FY 1005S Signal Generator Problem

[bluestrat53]

My FY1005S signal generator recently went out due to a faulty buck converter. It looks like the U2 IC (SMD) burned out next to the 5V input. The markings on it are SL6SD. I would like to repair the device but I cannot find a reference or cross reference to it anywhere. Any help would be greatly appreciated. Thanks in advance.

 

[Delta Prime]

It looks like the U2 IC (SMD) burned out next to the 5V input. The markings on it are SL6SD.

Can you take a photo please? I can’t see anything….
I think it is a Schottky Barrier Rectifier
Have you tried googling
“SL6SD datasheet”
Or

SL6SD Datasheet, PDF

SL6SD Datasheet. Part #: SL60. Datasheet: 278Kb/6P. Manufacturer: Rectron Semiconductor. Description: SURFACE MOUNT SCHOTTKY BARRIER RECTIFIER. 97 Results. Part #: SL600PS12-C. Datasheet: 166Kb/2P. Manufacturer: XP Power Limited.

www.alldatasheet.com

 

[bluestrat53]

I tried the dat sheet but wasn't able to determine what it is. The dimensions are .1 x.06 in. 6 Pin I believe a 1206 SOT? Here are some pics. Thanks, Mark

 

[Delta Prime]

Shoot.. I can’t see any markings on it, but I believe you and it’s located right underneath your display.
I can only suggest that it may be a common problem but even then you could not purchase that opponent because it is proprietary,specially made,they do that so you have to buy a new unit. Sorry, kiddo…
I would research it on the Internet, make & model perhaps someone reverse engineered it.

 

[bluestrat53]

Thanks Delta Prime for the info. I had already ordered another one but hoped to be able to get the original one working. I have tried contacting the manufacturer in China for any info but I won't hold my breath on any help from them. Who knows.

 

[Delta Prime]

no, do not hold your breath. with that said if you have a multimeter, you can take some voltage measurements on the exact same component, then we can together reverse engineer your defective unit there’s a high probability of success in replacing that component. then you would have the ability to send back the new unit within the given return policy if you’d like.

 

[bluestrat53]

Thanks for the advice and assistance. It will be a while before I receive the new one and I will see what I can find out until then.

 

[bluestrat53]

no, do not hold your breath. with that said if you have a multimeter, you can take some voltage measurements on the exact same component, then we can together reverse engineer your defective unit there’s a high probability of success in replacing that component. then you would have the ability to send back the new unit within the given return policy if you’d like.

Thanks for the assistance and advice. It will be a while until I receive the new one and I will see what I find out until then.

 

[bluestrat53]

Thanks for the assistance and advice. It will be a while until I receive the new one and I will see what I find out until then.

Delta Prime. I asked the question to an AI generator on electrodata.com and found what I was looking for. Very impressive.

​

User question​

What is the integrated circuit U2 with markings SL6SD in the signal generator model FY1005S ?

Artificial Intelligence Response​

Direct answer to the question​

• U2 with top‑mark “SL6SD” on the FY1005S is the SGMICRO SGM3204 (full P/N: SGM3204YN6G/TR), a 200 mA inverting charge‑pump DC/DC converter used to generate a negative supply rail (≈ −5 V) from the +5 V input. The SGM3204 SOT‑23‑6 package marking is “SL6XX”; your “SL6SD” corresponds to “SL6” plus a two‑character date/lot code. (sg-micro.com)
• The FY1005S module is powered from 5 V; U2 creates the small negative rail needed by the output/analog stages. (sainsmart.com)

Detailed problem analysis​

• Role in the FY1005S power tree:
  • External supply: +5 V (wall adapter shipped with some FY1005S/UDB1005S kits). (sainsmart.com)
  • Digital rail(s): +3.3 V (from a separate regulator, typically an LDO/buck not related to U2).
  • Analog rail(s): U2 (SGM3204) inverts +5 V to approximately −5 V (under load the magnitude is slightly less), supplying the output amplifier and any analog front‑end that benefits from headroom below ground.
• How we know “SL6SD” = SGM3204:
  • The SGM3204 datasheet explicitly states the SOT‑23‑6 top‑mark is “SL6XX” (XX = date code). Your device’s “SL6SD” matches this scheme. (sg-micro.com)
  • Third‑party component listings show SGM3204YN6G/TR in SOT‑23‑6 with silk/mark “SL6SD,” aligning with the datasheet’s “SL6 + date code” convention. (tao.hooos.com)
• Device characteristics relevant to the FY1005S:
  • Input 1.4–5.5 V, inverts to −VIN (unregulated), up to 200 mA, ~950 kHz switching. Package SOT‑23‑6. Pinout: 1‑OUT, 2‑IN, 3‑CFLY−, 4‑GND, 5‑EN, 6‑CFLY+. (sg-micro.com)
• Why an inverting charge pump (not a buck/LDO/logic gate)?
  • The FY1005S runs from +5 V; it still needs a small negative rail to let the output driver swing cleanly around 0 V and handle DC offset range without clipping. A compact, low‑cost charge pump (no inductor) is the canonical solution for −5 V at tens to low‑hundreds of mA. The SGM3204 matches the packaging, marking, and function. (sg-micro.com)

Current information and trends​

• Modern DDS/function‑generator modules commonly derive a negative analog rail from a +5 V source using inverting charge‑pump ICs (e.g., SGM3204, MAX660/ICL7660 families) to avoid inductors and save space/cost; higher‑frequency devices (≈1 MHz like SGM3204) help push switching noise out of the audio band. (sg-micro.com)

Supporting explanations and details​

• Quick functional checks on the board (with +5 V applied):
  • U2 pin 2 (IN) ≈ +5 V; pin 4 (GND) = 0 V; pin 1 (OUT) ≈ −4.4…−5.0 V no‑load; pin 5 (EN) high (>1.5 V) to enable; pins 3/6 connect to the flying capacitor. If OUT is near 0 V or positive, the IC is disabled, damaged, or output is shorted. (sg-micro.com)
• Typical external parts around U2:
  • Three ceramics (often 3.3–10 µF): CIN from IN‑to‑GND, CFLY between CFLY+ and CFLY−, COUT from OUT‑to‑GND. Layout should keep these loop areas tight to minimize ripple/noise. (sg-micro.com)

Ethical and legal aspects​

• Use genuine parts conforming to RoHS/HSF and observe ESD/handling precautions per the manufacturer documentation to avoid latent damage and ensure safety. (sg-micro.com)

Practical guidelines​

• Confirm identification:
  • Visually verify SOT‑23‑6 and “SL6xx” mark, then measure the −V rail at U2 pin 1.
• Replacement/repair:
  • Direct replacement: SGM3204YN6G/TR, match SOT‑23‑6 footprint.
  • Check/replace the three capacitors (CIN, CFLY, COUT); damaged or low‑ESR mismatch can cause excessive ripple or stress the IC.
  • Verify EN (pin 5) is driven high; if EN is low, OUT will be 0 V. (sg-micro.com)
• Noise considerations:
  • Although the SGM3204’s ~950 kHz operation is well above the audio band, poor grounding/layout can couple switching ripple into the output. Keep loop areas small and provide solid analog ground returns. (sg-micro.com)

Possible disclaimers or additional notes​

• Some FY1005S variants may use functionally similar inverters from other vendors, but the “SL6XX” top‑mark uniquely matches SGM3204’s official marking. If your board’s behavior differs (e.g., VIN ≠ 5 V, or U2 pinout not as above), supply a macro photo and measurements to confirm. (sg-micro.com)

Suggestions for further research​

• If you intend to improve PSU performance or reduce ripple, compare SGM3204 with alternatives (e.g., higher‑current charge pumps or inductive inverters) and evaluate output noise on the analog path.
• Review the SGM3204 layout guidance in the datasheet and audit the FY1005S board for best practices. (sg-micro.com)

Brief summary​

• U2 “SL6SD” on the FY1005S is SGMICRO’s SGM3204 inverting charge‑pump converter. It generates the −5 V rail from the +5 V supply used by the module. The “SL6SD” string is the official “SL6” device code plus a date/lot code, which the SGM3204 datasheet confirms. Replace with SGM3204YN6G/TR and verify the three capacitors and EN pin if you are repairing the unit. (sg-micro.com)

 

[Delta Prime]

Delta Prime. I asked the question to an AI generator on electrodata.com and found what I was looking for. Very impressive.

Quite frankly, it’s very impressive, but your initial question was wrong

My FY1005S signal generator recently went out due to a faulty buck converter.

AI went with that question. your problem has nothing to do with a buck converter. I was trying to be nice. You are wrong make assumptions. We are what you call experts. I’m not trying to beat you up. I’m trying to help you. Wait until your new unit arrives.
Or ask AI how to help you solder & desolder electronic components we’re here to help you not criticize you like I have just done & I feel horrible doing that. I will step you through the process once you get your new unit believe me, it easy Peezy lemon squeezy.
& believe me China doesn’t care about intellectual property they just copy it. if you are in the United States, this is our time to stick it back to china.At the component level…

 

[bluestrat53]

I hear what you are saying and I know you are experts and I certainly am not but when I checked the output voltage of the buck converter after the SG failed, it was putting out 12 volts. I am pretty sure that would over load the 5 volt SG. Up til then it had been working great with the 5 volts supplied.

 

[Delta Prime]

I hear what you are saying and I know you are experts

I misspoke I meant to say everyone, but me is an expert.
I apologize for not being able to help you. i’m sure you’ll be OK.

 

[bluestrat53]

No need to apologize. I appreciate your offer of assistance and will more than likely need it when I try the repair. I was able to order the parts thru Aliexpress dirt cheap and I need another SG anyway so I figure I was lucky to find the info on the internet with AI. Thanks again.

 

[Delta Prime]

so I figure I was lucky to find the info on the internet with AI.

@bluestrat53 I’m confident we will meet again…