tested as 10ohm collector to ground.
Attachments
I’m having trouble determining which transistors on the board I should be checking. The traditional type resistors (color bands) all seem to match up (10, 100, 1k ohms). The 3-legged type (drivers) I’ve only found 2 that came in at 10ohm and they were on the power side (right side in this photo).
I see some 2N5639s on the audio/left side but they are N-channel switches which I’m guessing are not what I’m looking for.
I’ll review and try testing more shortly.
I see some 2N5639s on the audio/left side but they are N-channel switches which I’m guessing are not what I’m looking for.
I’ll review and try testing more shortly.
The 5639s are muting transistors.
The driver transistors for the power supply are an MPSA06 and an adjacent MPSA56 with their bases directly connected with their emitters directly connected and the collector of the MPSA56 connected to ground via a 10 ohm resistor.
They will have their emitters directly connected to the gate resistors for the PS FETs and will be located very near the 4 banks of PS FETs.
The driver transistors for the power supply are an MPSA06 and an adjacent MPSA56 with their bases directly connected with their emitters directly connected and the collector of the MPSA56 connected to ground via a 10 ohm resistor.
They will have their emitters directly connected to the gate resistors for the PS FETs and will be located very near the 4 banks of PS FETs.
Thanks Perry. I checked the 4 MPSA56 collectors on the power side of the board. Collector to grounding lug measures 10 ohms for all 4.