D-D conv coil???  panasonic RQ-NX60V - Page 1
Forum section: electronics / repair

author: GreyPatch
author_rank: Contributor
timestamp: October 14, 2022, 05:16:49 pm
content: Hi alli need helpi have a panasonic RQ-NX60V from 1995. i need help identifying a part in order to replace it. Panasonic says its a D-D conv coil. Part number rlo9u034t-t made by tamaco. problem im running into is that the web has nothing on this. the part has no identifiable markings and the schematics are all Greek to me. i will attach pictures but seriously if anyone can help me id love to get this guy up and running again.thanksGreyPatchps help me eevblog, you're my only hope

author: fzabkar
author_rank: Super Contributor
timestamp: October 14, 2022, 11:59:01 pm
content: I think TAMACO is a supplier, not a manufacturer. For example, if you examine the parts list, TA2111FN is a Toshiba device, and LC72345 is a Sanyo device.Does the service manual provide any more info on this company?

author: GreyPatch
author_rank: Contributor
timestamp: October 15, 2022, 12:02:58 am
content: Yeah it's pretty empty. On the wire diagram, the is a 1.44 on one of the output lines. Do you think the voltage or wattage? Am trying to understand what this thing even did in the circuit

author: fzabkar
author_rank: Super Contributor
timestamp: October 15, 2022, 12:32:38 am
content: Those "R" part numbers appear to be specially coded.For example, RVTDC144TUX appears to be a Toshiba digital transistor, TDTC144E. It would appear that "R" denotes some special category, while "V" denotes a transistor.https://toshiba.semicon-storage.com/info/TDTC144E_datasheet_en_20201113.pdf?did=36376&prodName=TDTC144EIn the case of your coil, the "L" seems to be associated with inductors and filters. This would suggest that the base part number is O9U034T-T, but that still doesn't get us anywhere.As for its function, the coil appears to be part of a DC-DC boost converter. Q24, Q25 and Q26 constitute an oscillator. The boosted output voltage appears at the junction of C112 and D10.I can't see enough of the circuit to be certain, but it appears that D8 provides the supply voltage for the linear regulator at IC 5 (S81221SGQUT1). That's a Seiko-Epson 2.1V LDO regulator.https://datasheet.datasheetarchive.com/originals/distributors/Datasheets-30/DSA-595487.pdfIn short, it appears that the 3 transistors constitute a dual switchmode supply. If so, then it should be possible to replace that section with a modern supply module, or two.

author: GreyPatch
author_rank: Contributor
timestamp: October 15, 2022, 01:00:26 am
content: When I get home. I'll upload the complete manual. It's something like 20 pages. I'll try to ensure the the images are good 👍

author: fzabkar
author_rank: Super Contributor
timestamp: October 15, 2022, 01:11:16 am
content: Quote from: GreyPatch on October 15, 2022, 12:02:58 amThat's the average DC voltage (1.44V) that your multimeter would sense at that point. The actual voltage would be a sinusoid, I would think.There would be 2.6VDC on D8. That's one of the output voltages. I expect there would be a much higher DC voltage on D10. That's the other output voltage.

author: GreyPatch
author_rank: Contributor
timestamp: October 15, 2022, 01:26:12 am
content: Interesting

author: fzabkar
author_rank: Super Contributor
timestamp: October 15, 2022, 03:17:40 am
content: I found a similar DC-DC converter circuit in this manual:https://diagramas.diagramasde.com/audio/PANASONIC%20RQ-E30V%20EG.pdfThe outputs are 2.7VDC (at D6) and 12.6VDC peak (at D4). The 12V output doesn't have an electrolytic filter capacitor, so I'm not sure whether the voltage should be flat DC at this point (probably not).

author: fzabkar
author_rank: Super Contributor
timestamp: October 15, 2022, 03:40:27 am
content: https://news.panasonic.com/global/topics/4605Quotehttps://sg.linkedin.com/in/ngee-lin-lee-193356159Quote

author: wasedadoc
author_rank: Super Contributor
timestamp: October 15, 2022, 07:51:19 am
content: C104 at the bottom of the schematic snippet is the smoothing electrolytic for D8.

author: GreyPatch
author_rank: Contributor
timestamp: October 15, 2022, 03:57:02 pm
content: so i cannot upload enough attachments for the service manual, so ill post the linkhttps://servlib.com/panasonic/audio/rq-nx60v.html

author: fzabkar
author_rank: Super Contributor
timestamp: October 15, 2022, 04:55:54 pm
content: https://servlib.com/panasonic/audio/rq-nx60v.html?start=10There is a 13.6V supply at the bottom left of page 11. It is down-regulated to 12VDC by zener D11, C111 and R92.As I see it, the function of the DC-DC converter is to produce 2.6VDC and 13.6VDC supplies from a 1.5V battery. If a replacement coil cannot be found, then I would think that one could tap into the cathodes of D8 and D10 with two separate boost converter modules. I would imagine that a cheap LED flashlight powered by a 1.5V battery would have one such circuit.

author: wasedadoc
author_rank: Super Contributor
timestamp: October 15, 2022, 04:57:13 pm
content: Why do you want to replace that transformer? Have you concluded it is faulty and if yes, how have you reached that conclusion??

author: GreyPatch
author_rank: Contributor
timestamp: October 15, 2022, 07:12:34 pm
content: It was detached when I recieved the player

author: GreyPatch
author_rank: Contributor
timestamp: October 15, 2022, 08:35:54 pm
content: Well that should be easy.

author: GreyPatch
author_rank: Contributor
timestamp: March 28, 2023, 04:09:56 pm
content: Hi everyone, and thank you for the help along the way, so ive spent enough time looking for this part that i finally just bought a parts unit. once i confirm its operational and working correctly i will do some testing and identify what values the coil produces (and update with that info.again thank you everyone for the help

author: mouseman.net
author_rank: Newbie
timestamp: February 11, 2024, 12:05:53 am
content: Hi, I have the same problem, where did you buy this part and what are its values? Thank you.

author: wasedadoc
author_rank: Super Contributor
timestamp: February 11, 2024, 06:14:49 pm
content: Quote from: mouseman.net on February 11, 2024, 12:05:53 amA "parts unit" means another same or sufficiently similar equipment which the buyer cannibalises for spare parts.

author: GreyPatch
author_rank: Contributor
timestamp: February 11, 2024, 06:18:43 pm
content: Yes